SEISMIC DESIGN REFERENCE DOCUMENTS

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SEISMIC DESIGN REFERENCE DOCUMENTS

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233
Chapter 23
SEISMIC DESIGN REFERENCE DOCUMENTS
ACI 530
Sections 14.4.1, 14.4.2, 14.4.3, 14.4.3.1, 14.4.4,
14.4.4.1, 14.4.4.2.2, 14.4.5, 14.4.5.1, 14.4.5.2,
14.4.5.3, 14.4.5.4, 14.4.5.5, 14.4.5.6, 14.4.6,
14.4.6.1, 15.4.9.2
Building Code Requirements for Masonry Structures,
2008
ACI 530.1
Sections 14.4.1, 14.4.2, 14.4.7, 14.4.7.1
Specifi cation for Masonry Structures, 2008
ACI 313
Sections 15.7.9.3.3, 15.7.9.6, 15.7.9.7
Standard Practice for the Design and Construction of
Concrete Silos and Stacking Tubes for Storing
Granular Materials, 1997
*ACI 371R
Section 15.7.10.7
Guide to the Analysis, Design, and Construction of
Concrete-Pedestal Water Towers, 1998
ACI 350.3
Sections 15.7.6.1.1, 15.7.7.3
Standard Practice for the Seismic Design of
Liquid-Containing Concrete Structures, 2006
AF&PA
American Forest and Paper Association
1111 19th Street NW
Suite 800
Washington, DC 20036
AF&PA NDS
Sections 12.4.3.3, 12.14.2.2.2.3, 14.5.1
National Design Specifi cation for Wood
Construction, Including Supplements, AF&PA
NDS-05, 2005
AF&PA SDPWS
Sections 12.14.6.2, 14.5.1, 14.5.3, 14.5.3.1
AF&PA Special Design Provisions for Wind and
Seismic, 2008
AISC
American Institute of Steel Construction
One East Wacker Drive
Suite 700
Chicago, IL 60601-2001
23.1 CONSENSUS STANDARDS AND OTHER
REFERENCE DOCUMENTS
This section lists the reference documents that are
referenced in Chapters 11 through 22. The reference
documents are listed herein by the promulgating
agency of the reference document, the reference
document identifi cation, the section(s), and tables of
ASCE 7 that cite the reference document, the title,
and effective date. Unless identifi ed by an asterisk,
the following reference documents are consensus
standards and are to be considered part of this
standard to the extent referenced in the specifi ed
section. Those reference documents identifi ed by
an asterisk (*) are documents developed within the
industry and represent acceptable procedures for
design and construction to the extent referred to in
the specifi ed section.
AAMA
American Architectural Manufacturers
Association
1827 Waldon Offi ce Square
Suite 104
Schaumburg, IL 60173
*AAMA 501.6
Section 13.5.9.2
Recommended Dynamic Test Method for Determining
the Seismic Drift Causing Glass Fallout from a Wall
System, 2001
ACI
American Concrete Institute
P.O. Box 9094
Farmington Hills, MI 48333-9094
ACI 318
Sections 14.2.2, 14.2.2.1, 14.2.2.2, 14.2.2.3, 14.2.2.4,
14.2.2.5, 14.2.2.6, 14.2.2.7, 14.2.2.8, 14.2.2.9, 14.2.3,
14.2.3.1.1, 14.2.3.2.1, 14.2.3.2.2, 14.2.3.2.3,
14.2.3.2.5, 14.2.3.2.6, 14.3.1, 14.4.4.2.2, 14.4.5.2
Building Code Requirements for Structural Concrete
and Commentary, 2008
ACI 355.2
Section 13.4.2
Qualifi cation of Post-Installed Mechanical Anchors in
Concrete and Commentary, 2007
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CHAPTER 23 SEISMIC DESIGN REFERENCE DOCUMENTS
234
ANSI/AISC 360
Sections 14.1.1, 14.1.2.1, 14.1.2.2, 14.3.1, 14.3.2,
11A.1.3.6.2
Specifi cation for Structural Steel Buildings, 2010
ANSI/AISC 341
Sections 14.1.1, 14.1.2.2, 14.3.1, 14.3.3, 11A1.3.6,
11A.2.4
Seismic Provisions for Structural Steel Buildings,
2010
AISI
American Iron and Steel Institute
1140 Connecticut Avenue
Suite 705
Washington, DC 20036
ANSI/AISI S100
Sections 14.1.1, 14.1.31, 14.1.3.2, 14.1.4.1, 14.1.5
North American Specifi cation for the Design of
Cold-Formed Steel Structural Members, 2007
ANSI/AISI S110
Sections 14.1.1, 14.1.3.2, 14.1.3.3, Table 12.2-1
Standard for Seismic Design of Cold-Formed Steel
Structural Systems—Special Bolted Moment Frames,
2007
ANSI/AISI S230 with S2-08
Sections 14.1.1, 14.1.4.3
Standard for Cold-Formed Steel Framing—
Prescriptive Method for One- and Two-Family
Dwellings, 2007, with Supplement 2, 2008
ANSI/AISI S213 with S1-09
Sections 12.14.7.2, 14.1.1, 14.1.2, 14.1.4.2
North American Standard for Cold-Formed Steel
Framing—Lateral Design, 2007, with Supplement 1,
2009
API
American Petroleum Institute
1220 L Street
Washington, DC 20005-4070
API 12B
Section 15.7.8.2
Bolted Tanks for Storage of Production Liquids,
Specifi cation 12B, 14th edition, 1995
API 620
Sections 15.4.1, 15.7.8.1, 15.7.13.1
Design and Construction of Large, Welded, Low
Pressure Storage Tanks, 11th edition, Addendum 1,
2009
API 650
Sections 15.4.1, 15.7.8.1, 15.7.9.4
Welded Steel Tanks for Oil Storage, 11th Edition,
Addendum 1, 2008
API 653
Section 15.7.6.1.9
Tank Inspection, Repair, Alteration, and
Reconstruction, 3rd edition, 2001
ASCE/SEI
American Society of Civil Engineers
Structural Engineering Institute
1801 Alexander Bell Drive
Reston, VA 20191-4400
ASCE 4
Section 12.9.3
Seismic Analysis of Safety-Related Nuclear Structures,
1986
ASCE 5
Sections 14.4.1, 14.4.2, 14.4.3, 14.4.3.1, 14.4.4,
14.4.4.1, 14.4.4.2.2, 14.4.5, 14.4.5.1, 14.4.5.2,
14.4.5.3, 14.4.5.4, 14.4.5.5, 14.4.5.6, 14.4.6, 14.4.6.1,
15.4.9.2
Building Code Requirements for Masonry Structures,
2008
ASCE 6
Sections 14.4.1, 14.4.2, 14.4.7, 14.4.7.1
Specifi cation for Masonry Structures, 2008
ASCE 8
Sections 14.1.1, 14.1.3.1, 14.13.2, 14.1.5
Specifi cation for the Design of Cold-Formed Stainless
Steel Structural Members, 2002
ASCE 19
Sections 14.1.1, 14.1.6
Structural Applications for Steel Cables for Buildings,
1996
ASME
American Society of Mechanical Engineers
Three Park Avenue
New York, NY 10016-5900
ASME A17.1
Sections 13.6.10, 13.6.10.3
Safety Code for Elevators and Escalators, 2004
ASME B31 (consists of the following listed standards)
Sections 13.6.5.1, 13.6.8.1, 13.6.8.4
Table 13.6-1
Power Piping, ASME B31.1, 2001
Process Piping, ASME B31.3, 2002
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MINIMUM DESIGN LOADS
235
Liquid Transportation Systems for Hydrocarbons,
Liquid Petroleum Gas, Anhydrous Ammonia, and
Alcohols, ASME B31.4, 2002
Refrigeration Piping, ASME B31.5, 2001
Building Services Piping, ASME B31.9, 1996
Slurry Transportation Piping Systems, ASME B31.11,
2002
Gas Transmission and Distribution Piping Systems,
ASME B31.8, 1999
ASME BPVC-01
Sections 13.6.9, 13.6.11, 15.7.11.2, 15.7.11.6,
15.7.12.2
Boiler and Pressure Vessel Code, 2004 excluding
Section III, Nuclear Components, and Section XI,
In-Service Inspection of Nuclear Components
ASTM
ASTM International
100 Barr Harbor Drive
West Conshohocken, PA 19428-2959
ASTM A421/A421M
Section 14.2.2.4
Standard Specifi cation for Uncoated Stress-Relieved
Steel Wire for Prestressed Concrete, 2002
ASTM A435
Section 11A.2.5
Specifi cation for Straight Beam Ultrasound Examination
of Steel Plates, 2001
ASTM A615/A615M
Section 14.2.2.4
Standard Specifi cation for Deformed and Plain
Billet-Steel Bars for Concrete Reinforcement, 2004b
ASTM A706/A706M
Sections 14.2.2.4, 14.4.9
Standard Specifi cation for Low-Alloy Steel Deformed
and Plain Bars for Concrete Reinforcement, 2004b
ASTM A722 /A722M
Section 14.2.2.4
Standard Specifi cation for Uncoated High-Strength
Steel Bars for Prestressing Concrete, 2003
ASTM A898/A898M
Section 11A.2.5
Specifi cation for Straight Beam Ultrasound Examination
of Rolled Steel Structural Shapes, 2001
ASTM C635
Section 13.5.6.2.2
Standard Specifi cation for the Manufacture, Performance,
and Testing of Metal Suspension Systems for
Acoustical Tile and Lay-in Panel Ceilings, 2004
ASTM C636
Section 13.5.6.2.2
Standard Practice for Installation of Metal Ceiling
Suspension Systems for Acoustical Tile and Lay-in
Panels, 2004
ASTM D1586
Sections 11.3, 20.4.2
Standard Test Method for Penetration Test and
Split-Barrel Sampling of Soils, 2004
ASTM D2166
Sections 11.3, 20.4.3
Standard Test Method for Unconfi ned Compressive
Strength of Cohesive Soil, 2000
ASTM D2216
Sections 11.3, 20.4.3
Standard Test Method for Laboratory Determination
of Water (Moisture) Content of Soil and Rock by
Mass, 1998
ASTM D2850
Sections 11.3, 20.4.3
Standard Test Method for Unconsolidated-Undrained
Triaxial Compression Test on Cohesive Soils,
2003a
ASTM D4318
Sections 11.3, 20.4.3
Method for Liquid Limit, Plastic Limit, and Plasticity
Index of Soils, 2000
AWWA
American Water Works Association
6666 West Quincy Avenue
Denver, CO 80235
AWWA D100
Sections 15.4.1, 15.7.7.1, 15.7.9.4, 15.7.10.6,
15.7.10.6.2
Welded Steel Tanks for Water Storage, 2006
AWWA D103
Sections 15.4.1, 15.7.7.2, 15.7.9.5
Factory-Coated Bolted Steel Tanks for Water Storage,
1997
AWWA D110
Section 15.7.7.3
Wire- and Strand-Wound Circular Prestressed
Concrete Water Tanks, 2004
AWWA D115
Section 15.7.7.3
Tendon-Prestressed Concrete Water Tanks, 2006
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CHAPTER 23 SEISMIC DESIGN REFERENCE DOCUMENTS
236
ICC
International Code Council
5203 Leesburg Pike
Suite 600
Falls Church, VA 22041
* IRC
Section 11.1.2
2003 International Residential Code, 2003
ICC-ES
International Code Council Evaluation Service
5360 Workman Mill Road
Whittier, CA 90601
*ICC-ES AC 156-04 effective January 1, 2007
Section 13.2.5
Acceptance Criteria for Seismic Qualifi cation by
Shake-Table Testing of Nonstructural Components
and Systems, 2007
MSS
Manufacturers Standardization Society of the
Valve and Fitting Industry
127 Park Street NE
Vienna, VA 22180
*MSS SP-58
Section 13.6.5.1
Pipe Hangers and Supports—Materials, Design, and
Manufacture, 2002
NFPA
National Fire Protection Association
1 Batterymarch Park
Quincy, MA 02269-9101
NFPA 13
Sections 13.4.6, 13.6.5.1, 13.6.8, 13.6.8.2
Standard for the Installation of Sprinkler Systems,
2007
NFPA 59A
Section 15.4.8
Production, Storage, and Handling of Liquefi ed
Natural Gas (LNG), 2006
RMI
Rack Manufacturers Institute
8720 Red Oak Boulevard
Suite 201
Charlotte, NC 28217
ANSI/MH 16.1
Section 15.5.3
Specifi cation for the Design, Testing, and Utilization
of Industrial Steel Storage Racks, 2008
SJI
Steel Joist Institute
1173 B London Links Drive
Forest, VA 24551
ANSI/SJI-K-1.1
Section 14.1.1
Standard Specifi cations for Open Web Steel Joists,
K-Series, 2005
ANSI/SJI-LH/DLH-1.1
Section 14.1.1
Standard Specifi cations for Longspan Steel Joists,
LH-Series and Deep Longspan Steel Joists,
DLH-Series, 2005
ANSI/SJI-JG-1.1
Section 14.1.1
Standard Specifi cations for Joist Girders, 2005
ANSI/SJI-CJ-1.0
Section 14.1.1
Standard Specifi cations for Composite Steel Joists,
2006
TMS
The Masonry Society
3970 Broadway
Unit 201-D
Boulder, CO 80304-1135
TMS 402
Sections 14.4.1, 14.4.2, 14.4.3, 14.4.3.1, 14.4.4,
14.4.4.1, 14.4.4.2.2, 14.4.5, 14.4.5.1, 14.4.5.2,
14.4.5.3, 14.4.5.4, 14.4.5.5, 14.4.5.6, 14.4.6,
14.4.6.1, 15.4.9.2
Building Code Requirements for Masonry Structures,
2008
TMS 602
Sections 14.4.1, 14.4.2, 14.4.7, 14.4.7.1
Specifi cation for Masonry Structures, 2008
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237
Chapter 24
This chapter intentionally left blank.
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239
Chapter 25
This chapter intentionally left blank.
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241
Chapter 26
WIND LOADS: GENERAL REQUIREMENTS
26.2 DEFINITIONS
The following defi nitions apply to the provisions of
Chapters 26 through 31:
APPROVED: Acceptable to the authority having
jurisdiction.
BASIC WIND SPEED, V: Three-second gust
speed at 33 ft (10 m) above the ground in Exposure C
(see Section 26.7.3) as determined in accordance with
Section 26.5.1.
BUILDING, ENCLOSED: A building that does
not comply with the requirements for open or partially
enclosed buildings.
BUILDING ENVELOPE: Cladding, roofi ng,
exterior walls, glazing, door assemblies, window
assemblies, skylight assemblies, and other components
enclosing the building.
BUILDING AND OTHER STRUCTURE,
FLEXIBLE: Slender buildings and other structures
that have a fundamental natural frequency less than
1 Hz.
BUILDING, LOW-RISE: Enclosed or partially
enclosed buildings that comply with the following
conditions:
1. Mean roof height h less than or equal to 60 ft
(18 m).
2. Mean roof height h does not exceed least horizontal
dimension.
BUILDING, OPEN: A building having each
wall at least 80 percent open. This condition is
expressed for each wall by the equation Ao ≥ 0.8 Ag
where
Ao = total area of openings in a wall that receives
positive external pressure, in ft2
(m2
)
Ag = the gross area of that wall in which Ao is
identifi ed, in ft2
(m2
)
BUILDING, PARTIALLY ENCLOSED: A
building that complies with both of the following
conditions:
1. The total area of openings in a wall that receives
positive external pressure exceeds the sum of the
areas of openings in the balance of the building
envelope (walls and roof) by more than 10 percent.
2. The total area of openings in a wall that receives
positive external pressure exceeds 4 ft2
(0.37 m2
)
26.1 PROCEDURES
26.1.1 Scope
Buildings and other structures, including the
Main Wind-Force Resisting System (MWFRS) and all
components and cladding (C&C) thereof, shall be
designed and constructed to resist the wind loads
determined in accordance with Chapters 26 through
31. The provisions of this chapter defi ne basic wind
parameters for use with other provisions contained in
this standard.
26.1.2 Permitted Procedures
The design wind loads for buildings and other
structures, including the MWFRS and component and
cladding elements thereof, shall be determined using
one of the procedures as specifi ed in this section. An
outline of the overall process for the determination of
the wind loads, including section references, is
provided in Fig. 26.1-1.
26.1.2.1 Main Wind-Force Resisting
System (MWFRS)
Wind loads for MWFRS shall be determined
using one of the following procedures:
(1) Directional Procedure for buildings of all heights
as specifi ed in Chapter 27 for buildings meeting
the requirements specifi ed therein;
(2) Envelope Procedure for low-rise buildings as
specifi ed in Chapter 28 for buildings meeting the
requirements specifi ed therein;
(3) Directional Procedure for Building Appurtenances
(rooftop structures and rooftop equipment) and
Other Structures (such as solid freestanding walls
and solid freestanding signs, chimneys, tanks,
open signs, lattice frameworks, and trussed
towers) as specifi ed in Chapter 29;
(4) Wind Tunnel Procedure for all buildings and all
other structures as specifi ed in Chapter 31.
26.1.2.2 Components and Cladding
Wind loads on components and cladding on all
buildings and other structures shall be designed using
one of the following procedures:
(1) Analytical Procedures provided in Parts 1 through
6, as appropriate, of Chapter 30;
(2) Wind Tunnel Procedure as specifi ed in Chapter 31.
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CHAPTER 26 WIND LOADS: GENERAL REQUIREMENTS
242
or 1 percent of the area of that wall, whichever is
smaller, and the percentage of openings in the
balance of the building envelope does not exceed
20 percent.
These conditions are expressed by the following
equations:
1. Ao > 1.10Aoi
2. Ao > 4 ft2
(0.37 m2
) or > 0.01Ag, whichever is
smaller, and Aoi/Agi ≤ 0.20
where
Ao, Ag are as defi ned for Open Building
Aoi = the sum of the areas of openings in the building
envelope (walls and roof) not including Ao,
in ft2
(m2
)
Agi = the sum of the gross surface areas of the
building envelope (walls and roof) not including
Ag, in ft2
(m2
)
BUILDING OR OTHER STRUCTURE,
REGULAR-SHAPED: A building or other structure
having no unusual geometrical irregularity in spatial
form.
BUILDING OR OTHER STRUCTURES,
RIGID: A building or other structure whose fundamental
frequency is greater than or equal to 1 Hz.
BUILDING, SIMPLE DIAPHRAGM: A
building in which both windward and leeward wind
loads are transmitted by roof and vertically spanning
wall assemblies, through continuous fl oor and roof
diaphragms, to the MWFRS.
BUILDING, TORSIONALLY REGULAR
UNDER WIND LOAD: A building with the
MWFRS about each principal axis proportioned so
that the maximum displacement at each story under
Case 2, the torsional wind load case, of Fig. 27.4-8,
does not exceed the maximum displacement at the
same location under Case 1 of Fig. 27.4-8, the basic
wind load case.
Chapter 26- General Requirements: Use to determine the basic parameters for
determining wind loads on both the MWFRS and C&C. These basic parameters are:
Basic wind speed, V, see Figure 26.5-1A, B or C
Wind directionality factor, Kd , see Section 26.6
Exposure category, see Section 26.7
Topographic factor, Kzt, see Section 26.8
Gust Effect Factor, see Section 26.9
Enclosure classification, see Section 26.10
Internal pressure coefficient, (GC pi), see Section 26-11
Wind loads on the MWFRS may be
determined by:
Wind loads on the C&C may be
determined by:
Chapter 27: Directional procedure for
buildings of all heights
Chapter 28: Envelope procedure for low rise
buildings
Chapter 29: Directional procedure for
building appurtenances (roof overhangs and
parapets) and other structures
Chapter 31: Wind tunnel procedure for any
building or other structure
Chapter 30:
- Envelope Procedure in Parts 1 and 2, or
- Directional Procedure in Parts 3, 4 and 5
- Building appurtenances (roof overhangs
and parapets) in Part 6
Chapter 31: Wind tunnel procedure
for any building or other structure
FIGURE 26.1-1 Outline of Process for Determining Wind Loads. Additional outlines and User Notes are
provided at the beginning of each chapter for more detailed step-by-step procedures for determining the
wind loads.
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MINIMUM DESIGN LOADS
243
COMPONENTS AND CLADDING (C&C):
Elements of the building envelope that do not qualify
as part of the MWFRS.
DESIGN FORCE, F: Equivalent static force to
be used in the determination of wind loads for other
structures.
DESIGN PRESSURE, p: Equivalent static
pressure to be used in the determination of wind loads
for buildings.
DIAPHRAGM: Roof, fl oor, or other membrane
or bracing system acting to transfer lateral forces to
the vertical Main Wind-Force Resisting System. For
analysis under wind loads, diaphragms constructed of
untopped steel decks, concrete fi lled steel decks, and
concrete slabs, each having a span-to-depth ratio of
two or less, shall be permitted to be idealized as rigid.
Diaphragms constructed of wood structural panels are
permitted to be idealized as fl exible.
DIRECTIONAL PROCEDURE: A procedure
for determining wind loads on buildings and other
structures for specifi c wind directions, in which the
external pressure coeffi cients utilized are based on
past wind tunnel testing of prototypical building
models for the corresponding direction of wind.
EAVE HEIGHT, he: The distance from the
ground surface adjacent to the building to the roof
eave line at a particular wall. If the height of the eave
varies along the wall, the average height shall be
used.
EFFECTIVE WIND AREA, A: The area used
to determine (GCp). For component and cladding
elements, the effective wind area in Figs. 30.4-1
through 30.4-7, 30.5-1. 30.6-1, and 30.8-1 through
30.8-3 is the span length multiplied by an effective
width that need not be less than one-third the span
length. For cladding fasteners, the effective wind area
shall not be greater than the area that is tributary to an
individual fastener.
ENVELOPE PROCEDURE: A procedure for
determining wind load cases on buildings, in which
pseudo-external pressure coeffi cients are derived from
past wind tunnel testing of prototypical building
models successively rotated through 360 degrees, such
that the pseudo-pressure cases produce key structural
actions (uplift, horizontal shear, bending moments,
etc.) that envelop their maximum values among all
possible wind directions.
ESCARPMENT: Also known as scarp, with
respect to topographic effects in Section 26.8, a cliff
or steep slope generally separating two levels or
gently sloping areas (see Fig. 26.8-1).
FREE ROOF: Roof with a confi guration
generally conforming to those shown in Figs. 27.4-4
through 27.4-6 (monoslope, pitched, or troughed) in
an open building with no enclosing walls underneath
the roof surface.
GLAZING: Glass or transparent or translucent
plastic sheet used in windows, doors, skylights, or
curtain walls.
GLAZING, IMPACT RESISTANT: Glazing
that has been shown by testing to withstand the
impact of test missiles. See Section 26.10.3.2.
HILL: With respect to topographic effects
in Section 26.8, a land surface characterized by
strong relief in any horizontal direction (see
Fig. 26.8-1).
HURRICANE PRONE REGIONS: Areas
vulnerable to hurricanes; in the United States and its
territories defi ned as
1. The U.S. Atlantic Ocean and Gulf of Mexico
coasts where the basic wind speed for Risk
Category II buildings is greater than 115 mi/h, and
2. Hawaii, Puerto Rico, Guam, Virgin Islands, and
American Samoa.
IMPACT PROTECTIVE SYSTEM: Construction
that has been shown by testing to withstand the
impact of test missiles and that is applied, attached, or
locked over exterior glazing. See Section 26.10.3.2.
MAIN WIND-FORCE RESISTING SYSTEM
(MWFRS): An assemblage of structural elements
assigned to provide support and stability for the
overall structure. The system generally receives wind
loading from more than one surface.
MEAN ROOF HEIGHT, h: The average of the
roof eave height and the height to the highest point on
the roof surface, except that, for roof angles of less
than or equal to 10°, the mean roof height is permitted
to be taken as the roof eave height.
OPENINGS: Apertures or holes in the building
envelope that allow air to fl ow through the building
envelope and that are designed as “open” during
design winds as defi ned by these provisions.
RECOGNIZED LITERATURE: Published
research fi ndings and technical papers that are
approved.
RIDGE: With respect to topographic effects in
Section 26.8 an elongated crest of a hill characterized
by strong relief in two directions (see Fig. 26.8-1).
WIND TUNNEL PROCEDURE: A procedure
for determining wind loads on buildings and other
structures, in which pressures and/or forces and
moments are determined for each wind direction
considered, from a model of the building or other
structure and its surroundings, in accordance with
Chapter 31.
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CHAPTER 26 WIND LOADS: GENERAL REQUIREMENTS
244
WIND-BORNE DEBRIS REGIONS: Areas
within hurricane prone regions where impact protection
is required for glazed openings, see Section
26.10.3.
26.3 SYMBOLS AND NOTATION
The following symbols and notation apply only to the
provisions of Chapters 26 through 31:
A = effective wind area, in ft2
(m2
)
Af = area of open buildings and other structures
either normal to the wind direction
or projected on a plane normal to the
wind direction, in ft2
(m2
)
Ag = the gross area of that wall in which Ao is
identifi ed, in ft2
(m2
)
Agi = the sum of the gross surface areas of the
building envelope (walls and roof) not
including Ag, in ft2
(m2
)
Ao = total area of openings in a wall that
receives positive external pressure, in ft2
(m2
)
Aoi = the sum of the areas of openings in the
building envelope (walls and roof) not
including Ao, in ft2
(m2
)
Aog = total area of openings in the building
envelope in ft2 (m2
)
As = gross area of the solid freestanding wall
or solid sign, in ft2 (m2
)
a = width of pressure coeffi cient zone, in ft
(m)
B = horizontal dimension of building measured
normal to wind direction, in ft (m)
b_
= mean hourly wind speed factor in Eq.
26.9-16 from Table 26.9-1
bˆ = 3-s gust speed factor from Table 26.9-1
Cf = force coeffi cient to be used in determination
of wind loads for other structures
CN = net pressure coeffi cient to be used in
determination of wind loads for open
buildings
Cp = external pressure coeffi cient to be used in
determination of wind loads for buildings
c = turbulence intensity factor in Eq. 26.9-7
from Table 26.9-1
D = diameter of a circular structure or
member, in ft (m)
D′ = depth of protruding elements such as ribs
and spoilers, in ft (m)
F = design wind force for other structures, in
lb (N)
G = gust-effect factor
Gf = gust-effect factor for MWFRS of fl exible
buildings and other structures
(GCpn) = combined net pressure coeffi cient for a
parapet
(GCp) = product of external pressure coeffi cient
and gust-effect factor to be used in
determination of wind loads for buildings
(GCpf) = product of the equivalent external
pressure coeffi cient and gust-effect factor
to be used in determination of wind loads
for MWFRS of low-rise buildings
(GCpi) = product of internal pressure coeffi cient
and gust-effect factor to be used in
determination of wind loads for buildings
(GCr) = product of external pressure coeffi cient
and gust-effect factor to be used in
determination of wind loads for rooftop
structures
gQ = peak factor for background response in
Eqs. 26.9-6 and 26.9-10
gR = peak factor for resonant response in Eq.
26.9-10
gv = peak factor for wind response in Eqs.
26.9-6 and 26.9-10
H = height of hill or escarpment in Fig.
26.8-1, in ft (m)
h = mean roof height of a building or height
of other structure, except that eave height
shall be used for roof angle θ less than or
equal to 10°, in ft (m)
he = roof eave height at a particular wall, or
the average height if the eave varies
along the wall
hp = height to top of parapet in Fig. 27.6-4
and 30.7-1
Iz
_ = intensity of turbulence from Eq. 26.9-7
K1, K2, K3 = multipliers in Fig. 26.8-1 to obtain Kzt
Kd = wind directionality factor in Table 26.6-1
Kh = velocity pressure exposure coeffi cient
evaluated at height z = h
Kz = velocity pressure exposure coeffi cient
evaluated at height z
Kzt = topographic factor as defi ned in Section
26.8
L = horizontal dimension of a building
measured parallel to the wind direction,
in ft (m)
Lh = distance upwind of crest of hill or
escarpment in Fig. 26.8-1 to where the
difference in ground elevation is half
the height of the hill or escarpment,
in ft (m)
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MINIMUM DESIGN LOADS
245
Lz = integral length scale of turbulence, in ft
(m)
Lr = horizontal dimension of return corner for
a solid freestanding wall or solid sign
from Fig. 29.4-1, in ft (m)
= integral length scale factor from Table
26.9-1, ft (m)
N1 = reduced frequency from Eq. 26.9-14
na = approximate lower bound natural
frequency (Hz) from Section 26.9.2
n1 = fundamental natural frequency, Hz
p = design pressure to be used in determination
of wind loads for buildings, in lb/ft2
(N/m2
)
PL = wind pressure acting on leeward face in
Fig. 27.4-8, in lb/ft2 (N/m2
)
pnet = net design wind pressure from Eq.
30.5-1, in lb/ft2
(N/m2
)
pnet30 = net design wind pressure for Exposure B
at h = 30 ft and I = 1.0 from Fig. 30.5-1,
in lb/ft2
(N/m2
)
pp = combined net pressure on a parapet from
Eq. 27.4-5, in lb/ft2 (N/m2
)
ps = net design wind pressure from Eq.
28.6-1, in lb/ft2
(N/m2
)
ps30 = simplifi ed design wind pressure for
Exposure B at h = 30 ft and I = 1.0 from
Fig. 28.6-1, in lb/ft2
(N/m2
)
PW = wind pressure acting on windward face in
Fig. 27.4-8, in lb/ft2 (N/m2
)
Q = background response factor from Eq.
26.9-8
q = velocity pressure, in lb/ft2
(N/m2
)
qh = velocity pressure evaluated at height
z = h, in lb/ft2 (N/m2
)
qi = velocity pressure for internal pressure
determination, in lb/ft2
(N/m2
)
qp = velocity pressure at top of parapet, in lb/
ft2
(N/m2
)
qz = velocity pressure evaluated at height z
above ground, in lb/ft2
(N/m2
)
R = resonant response factor from
Eq. 26.9-12
RB, Rh, RL = values from Eqs. 26.9-15
Ri = reduction factor from Eq. 26.11-1
Rn = value from Eq. 26.9-13
s = vertical dimension of the solid freestanding
wall or solid sign from Fig. 29.4-1,
in ft (m)
r = rise-to-span ratio for arched roofs
V = basic wind speed obtained from Fig.
26.5-1A through 26.5-1C, in mi/h (m/s).
The basic wind speed corresponds to a
3-sec gust speed at 33 ft (10 m) above
the ground in Exposure Category C
Vi = unpartitioned internal volume, ft3
(m3
)
V_
z
_ = mean hourly wind speed at height z_
, ft/s
(m/s)
W = width of building in Figs. 30.4-3 and
30.4-5A and 30.4-5B and width of span
in Figs. 30.4-4 and 30.4-6, in ft (m)
x = distance upwind or downwind of crest in
Fig. 26.8-1, in ft (m)
z = height above ground level, in ft (m)
z
_
= equivalent height of structure, in ft (m)
zg = nominal height of the atmospheric
boundary layer used in this standard.
Values appear in Table 26.9-1
zmin = exposure constant from Table 26.9-1
α = 3-sec gust-speed power law exponent
from Table 26.9-1
αˆ = reciprocal of α from Table 26.9-1
α_
= mean hourly wind-speed power law
exponent in Eq. 26.9-16 from Table
26.9-1
β = damping ratio, percent critical for
buildings or other structures
∈ = ratio of solid area to gross area for solid
freestanding wall, solid sign, open sign,
face of a trussed tower, or lattice structure
λ = adjustment factor for building height and
exposure from Figs. 28.6-1 and 30.5-1
∈_
= integral length scale power law exponent
in Eq. 26.9-9 from Table 26.9-1
η = value used in Eq. 26.9-15 (see Section
26.9.4)
θ = angle of plane of roof from horizontal, in
degrees
v = height-to-width ratio for solid sign
26.4 GENERAL
26.4.1 Sign Convention
Positive pressure acts toward the surface and
negative pressure acts away from the surface.
26.4.2 Critical Load Condition
Values of external and internal pressures shall be
combined algebraically to determine the most critical
load.
26.4.3 Wind Pressures Acting on Opposite Faces of
Each Building Surface
In the calculation of design wind loads for the
MWFRS and for components and cladding for
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CHAPTER 26 WIND LOADS: GENERAL REQUIREMENTS
246
buildings, the algebraic sum of the pressures acting on
opposite faces of each building surface shall be taken
into account.
26.5 WIND HAZARD MAP
26.5.1 Basic Wind Speed
The basic wind speed, V, used in the determination
of design wind loads on buildings and other structures
shall be determined from Fig. 26.5-1 as follows, except
as provided in Section 26.5.2 and 26.5.3:
For Risk Category II buildings and structures – use
Fig. 26.5-1A.
For Risk Category III and IV buildings and structures
– use Fig. 26.5-1B.
For Risk Category I buildings and structures - use
Fig. 26.5-1C.
The wind shall be assumed to come from any
horizontal direction. The basic wind speed shall be
increased where records or experience indicate that
the wind speeds are higher than those refl ected in Fig.
26.5-1.
26.5.2 Special Wind Regions
Mountainous terrain, gorges, and special wind
regions shown in Fig. 26.5-1 shall be examined for
unusual wind conditions. The authority having jurisdiction
shall, if necessary, adjust the values given in Fig.
26.5-1 to account for higher local wind speeds. Such
adjustment shall be based on meteorological information
and an estimate of the basic wind speed obtained in
accordance with the provisions of Section 26.5.3.
26.5.3 Estimation of Basic Wind Speeds from
Regional Climatic Data
In areas outside hurricane-prone regions, regional
climatic data shall only be used in lieu of the basic
wind speeds given in Fig. 26.5-1 when (1) approved
extreme-value statistical-analysis procedures have
been employed in reducing the data; and (2) the
length of record, sampling error, averaging time,
anemometer height, data quality, and terrain exposure
of the anemometer have been taken into account.
Reduction in basic wind speed below that of Fig.
26.5-1 shall be permitted.
In hurricane-prone regions, wind speeds derived
from simulation techniques shall only be used in lieu
of the basic wind speeds given in Fig. 26.5-1 when
approved simulation and extreme value statistical
analysis procedures are used. The use of regional wind
speed data obtained from anemometers is not permitted
to defi ne the hurricane wind-speed risk along the
Gulf and Atlantic coasts, the Caribbean, or Hawaii.
In areas outside hurricane-prone regions, when the
basic wind speed is estimated from regional climatic
data, the basic wind speed shall not be less than the
wind speed associated with the specifi ed mean
recurrence interval, and the estimate shall be adjusted
for equivalence to a 3-sec gust wind speed at 33 ft
(10 m) above ground in Exposure C. The data analysis
shall be performed in accordance with this chapter.
26.5.4 Limitation
Tornadoes have not been considered in developing
the basic wind-speed distributions.
26.6 WIND DIRECTIONALITY
The wind directionality factor, Kd, shall be determined
from Table 26.6-1. This directionality factor shall
only be included in determining wind loads when the
load combinations specifi ed in Sections 2.3 and 2.4
are used for the design. The effect of wind directionality
in determining wind loads in accordance with
Chapter 31 shall be based on an analysis for wind
speeds that conforms to the requirements of Section
26.5.3.
26.7 EXPOSURE
For each wind direction considered, the upwind
exposure shall be based on ground surface roughness
that is determined from natural topography, vegetation,
and constructed facilities.
26.7.1 Wind Directions and Sectors
For each selected wind direction at which the
wind loads are to be determined, the exposure of the
building or structure shall be determined for the two
upwind sectors extending 45º either side of the
selected wind direction. The exposure in these two
sectors shall be determined in accordance with
Sections 26.7.2 and 26.7.3, and the exposure whose
use would result in the highest wind loads shall be
used to represent the winds from that direction.
26.7.2 Surface Roughness Categories
A ground Surface Roughness within each 45°
sector shall be determined for a distance upwind
of the site as defi ned in Section 26.7.3 from the
categories defi ned in the following text, for the
purpose of assigning an exposure category as defi ned
in Section 26.7.3.
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CHAPTER 26 WIND LOADS: GENERAL REQUIREMENTS
247a
Figure 26.5-1A Basic Wind Speeds for Occupancy Category II Buildings and Other Structures.
Notes:
1. Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for
Exposure C category.
2. Linear interpolation between contours is permitted.
3. Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
4. Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind
conditions.
5. Wind speeds correspond to approximately a 7% probability of exceedance in 50 years (Annual Exceedance
Probability = 0.00143, MRI = 700 Years).
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247b
Figure 26.5-1A (Continued)
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CHAPTER 26 WIND LOADS: GENERAL REQUIREMENTS
248a
Figure 26.5-1B Basic Wind Speeds for Occupancy Category III and IV Buildings and Other Structures.
Notes:
1. Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for
Exposure C category.
2. Linear interpolation between contours is permitted.
3. Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
4. Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind
conditions.
5. Wind speeds correspond to approximately a 3% probability of exceedance in 50 years (Annual Exceedance
Probability = 0.000588, MRI = 1700 Years).
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248b
Figure 26.5-1B (Continued)
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CHAPTER 26 WIND LOADS: GENERAL REQUIREMENTS
249a
Figure 26.5-1C Basic Wind Speeds for Occupancy Category I Buildings and Other Structures.
Notes:
1. Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33 ft (10m) above ground for
Exposure C category.
2. Linear interpolation between contours is permitted.
3. Islands and coastal areas outside the last contour shall use the last wind speed contour of the coastal area.
4. Mountainous terrain, gorges, ocean promontories, and special wind regions shall be examined for unusual wind
conditions.
5. Wind speeds correspond to approximately a 15% probability of exceedance in 50 years (Annual Exceedance
Probability = 0.00333, MRI = 300 Years).
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249b
Figure 26.5-1c (Continued)
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CHAPTER 26 WIND LOADS: GENERAL REQUIREMENTS
250
Wind Directionality Factor, Kd
Table 26.6-1
Structure Type Directionality Factor Kd*
Buildings
Main Wind Force Resisting System
Components and Cladding
0.85
0.85
Arched Roofs 0.85
Chimneys, Tanks, and Similar Structures
Square
Hexagonal
Round
0.90
0.95
0.95
Solid Freestanding Walls and Solid
Freestanding and Attached Signs 0.85
Open Signs and Lattice Framework 0.85
Trussed Towers
Triangular, square, rectangular
All other cross sections
0.85
0.95
*Directionality Factor Kd has been calibrated with combinations of loads
specified in Chapter 2. This factor shall only be applied when used in
conjunction with load combinations specified in Sections 2.3 and 2.4.
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MINIMUM DESIGN LOADS
251
Surface Roughness B: Urban and suburban areas,
wooded areas, or other terrain with numerous closely
spaced obstructions having the size of single-family
dwellings or larger.
Surface Roughness C: Open terrain with scattered
obstructions having heights generally less than 30 ft
(9.1 m). This category includes fl at open country and
grasslands.
Surface Roughness D: Flat, unobstructed areas
and water surfaces. This category includes smooth
mud fl ats, salt fl ats, and unbroken ice.
26.7.3 Exposure Categories
Exposure B: For buildings with a mean roof
height of less than or equal to 30 ft (9.1 m), Exposure
B shall apply where the ground surface roughness, as
defi ned by Surface Roughness B, prevails in the
upwind direction for a distance greater than 1,500 ft
(457 m). For buildings with a mean roof height greater
than 30 ft (9.1 m), Exposure B shall apply where
Surface Roughness B prevails in the upwind direction
for a distance greater than 2,600 ft (792 m) or 20 times
the height of the building, whichever is greater.
Exposure C: Exposure C shall apply for all cases
where Exposures B or D do not apply.
Exposure D: Exposure D shall apply where the
ground surface roughness, as defi ned by Surface
Roughness D, prevails in the upwind direction for a
distance greater than 5,000 ft (1,524 m) or 20 times
the building height, whichever is greater. Exposure D
shall also apply where the ground surface roughness
immediately upwind of the site is B or C, and the site
is within a distance of 600 ft (183 m) or 20 times the
building height, whichever is greater, from an Exposure
D condition as defi ned in the previous sentence.
For a site located in the transition zone between
exposure categories, the category resulting in the
largest wind forces shall be used.
EXCEPTION: An intermediate exposure between
the preceding categories is permitted in a transition
zone provided that it is determined by a rational
analysis method defi ned in the recognized literature.
26.7.4 Exposure Requirements.
26.7.4.1 Directional Procedure (Chapter 27)
For each wind direction considered, wind loads
for the design of the MWFRS of enclosed and
partially enclosed buildings using the Directional
Procedure of Chapter 27 shall be based on the
exposures as defi ned in Section 26.7.3. Wind loads for
the design of open buildings with monoslope, pitched,
or troughed free roofs shall be based on the exposures,
as defi ned in Section 26.7.3, resulting in the
highest wind loads for any wind direction at the site.
26.7.4.2 Envelope Procedure (Chapter 28)
Wind loads for the design of the MWFRS for all
low-rise buildings designed using the Envelope
Procedure of Chapter 28 shall be based on the
exposure category resulting in the highest wind loads
for any wind direction at the site.
26.7.4.3 Directional Procedure for Building
Appurtenances and Other Structures (Chapter 29)
Wind loads for the design of building appurtenances
(such as rooftop structures and equipment) and
other structures (such as solid freestanding walls and
freestanding signs, chimneys, tanks, open signs, lattice
frameworks, and trussed towers) as specifi ed in
Chapter 29 shall be based on the appropriate exposure
for each wind direction considered.
26.7.4.4 Components and Cladding (Chapter 30)
Design wind pressures for components and
cladding shall be based on the exposure category
resulting in the highest wind loads for any wind
direction at the site.
26.8 TOPOGRAPHIC EFFECTS
26.8.1 Wind Speed-Up over Hills, Ridges,
and Escarpments
Wind speed-up effects at isolated hills, ridges,
and escarpments constituting abrupt changes in the
general topography, located in any exposure category,
shall be included in the design when buildings and
other site conditions and locations of structures meet
all of the following conditions:
1. The hill, ridge, or escarpment is isolated and
unobstructed upwind by other similar topographic
features of comparable height for 100 times the
height of the topographic feature (100H) or 2 mi
(3.22 km), whichever is less. This distance shall be
measured horizontally from the point at which the
height H of the hill, ridge, or escarpment is
determined.
2. The hill, ridge, or escarpment protrudes above the
height of upwind terrain features within a 2-mi
(3.22-km) radius in any quadrant by a factor of two
or more.
3. The structure is located as shown in Fig. 26.8-1 in
the upper one-half of a hill or ridge or near the
crest of an escarpment.
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CHAPTER 26 WIND LOADS: GENERAL REQUIREMENTS
252
Topographic Factor, Kzt
Figure 26.8-1
Topographic Multipliers for Exposure C
K1 Multiplier K2 Multiplier K3 Multiplier
H/Lh 2-D
Ridge
2-D
Escarp.
3-D
Axisym.
Hill
x/Lh 2-D
Escarp.
All
Other
Cases
z/Lh 2-D
Ridge
2-D
Escarp.
3-D
Axisym.
Hill
0.20 0.29 0.17 0.21 0.00 1.00 1.00 0.00 1.00 1.00 1.00
0.25 0.36 0.21 0.26 0.50 0.88 0.67 0.10 0.74 0.78 0.67
0.30 0.43 0.26 0.32 1.00 0.75 0.33 0.20 0.55 0.61 0.45
0.35 0.51 0.30 0.37 1.50 0.63 0.00 0.30 0.41 0.47 0.30
0.40 0.58 0.34 0.42 2.00 0.50 0.00 0.40 0.30 0.37 0.20
0.45 0.65 0.38 0.47 2.50 0.38 0.00 0.50 0.22 0.29 0.14
0.50 0.72 0.43 0.53 3.00 0.25 0.00 0.60 0.17 0.22 0.09
3.50 0.13 0.00 0.70 0.12 0.17 0.06
4.00 0.00 0.00 0.80 0.09 0.14 0.04
0.90 0.07 0.11 0.03
1.00 0.05 0.08 0.02
1.50 0.01 0.02 0.00
2.00 0.00 0.00 0.00
Notes:
1. For values of H/Lh, x/Lh and z/Lh other than those shown, linear interpolation is permitted.
2. For H/Lh > 0.5, assume H/Lh = 0.5 for evaluating K1 and substitute 2H for Lh for evaluating K2 and K3.
3. Multipliers are based on the assumption that wind approaches the hill or escarpment along the
direction of maximum slope.
4. Notation:
H: Height of hill or escarpment relative to the upwind terrain, in feet (meters).
Lh: Distance upwind of crest to where the difference in ground elevation is half the height of hill or
escarpment, in feet (meters).
K1: Factor to account for shape of topographic feature and maximum speed-up effect.
K2: Factor to account for reduction in speed-up with distance upwind or downwind of crest.
K3: Factor to account for reduction in speed-up with height above local terrain.
x: Distance (upwind or downwind) from the crest to the building site, in feet (meters).
z: Height above ground surface at building site, in feet (meters).
μ: Horizontal attenuation factor.
γ: Height attenuation factor.
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253
Topographic Factor, Kzt
Figure 26.8-1 (cont’d)
Equations:
2
zt 1 2 3 K = (1+ K K K )
K1 determined from table below
) L
x
K (1-
h
2
μ =
- z/Lh 3 K e γ =
Parameters for Speed-Up Over Hills and Escarpments
K1/(H/Lh) m
Hill Shape Exposure g Upwind Downwind
B C D of Crest of Crest
2-dimensional ridges
(or valleys with negative
H in K1/(H/Lh)
1.30 1.45 1.55 3 1.5 1.5
2-dimensional escarpments 0.75 0.85 0.95 2.5 1.5 4
3-dimensional axisym. hill 0.95 1.05 1.15 4 1.5 1.5
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CHAPTER 26 WIND LOADS: GENERAL REQUIREMENTS
254
4. H/Lh ≥ 0.2.
5. H is greater than or equal to 15 ft (4.5 m) for
Exposure C and D and 60 ft (18 m) for Exposure B.
26.8.2 Topographic Factor
The wind speed-up effect shall be included in the
calculation of design wind loads by using the factor
Kzt:
Kzt = (1 + K1K2K3)
2 (26.8-1)
where K1, K2, and K3 are given in Fig. 26.8-1.
If site conditions and locations of structures do
not meet all the conditions specifi ed in Section 26.8.1
then Kzt = 1.0.
26.9 GUST-EFFECTS
26.9.1 Gust-Effect Factor: The gust-effect factor for
a rigid building or other structure is permitted to be
taken as 0.85.
26.9.2 Frequency Determination
To determine whether a building or structure is
rigid or fl exible as defi ned in Section 26.2, the
fundamental natural frequency, n1, shall be established
using the structural properties and deformational
characteristics of the resisting elements in a properly
substantiated analysis. Low-Rise Buildings, as defi ned
in 26.2, are permitted to be considered rigid.
26.9.2.1 Limitations for Approximate
Natural Frequency
As an alternative to performing an analysis to
determine n1, the approximate building natural
frequency, na, shall be permitted to be calculated in
accordance with Section 26.9.3 for structural steel,
concrete, or masonry buildings meeting the following
requirements:
1. The building height is less than or equal to 300 ft
(91 m), and
2. The building height is less than 4 times its effective
length, Leff.
The effective length, Leff, in the direction under
consideration shall be determined from the following
equation:
L
h L
h
eff
i i
i
n
i
i
n = =
=


1
1
(26.9-1)
The summations are over the height of the building
where
hi is the height above grade of level i
Li is the building length at level i parallel to the wind
direction
26.9.3 Approximate Natural Frequency
The approximate lower-bound natural frequency
(na), in Hertz, of concrete or structural steel buildings
meeting the conditions of Section 26.9.2.1, is permitted
to be determined from one of the following
equations:
For structural steel moment-resisting-frame
buildings:
na = 22.2/h0.8 (26.9-2)
For concrete moment-resisting frame buildings:
na = 43.5/h0.9 (26.9-3)
For structural steel and concrete buildings with
other lateral-force-resisting systems:
na = 75/h (26.9-4)
For concrete or masonry shear wall buildings, it
is also permitted to use
na = 385(Cw)
0.5/h (26.9-5)
where
C
A
h
h
A
h
D
w
B i i
n i
i
i
= ⎛

⎜ ⎞


+ ⎛

⎜ ⎞

⎟ ⎡

⎢ ⎤

⎥ =
∑ 100
1 0 83 1
2
2
.
where
h = mean roof height (ft)
n = number of shear walls in the building effective
in resisting lateral forces in the direction under
consideration
AB = base area of the structure (ft2
)
Ai = horizontal cross-section area of shear wall “i” (ft2
)
Di = length of shear wall “i” (ft)
hi = height of shear wall “i” (ft)
26.9.4 Rigid Buildings or Other Structures
For rigid buildings or other structures as defi ned
in Section 26.2, the gust-effect factor shall be taken as
0.85 or calculated by the formula:
G gIQ
g I
Q z
v z
= +
+


⎜ ⎞

⎟ 0 925 1 17
1 17 . .
. (26.9-6)
I c
z z = ⎛

⎜ ⎞

⎟ 33 1 6/
(26.9-7)
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MINIMUM DESIGN LOADS
255
In SI: I c
z z = ⎛

⎜ ⎞

⎟ 10 1 6/
where Iz
_ is the intensity of turbulence at height z_
where z_
is the equivalent height of the structure
defi ned as 0.6h, but not less than zmin for all building
heights h. zmin and c are listed for each exposure in
Table 26.9-1; gQ and gv shall be taken as 3.4. The
background response Q is given by
Q
B h
Lz
=
+ ⎛ +

⎜ ⎞


1
1 0 63
0 63
.
. (26.9-8)
where B and h are defi ned in Section 26.3 and Lz
_ is
the integral length scale of turbulence at the equivalent
height given by
L z z = ⎛

⎜ ⎞


33 (26.9-9)
In SI: L z z = ⎛

⎜ ⎞


10
in which and ∈
_
are constants listed in Table 26.9-1.
26.9.5 Flexible or Dynamically Sensitive Buildings
or Other Structures
For fl exible or dynamically sensitive buildings or
other structures as defi ned in Section 26.2, the
gust-effect factor shall be calculated by
G I gQ gR
g I f
zQ R
v z
= + +
+







⎟ 0 925 1 17
1 17
22 22
. .
. (26.9-10)
gQ and gv shall be taken as 3.4 and gR is given by
g n n R = ( ) +
( )
2 3 600 0 577
2 3 600 1
1
ln , .
ln ,
(26.9-11)
R, the resonant response factor, is given by
R RRR R = + nhB L ( ) 1 0 53 0 47
β . . (26.9-12)
R N
N n =
( ) +
7 47
1 10 3
1
1
5 3
.
. / (26.9-13)
N n L
V
z
z
1
1 = (26.9-14)
R e =− − ( ) 1 1 −
2
1 2
2
η η
η for η > 0 (26.9-15a)
R = 1 for η = 0 (26.9-15b)
where the subscript in Eqs. 26.9-15 shall be taken as
h, B, and L, respectively, where h, B, and L are
defi ned in Section 26.3.
n1 = fundamental natural frequency
R = Rh setting η = 4.6n1h/V
_
z
_
R = RB setting η = 4.6n1B/V
_
z
_
R = RL setting η = 15.4n1L/V
_
z
_
β = damping ratio, percent of critical (i.e. for 2% use
0.02 in the equation)
V
_
z
_ = mean hourly wind speed (ft/s) at height z_
determined from Eq. 26.9-16:
V b z z = V ⎛

⎜ ⎞

⎟ ⎛

⎜ ⎞

⎟ 33
88
60
α
(26.9-16)
In SI: V b z z = V ⎛

⎜ ⎞

⎟ 10
α
where b
_
and α
_
are constants listed in Table 26.9-1 and
V is the basic wind speed in mi/h.
26.9.6 Rational Analysis
In lieu of the procedure defi ned in Sections 26.9.3
and 26.9.4, determination of the gust-effect factor by
any rational analysis defi ned in the recognized
literature is permitted.
26.9.7 Limitations
Where combined gust-effect factors and pressure
coeffi cients (GCp), (GCpi), and (GCpf) are given in
fi gures and tables, the gust-effect factor shall not be
determined separately.
26.10 ENCLOSURE CLASSIFICATION
26.10.1 General
For the purpose of determining internal pressure
coeffi cients, all buildings shall be classifi ed as
enclosed, partially enclosed, or open as defi ned in
Section 26.2.
26.10.2 Openings
A determination shall be made of the amount of
openings in the building envelope for use in determining
the enclosure classifi cation.
26.10.3 Protection of Glazed Openings
Glazed openings in Risk Category II, III or IV
buildings located in hurricane-prone regions shall be
protected as specifi ed in this Section.
26.10.3.1 Wind-borne Debris Regions
Glazed openings shall be protected in
accordance with Section 26.10.3.2 in the following
locations:
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CHAPTER 26 WIND LOADS: GENERAL REQUIREMENTS
256
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MINIMUM DESIGN LOADS
257
1. Within 1 mi of the coastal mean high water line
where the basic wind speed is equal to or greater
than 130 mi/h (58 m/s), or
2. In areas where the basic wind speed is equal to or
greater than 140 mi/h (63 m/s).
For Risk Category II buildings and structures and
Risk Category III buildings and structures, except
health care facilities, the wind-borne debris region
shall be based on Fig. 26.5-1A. For Risk Category III
health care facilities and Risk Category IV buildings
and structures, the wind-borne debris region shall be
based on Fig. 26.5-1B. Risk Categories shall be
determined in accordance with Section 1.5.
EXCEPTION: Glazing located over 60 ft
(18.3 m) above the ground and over 30 ft (9.2 m)
above aggregate-surfaced-roofs, including roofs
with gravel or stone ballast, located within 1,500
ft (458 m) of the building shall be permitted to be
unprotected.
26.10.3.2 Protection Requirements for
Glazed Openings
Glazing in buildings requiring protection shall be
protected with an impact-protective system or shall be
impact-resistant glazing.
Impact-protective systems and impact-resistant
glazing shall be subjected to missile test and cyclic
pressure differential tests in accordance with ASTM
E1996 as applicable. Testing to demonstrate compliance
with ASTM E1996 shall be in accordance with
ASTM E1886. Impact-resistant glazing and impactprotective
systems shall comply with the pass/fail
criteria of Section 7 of ASTM E1996 based on the
missile required by Table 3 or Table 4 of ASTM
E1996.
EXCEPTION: Other testing methods and/or
performance criteria are permitted to be used when
approved.
Glazing and impact-protective systems in
buildings and structures classifi ed as Risk Category
IV in accordance with Section 1.5 shall comply with
the “enhanced protection” requirements of Table 3 of
ASTM E1996. Glazing and impact-protective systems
in all other structures shall comply with the “basic
protection” requirements of Table 3 of ASTM E1996.
User Note: The wind zones that are specifi ed in ASTM
E1996 for use in determining the applicable missile size
for the impact test, have to be adjusted for use with the
wind speed maps of ASCE 7-10 and the corresponding
wind borne debris regions, see Section C26.10.3.2.
26.10.4 Multiple Classifi cations
If a building by defi nition complies with both the
“open” and “partially enclosed” defi nitions, it shall be
classifi ed as an “open” building. A building that does
not comply with either the “open” or “partially
enclosed” defi nitions shall be classifi ed as an
“enclosed” building.
26.11 INTERNAL PRESSURE COEFFICIENT
26.11.1 Internal Pressure Coeffi cients
Internal pressure coeffi cients, (GCpi), shall be
determined from Table 26.11-1 based on building
enclosure classifi cations determined from Section
26.10.
26.11.1.1 Reduction Factor for Large Volume
Buildings, Ri
For a partially enclosed building containing a
single, unpartitioned large volume, the internal
pressure coeffi cient, (GCpi), shall be multiplied by the
following reduction factor, Ri:
Ri = 1.0 or
R
V
A
i
i
og
= +
+












05 1 <
1
1
22 800
. 1 0
.
. (26.11-1)
where
Aog = total area of openings in the building envelope
(walls and roof, in ft2
)
Vi = unpartitioned internal volume, in ft3
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CHAPTER 26 WIND LOADS: GENERAL REQUIREMENTS
258
Main Wind Force Resisting System and Components and
Cladding
All Heights
Table 26.11-1 Internal Pressure Coefficient, (GC pi) Walls & Roofs Enclosed, Partially Enclosed, and Open Buildings
Enclosure Classification (GC pi)
Open Buildings 0.00
Partially Enclosed Buildings +0.55
-0.55
Enclosed Buildings +0.18
-0.18
Notes:
1. Plus and minus signs signify pressures acting toward and away
from the internal surfaces, respectively.
2. Values of (GC pi) shall be used with qz or qh as specified.
3. Two cases shall be considered to determine the critical load
requirements for the appropriate condition:
(i) a positive value of (GC pi) applied to all internal surfaces
(ii) a negative value of (GC pi) applied to all internal surfaces
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259
Chapter 27
WIND LOADS ON BUILDINGS—MWFRS
(DIRECTIONAL PROCEDURE)
PART 1: ENCLOSED, PARTIALLY ENCLOSED,
AND OPEN BUILDINGS OF ALL HEIGHTS
27.2 GENERAL REQUIREMENTS
The steps to determine the wind loads on the MWFRS
for enclosed, partially enclosed and open buildings of
all heights are provided in Table 27.2-1.
27.1 SCOPE
27.1.1 Building Types
This chapter applies to the determination of
MWFRS wind loads on enclosed, partially enclosed,
and open buildings of all heights using the Directional
Procedure.
1) Part 1 applies to buildings of all heights where it is
necessary to separate applied wind loads onto the
windward, leeward, and side walls of the building
to properly assess the internal forces in the
MWFRS members.
2) Part 2 applies to a special class of buildings
designated as enclosed simple diaphragm buildings,
as defi ned in Section 26.2, with h ≤ 160 ft
(48.8 m).
27.1.2 Conditions
A building whose design wind loads are determined
in accordance with this chapter shall comply
with all of the following conditions:
1. The building is a regular-shaped building or
structure as defi ned in Section 26.2.
2. The building does not have response characteristics
making it subject to across-wind loading, vortex
shedding, instability due to galloping or fl utter; or
it does not have a site location for which channeling
effects or buffeting in the wake of upwind
obstructions warrant special consideration.
27.1.3 Limitations
The provisions of this chapter take into consideration
the load magnifi cation effect caused by gusts in
resonance with along-wind vibrations of fl exible
buildings. Buildings not meeting the requirements of
Section 27.1.2, or having unusual shapes or response
characteristics shall be designed using recognized
literature documenting such wind load effects or
shall use the wind tunnel procedure specifi ed in
Chapter 31.
27.1.4 Shielding
There shall be no reductions in velocity pressure
due to apparent shielding afforded by buildings and
other structures or terrain features.
User Note: Use Part 1 of Chapter 27 to determine wind
pressures on the MWFRS of enclosed, partially enclosed
or an open building with any general plan shape,
building height or roof geometry that matches the fi gures
provided. These provisions utilize the traditional “all
heights” method (Directional Procedure) by calculating
wind pressures using specifi c wind pressure equations
applicable to each building surface.
27.2.1 Wind Load Parameters Specifi ed in
Chapter 26
The following wind load parameters shall be
determined in accordance with Chapter 26:
– Basic Wind Speed, V (Section 26.5)
– Wind directionality factor, Kd (Section 26.6)
– Exposure category (Section 26.7)
– Topographic factor, Kzt (Section 26.8)
– Gust-effect factor (Section 26.9)
– Enclosure classifi cation (Section 26.10)
– Internal pressure coeffi cient, (GCpi) (Section 26-11).
27.3 VELOCITY PRESSURE
27.3.1 Velocity Pressure Exposure Coeffi cient
Based on the exposure category determined in
Section 26.7.3, a velocity pressure exposure coeffi -
cient Kz or Kh, as applicable, shall be determined from
Table 27.3-1. For a site located in a transition zone
between exposure categories that is near to a change
in ground surface roughness, intermediate values of Kz
or Kh, between those shown in Table 27.3-1 are
permitted provided that they are determined by a
rational analysis method defi ned in the recognized
literature.
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CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
260
27.3.2 Velocity Pressure
Velocity pressure, qz, evaluated at height z shall
be calculated by the following equation:
qz = 0.00256KzKztKdV2 (lb/ft2
) (27.3-1)
[In SI: qz = 0.613KzKztKdV2
(N/m2
); V in m/s]
where
Kd = wind directionality factor, see Section 26.6
Kz = velocity pressure exposure coeffi cient, see
Section 27.3.1
Kzt = topographic factor defi ned, see Section 26.8.2
V = basic wind speed, see Section 26.5
qz = velocity pressure calculated using Eq. 27.3-1 at
height z
qh = velocity pressure calculated using Eq. 27.3-1 at
mean roof height h.
The numerical coeffi cient 0.00256 (0.613 in SI)
shall be used except where suffi cient climatic data are
available to justify the selection of a different value of
this coeffi cient for a design application.
27.4 WIND LOADS—MAIN WIND
FORCE-RESISTING SYSTEM
27.4.1 Enclosed and Partially Enclosed
Rigid Buildings
Design wind pressures for the MWFRS of
buildings of all heights shall be determined by the
following equation:
p = qGCp – qi(GCpi) (lb/ft2
) (N/m2
) (27.4-1)
where
q = qz for windward walls evaluated at height z
above the ground
q = qh for leeward walls, side walls, and roofs,
evaluated at height h
qi = qh for windward walls, side walls, leeward
walls, and roofs of enclosed buildings and
for negative internal pressure evaluation in
partially enclosed buildings
qi = qz for positive internal pressure evaluation in
partially enclosed buildings where height z is
defi ned as the level of the highest opening in
the building that could affect the positive
internal pressure. For buildings sited in
wind-borne debris regions, glazing that is not
impact resistant or protected with an impact
resistant covering shall be treated as an
opening in accordance with Section 26.10.3.
For positive internal pressure evaluation,
qi may conservatively be evaluated at height
h(qi = qh)
G = gust-effect factor, see Section 26.9
Cp = external pressure coeffi cient from Figs.
27.4-1, 27.4-2 and 27.4-3
(GCpi) = internal pressure coeffi cient from Table
26.11-1
q and qi shall be evaluated using exposure
defi ned in Section 26.7.3. Pressure shall be applied
simultaneously on windward and leeward walls and
on roof surfaces as defi ned in Figs. 27.4-1, 27.4-2 and
27.4-3.
Table 27.2-1 Steps to Determine MWFRS Wind
Loads for Enclosed, Partially Enclosed and
Open Buildings of All Heights
Step 1: Determine risk category of building or other
structure, see Table 1.4-1
Step 2: Determine the basic wind speed, V, for the
applicable risk category, see Figure 26.5-1A, B
or C
Step 3: Determine wind load parameters:
➢ Wind directionality factor, Kd , see Section
26.6 and Table 26.6-1
➢ Exposure category, see Section 26.7
➢ Topographic factor, Kzt, see Section 26.8 and
Table 26.8-1
➢ Gust Effect Factor, G, see Section 26.9
➢ Enclosure classifi cation, see Section 26.10
➢ Internal pressure coeffi cient, (GCpi), see
Section 26.11 and Table 26.11-1
Step 4: Determine velocity pressure exposure
coeffi cient, Kz or Kh, see Table 27.3-1
Step 5: Determine velocity pressure qz or qh Eq. 27.3-1
Step 6: Determine external pressure coeffi cient, Cp or CN
➢ Fig. 27.4-1 for walls and fl at, gable, hip,
monoslope or mansard roofs
➢ Fig. 27.4-2 for domed roofs
➢ Fig. 27.4-3 for arched roofs
➢ Fig. 27.4-4 for monoslope roof, open building
➢ Fig. 27.4-5 for pitched roof, open building
➢ Fig. 27.4-6 for troughed roof, open building
➢ Fig. 27.4-7 for along-ridge/valley wind load
case for monoslope, pitched or troughed roof,
open building
Step 7: Calculate wind pressure, p, on each building
surface
➢ Eq. 27.4-1 for rigid buildings
➢ Eq. 27.4-2 for fl exible buildings
➢ Eq. 27.4-3 for open buildings
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CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
262
27.4.2 Enclosed and Partially Enclosed
Flexible Buildings
Design wind pressures for the MWFRS of
fl exible buildings shall be determined from the
following equation:
p = qGfCp – qi(GCpi) (lb/ft2
) (N/m2
) (27.4-2)
where q, qi, Cp, and (GCpi) are as defi ned in Section
27.4.1 and Gf (gust-effect factor) is determined in
accordance with Section 26.9.5.
27.4.3 Open Buildings with Monoslope, Pitched,
or Troughed Free Roofs
The net design pressure for the MWFRS of open
buildings with monoslope, pitched, or troughed roofs
shall be determined by the following equation:
p = qhGCN (27.4-3)
where
qh = velocity pressure evaluated at mean roof height
h using the exposure as defi ned in Section 26.7.3
that results in the highest wind loads for any
wind direction at the site
G = gust-effect factor from Section 26.9
CN = net pressure coeffi cient determined from Figs.
27.4-4 through 27.4-7
Net pressure coeffi cients, CN, include contributions
from top and bottom surfaces. All load cases
shown for each roof angle shall be investigated.
Plus and minus signs signify pressure acting toward
and away from the top surface of the roof,
respectively.
For free roofs with an angle of plane of roof from
horizontal θ less than or equal to 5° and containing
fascia panels, the fascia panel shall be considered an
inverted parapet. The contribution of loads on the
fascia to the MWFRS loads shall be determined using
Section 27.4.5 with qp equal to qh.
27.4.4 Roof Overhangs
The positive external pressure on the bottom
surface of windward roof overhangs shall be determined
using Cp = 0.8 and combined with the top
surface pressures determined using Fig. 27.4-1.
27.4.5 Parapets
The design wind pressure for the effect of
parapets on MWFRS of rigid or fl exible buildings
with fl at, gable, or hip roofs shall be determined by
the following equation:
pp = qp(GCpn) (lb/ft2
) (27.4-4)
where
pp = combined net pressure on the parapet due to
the combination of the net pressures from
the front and back parapet surfaces. Plus
(and minus) signs signify net pressure acting
toward (and away from) the front (exterior)
side of the parapet
qp = velocity pressure evaluated at the top of the
parapet
(GCpn) = combined net pressure coeffi cient
= +1.5 for windward parapet
= –1.0 for leeward parapet
27.4.6 Design Wind Load Cases
The MWFRS of buildings of all heights, whose
wind loads have been determined under the provisions
of this chapter, shall be designed for the wind load
cases as defi ned in Fig. 27.4-8.
EXCEPTION: Buildings meeting the requirements
of Section D1.1 of Appendix D need
only be designed for Case 1 and Case 3 of
Fig. 27.4-8.
The eccentricity e for rigid structures shall be
measured from the geometric center of the building
face and shall be considered for each principal axis
(eX, eY). The eccentricity e for fl exible structures shall
be determined from the following equation and shall
be considered for each principal axis (eX, eY):
e
e I g Qe g Re
I gQ gR
Q z QQ RR
zQ R
= + ( ) + ( )
+ ( ) + ( )
1 7
1 17
2 2
2 2
.
.
(27.4-5)
where
eQ = eccentricity e as determined for rigid structures
in Fig. 27.4-8
eR = distance between the elastic shear center and
center of mass of each fl oor
Iz
_, gQ, Q, gR, and R shall be as defi ned in Section 26.9
The sign of the eccentricity e shall be plus or
minus, whichever causes the more severe load effect.
27.4.7 Minimum Design Wind Loads
The wind load to be used in the design of the
MWFRS for an enclosed or partially enclosed
building shall not be less than 16 lb/ft2
(0.77 kN/m2
)
multiplied by the wall area of the building and 8 lb/ft2
(0.38 kN/m2
) multiplied by the roof area of the
building projected onto a vertical plane normal to the
assumed wind direction. Wall and roof loads shall
be applied simultaneously. The design wind force
for open buildings shall be not less than 16 lb/ft2
(0.77 kN/m2
) multiplied by the area Af.
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263
Main Wind Force Resisting System – Part 1 All Heights
Figure 27.4-1 External Pressure Coefficients, Cp Walls & Roofs Enclosed, Partially Enclosed Buildings
θ
θ
θ
θ
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CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
264
Main Wind Force Resisting System – Part 1 All Heights
Figure 27.4-1 (cont.) External Pressure Coefficients, Cp
Walls & Roofs Enclosed, Partially Enclosed Buildings
Wall Pressure Coefficients, Cp
Surface L/B Cp Use With
Windward Wall All values 0.8 qz
0-1 -0.5
Leeward Wall 2 -0.3 qh
≥4 -0.2
Side Wall All values -0.7 qh
Roof Pressure Coefficients, Cp, for use with qh
Windward Leeward
Wind
Direction Angle, θ (degrees) Angle, θ (degrees)
h/L 10 15 20 25 30 35 45 ≥60# 10 15 ≥20
Normal ≤0.25
-0.7
-0.18
-0.5
0.0*
-0.3
0.2
-0.2
0.3
-0.2
0.3
0.0*
0.4 0.4 0.01 θ -0.3 -0.5 -0.6
to
ridge for 0.5
-0.9
-0.18
-0.7
-0.18
-0.4
0.0*
-0.3
0.2
-0.2
0.2
-0.2
0.3
0.0*
0.4 0.01 θ -0.5 -0.5 -0.6
0 ≥ 10°
≥1.0
-1.3**
-0.18
-1.0
-0.18
-0.7
-0.18
-0.5
0.0*
-0.3
0.2
-0.2
0.2
0.0*
0.3 0.01 θ -0.7 -0.6 -0.6
Horiz distance from
windward edge Cp
*Value is provided for interpolation
Normal purposes.
to 0 to h/2 -0.9, -0.18
ridge for ≤ 0.5 h/2 to h -0.9, -0.18 **Value can be reduced linearly with area
θ < 10 h to 2 h -0.5, -0.18 over which it is applicable as follows
and > 2h -0.3, -0.18
Parallel 0 to h/2 -1.3**, -0.18 Area (sq ft) Reduction Factor
to ridge ≥ 1.0 ≤ 100 (9.3 sq m) 1.0
for all θ > h/2 -0.7, -0.18 250 (23.2 sq m) 0.9
≥ 1000 (92.9 sq m) 0.8
Notes:
1. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
2. Linear interpolation is permitted for values of L/B, h/L and θ other than shown. Interpolation shall only be
carried out between values of the same sign. Where no value of the same sign is given, assume 0.0 for
interpolation purposes.
3. Where two values of Cp are listed, this indicates that the windward roof slope is subjected to either positive
or negative pressures and the roof structure shall be designed for both conditions. Interpolation for
intermediate ratios of h/L in this case shall only be carried out between Cp values of like sign.
4. For monoslope roofs, entire roof surface is either a windward or leeward surface.
5. For flexible buildings use appropriate Gf as determined by Section 26.9.4.
6. Refer to Figure 27.4-2 for domes and Figure 27.4-3 for arched roofs.
7. Notation:
B: Horizontal dimension of building, in feet (meter), measured normal to wind direction.
L: Horizontal dimension of building, in feet (meter), measured parallel to wind direction.
h: Mean roof height in feet (meters), except that eave height shall be used for θ ≤ 10 degrees. z: Height above ground, in feet (meters).
G: Gust effect factor.
qz,qh: Velocity pressure, in pounds per square foot (N/m2
), evaluated at respective height.
θ: Angle of plane of roof from horizontal, in degrees.
8. For mansard roofs, the top horizontal surface and leeward inclined surface shall be treated as leeward
surfaces from the table.
9. Except for MWFRS’s at the roof consisting of moment resisting frames, the total horizontal shear shall not
be less than that determined by neglecting wind forces on roof surfaces.
#For roof slopes greater than 80°, use Cp = 0.8
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MINIMUM DESIGN LOADS
265
Main Wind Force Resisting System – Part 1 All Heights
Figure 27.4-2 External Pressure Coefficients, Cp Domed Roofs Enclosed, Partially Enclosed Buildings and Structures
D
o
A o o
B
o
C
h
f o
o
B
A o oB Co
B
Wind
Wind
Notes:
1. Two load cases shall be considered:
Case A. Cp values between A and B and between B and C shall be determined by linear
interpolation along arcs on the dome parallel to the wind direction;
Case B. Cp shall be the constant value of A for θ ≤ 25 degrees, and shall be determined by linear
interpolation from 25 degrees to B and from B to C.
2. Values denote Cp to be used with q(hD+f) where hD + f is the height at the top of the dome.
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Cp is constant on the dome surface for arcs of circles perpendicular to the wind direction; for
example, the arc passing through B-B-B and all arcs parallel to B-B-B.
5. For values of hD/D between those listed on the graph curves, linear interpolation shall be permitted.
6. θ = 0 degrees on dome springline, θ = 90 degrees at dome center top point. f is measured from
springline to top.
7. The total horizontal shear shall not be less than that determined by neglecting wind forces on roof
surfaces.
8. For f/D values less than 0.05, use Figure 27.4-1.
External Pressure Coefficients for Domes with a Circular Base.
(Adapted from Eurocode, 1995)
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CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
266
Main Wind Force Resisting System and Components and
Cladding – Part 1 All Heights
Figure 27.4-3 External Pressure Coefficients, Cp Arched Roofs Enclosed, Partially Enclosed Buildings and Structures
Conditions
Rise-to-span
ratio, r
Cp
Windward
quarter
Center
half
Leeward
quarter
Roof on elevated structure
0 < r < 0.2 -0.9 -0.7 - r -0.5
0.2 ≤ r < 0.3* 1.5r - 0.3 -0.7 - r -0.5
0.3 ≤ r ≤ 0.6 2.75r - 0.7 -0.7 - r -0.5
Roof springing from ground level 0 < r ≤ 0.6 1.4r -0.7 - r -0.5
*When the rise-to-span ratio is 0.2 ≤ r ≤ 0.3, alternate coefficients given by 6r - 2.1 shall also be used for
the windward quarter.
Notes:
1. Values listed are for the determination of average loads on main wind force resisting systems.
2. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
3. For wind directed parallel to the axis of the arch, use pressure coefficients from Fig. 27.4-1 with wind
directed parallel to ridge.
4. For components and cladding: (1) At roof perimeter, use the external pressure coefficients in Fig. 30.4-
2A, B and C with θ based on spring-line slope and (2) for remaining roof areas, use external pressure
coefficients of this table multiplied by 0.87.
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267
Notes:
1. CNW and CNL denote net pressures (contributions from top and bottom surfaces) for windward and leeward half of
roof surfaces, respectively.
2. Clear wind flow denotes relatively unobstructed wind flow with blockage less than or equal to 50%. Obstructed
wind flow denotes objects below roof inhibiting wind flow (>50% blockage).
3. For values of θ between 7.5o
and 45o
, linear interpolation is permitted. For values of θ less than 7.5o
, use load
coefficients for 0o
.
4. Plus and minus signs signify pressures acting towards and away from the top roof surface, respectively.
5. All load cases shown for each roof angle shall be investigated.
6. Notation:
L : horizontal dimension of roof, measured in the along wind direction, ft. (m)
h : mean roof height, ft. (m)
γ : direction of wind, degrees
θ : angle of plane of roof from horizontal, degrees
Main Wind Force Resisting System – Part 1 0.2 h/L 1.0
Figure 27.4-4 Net Pressure Coefficient, CN Monoslope Free Roofs
Open Buildings 45°, = 0°, 180°
Roof Load
Angle Case
θ CNW CNL CNW CNL CNW CNL CNW CNL
A 1.2 0.3 -0.5 -1.2 1.2 0.3 -0.5 -1.2
B -1.1 -0.1 -1.1 -0.6 -1.1 -0.1 -1.1 -0.6
A -0.6 -1 -1 -1.5 0.9 1.5 -0.2 -1.2
B -1.4 0 -1.7 -0.8 1.6 0.3 0.8 -0.3
A -0.9 -1.3 -1.1 -1.5 1.3 1.6 0.4 -1.1
B -1.9 0 -2.1 -0.6 1.8 0.6 1.2 -0.3
A -1.5 -1.6 -1.5 -1.7 1.7 1.8 0.5 -1
B -2.4 -0.3 -2.3 -0.9 2.2 0.7 1.3 0
A -1.8 -1.8 -1.5 -1.8 2.1 2.1 0.6 -1
B -2.5 -0.5 -2.3 -1.1 2.6 1 1.6 0.1
A -1.8 -1.8 -1.5 -1.8 2.1 2.2 0.7 -0.9
B -2.4 -0.6 -2.2 -1.1 2.7 1.1 1.9 0.3
A -1.6 -1.8 -1.3 -1.8 2.2 2.5 0.8 -0.9
B -2.3 -0.7 -1.9 -1.2 2.6 1.4 2.1 0.4
Wind Direction, γ = 0o Wind Direction, γ = 180o
Clear Wind Flow Obstructed Wind Flow Clear Wind Flow Obstructed Wind Flow
0
o
7.5o
15o
22.5o
30o
37.5o
45o
5 £ h/L £
q £ g
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268
Main Wind Force Resisting System – Part 1 0.2 1.0
Figure 27.4-5 Net Pressure Coefficient, CN Pitched Free Roofs
Open Buildings 45°, = 0°, 180°
Roof
Angle, θ
Load
Case
Wind Direction, γ = 0o
, 180o
Clear Wind Flow Obstructed Wind Flow
CNW CNL CNW CNL
7.5o A 1.1 -0.3 -1.6 -1
B 0.2 -1.2 -0.9 -1.7
15o A 1.1 -0.4 -1.2 -1
B 0.1 -1.1 -0.6 -1.6
22.5o A 1.1 0.1 -1.2 -1.2
B -0.1 -0.8 -0.8 -1.7
30o A 1.3 0.3 -0.7 -0.7
B -0.1 -0.9 -0.2 -1.1
37.5o A 1.3 0.6 -0.6 -0.6
B -0.2 -0.6 -0.3 -0.9
45o A 1.1 0.9 -0.5 -0.5
B -0.3 -0.5 -0.3 -0.7
Notes:
1. CNW and CNL denote net pressures (contributions from top and bottom surfaces) for windward and leeward half of
roof surfaces, respectively.
2. Clear wind flow denotes relatively unobstructed wind flow with blockage less than or equal to 50%. Obstructed
wind flow denotes objects below roof inhibiting wind flow (>50% blockage).
3. For values of θ between 7.5o
and 45o
, linear interpolation is permitted. For values of θ less than 7.5o
, use
monoslope roof load coefficients.
4. Plus and minus signs signify pressures acting towards and away from the top roof surface, respectively.
5. All load cases shown for each roof angle shall be investigated.
6. Notation:
L : horizontal dimension of roof, measured in the along wind direction, ft. (m)
h : mean roof height, ft. (m)
γ : direction of wind, degrees
θ : angle of plane of roof from horizontal, degrees
5 £ h/L £
q £ g
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MINIMUM DESIGN LOADS
269
Main Wind Force Resisting System 0.25 £ h/L £ 1.0
Figure 27.4-6 Net Pressure Coefficient, CN Troughed Free Roofs
Open Buildings q £ 45°, g = 0°, 180°
Roof Load
Angle Case
θ CNW CNL CNW CNL
A -1.1 0.3 -1.6 -0.5
B -0.2 1.2 -0.9 -0.8
A -1.1 0.4 -1.2 -0.5
B 0.1 1.1 -0.6 -0.8
A -1.1 -0.1 -1.2 -0.6
B -0.1 0.8 -0.8 -0.8
A -1.3 -0.3 -1.4 -0.4
B -0.1 0.9 -0.2 -0.5
A -1.3 -0.6 -1.4 -0.3
B 0.2 0.6 -0.3 -0.4
A -1.1 -0.9 -1.2 -0.3
B 0.3 0.5 -0.3 -0.4
Wind Direction, γ = 0o
, 180o
Clear Wind Flow Obstructed Wind Flow
37.5o
45o
7.5o
15o
22.5o
30o
Notes:
1. CNW and CNL denote net pressures (contributions from top and bottom surfaces) for windward and leeward half of roof
surfaces, respectively.
2. Clear wind flow denotes relatively unobstructed wind flow with blockage less than or equal to 50%. Obstructed wind flow
denotes objects below roof inhibiting wind flow (>50% blockage).
3. For values of θ between 7.5o
and 45o
, linear interpolation is permitted. For values of θ less than 7.5o
, use monoslope roof
load coefficients.
4. Plus and minus signs signify pressures acting towards and away from the top roof surface, respectively.
5. All load cases shown for each roof angle shall be investigated.
6. Notation:
L : horizontal dimension of roof, measured in the along wind direction, ft. (m)
h : mean roof height, ft. (m)
γ : direction of wind, degrees
θ : angle of plane of roof from horizontal, degrees
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CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
270
Main Wind Force Resisting System – Part 1 0.2 1.0
Figure 27.4-7 Net Pressure Coefficient, CN Free Roofs
Open Buildings 45°, = 90°, 270°
Horizontal
Distance from
Windward Edge
Roof Angle θ Load Case
Clear Wind
Flow
Obstructed
Wind Flow
CN CN
< h
All Shapes A -0.8 -1.2
θ < 45o B 0.8 0.5
> h, < 2h
All Shapes A -0.6 -0.9
θ < 45o B 0.5 0.5
> 2h
All Shapes A -0.3 -0.6
θ < 45o B 0.3 0.3
Notes:
1. CN denotes net pressures (contributions from top and bottom surfaces).
2. Clear wind flow denotes relatively unobstructed wind flow with blockage less than or equal to 50%. Obstructed wind
flow denotes objects below roof inhibiting wind flow (>50% blockage).
3. Plus and minus signs signify pressures acting towards and away from the top roof surface, respectively.
4. All load cases shown for each roof angle shall be investigated.
5. For monoslope roofs with theta less than 5 degrees, Cn values shown apply also for cases where gamma = 0 degrees and
0.05 less than or equal to h/L less than or equal to 0.25. See Figure 27.4-4 for other h/L values.
6. Notation:
L : horizontal dimension of roof, measured in the along wind direction, ft. (m)
h : mean roof height, ft. (m). See Figures 27.4-4, 27.4-5 or 27.4-6 for a graphical depiction of this dimension.
γ : direction of wind, degrees
θ : angle of plane of roof from horizontal, degrees
5 £ h/L £
q £ g
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MINIMUM DESIGN LOADS
271
Main Wind Force Resisting System – Part 1 All Heights
Figure 27.4-8 Design Wind Load Cases
MT = 0.75 (PWX+PLX)BX eX MT = 0.75 (PWY+PLY)BY eY MT = 0.563 (PWX+PLX)BX eX + 0.563 (PWY+PLY)BY eY
eX = ± 0.15 BX eY = ± 0.15 BY eX = ± 0.15 BX eY = ± 0.15 BY
CASE 2 CASE 4
Case 1. Full design wind pressure acting on the projected area perpendicular to each principal axis of the
structure, considered separately along each principal axis.
Case 2. Three quarters of the design wind pressure acting on the projected area perpendicular to each
principal axis of the structure in conjunction with a torsional moment as shown, considered
separately for each principal axis.
Case 3. Wind loading as defined in Case 1, but considered to act simultaneously at 75% of the specified
value.
Case 4. Wind loading as defined in Case 2, but considered to act simultaneously at 75% of the specified
value.
Notes:
1. Design wind pressures for windward and leeward faces shall be determined in accordance with the
provisions of 27.4.1 and 27.4.2 as applicable for building of all heights.
2. Diagrams show plan views of building.
3. Notation:
PWX, PWY : Windward face design pressure acting in the x, y principal axis, respectively.
PLX, PLY : Leeward face design pressure acting in the x, y principal axis, respectively.
e (eX. eY) : Eccentricity for the x, y principal axis of the structure, respectively.
MT : Torsional moment per unit height acting about a vertical axis of the building.
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272
Table 27.5-1 Steps to Determine MWFRS Wind
Loads Enclosed Simple Diaphragm Buildings
( h ≤ 160 ft. (48.8 m))
Step 1: Determine risk category of building or other
structure, see Table 1.5-1
Step 2: Determine the basic wind speed, V, for
applicable risk category, see Figure 26.5-1A, B
or C
Step 3: Determine wind load parameters:
➢ Wind directionality factor, Kd, see Section
26.6 and Table 26.6-1
➢ Exposure category B, C or D, see Section
26.7
➢ Topographic factor, Kzt, see Section 26.8 and
Figure 26.8-1
➢ Enclosure classifi cation, see Section 26.10
Step 4: Enter table to determine net pressures on walls
at top and base of building respectively, ph , p0,
Table 27.6-1
Step 5: Enter table to determine net roof pressures, pz,
Table 27.6-2
Step 6: Determine topographic factor, Kzt, and apply
factor to wall and roof pressures (if applicable),
see Section 26.8
Step 7: Apply loads to walls and roofs simultaneously.
PART 2: ENCLOSED SIMPLE DIAPHRAGM
BUILDINGS WITH h ≤ 160 ft (48.8 m)
27.5 GENERAL REQUIREMENTS
27.5.1 Design Procedure
The procedure specifi ed herein applies to the
determination of MWFRS wind loads of enclosed
simple diaphragm buildings, as defi ned in Section
26.2, with a mean roof height h ≤ 160 ft (48.8 m).
The steps required for the determination of MWFRS
wind loads on enclosed simple diaphragm buildings
are shown in Table 27.5-1.
27.5.2 Conditions
In addition to the requirements in Section 27.1.2,
a building whose design wind loads are determined in
accordance with this section shall meet all of the
following conditions for either a Class 1 or Class 2
building (see Fig. 27.5-1):
Class 1 Buildings:
1. The building shall be an enclosed simple diaphragm
building as defi ned in Section 26.2.
2. The building shall have a mean roof height h ≤ 60
ft (18.3 m).
3. The ratio of L/B shall not be less than 0.2 nor more
than 5.0 (0.2 ≤ L/B ≤ 5.0).
4. The topographic effect factor Kzt = 1.0 or the wind
pressures determined from this section shall be
multiplied by Kzt at each height z as determined
from Section 26.8. It shall be permitted to use one
value of Kzt for the building calculated at 0.33h.
Alternatively it shall be permitted to enter the
pressure table with a wind velocity equal to V
Kzt where Kzt is determined at a height of 0.33h.
Class 2 Buildings:
1. The building shall be an enclosed simple diaphragm
building as defi ned in Section 26.2.
2. The building shall have a mean roof height 60 ft <
h ≤ 160 ft (18.3 m < h ≤ 48.8 m).
3. The ratio of L/B shall not be less than 0.5 nor more
than 2.0 (0.5 ≤ L/B ≤ 2.0).
4. The fundamental natural frequency (Hertz) of the
building shall not be less 75/h where h is in feet.
5. The topographic effect factor Kzt = 1.0 or the wind
pressures determined from this section shall be
multiplied by Kzt at each height z as determined
from Section 26.8. It shall be permitted to use one
value of Kzt for the building calculated at 0.33h.
Alternatively it shall be permitted to enter the
pressure table with a wind velocity equal to V
Kzt where Kzt is determined at a height of 0.33h.
27.5.3 Wind Load Parameters Specifi ed
in Chapter 26
Refer to Chapter 26 for determination of Basic
Wind Speed V (Section 26.5) and exposure category
(Section 26.7) and topographic factor Kzt (Section
26.8).
27.5.4 Diaphragm Flexibility
The design procedure specifi ed herein applies to
buildings having either rigid or fl exible diaphragms.
The structural analysis shall consider the relative
User Note: Part 2 of Chapter 27 is a simplifi ed method
for determining the wind pressures for the MWFRS of
enclosed, simple diaphragm buildings whose height h is
≤ 160 ft (48.8 m). The wind pressures are obtained
directly from a table. The building may be of any
general plan shape and roof geometry that matches the
specifi ed fi gures. This method is a simplifi cation of the
traditional “all heights” method (Directional Procedure)
contained in Part 1 of Chapter 27.
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MINIMUM DESIGN LOADS
273
stiffness of diaphragms and the vertical elements of
the MWFRS.
Diaphragms constructed of wood panels can be
idealized as fl exible. Diaphragms constructed of
untopped metal decks, concrete fi lled metal decks, and
concrete slabs, each having a span-to-depth ratio of 2
or less, are permitted to be idealized as rigid for
consideration of wind loading.
27.6 WIND LOADS—MAIN WIND
FORCE-RESISTING SYSTEM
27.6.1 Wall and Roof Surfaces—Class 1
and 2 Buildings
Net wind pressures for the walls and roof
surfaces shall be determined from Tables 27.6-1 and
27.6-2, respectively, for the applicable exposure
category as determined by Section 26.7.
For Class 1 building with L/B values less than
0.5, use wind pressures tabulated for L/B = 0.5. For
Class 1 building with L/B values greater than 2.0, use
wind pressures tabulated for L/B = 2.0.
Net wall pressures shall be applied to the projected
area of the building walls in the direction of
the wind, and exterior side wall pressures shall be
applied to the projected area of the building walls
normal to the direction of the wind acting outward
according to Note 3 of Table 27.6-1, simultaneously
with the roof pressures from Table 27.6-2 as shown in
Fig. 27.6-1.
Where two load cases are shown in the table of
roof pressures, the effects of each load case shall be
investigated separately. The MWFRS in each direction
shall be designed for the wind load cases as
defi ned in Fig. 27.4-8.
EXCEPTION: The torsional load cases in
Fig. 27.4-8 (Case 2 and Case 4) need not be considered
for buildings which meet the requirements of
Appendix D.
27.6.2 Parapets
The effect of horizontal wind loads applied to all
vertical surfaces of roof parapets for the design of the
MWFRS shall be based on the application of an
additional net horizontal wind pressure applied to the
projected area of the parapet surface equal to 2.25
times the wall pressures tabulated in Table 27.6-1 for
L/B = 1.0. The net pressure specifi ed accounts for
both the windward and leeward parapet loading on
both the windward and leeward building surface. The
parapet pressure shall be applied simultaneously with
the specifi ed wall and roof pressures shown in the
table as shown in Fig. 27.6-2. The height h used to
enter Table 27.6-1 to determine the parapet pressure
shall be the height to the top of the parapet as shown
in Fig. 27.6-2 (use h = hp).
27.6.3 Roof Overhangs
The effect of vertical wind loads on any roof
overhangs shall be based on the application of a
positive wind pressure on the underside of the
windward overhang equal to 75% of the roof edge
pressure from Table 27.6-2 for Zone 1 or Zone 3 as
applicable. This pressure shall be applied to the
windward roof overhang only and shall be applied
simultaneously with other tabulated wall and roof
pressures as shown in Fig. 27.6-3.
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CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
274
0.2L ≤ B ≤ 5L
L
h ≤ 60 ft
Plan
Elevation
Class 1 Building
Plan
0.5L ≤ B ≤ 2L
L
h = 60 - 160 ft
Class 2 Building
Note: Roof form may be flat, gable, mansard or hip
Elevation
Mean roof ht.
Mean roof ht.
Main Wind Force Resisting System – Part 2 h £ 160 ft.
Figure 27.5-1 Building Class Building Geometry Requirements Enclosed Simple Diaphragm Buildings
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MINIMUM DESIGN LOADS
275
po
ph
Mean roof ht.
L
B
Plan
Wind
h
See Fig 27.6-2 for
parapet wind
pressures
Wall Pressures
See Table 27.6-1
Roof Pressures
See Table 27.6-2
Elevation
Main Wind Force Resisting System – Part 2 h £ 160 ft.
Figure 27.6-1 Wind Pressures – Walls and Roof Application of Wind Pressures
Enclosed Simple Diaphragm Buildings See Tables 27.6-1 and 27.6-2
θ
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CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
276
Main Wind Force Resisting System – Part 2 h £ 160 ft.
Application of Parapet Wind Loads - See
Table 27.6-1 Figure 27.6-2 Parapet Wind Loads
Enclosed Simple Diaphragm Buildings
pp
ph wall pressure
from Table 27.6-1
at height h
h
hp
Additional load on MWFRS
from all parapets and parapet surfaces
pp = 2.25 times the pressure
determined from Table 27.6-1
for a height measured to the top
of the parapet (hp)
mean roof ht.
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277
Main Wind Force Resisting System – Part 2 h £ 160 ft.
Application of Roof Overhang
Wind Loads – See Table 27.6-2
Figure 27.6-3 Roof Overhang Wind Loads
Enclosed Simple Diaphragm Buildings
Roof edge pressure from table
Zones 1 or 3 as applicable
p1 or p3
povh
Wind Direction
povh = 0.75 x p1 or p3 as applicable,
applied as an additional upward loading
(positive pressure) to roof negative edge
pressures shown
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278
Main Force Resisting System – Part 2 h £ 160 ft.
Application of Wall Pressures
Table 27.6-1 Wind Pressures - Walls
Enclosed Simple Diaphragm Buildings

Plan Wind Pressure Elevation
Notes to Wall Pressure Table 27.6-1:
1. From table for each Exposure (B, C or D), V, L/B and h, determine ph (top number) and p0 (bottom number)
horizontal along-wind net wall pressures.
2. Side wall external pressures shall be uniform over the wall surface acting outward and shall be taken as 54%
of the tabulated ph pressure for 0.2 ≤ L/B ≤ 1.0 and 64% of the tabulated ph pressure for 2.0 ≤ L/B ≤ 5.0.
Linear interpolation shall apply for 1.0 < L/B < 2.0. Side wall external pressures do not include effect of
internal pressure.
3. Apply along-wind net wall pressures as shown above to the projected area of the building walls in the
direction of the wind and apply external side wall pressures to the projected area of the building walls
normal to the direction wind, simultaneously with the roof pressures from Table 27.6-2.
4. Distribution of tabulated net wall pressures between windward and leeward wall faces shall be based on the
linear distribution of total net pressure with building height as shown above and the leeward external wall
pressures assumed uniformly distributed over the leeward wall surface acting outward at 38% of ph for
0.2 ≤ L/B ≤ 1.0 and 27% of ph for 2.0 ≤ L/B ≤ 5.0. Linear interpolation shall be used for 1.0 < L/B < 2.0.
The remaining net pressure shall be applied to the windward walls as an external wall pressure acting
towards the wall surface. Windward and leeward wall pressures so determined do not include effect of
internal pressure.
5. Interpolation between values of V, h and L/B is permitted.
Notation:
L = building plan dimension parallel to wind direction (ft.)
B = building plan dimension perpendicular to wind direction (ft)
h = mean roof height (ft.)
ph, p0 = along-wind net wall pressure at top and base of building respectively (psf)
h
L
B
Wind h
ph
p0
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MINIMUM DESIGN LOADS
279
V(mph) 110 115 120 130 140 160 180 200
h(ft.), L/B 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2
160 38.1 37.7 34.1 42.1 41.7 37.8 46.4 45.9 41.7 55.8 55.1 50.2 66.3 65.4 59.7 91.0 89.4 81.8 120.8 118.3 108.5 156.2 152.4 140.0
25.6 25.4 21.0 28.3 28.1 23.3 31.2 30.9 25.7 37.5 37.1 30.9 44.6 44.0 36.8 61.2 60.1 50.4 81.3 79.6 66.9 105.2 102.6 86.2
150 36.9 36.6 33.0 40.7 40.4 36.5 44.9 44.4 40.3 53.9 53.3 48.5 63.9 63.1 57.6 87.5 86.1 78.9 116.1 113.8 104.5 149.9 146.5 134.7
25.1 24.9 20.6 27.7 27.5 22.8 30.5 30.2 25.2 36.7 36.2 30.3 43.5 43.0 36.0 59.6 58.6 49.3 79.0 77.4 65.3 102.0 99.7 84.2
140 35.6 35.4 31.9 39.3 39.1 35.3 43.3 42.9 38.9 51.9 51.4 46.7 61.5 60.8 55.5 84.0 82.8 75.9 111.2 109.2 100.4 143.5 140.5 129.3
24.5 24.4 20.2 27.1 26.9 22.4 29.8 29.6 24.6 35.7 35.4 29.6 42.4 41.9 35.2 57.9 57.0 48.1 76.6 75.2 63.7 98.8 96.7 82.0
130 34.4 34.2 30.8 37.9 37.7 34.0 41.7 41.4 37.4 49.9 49.5 44.9 59.1 58.5 53.3 80.5 79.5 72.8 106.3 104.6 96.2 136.9 134.3 123.8
24.0 23.9 19.8 26.5 26.3 21.9 29.1 28.9 24.1 34.8 34.5 28.9 41.2 40.8 34.3 56.2 55.4 46.9 74.2 73.0 62.0 95.5 93.7 79.8
120 33.1 33.0 29.6 36.5 36.3 32.7 40.1 39.9 35.9 47.9 47.6 43.1 56.6 56.2 51.0 76.9 76.1 69.6 101.3 99.9 91.8 130.2 128.0 118.0
23.4 23.3 19.4 25.8 25.7 21.4 28.4 28.2 23.6 33.9 33.7 28.3 40.1 39.7 33.5 54.4 53.8 45.6 71.7 70.7 60.2 92.2 90.6 77.4
110 31.8 31.7 28.4 35.1 34.9 31.3 38.5 38.3 34.4 45.9 45.6 41.2 54.1 53.8 48.8 73.3 72.6 66.3 96.3 95.1 87.4 123.5 121.6 112.1
22.9 22.8 19.0 25.2 25.1 20.9 27.7 27.5 23.0 33.0 32.8 27.6 38.9 38.7 32.6 52.7 52.2 44.4 69.2 68.4 58.4 88.8 87.4 75.0
100 30.5 30.4 27.1 33.6 33.5 29.9 36.8 36.7 32.9 43.8 43.6 39.3 51.6 51.3 46.4 69.6 69.1 62.9 91.2 90.3 82.8 116.6 115.1 106.0
22.3 22.3 18.5 24.6 24.5 20.4 26.9 26.8 22.5 32.1 31.9 26.8 37.8 37.6 31.7 50.9 50.5 43.0 66.7 66.0 56.6 85.3 84.2 72.5
90 29.2 29.1 25.9 32.1 32.0 28.5 35.1 35.0 31.2 44.7 41.6 37.3 49.1 48.8 44.0 65.9 65.5 59.5 86.0 85.3 78.0 109.6 108.5 99.8
21.8 21.7 18.1 23.9 23.9 19.9 26.2 26.1 21.9 31.1 31.0 26.1 36.6 36.4 30.8 49.2 48.9 41.7 64.2 63.6 54.6 81.8 80.9 69.9
80 27.8 27.7 24.5 30.5 30.5 27.0 33.4 33.3 29.6 39.6 39.5 35.2 46.4 46.3 41.5 62.2 61.9 55.9 80.8 80.3 73.1 102.6 101.7 93.3
21.2 21.2 17.7 23.3 23.2 19.4 25.5 25.4 21.3 30.2 30.1 25.4 35.4 35.3 29.9 47.4 47.2 40.3 61.6 61.2 52.6 78.3 77.6 67.2
70 26.3 26.3 23.1 28.9 28.8 25.4 31.6 31.5 27.9 37.4 37.3 33.1 43.7 43.6 38.9 58.3 58.1 52.2 75.5 75.1 68.1 95.5 94.9 86.6
20.6 20.6 17.2 22.6 22.6 18.9 24.7 24.7 20.7 29.3 29.2 24.6 34.2 34.2 28.9 45.6 45.5 38.8 59.1 58.8 50.6 74.7 74.3 64.3
60 24.8 24.8 21.7 27.2 27.1 23.8 29.7 29.6 26.1 35.1 35.0 30.9 41.0 40.9 36.2 54.4 54.2 48.4 70.1 69.8 62.8 88.2 87.9 79.6
20.0 20.0 16.7 21.9 21.9 18.4 23.9 23.9 20.1 28.3 28.2 23.6 33.0 33.0 27.9 43.9 43.8 37.3 56.5 56.3 48.5 71.2 70.9 61.4
50 23.1 23.1 20.2 25.3 25.3 22.1 27.6 27.6 24.2 32.6 32.6 28.6 38.0 38.0 33.4 50.3 50.2 44.5 64.5 64.4 57.4 80.9 80.7 72.5
19.3 19.3 16.3 21.2 21.2 17.8 23.1 23.1 19.5 27.3 27.3 23.0 31.8 31.8 26.9 42.0 42.0 35.8 54.0 53.8 46.3 67.6 67.5 58.4
40 21.5 21.5 18.6 23.5 23.5 20.4 25.6 25.6 22.3 30.2 30.2 26.3 35.1 35.1 30.7 46.3 46.2 40.7 59.2 59.1 52.3 73.9 73.8 65.7
18.8 18.7 15.8 20.5 20.5 17.4 22.4 22.4 18.9 26.4 26.4 22.4 30.7 30.7 26.1 40.5 40.4 34.6 51.7 51.7 44.5 64.6 64.5 55.8
30 19.6 19.6 16.9 21.4 21.4 18.5 23.3 23.3 20.2 27.5 27.4 23.8 31.9 31.9 27.7 41.9 41.9 36.6 53.4 53.4 46.8 66.5 66.4 58.5
18.1 18.1 15.4 19.8 19.8 16.8 21.5 21.5 18.4 25.3 25.3 21.6 29.5 29.5 25.2 38.7 38.7 33.2 49.3 49.3 42.5 61.4 61.3 53.1
20 17.5 17.5 15.1 19.2 19.2 16.6 20.9 20.9 18.1 24.5 24.5 21.2 28.5 28.5 24.7 37.3 37.3 32.4 47.4 47.4 41.3 58.8 58.8 51.4
17.2 17.2 14.8 18.8 18.8 16.2 20.5 20.5 17.7 24.1 24.1 20.8 28.0 28.0 24.2 36.7 36.7 31.7 46.6 46.6 40.4 57.8 57.7 50.3
15 16.7 16.7 14.5 18.2 18.2 15.8 19.9 19.9 17.3 23.3 23.3 20.3 27.1 27.1 23.6 35.4 35.4 30.9 44.9 44.9 39.3 55.6 55.6 48.7
16.7 16.7 14.5 18.2 18.2 15.8 19.9 19.9 17.3 23.3 23.3 20.3 27.1 27.1 23.6 35.4 35.4 30.9 44.9 44.9 39.3 55.6 55.6 48.7
Table 27.6-1
MWFRS – Part 2: Wind Loads – Walls
Exposure B
c27.indd 279 4/14/2010 11:04:43 AM
CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
280
V(mph) 110 115 120 130 140 160 180 200
h(ft.), L/B 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2
160 49.2 48.7 43.7 54.5 53.8 48.3 60.0 59.3 53.3 72.2 71.1 64.1 85.8 84.3 76.1 117.4 115.0 103.9 155.4 151.8 137.2 200.2 195.0 176.2
36.1 35.7 30.0 40.0 39.5 33.2 44.1 43.5 36.6 53.0 52.2 44.0 62.9 61.9 52.3 86.2 84.4 71.5 114.1 111.4 94.3 146.9 143.1 121.1
150 48.0 47.5 42.6 53.0 52.4 47.1 58.4 57.7 51.9 70.1 69.2 62.3 83.3 82.0 74.0 113.8 111.7 101.0 150.6 147.3 133.3 193.8 189.0 171.0
35.5 35.2 29.6 39.3 38.8 32.7 43.3 42.8 36.1 52.0 51.3 43.3 61.7 60.7 51.4 84.3 82.8 70.2 111.5 109.1 92.7 143.5 140.0 118.9
140 46.6 46.2 41.4 51.5 51.0 45.8 56.7 56.1 50.4 68.1 67.2 60.6 80.7 79.6 71.8 110.2 108.3 98.0 145.6 142.6 129.2 187.2 182.9 165.7
34.9 34.6 29.1 38.6 38.2 32.2 42.4 42.0 35.5 50.9 50.3 42.6 60.4 59.5 50.6 82.4 81.0 68.9 108.9 106.7 90.9 140.0 136.8 116.6
130 45.3 45.0 40.2 50.0 49.6 44.5 55.0 54.5 48.9 65.9 65.2 58.7 78.1 77.1 69.6 106.4 104.7 94.8 140.4 137.7 124.9 180.4 176.5 160.1
34.3 34.0 28.7 37.8 37.5 31.7 41.6 41.2 34.9 49.9 49.3 41.9 59.1 58.3 49.6 80.5 79.2 67.6 106.2 104.1 89.1 136.4 133.4 114.2
120 43.9 43.6 39.0 48.5 48.1 43.1 53.3 52.8 47.4 63.8 63.1 56.8 75.4 74.6 67.3 102.6 101.1 91.5 135.1 132.7 120.5 173.3 169.8 154.3
33.6 33.4 28.2 37.1 36.8 31.1 40.7 40.4 34.3 48.8 48.3 41.1 57.7 57.1 48.7 78.5 77.3 66.2 103.3 101.5 87.1 132.6 129.9 111.6
110 42.5 42.3 37.7 46.9 46.6 41.6 51.5 51.1 45.8 61.5 61.0 54.8 72.7 72.0 64.8 98.6 97.3 88.1 129.6 127.6 115.8 166.0 163.0 148.2
32.9 32.8 27.7 36.3 36.1 30.6 39.9 39.6 33.6 47.7 47.3 40.3 56.3 55.8 47.6 76.4 75.4 64.7 100.4 98.8 85.1 128.6 126.3 108.9
100 41.1 40.9 36.4 45.2 45.0 40.1 49.6 49.3 44.1 59.2 58.8 52.7 69.8 69.3 62.3 94.5 93.5 84.5 123.9 122.2 111.0 158.5 155.9 141.9
32.3 32.1 27.2 35.5 35.4 30.0 39.0 38.8 33.0 46.5 46.2 39.4 54.9 54.4 46.6 74.2 73.4 63.2 97.4 96.0 82.9 124.5 122.5 106.1
90 39.6 39.4 35.0 43.5 43.3 38.5 47.7 47.5 42.3 56.8 56.5 50.6 66.9 66.5 59.7 90.3 89.4 80.8 118.1 116.7 105.9 150.6 148.5 135.2
31.6 31.5 26.6 34.7 34.6 29.4 38.1 37.9 32.3 45.4 45.1 38.5 53.4 53.1 45.5 72.1 71.4 61.6 94.2 93.2 80.7 120.3 118.6 103.0
80 38.0 37.9 33.5 41.8 41.6 36.9 45.8 45.6 40.5 54.4 54.2 48.3 63.9 63.6 56.9 85.9 85.3 76.8 112.0 111.0 100.5 142.6 140.9 128.1
30.9 30.8 26.1 33.9 33.8 28.7 37.2 37.1 31.5 44.2 44.0 37.6 52.0 51.7 44.3 69.8 69.3 59.8 91.0 90.2 78.3 115.8 114.5 99.8
70 36.4 36.3 32.0 39.9 39.9 35.2 43.7 43.6 38.6 51.9 51.7 45.9 60.8 60.6 54.0 81.4 81.0 72.7 105.8 105.0 94.9 134.2 133.0 120.7
30.2 30.1 25.5 33.1 33.1 28.1 36.3 36.2 30.8 43.0 42.9 36.6 50.5 50.3 43.1 67.5 67.2 58.0 87.8 87.1 75.7 111.3 110.3 96.3
60 34.6 34.6 30.3 38.0 38.0 33.3 41.6 41.5 36.5 49.2 49.1 43.4 57.6 57.4 50.9 76.8 76.5 68.3 99.4 98.8 88.9 125.6 124.7 112.8
29.4 29.4 24.9 32.3 32.2 27.4 35.3 35.2 30.0 41.8 41.7 35.6 48.9 48.8 41.9 65.2 65.0 56.1 84.4 83.9 73.0 106.7 105.9 92.7
50 32.8 32.8 28.6 36.0 35.9 31.4 39.3 39.2 34.3 46.4 46.3 40.7 54.2 54.1 47.7 72.0 71.8 63.7 92.7 92.4 82.5 116.7 116.1 104.4
28.7 28.6 24.3 31.4 31.4 26.7 34.3 34.3 29.2 40.5 40.5 34.6 47.4 47.3 40.5 62.9 62.7 54.2 81.0 80.7 70.2 101.9 101.4 88.8
40 30.8 30.8 26.7 33.7 33.7 29.3 36.8 36.8 32.0 43.4 43.4 37.8 50.6 50.5 44.2 66.9 66.8 58.8 85.8 85.6 75.8 107.4 107.1 95.5
27.8 27.8 23.6 30.5 30.5 25.9 33.3 33.2 28.3 39.2 39.2 33.5 45.7 45.7 39.2 60.4 60.3 52.1 77.5 77.3 67.2 97.1 96.8 84.6
30 28.5 28.5 24.6 31.2 31.2 27.0 34.1 34.1 29.5 40.1 40.1 34.8 46.7 46.6 40.5 61.4 61.4 53.6 78.4 78.3 68.8 97.8 97.6 86.1
26.9 26.9 22.9 29.4 29.4 25.1 32.1 32.1 27.4 37.8 37.8 32.4 44.0 43.9 37.7 57.9 57.8 49.9 73.9 73.8 64.0 92.1 91.9 80.2
20 26.2 26.2 22.6 28.6 28.6 24.7 31.2 31.2 26.9 36.7 36.7 31.7 42.6 42.6 36.9 55.9 55.9 48.5 71.1 71.1 61.9 88.2 88.2 77.0
25.8 25.8 22.2 28.3 28.3 24.3 30.8 30.8 26.5 36.2 36.2 31.2 42.1 42.1 36.3 55.2 55.1 47.7 70.1 70.1 60.9 87.1 87.0 75.8
15 25.2 25.2 21.8 27.6 27.6 23.8 30.0 30.0 26.0 35.3 35.3 30.6 41.0 41.0 35.5 53.7 53.7 46.6 68.1 68.1 59.3 84.4 84.4 73.6
25.2 25.2 21.8 27.6 27.6 23.8 30.0 30.0 26.0 35.3 35.3 30.6 41.0 41.0 35.5 53.7 53.7 46.6 68.1 68.1 59.3 84.4 84.4 73.6
Table 27.6-1
MWFRS – Part 2: Wind Loads – Walls
Exposure C
c27.indd 280 4/14/2010 11:04:43 AM
MINIMUM DESIGN LOADS
281
V(mph) 110 115 120 130 140 160 180 200
h(ft.), L/B 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2 0.5 1 2
160 55.7 55.1 49.1 61.6 60.8 54.3 67.9 67.0 59.7 81.5 80.3 71.7 96.7 95.0 85.0 131.9 129.2 115.6 173.9 169.9 152.0 223.0 217.5 194.4
42.9 42.4 35.7 47.4 46.8 39.5 52.2 51.5 43.5 62.7 61.7 52.2 74.4 73.1 61.9 101.4 99.4 84.2 133.7 130.7 110.7 171.5 167.2 141.6
150 54.5 53.9 48.0 60.2 59.5 53.0 66.3 65.4 58.4 79.5 78.4 70.0 94.3 92.8 83.0 128.5 126.0 112.8 169.3 165.6 148.3 217.0 211.8 189.6
42.2 41.8 35.3 46.7 46.1 39.0 51.4 50.7 43.0 61.6 60.8 51.5 73.1 71.9 61.0 99.6 97.7 83.0 131.2 128.3 109.1 168.2 164.2 139.4
140 53.2 52.7 46.9 58.7 58.1 51.8 64.6 63.9 57.0 77.5 76.5 68.3 91.8 90.4 80.9 124.9 122.7 109.9 164.5 161.1 144.4 210.7 205.9 184.5
41.6 41.2 34.8 45.9 45.4 38.5 50.5 49.9 42.4 60.6 59.8 50.8 71.7 70.7 60.1 97.7 95.9 81.7 128.6 125.9 107.3 164.7 160.9 137.2
130 51.8 51.4 45.7 57.2 56.7 50.5 62.9 62.3 55.5 75.4 74.5 66.5 89.2 88.0 78.7 121.2 119.2 106.9 159.5 156.4 140.3 204.2 199.7 179.2
40.9 40.5 34.4 45.1 44.7 38.0 49.7 49.1 41.8 59.5 58.8 50.0 70.4 69.4 59.2 95.7 94.1 80.4 125.8 123.4 105.5 161.1 157.6 134.7
120 50.4 50.1 44.5 55.7 55.2 49.1 61.2 60.6 54.0 73.2 72.4 64.7 86.5 85.5 76.5 117.4 115.6 103.7 154.2 151.5 136.1 197.3 193.3 173.7
40.2 39.9 33.9 44.4 44.0 37.4 48.8 48.3 41.1 58.3 57.7 49.2 69.0 68.1 58.2 93.6 92.2 78.9 122.9 120.7 103.5 157.3 154.0 132.2
110 49.0 48.7 43.2 54.0 53.6 47.7 59.4 58.9 52.4 70.9 70.2 62.7 83.8 82.8 74.1 113.4 111.9 100.4 148.8 146.3 131.6 190.2 186.5 167.9
39.5 39.2 33.3 43.5 43.2 36.8 47.8 47.5 40.4 57.2 56.6 48.4 67.5 66.8 57.2 91.4 90.2 77.4 119.9 117.9 101.5 153.2 150.3 129.5
100 47.5 47.3 41.9 52.4 52.0 46.2 57.5 57.1 50.8 68.6 68.0 60.7 80.9 80.1 71.6 109.3 108.0 96.9 143.1 141.0 126.8 182.7 179.5 161.7
38.8 38.6 32.8 42.7 42.5 36.2 46.9 46.6 39.7 55.9 55.5 47.5 66.0 65.4 56.1 89.2 88.1 75.9 116.8 115.0 99.3 149.0 146.4 126.6
90 46.0 45.8 40.5 50.6 50.4 44.6 55.5 55.2 49.0 66.2 65.7 58.5 77.9 77.3 69.0 105.0 103.9 93.2 137.2 135.4 121.8 174.8 172.1 155.2
38.0 37.9 32.2 41.9 41.7 35.5 45.9 45.7 39.0 54.7 54.3 46.6 64.4 63.9 54.9 86.8 85.9 74.2 113.5 112.0 97.0 144.6 142.3 123.5
80 44.4 44.2 39.0 48.8 48.6 43.0 53.5 53.3 47.2 63.6 63.3 56.2 74.8 74.3 66.2 100.6 99.7 89.3 131.0 129.6 116.5 166.6 164.4 148.2
37.3 37.1 31.6 41.0 40.8 34.8 44.9 44.7 38.2 53.4 53.1 45.6 62.8 62.4 53.7 84.4 83.7 72.4 110.0 108.8 94.5 139.9 138.0 120.2
70 42.7 42.6 37.4 46.9 46.8 41.2 51.4 51.2 45.2 61.0 60.7 53.8 71.6 71.2 63.3 95.9 95.2 85.1 124.6 123.5 110.9 158.0 156.3 140.8
36.5 36.4 31.0 40.1 40.0 34.1 43.9 43.8 37.4 52.1 51.9 44.5 61.2 60.9 52.4 81.9 81.4 70.5 106.5 105.5 91.8 135.0 133.5 116.6
60 40.9 40.9 35.8 44.9 44.8 39.3 49.2 49.0 43.1 58.2 58.1 51.2 68.2 68.0 60.1 91.0 90.6 80.6 117.9 117.1 104.8 149.0 147.7 132.8
35.7 35.6 30.3 39.2 39.1 33.4 42.9 42.8 36.6 50.8 50.6 43.4 59.5 59.3 51.0 79.4 79.0 68.4 102.8 102.1 88.9 129.9 128.8 112.7
50 39.0 39.0 34.0 42.8 42.7 37.3 46.8 46.7 40.8 55.3 55.2 48.4 64.7 64.5 56.8 85.9 85.6 75.9 110.8 110.3 98.3 139.5 138.7 124.2
34.9 34.8 29.7 38.2 38.2 32.6 41.8 41.7 35.7 49.4 49.3 42.3 57.7 57.6 49.6 76.7 76.5 66.2 99.0 98.5 85.8 124.6 123.8 108.5
40 37.0 36.9 32.0 40.5 40.5 35.1 44.2 44.2 38.4 52.2 52.1 45.4 60.9 60.8 53.1 80.5 80.4 70.7 103.4 103.1 91.2 129.6 129.1 114.9
34.0 33.9 28.9 37.2 37.2 31.7 40.6 40.6 34.7 47.9 47.9 41.1 55.9 55.8 48.0 74.0 73.8 63.9 95.0 94.7 82.5 119.1 118.7 103.9
30 34.7 34.6 29.9 37.9 37.9 32.7 41.4 41.4 35.7 48.7 48.7 42.2 56.7 56.7 49.2 74.8 74.7 65.2 95.5 95.4 83.7 119.2 119.0 104.9
33.0 33.0 28.2 36.1 36.1 30.9 39.4 39.4 33.7 46.4 46.3 39.8 54.0 54.0 46.4 71.1 71.1 61.4 90.9 90.8 78.9 113.5 113.2 98.9
20 32.2 32.1 27.6 35.2 35.2 30.3 38.3 38.3 33.0 45.1 45.1 38.8 52.4 52.4 45.2 68.7 68.7 59.5 87.5 87.4 76.0 108.6 108.5 94.7
31.8 31.8 27.3 34.8 34.8 29.9 37.9 37.9 32.6 44.6 44.6 38.3 51.8 51.8 44.6 68.0 68.0 58.8 86.5 86.5 75.0 107.5 107.4 93.5
15 31.1 31.1 26.8 34.0 34.0 29.3 37.0 37.0 31.9 43.5 43.5 37.5 50.5 50.5 43.6 66.2 66.1 57.3 84.0 84.0 73.0 104.1 104.1 90.7
31.1 31.1 26.8 34.0 34.0 29.3 37.0 37.0 31.9 43.5 43.5 37.5 50.5 50.5 43.6 66.2 66.1 57.3 84.0 84.0 73.0 104.1 104.1 90.7
Table 27.6-1
MWFRS – Part 2: Wind Loads – Walls
Exposure D
c27.indd 281 4/14/2010 11:04:43 AM
CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
282
Main Wind Force Resisting System – Part 2 h £ 160 ft.
Application of Roof Pressures Table 27.6-2 Wind Pressures - Roof
Enclosed Simple Diaphragm Buildings
Notes to Roof Pressure Table 27.6-2:
1. From table for Exposure C, V, h and roof slope, determine roof pressure ph for each roof zone shown in the
figures for the applicable roof form. For other exposures B or D, multiply pressures from table by
appropriate exposure adjustment factor as determined from figure below.
2. Where two load cases are shown, both load cases shall be investigated. Load case 2 is required to investigate
maximum overturning on the building from roof pressures shown.
3. Apply along-wind net wall pressures to the projected area of the building walls in the direction of the wind
and apply exterior side wall pressures to the projected area of the building walls normal to the direction of
the wind acting outward, simultaneously with the roof pressures from Table 27.6-2.
4. Where a value of zero is shown in the tables for the flat roof case, it is provided for the purpose of
interpolation.
5. Interpolation between V, h and roof slope is permitted.
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25
Building height h (ft.)
Exposure Adjustment Factor
Roof Pressures - MWFRS
Exposure Adjustment Factor
Exposure B Exposure D
Exposure Adjustment Factor
h (ft.) Exp B Exp D
160 0.809 1.113
150 0.805 1.116
140 0.801 1.118
130 0.796 1.121
120 0.792 1.125
110 0.786 1.128
100 0.781 1.132
90 0.775 1.137
80 0.768 1.141
70 0.760 1.147
60 0.751 1.154
50 0.741 1.161
40 0.729 1.171
30 0.713 1.183
20 0.692 1.201
15 0.677 1.214
c27.indd 282 4/14/2010 11:04:44 AM
MINIMUM DESIGN LOADS
283
Main Wind Force Resisting System – Part 2 h £ 160 ft.
Table 27.6-2 Wind Pressures - Roof
Application of Roof Pressures Enclosed Simple Diaphragm Buildings


0.5h
0.5h
3 h
4
5
Wind
θ
1
2
Wind
θ
h Wind 0.5h
0.5h
3
4
5
5 4
3
1
2
3
4
5
4 5
3
h
0.5h
0.5h
Wind
1
2
3 4
5
5
4
3
h
0.5h
0.5h
Wind
1
h θ
Wind
2
h θ
Wind
3 4
Wind
5
h
0.5h 0.5h
θ
1
2
Wind
2
Flat Roof
(θ < 10 deg)
Gable Roof
Hip Roof
Monoslope
Roof
4
h
Wind
3
5
0.5h
0.5h
Mansard Roof
c27.indd 283 4/14/2010 11:04:44 AM
CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
284
V (MPH) 110 115 120
Load Zone Zone Zone
h (ft) Roof Slope Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat < 2:12 (9.46 deg) 1 NA NA -29.1 -26.0 -21.3 NA NA -31.8 -28.4 -23.3 NA NA -34.7 -30.9 -25.3
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -28.6 -19.4 -29.1 -26.0 -21.3 -31.2 -22.5 -31.8 -28.4 -23.3 -34.0 -23.1 -34.7 -30.9 -25.3
2 4.1 -5.8 0.0 0.0 0.0 4.5 -6.3 0.0 0.0 0.0 4.9 -6.9 0.0 0.0 0.0
4:12 (18.4 deg) 1 -23.5 -19.0 -29.1 -26.0 -21.3 -25.7 -20.7 -31.8 -28.4 -23.3 -28.0 -22.6 -34.7 -30.9 -25.3
2 8.1 -8.3 0.0 0.0 0.0 8.9 -9.1 0.0 0.0 0.0 9.7 -9.9 0.0 0.0 0.0
40 5:12 (22.6 deg) 1 -18.8 -19.0 -29.1 -26.0 -21.3 -20.6 -20.7 -31.8 -28.4 -23.3 -22.4 -22.6 -34.7 -30.9 -25.3
2 10.8 -9.1 0.0 0.0 0.0 11.8 -9.9 0.0 0.0 0.0 12.9 -10.8 0.0 0.0 0.0
6:12 (26.6 deg) 1 -15.1 -19.0 -29.1 -26.0 -21.3 -16.5 -20.7 -31.8 -28.4 -23.3 -18.0 -22.6 -34.7 -30.9 -25.3
2 12.0 -9.1 0.0 0.0 0.0 13.1 -9.9 0.0 0.0 0.0 14.2 -10.8 0.0 0.0 0.0
9:12 (36.9 deg) 1 -8.8 -19.0 -29.1 -26.0 -21.3 -9.6 -20.7 -31.8 -28.4 -23.3 -10.4 -22.6 -34.7 -30.9 -25.3
2 14.3 -9.1 0.0 0.0 0.0 15.6 -9.9 0.0 0.0 0.0 17.0 -10.8 0.0 0.0 0.0
12:12 (45.0 deg) 1 -4.9 -19.0 -29.1 -26.0 -21.3 -5.4 -20.7 -31.8 -28.4 -23.3 -5.9 -22.6 -34.7 -30.9 -25.3
2 14.3 -9.1 0.0 0.0 0.0 15.6 -9.9 0.0 0.0 0.0 17.0 -10.8 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -27.4 -24.4 -20.0 NA NA -30.0 -26.7 -21.9 NA NA -32.6 -29.1 -23.9
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -26.9 -18.3 -27.4 -24.4 -20.0 -29.4 -21.2 -30.0 -26.7 -21.9 -32.0 -21.8 -32.6 -29.1 -23.9
2 3.9 -5.5 0.0 0.0 0.0 4.2 -6.0 0.0 0.0 0.0 4.6 -6.5 0.0 0.0 0.0
4:12 (18.4 deg) 1 -22.1 -17.8 -27.4 -24.4 -20.0 -24.2 -19.5 -30.0 -26.7 -21.9 -26.3 -21.2 -32.6 -29.1 -23.9
2 7.7 -7.8 0.0 0.0 0.0 8.4 -8.6 0.0 0.0 0.0 9.1 -9.3 0.0 0.0 0.0
30 5:12 (22.6 deg) 1 -17.7 -17.8 -27.4 -24.4 -20.0 -19.4 -19.5 -30.0 -26.7 -21.9 -21.1 -21.2 -32.6 -29.1 -23.9
2 10.2 -8.5 0.0 0.0 0.0 11.1 -9.3 0.0 0.0 0.0 12.1 -10.2 0.0 0.0 0.0
6:12 (26.6 deg) 1 -14.3 -17.8 -27.4 -24.4 -20.0 -15.6 -19.5 -30.0 -26.7 -21.9 -17.0 -21.2 -32.6 -29.1 -23.9
2 11.3 -8.5 0.0 0.0 0.0 12.3 -9.3 0.0 0.0 0.0 13.4 -10.2 0.0 0.0 0.0
9:12 (36.9 deg) 1 -8.3 -17.8 -27.4 -24.4 -20.0 -9.0 -19.5 -30.0 -26.7 -21.9 -9.8 -21.2 -32.6 -29.1 -23.9
2 13.4 -8.5 0.0 0.0 0.0 14.7 -9.3 0.0 0.0 0.0 16.0 -10.2 0.0 0.0 0.0
12:12 (45.0 deg) 1 -4.7 -17.8 -27.4 -24.4 -20.0 -5.1 -19.5 -30.0 -26.7 -21.9 -5.5 -21.2 -32.6 -29.1 -23.9
2 13.4 -8.5 0.0 0.0 0.0 14.7 -9.3 0.0 0.0 0.0 16.0 -10.2 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -25.2 -22.4 -18.4 NA NA -27.5 -24.5 -20.1 NA NA -30.0 -26.7 -21.9
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -24.7 -16.8 -25.2 -22.4 -18.4 -27.0 -19.4 -27.5 -24.5 -20.1 -29.4 -20.0 -30.0 -26.7 -21.9
2 3.6 -5.0 0.0 0.0 0.0 3.9 -5.5 0.0 0.0 0.0 4.2 -6.0 0.0 0.0 0.0
4:12 (18.4 deg) 1 -20.3 -16.4 -25.2 -22.4 -18.4 -22.2 -17.9 -27.5 -24.5 -20.1 -24.2 -19.5 -30.0 -26.7 -21.9
2 7.0 -7.2 0.0 0.0 0.0 7.7 -7.9 0.0 0.0 0.0 8.4 -8.6 0.0 0.0 0.0
20 5:12 (22.6 deg) 1 -16.3 -16.4 -25.2 -22.4 -18.4 -17.8 -17.9 -27.5 -24.5 -20.1 -19.4 -19.5 -30.0 -26.7 -21.9
2 9.4 -7.8 0.0 0.0 0.0 10.2 -8.6 0.0 0.0 0.0 11.1 -9.3 0.0 0.0 0.0
6:12 (26.6 deg) 1 -13.1 -16.4 -25.2 -22.4 -18.4 -14.3 -17.9 -27.5 -24.5 -20.1 -15.6 -19.5 -30.0 -26.7 -21.9
2 10.3 -7.8 0.0 0.0 0.0 11.3 -8.6 0.0 0.0 0.0 12.3 -9.3 0.0 0.0 0.0
9:12 (36.9 deg) 1 -7.6 -16.4 -25.2 -22.4 -18.4 -8.3 -17.9 -27.5 -24.5 -20.1 -9.0 -19.5 -30.0 -26.7 -21.9
2 12.3 -7.8 0.0 0.0 0.0 13.5 -8.6 0.0 0.0 0.0 14.7 -9.3 0.0 0.0 0.0
12:12 (45.0 deg) 1 -4.3 -16.4 -25.2 -22.4 -18.4 -4.7 -17.9 -27.5 -24.5 -20.1 -5.1 -19.5 -30.0 -26.7 -21.9
2 12.3 -7.8 0.0 0.0 0.0 13.5 -8.6 0.0 0.0 0.0 14.7 -9.3 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -23.7 -21.1 -17.3 NA NA -25.9 -23.1 -18.9 NA NA -28.2 -25.1 -20.6
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -23.2 -15.8 -23.7 -21.1 -17.3 -25.4 -18.3 -25.9 -23.1 -18.9 -27.7 -18.8 -28.2 -25.1 -20.6
2 3.4 -4.7 0.0 0.0 0.0 3.7 -5.2 0.0 0.0 0.0 4.0 -5.6 0.0 0.0 0.0
4:12 (18.4 deg) 1 -19.1 -15.4 -23.7 -21.1 -17.3 -20.9 -16.9 -25.9 -23.1 -18.9 -22.7 -18.4 -28.2 -25.1 -20.6
2 6.6 -6.8 0.0 0.0 0.0 7.2 -7.4 0.0 0.0 0.0 7.9 -8.1 0.0 0.0 0.0
15 5:12 (22.6 deg) 1 -15.3 -15.4 -23.7 -21.1 -17.3 -16.8 -16.9 -25.9 -23.1 -18.9 -18.2 -18.4 -28.2 -25.1 -20.6
2 8.8 -7.4 0.0 0.0 0.0 9.6 -8.1 0.0 0.0 0.0 10.5 -8.8 0.0 0.0 0.0
6:12 (26.6 deg) 1 -12.3 -15.4 -23.7 -21.1 -17.3 -13.5 -16.9 -25.9 -23.1 -18.9 -14.7 -18.4 -28.2 -25.1 -20.6
2 9.7 -7.4 0.0 0.0 0.0 10.6 -8.1 0.0 0.0 0.0 11.6 -8.8 0.0 0.0 0.0
9:12 (36.9 deg) 1 -7.1 -15.4 -23.7 -21.1 -17.3 -7.8 -16.9 -25.9 -23.1 -18.9 -8.5 -18.4 -28.2 -25.1 -20.6
2 11.6 -7.4 0.0 0.0 0.0 12.7 -8.1 0.0 0.0 0.0 13.8 -8.8 0.0 0.0 0.0
12:12 (45.0 deg) 1 -4.0 -15.4 -23.7 -21.1 -17.3 -4.4 -16.9 -25.9 -23.1 -18.9 -4.8 -18.4 -28.2 -25.1 -20.6
2 11.6 -7.4 0.0 0.0 0.0 12.7 -8.1 0.0 0.0 0.0 13.8 -8.8 0.0 0.0 0.0
Table 27.6-2
MWFRS- Part 2: Wind Loads - Roof
Exposure C
MWFRS – Roof
V = 110–120 mph
h = 15–40 ft.
c27.indd 284 4/14/2010 11:04:45 AM
MINIMUM DESIGN LOADS
285
V (MPH) 130 140 150
Load Zone Zone Zone
h (ft) Roof Slope Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat < 2:12 (9.46 deg) 1 NA NA -40.7 -36.3 -29.7 NA NA -47.2 -42.1 -34.5 NA NA -54.2 -48.3 -39.6
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -39.9 -27.1 -40.7 -36.3 -29.7 -46.3 -31.5 -47.2 -42.1 -34.5 -53.1 -36.1 -54.2 -48.3 -39.6
2 5.8 -8.1 0.0 0.0 0.0 6.7 -9.4 0.0 0.0 0.0 7.7 -10.8 0.0 0.0 0.0
4:12 (18.4 deg) 1 -32.8 -26.5 -40.7 -36.3 -29.7 -38.1 -30.7 -47.2 -42.1 -34.5 -43.7 -35.3 -54.2 -48.3 -39.6
2 11.4 -11.6 0.0 0.0 0.0 13.2 -13.5 0.0 0.0 0.0 15.1 -15.5 0.0 0.0 0.0
40 5:12 (22.6 deg) 1 -26.3 -26.5 -40.7 -36.3 -29.7 -30.5 -30.7 -47.2 -42.1 -34.5 -35.1 -35.3 -54.2 -48.3 -39.6
2 15.1 -12.7 0.0 0.0 0.0 17.5 -14.7 0.0 0.0 0.0 20.1 -16.9 0.0 0.0 0.0
6:12 (26.6 deg) 1 -21.1 -26.5 -40.7 -36.3 -29.7 -24.5 -30.7 -47.2 -42.1 -34.5 -28.2 -35.3 -54.2 -48.3 -39.6
2 16.7 -12.7 0.0 0.0 0.0 19.4 -14.7 0.0 0.0 0.0 22.2 -16.9 0.0 0.0 0.0
9:12 (36.9 deg) 1 -12.2 -26.5 -40.7 -36.3 -29.7 -14.2 -30.7 -47.2 -42.1 -34.5 -16.3 -35.3 -54.2 -48.3 -39.6
2 20.0 -12.7 0.0 0.0 0.0 23.1 -14.7 0.0 0.0 0.0 8.5 -16.9 0.0 0.0 0.0
12:12 (45.0 deg) 1 -6.9 -26.5 -40.7 -36.3 -29.7 -8.0 -30.7 -47.2 -42.1 -34.5 -9.2 -35.3 -54.2 -48.3 -39.6
2 20.0 -12.7 0.0 0.0 0.0 23.1 -14.7 0.0 0.0 0.0 26.6 -16.9 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -38.3 -34.1 -28.0 NA NA -44.4 -39.6 -32.5 NA NA -51.0 -45.4 -37.3
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -37.6 -25.5 -38.3 -34.1 -28.0 -43.6 -29.6 -44.4 -39.6 -32.5 -50.0 -34.0 -51.0 -45.4 -37.3
2 5.4 -7.6 0.0 0.0 0.0 6.3 -8.8 0.0 0.0 0.0 7.2 -10.1 0.0 0.0 0.0
4:12 (18.4 deg) 1 -30.9 -24.9 -38.3 -34.1 -28.0 -35.8 -28.9 -44.4 -39.6 -32.5 -41.1 -33.2 -51.0 -45.4 -37.3
2 10.7 -10.9 0.0 0.0 0.0 12.4 -12.7 0.0 0.0 0.0 14.2 -14.6 0.0 0.0 0.0
30 5:12 (22.6 deg) 1 -24.8 -24.9 -38.3 -34.1 -28.0 -28.7 -28.9 -44.4 -39.6 -32.5 -33.0 -33.2 -51.0 -45.4 -37.3
2 14.2 -11.9 0.0 0.0 0.0 16.5 -13.8 0.0 0.0 0.0 18.9 -15.9 0.0 0.0 0.0
6:12 (26.6 deg) 1 -19.9 -24.9 -38.3 -34.1 -28.0 -23.1 -28.9 -44.4 -39.6 -32.5 -26.5 -33.2 -51.0 -45.4 -37.3
2 15.7 -11.9 0.0 0.0 0.0 18.2 -13.8 0.0 0.0 0.0 20.9 -15.9 0.0 0.0 0.0
9:12 (36.9 deg) 1 -11.5 -24.9 -38.3 -34.1 -28.0 -13.4 -28.9 -44.4 -39.6 -32.5 -15.3 -33.2 -51.0 -45.4 -37.3
2 18.8 -11.9 0.0 0.0 0.0 21.8 -13.8 0.0 0.0 0.0 8.0 -15.9 0.0 0.0 0.0
12:12 (45.0 deg) 1 -6.5 -24.9 -38.3 -34.1 -28.0 -7.5 -28.9 -44.4 -39.6 -32.5 -8.7 -33.2 -51.0 -45.4 -37.3
2 18.8 -11.9 0.0 0.0 0.0 21.8 -13.8 0.0 0.0 0.0 25.0 -15.9 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -35.2 -31.3 -25.7 NA NA -40.8 -36.3 -29.8 NA NA -46.8 -41.7 -34.2
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -34.5 -23.4 -35.2 -31.3 -25.7 -40.0 -27.2 -40.8 -36.3 -29.8 -45.9 -31.2 -46.8 -41.7 -34.2
2 5.0 -7.0 0.0 0.0 0.0 5.8 -8.1 0.0 0.0 0.0 6.6 -9.3 0.0 0.0 0.0
4:12 (18.4 deg) 1 -28.4 -22.9 -35.2 -31.3 -25.7 -32.9 -26.5 -40.8 -36.3 -29.8 -37.8 -30.5 -46.8 -41.7 -34.2
2 9.8 -10.0 0.0 0.0 0.0 11.4 -11.7 0.0 0.0 0.0 13.1 -13.4 0.0 0.0 0.0
20 5:12 (22.6 deg) 1 -22.8 -22.9 -35.2 -31.3 -25.7 -26.4 -26.5 -40.8 -36.3 -29.8 -30.3 -30.5 -46.8 -41.7 -34.2
2 13.1 -10.9 0.0 0.0 0.0 15.2 -12.7 0.0 0.0 0.0 17.4 -14.6 0.0 0.0 0.0
6:12 (26.6 deg) 1 -18.3 -22.9 -35.2 -31.3 -25.7 -21.2 -26.5 -40.8 -36.3 -29.8 -24.3 -30.5 -46.8 -41.7 -34.2
2 14.4 -10.9 0.0 0.0 0.0 16.7 -12.7 0.0 0.0 0.0 19.2 -14.6 0.0 0.0 0.0
9:12 (36.9 deg) 1 -10.6 -22.9 -35.2 -31.3 -25.7 -12.3 -26.5 -40.8 -36.3 -29.8 -14.1 -30.5 -46.8 -41.7 -34.2
2 17.2 -10.9 0.0 0.0 0.0 20.0 -12.7 0.0 0.0 0.0 7.4 -14.6 0.0 0.0 0.0
12:12 (45.0 deg) 1 -6.0 -22.9 -35.2 -31.3 -25.7 -6.9 -26.5 -40.8 -36.3 -29.8 -7.9 -30.5 -46.8 -41.7 -34.2
2 17.2 -10.9 0.0 0.0 0.0 20.0 -12.7 0.0 0.0 0.0 23.0 -14.6 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -33.1 -29.5 -24.2 NA NA -38.4 -34.2 -28.1 NA NA -44.1 -39.3 -32.2
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -32.5 -22.1 -33.1 -29.5 -24.2 -37.7 -25.6 -38.4 -34.2 -28.1 -43.2 -29.4 -44.1 -39.3 -32.2
2 4.7 -6.6 0.0 0.0 0.0 5.4 -7.6 0.0 0.0 0.0 6.2 -8.8 0.0 0.0 0.0
4:12 (18.4 deg) 1 -26.7 -21.5 -33.1 -29.5 -24.2 -31.0 -25.0 -38.4 -34.2 -28.1 -35.5 -28.7 -44.1 -39.3 -32.2
2 9.2 -9.5 0.0 0.0 0.0 10.7 -11.0 0.0 0.0 0.0 12.3 -12.6 0.0 0.0 0.0
15 5:12 (22.6 deg) 1 -21.4 -21.5 -33.1 -29.5 -24.2 -24.8 -25.0 -38.4 -34.2 -28.1 -28.5 -28.7 -44.1 -39.3 -32.2
2 12.3 -10.3 0.0 0.0 0.0 14.3 -11.9 0.0 0.0 0.0 16.4 -13.7 0.0 0.0 0.0
6:12 (26.6 deg) 1 -17.2 -21.5 -33.1 -29.5 -24.2 -19.9 -25.0 -38.4 -34.2 -28.1 -22.9 -28.7 -44.1 -39.3 -32.2
2 13.6 -10.3 0.0 0.0 0.0 15.7 -11.9 0.0 0.0 0.0 18.1 -13.7 0.0 0.0 0.0
9:12 (36.9 deg) 1 -10.0 -21.5 -33.1 -29.5 -24.2 -11.5 -25.0 -38.4 -34.2 -28.1 -13.3 -28.7 -44.1 -39.3 -32.2
2 16.2 -10.3 0.0 0.0 0.0 18.8 -11.9 0.0 0.0 0.0 6.9 -13.7 0.0 0.0 0.0
12:12 (45.0 deg) 1 -5.6 -21.5 -33.1 -29.5 -24.2 -6.5 -25.0 -38.4 -34.2 -28.1 -7.5 -28.7 -44.1 -39.3 -32.2
2 16.2 -10.3 0.0 0.0 0.0 18.8 -11.9 0.0 0.0 0.0 21.6 -13.7 0.0 0.0 0.0
Table 27.6-2
MWFRS- Part 2: Wind Loads - Roof
Exposure C
MWFRS – Roof
V = 130–150 mph
h = 15–40 ft.
c27.indd 285 4/14/2010 11:04:45 AM
CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
286
V (MPH) 160 180 200
Load Zone Zone Zone
h (ft) Roof Slope Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat < 2:12 (9.46 deg) 1 NA NA -61.6 -54.9 -45.1 NA NA -78.0 -69.5 -57.0 NA NA -96.3 -85.8 -70.4
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -60.5 -43.5 -61.6 -54.9 -45.1 -76.5 -52.0 -78.0 -69.5 -57.0 -94.5 -64.2 -96.3 -85.8 -70.4
2 8.7 -12.3 0.0 0.0 0.0 11.0 -15.5 0.0 0.0 0.0 13.6 -19.2 0.0 0.0 0.0
4:12 (18.4 deg) 1 -49.7 -40.1 -61.6 -54.9 -45.1 -62.9 -50.8 -78.0 -69.5 -57.0 -77.7 -62.7 -96.3 -85.8 -70.4
2 17.2 -17.6 0.0 0.0 0.0 21.8 -22.3 0.0 0.0 0.0 26.9 -27.5 0.0 0.0 0.0
40 5:12 (22.6 deg) 1 -39.9 -40.1 -61.6 -54.9 -45.1 -50.5 -50.8 -78.0 -69.5 -57.0 -62.3 -62.7 -96.3 -85.8 -70.4
2 22.9 -19.2 0.0 0.0 0.0 29.0 -24.3 0.0 0.0 0.0 35.8 -30.0 0.0 0.0 0.0
6:12 (26.6 deg) 1 -32.0 -40.1 -61.6 -54.9 -45.1 -40.5 -50.8 -78.0 -69.5 -57.0 -50.0 -62.7 -96.3 -85.8 -70.4
2 25.3 -19.2 0.0 0.0 0.0 32.0 -24.3 0.0 0.0 0.0 39.5 -30.0 0.0 0.0 0.0
9:12 (36.9 deg) 1 -18.5 -40.1 -61.6 -54.9 -45.1 -23.5 -50.8 -78.0 -69.5 -57.0 -29.0 -62.7 -96.3 -85.8 -70.4
2 30.2 -19.2 0.0 0.0 0.0 38.3 -24.3 0.0 0.0 0.0 47.2 -30.0 0.0 0.0 0.0
12:12 (45.0 deg) 1 -10.5 -40.1 -61.6 -54.9 -45.1 -13.2 -50.8 -78.0 -69.5 -57.0 -16.3 -62.7 -96.3 -85.8 -70.4
2 30.2 -19.2 0.0 0.0 0.0 38.3 -24.3 0.0 0.0 0.0 47.2 -30.0 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -58.0 -51.7 -42.4 NA NA -73.4 -65.4 -53.7 NA NA -90.6 -80.8 -66.3
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -56.9 -41.0 -58.0 -51.7 -42.4 -72.0 -49.0 -73.4 -65.4 -53.7 -88.9 -60.4 -90.6 -80.8 -66.3
2 8.2 -11.5 0.0 0.0 0.0 10.4 -14.6 0.0 0.0 0.0 12.8 -18.0 0.0 0.0 0.0
4:12 (18.4 deg) 1 -46.8 -37.8 -58.0 -51.7 -42.4 -59.2 -47.8 -73.4 -65.4 -53.7 -73.1 -59.0 -90.6 -80.8 -66.3
2 16.2 -16.6 0.0 0.0 0.0 20.5 -21.0 0.0 0.0 0.0 25.3 -25.9 0.0 0.0 0.0
30 5:12 (22.6 deg) 1 -37.5 -37.8 -58.0 -51.7 -42.4 -47.5 -47.8 -73.4 -65.4 -53.7 -58.6 -59.0 -90.6 -80.8 -66.3
2 21.6 -18.1 0.0 0.0 0.0 27.3 -22.9 0.0 0.0 0.0 33.7 -28.2 0.0 0.0 0.0
6:12 (26.6 deg) 1 -30.1 -37.8 -58.0 -51.7 -42.4 -38.2 -47.8 -73.4 -65.4 -53.7 -47.1 -59.0 -90.6 -80.8 -66.3
2 23.8 -18.1 0.0 0.0 0.0 30.1 -22.9 0.0 0.0 0.0 37.2 -28.2 0.0 0.0 0.0
9:12 (36.9 deg) 1 -17.5 -37.8 -58.0 -51.7 -42.4 -22.1 -47.8 -73.4 -65.4 -53.7 -27.3 -59.0 -90.6 -80.8 -66.3
2 28.5 -18.1 0.0 0.0 0.0 36.0 -22.9 0.0 0.0 0.0 44.5 -28.2 0.0 0.0 0.0
12:12 (45.0 deg) 1 -9.8 -37.8 -58.0 -51.7 -42.4 -12.5 -47.8 -73.4 -65.4 -53.7 -15.4 -59.0 -90.6 -80.8 -66.3
2 28.5 -18.1 0.0 0.0 0.0 36.0 -22.9 0.0 0.0 0.0 44.5 -28.2 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -53.3 -47.5 -38.9 NA NA -67.4 -60.1 -49.3 NA NA -83.2 -74.2 -60.8
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -52.2 -37.6 -53.3 -47.5 -38.9 -66.1 -45.0 -67.4 -60.1 -49.3 -81.6 -55.5 -83.2 -74.2 -60.8
2 7.5 -10.6 0.0 0.0 0.0 9.5 -13.4 0.0 0.0 0.0 11.8 -16.6 0.0 0.0 0.0
4:12 (18.4 deg) 1 -43.0 -34.7 -53.3 -47.5 -38.9 -54.4 -43.9 -67.4 -60.1 -49.3 -67.1 -54.2 -83.2 -74.2 -60.8
2 14.9 -15.2 0.0 0.0 0.0 18.8 -19.3 0.0 0.0 0.0 23.2 -23.8 0.0 0.0 0.0
20 5:12 (22.6 deg) 1 -34.5 -34.7 -53.3 -47.5 -38.9 -43.6 -43.9 -67.4 -60.1 -49.3 -53.9 -54.2 -83.2 -74.2 -60.8
2 19.8 -16.6 0.0 0.0 0.0 25.1 -21.0 0.0 0.0 0.0 30.9 -25.9 0.0 0.0 0.0
6:12 (26.6 deg) 1 -27.7 -34.7 -53.3 -47.5 -38.9 -35.0 -43.9 -67.4 -60.1 -49.3 -43.3 -54.2 -83.2 -74.2 -60.8
2 21.9 -16.6 0.0 0.0 0.0 27.7 -21.0 0.0 0.0 0.0 34.1 -25.9 0.0 0.0 0.0
9:12 (36.9 deg) 1 -16.0 -34.7 -53.3 -47.5 -38.9 -20.3 -43.9 -67.4 -60.1 -49.3 -25.0 -54.2 -83.2 -74.2 -60.8
2 26.1 -16.6 0.0 0.0 0.0 33.1 -21.0 0.0 0.0 0.0 40.8 -25.9 0.0 0.0 0.0
12:12 (45.0 deg) 1 -9.0 -34.7 -53.3 -47.5 -38.9 -11.4 -43.9 -67.4 -60.1 -49.3 -14.1 -54.2 -83.2 -74.2 -60.8
2 26.1 -16.6 0.0 0.0 0.0 33.1 -21.0 0.0 0.0 0.0 40.8 -25.9 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -50.1 -44.7 -36.6 NA NA -63.4 -56.6 -46.4 NA NA -78.3 -69.8 -57.3
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -49.2 -35.4 -50.1 -44.7 -36.6 -62.2 -42.3 -63.4 -56.6 -46.4 -76.8 -52.2 -78.3 -69.8 -57.3
2 7.1 -10.0 0.0 0.0 0.0 9.0 -12.6 0.0 0.0 0.0 11.1 -15.6 0.0 0.0 0.0
4:12 (18.4 deg) 1 -40.4 -32.6 -50.1 -44.7 -36.6 -51.2 -41.3 -63.4 -56.6 -46.4 -63.2 -51.0 -78.3 -69.8 -57.3
2 14.0 -14.3 0.0 0.0 0.0 17.7 -18.1 0.0 0.0 0.0 21.9 -22.4 0.0 0.0 0.0
15 5:12 (22.6 deg) 1 -32.4 -32.6 -50.1 -44.7 -36.6 -41.1 -41.3 -63.4 -56.6 -46.4 -50.7 -51.0 -78.3 -69.8 -57.3
2 18.6 -15.6 0.0 0.0 0.0 23.6 -19.7 0.0 0.0 0.0 29.1 -24.4 0.0 0.0 0.0
6:12 (26.6 deg) 1 -26.1 -32.6 -50.1 -44.7 -36.6 -33.0 -41.3 -63.4 -56.6 -46.4 -40.7 -51.0 -78.3 -69.8 -57.3
2 20.6 -15.6 0.0 0.0 0.0 26.0 -19.7 0.0 0.0 0.0 32.1 -24.4 0.0 0.0 0.0
9:12 (36.9 deg) 1 -15.1 -32.6 -50.1 -44.7 -36.6 -19.1 -41.3 -63.4 -56.6 -46.4 -23.6 -51.0 -78.3 -69.8 -57.3
2 24.6 -15.6 0.0 0.0 0.0 31.1 -19.7 0.0 0.0 0.0 38.4 -24.4 0.0 0.0 0.0
12:12 (45.0 deg) 1 -8.5 -32.6 -50.1 -44.7 -36.6 -10.8 -41.3 -63.4 -56.6 -46.4 -13.3 -51.0 -78.3 -69.8 -57.3
2 24.6 -15.6 0.0 0.0 0.0 31.1 -19.7 0.0 0.0 0.0 38.4 -24.4 0.0 0.0 0.0
Table 27.6-2
MWFRS- Part 2: Wind Loads - Roof
Exposure C
MWFRS – Roof
V = 160–200 mph
h = 15–40 ft.
c27.indd 286 4/14/2010 11:04:45 AM
MINIMUM DESIGN LOADS
287
V (MPH) 110 115 120
Load Zone Zone Zone
h (ft) Roof Slope Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat < 2:12 (9.46 deg) 1 NA NA -33.7 -30.0 -24.6 NA NA -36.8 -32.8 -26.9 NA NA -40.1 -35.8 -29.3
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -33.1 -22.5 -33.7 -30.0 -24.6 -36.1 -26.0 -36.8 -32.8 -26.9 -39.4 -26.8 -40.1 -35.8 -29.3
2 4.8 -6.7 0.0 0.0 0.0 5.2 -7.3 0.0 0.0 0.0 5.7 -8.0 0.0 0.0 0.0
4:12 (18.4 deg) 1 -27.2 -21.9 -33.7 -30.0 -24.6 -29.7 -24.0 -36.8 -32.8 -26.9 -32.4 -26.1 -40.1 -35.8 -29.3
2 9.4 -9.6 0.0 0.0 0.0 10.3 -10.5 0.0 0.0 0.0 11.2 -11.5 0.0 0.0 0.0
80 5:12 (22.6 deg) 1 -21.8 -21.9 -33.7 -30.0 -24.6 -23.8 -24.0 -36.8 -32.8 -26.9 -26.0 -26.1 -40.1 -35.8 -29.3
2 12.5 -10.5 0.0 0.0 0.0 13.7 -11.5 0.0 0.0 0.0 14.9 -12.5 0.0 0.0 0.0
6:12 (26.6 deg) 1 -17.5 -21.9 -33.7 -30.0 -24.6 -19.1 -24.0 -36.8 -32.8 -26.9 -20.8 -26.1 -40.1 -35.8 -29.3
2 13.8 -10.5 0.0 0.0 0.0 15.1 -11.5 0.0 0.0 0.0 16.5 -12.5 0.0 0.0 0.0
9:12 (36.9 deg) 1 -10.1 -21.9 -33.7 -30.0 -24.6 -11.1 -24.0 -36.8 -32.8 -26.9 -12.1 -26.1 -40.1 -35.8 -29.3
2 16.5 -10.5 0.0 0.0 0.0 18.1 -11.5 0.0 0.0 0.0 19.7 -12.5 0.0 0.0 0.0
12:12 (45.0 deg) 1 -5.7 -21.9 -33.7 -30.0 -24.6 -6.3 -24.0 -36.8 -32.8 -26.9 -6.8 -26.1 -40.1 -35.8 -29.3
2 16.5 -10.5 0.0 0.0 0.0 18.1 -11.5 0.0 0.0 0.0 19.7 -12.5 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -32.8 -29.2 -24.0 NA NA -35.8 -31.9 -26.2 NA NA -39.0 -34.8 -28.5
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -32.1 -21.9 -32.8 -29.2 -24.0 -35.1 -25.3 -35.8 -31.9 -26.2 -38.3 -26.0 -39.0 -34.8 -28.5
2 4.6 -6.5 0.0 0.0 0.0 5.1 -7.1 0.0 0.0 0.0 5.5 -7.8 0.0 0.0 0.0
4:12 (18.4 deg) 1 -26.4 -21.3 -32.8 -29.2 -24.0 -28.9 -23.3 -35.8 -31.9 -26.2 -31.5 -25.4 -39.0 -34.8 -28.5
2 9.2 -9.4 0.0 0.0 0.0 10.0 -10.2 0.0 0.0 0.0 10.9 -11.1 0.0 0.0 0.0
70 5:12 (22.6 deg) 1 -21.2 -21.3 -32.8 -29.2 -24.0 -23.2 -23.3 -35.8 -31.9 -26.2 -25.2 -25.4 -39.0 -34.8 -28.5
2 12.2 -10.2 0.0 0.0 0.0 13.3 -11.1 0.0 0.0 0.0 14.5 -12.1 0.0 0.0 0.0
6:12 (26.6 deg) 1 -17.0 -21.3 -32.8 -29.2 -24.0 -18.6 -23.3 -35.8 -31.9 -26.2 -20.3 -25.4 -39.0 -34.8 -28.5
2 13.4 -10.2 0.0 0.0 0.0 14.7 -11.1 0.0 0.0 0.0 16.0 -12.1 0.0 0.0 0.0
9:12 (36.9 deg) 1 -9.9 -21.3 -32.8 -29.2 -24.0 -10.8 -23.3 -35.8 -31.9 -26.2 -11.7 -25.4 -39.0 -34.8 -28.5
2 16.1 -10.2 0.0 0.0 0.0 17.6 -11.1 0.0 0.0 0.0 19.1 -12.1 0.0 0.0 0.0
12:12 (45.0 deg) 1 -5.6 -21.3 -32.8 -29.2 -24.0 -6.1 -23.3 -35.8 -31.9 -26.2 -6.6 -25.4 -39.0 -34.8 -28.5
2 16.1 -10.2 0.0 0.0 0.0 17.6 -11.1 0.0 0.0 0.0 19.1 -12.1 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -31.7 -28.3 -23.2 NA NA -34.7 -30.9 -25.3 NA NA -37.8 -33.7 -27.6
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -31.1 -21.2 -31.7 -28.3 -23.2 -34.0 -24.5 -34.7 -30.9 -25.3 -37.0 -25.2 -37.8 -33.7 -27.6
2 4.5 -6.3 0.0 0.0 0.0 4.9 -6.9 0.0 0.0 0.0 5.3 -7.5 0.0 0.0 0.0
4:12 (18.4 deg) 1 -25.6 -20.6 -31.7 -28.3 -23.2 -28.0 -22.6 -34.7 -30.9 -25.3 -30.4 -24.6 -37.8 -33.7 -27.6
2 8.9 -9.1 0.0 0.0 0.0 9.7 -9.9 0.0 0.0 0.0 10.5 -10.8 0.0 0.0 0.0
60 5:12 (22.6 deg) 1 -20.5 -20.6 -31.7 -28.3 -23.2 -22.4 -22.6 -34.7 -30.9 -25.3 -24.4 -24.6 -37.8 -33.7 -27.6
2 11.8 -9.9 0.0 0.0 0.0 12.9 -10.8 0.0 0.0 0.0 14.0 -11.8 0.0 0.0 0.0
6:12 (26.6 deg) 1 -16.5 -20.6 -31.7 -28.3 -23.2 -18.0 -22.6 -34.7 -30.9 -25.3 -19.6 -24.6 -37.8 -33.7 -27.6
2 13.0 -9.9 0.0 0.0 0.0 14.2 -10.8 0.0 0.0 0.0 15.5 -11.8 0.0 0.0 0.0
9:12 (36.9 deg) 1 -9.5 -20.6 -31.7 -28.3 -23.2 -10.4 -22.6 -34.7 -30.9 -25.3 -11.4 -24.6 -37.8 -33.7 -27.6
2 15.6 -9.9 0.0 0.0 0.0 17.0 -10.8 0.0 0.0 0.0 18.5 -11.8 0.0 0.0 0.0
12:12 (45.0 deg) 1 -5.4 -20.6 -31.7 -28.3 -23.2 -5.9 -22.6 -34.7 -30.9 -25.3 -6.4 -24.6 -37.8 -33.7 -27.6
2 15.6 -9.9 0.0 0.0 0.0 17.0 -10.8 0.0 0.0 0.0 18.5 -11.8 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -30.5 -27.2 -22.3 NA NA -33.4 -29.7 -24.4 NA NA -36.3 -32.4 -26.6
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -30.0 -20.4 -30.5 -27.2 -22.3 -32.7 -23.6 -33.4 -29.7 -24.4 -35.6 -24.2 -36.3 -32.4 -26.6
2 4.3 -6.1 0.0 0.0 0.0 4.7 -6.6 0.0 0.0 0.0 5.1 -7.2 0.0 0.0 0.0
4:12 (18.4 deg) 1 -24.6 -19.9 -30.5 -27.2 -22.3 -26.9 -21.7 -33.4 -29.7 -24.4 -29.3 -23.6 -36.3 -32.4 -26.6
2 8.5 -8.7 0.0 0.0 0.0 9.3 -9.5 0.0 0.0 0.0 10.1 -10.4 0.0 0.0 0.0
50 5:12 (22.6 deg) 1 -19.8 -19.9 -30.5 -27.2 -22.3 -21.6 -21.7 -33.4 -29.7 -24.4 -23.5 -23.6 -36.3 -32.4 -26.6
2 11.3 -9.5 0.0 0.0 0.0 12.4 -10.4 0.0 0.0 0.0 13.5 -11.3 0.0 0.0 0.0
6:12 (26.6 deg) 1 -15.9 -19.9 -30.5 -27.2 -22.3 -17.3 -21.7 -33.4 -29.7 -24.4 -18.9 -23.6 -36.3 -32.4 -26.6
2 12.5 -9.5 0.0 0.0 0.0 13.7 -10.4 0.0 0.0 0.0 14.9 -11.3 0.0 0.0 0.0
9:12 (36.9 deg) 1 -9.2 -19.9 -30.5 -27.2 -22.3 -10.0 -21.7 -33.4 -29.7 -24.4 -10.9 -23.6 -36.3 -32.4 -26.6
2 15.0 -9.5 0.0 0.0 0.0 16.4 -10.4 0.0 0.0 0.0 17.8 -11.3 0.0 0.0 0.0
12:12 (45.0 deg) 1 -5.2 -19.9 -30.5 -27.2 -22.3 -5.7 -21.7 -33.4 -29.7 -24.4 -6.2 -23.6 -36.3 -32.4 -26.6
2 15.0 -9.5 0.0 0.0 0.0 16.4 -10.4 0.0 0.0 0.0 17.8 -11.3 0.0 0.0 0.0
Table 27.6-2
MWFRS- Part 2: Wind Loads - Roof
Exposure C
MWFRS – Roof
V = 110–120 mph
h = 50–80 ft.
c27.indd 287 4/14/2010 11:04:45 AM
CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
288
V (MPH) 130 140 150
Load Zone Zone Zone
h (ft) Roof Slope Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat < 2:12 (9.46 deg) 1 NA NA -47.1 -42.0 -34.4 NA NA -54.6 -48.7 -39.9 NA NA -62.7 -55.9 -45.8
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -46.2 -31.4 -47.1 -42.0 -34.4 -53.6 -36.4 -54.6 -48.7 -39.9 -61.5 -41.8 -62.7 -55.9 -45.8
2 6.7 -9.4 0.0 0.0 0.0 7.7 -10.9 0.0 0.0 0.0 8.9 -12.5 0.0 0.0 0.0
4:12 (18.4 deg) 1 -38.0 -30.6 -47.1 -42.0 -34.4 -44.0 -35.5 -54.6 -48.7 -39.9 -50.5 -40.8 -62.7 -55.9 -45.8
2 13.1 -13.5 0.0 0.0 0.0 15.2 -15.6 0.0 0.0 0.0 17.5 -17.9 0.0 0.0 0.0
80 5:12 (22.6 deg) 1 -30.5 -30.6 -47.1 -42.0 -34.4 -35.3 -35.5 -54.6 -48.7 -39.9 -40.6 -40.8 -62.7 -55.9 -45.8
2 17.5 -14.7 0.0 0.0 0.0 20.3 -17.0 0.0 0.0 0.0 23.3 -19.5 0.0 0.0 0.0
6:12 (26.6 deg) 1 -24.5 -30.6 -47.1 -42.0 -34.4 -28.4 -35.5 -54.6 -48.7 -39.9 -32.6 -40.8 -62.7 -55.9 -45.8
2 19.3 -14.7 0.0 0.0 0.0 22.4 -17.0 0.0 0.0 0.0 25.7 -19.5 0.0 0.0 0.0
9:12 (36.9 deg) 1 -14.2 -30.6 -47.1 -42.0 -34.4 -16.4 -35.5 -54.6 -48.7 -39.9 -18.9 -40.8 -62.7 -55.9 -45.8
2 23.1 -14.7 0.0 0.0 0.0 26.8 -17.0 0.0 0.0 0.0 9.9 -19.5 0.0 0.0 0.0
12:12 (45.0 deg) 1 -8.0 -30.6 -47.1 -42.0 -34.4 -9.3 -35.5 -54.6 -48.7 -39.9 -10.6 -40.8 -62.7 -55.9 -45.8
2 23.1 -14.7 0.0 0.0 0.0 26.8 -17.0 0.0 0.0 0.0 30.7 -19.5 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -45.8 -40.8 -33.5 NA NA -53.1 -47.3 -38.8 NA NA -60.9 -54.3 -44.5
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -44.9 -30.5 -45.8 -40.8 -33.5 -52.1 -35.4 -53.1 -47.3 -38.8 -59.8 -40.6 -60.9 -54.3 -44.5
2 6.5 -9.1 0.0 0.0 0.0 7.5 -10.6 0.0 0.0 0.0 8.6 -12.1 0.0 0.0 0.0
4:12 (18.4 deg) 1 -36.9 -29.8 -45.8 -40.8 -33.5 -42.8 -34.6 -53.1 -47.3 -38.8 -49.1 -39.7 -60.9 -54.3 -44.5
2 12.8 -13.1 0.0 0.0 0.0 14.8 -15.2 0.0 0.0 0.0 17.0 -17.4 0.0 0.0 0.0
70 5:12 (22.6 deg) 1 -29.6 -29.8 -45.8 -40.8 -33.5 -34.4 -34.6 -53.1 -47.3 -38.8 -39.4 -39.7 -60.9 -54.3 -44.5
2 17.0 -14.2 0.0 0.0 0.0 19.7 -16.5 0.0 0.0 0.0 22.6 -19.0 0.0 0.0 0.0
6:12 (26.6 deg) 1 -23.8 -29.8 -45.8 -40.8 -33.5 -27.6 -34.6 -53.1 -47.3 -38.8 -31.7 -39.7 -60.9 -54.3 -44.5
2 18.8 -14.2 0.0 0.0 0.0 21.8 -16.5 0.0 0.0 0.0 25.0 -19.0 0.0 0.0 0.0
9:12 (36.9 deg) 1 -13.8 -29.8 -45.8 -40.8 -33.5 -16.0 -34.6 -53.1 -47.3 -38.8 -18.3 -39.7 -60.9 -54.3 -44.5
2 22.5 -14.2 0.0 0.0 0.0 26.0 -16.5 0.0 0.0 0.0 9.6 -19.0 0.0 0.0 0.0
12:12 (45.0 deg) 1 -7.8 -29.8 -45.8 -40.8 -33.5 -9.0 -34.6 -53.1 -47.3 -38.8 -10.3 -39.7 -60.9 -54.3 -44.5
2 22.5 -14.2 0.0 0.0 0.0 26.0 -16.5 0.0 0.0 0.0 29.9 -19.0 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -44.3 -39.5 -32.4 NA NA -51.4 -45.8 -37.6 NA NA -59.0 -52.6 -43.1
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -43.5 -29.6 -44.3 -39.5 -32.4 -50.4 -34.3 -51.4 -45.8 -37.6 -57.9 -39.3 -59.0 -52.6 -43.1
2 6.3 -8.8 0.0 0.0 0.0 7.3 -10.2 0.0 0.0 0.0 8.3 -11.7 0.0 0.0 0.0
4:12 (18.4 deg) 1 -35.7 -28.8 -44.3 -39.5 -32.4 -41.4 -33.4 -51.4 -45.8 -37.6 -47.6 -38.4 -59.0 -52.6 -43.1
2 12.4 -12.7 0.0 0.0 0.0 14.3 -14.7 0.0 0.0 0.0 16.5 -16.9 0.0 0.0 0.0
60 5:12 (22.6 deg) 1 -28.7 -28.8 -44.3 -39.5 -32.4 -33.3 -33.4 -51.4 -45.8 -37.6 -38.2 -38.4 -59.0 -52.6 -43.1
2 16.5 -13.8 0.0 0.0 0.0 19.1 -16.0 0.0 0.0 0.0 21.9 -18.4 0.0 0.0 0.0
6:12 (26.6 deg) 1 -23.0 -28.8 -44.3 -39.5 -32.4 -26.7 -33.4 -51.4 -45.8 -37.6 -30.7 -38.4 -59.0 -52.6 -43.1
2 18.2 -13.8 0.0 0.0 0.0 21.1 -16.0 0.0 0.0 0.0 24.2 -18.4 0.0 0.0 0.0
9:12 (36.9 deg) 1 -13.3 -28.8 -44.3 -39.5 -32.4 -15.5 -33.4 -51.4 -45.8 -37.6 -17.8 -38.4 -59.0 -52.6 -43.1
2 21.7 -13.8 0.0 0.0 0.0 25.2 -16.0 0.0 0.0 0.0 9.3 -18.4 0.0 0.0 0.0
12:12 (45.0 deg) 1 -7.5 -28.8 -44.3 -39.5 -32.4 -8.7 -33.4 -51.4 -45.8 -37.6 -10.0 -38.4 -59.0 -52.6 -43.1
2 21.7 -13.8 0.0 0.0 0.0 25.2 -16.0 0.0 0.0 0.0 28.9 -18.4 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -42.6 -38.0 -31.2 NA NA -49.4 -44.1 -36.2 NA NA -56.8 -50.6 -41.5
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -41.8 -28.4 -42.6 -38.0 -31.2 -48.5 -33.0 -49.4 -44.1 -36.2 -55.7 -37.9 -56.8 -50.6 -41.5
2 6.0 -8.5 0.0 0.0 0.0 7.0 -9.8 0.0 0.0 0.0 8.0 -11.3 0.0 0.0 0.0
4:12 (18.4 deg) 1 -34.4 -27.8 -42.6 -38.0 -31.2 -39.9 -32.2 -49.4 -44.1 -36.2 -45.8 -37.0 -56.8 -50.6 -41.5
2 11.9 -12.2 0.0 0.0 0.0 13.8 -14.1 0.0 0.0 0.0 15.9 -16.2 0.0 0.0 0.0
50 5:12 (22.6 deg) 1 -27.6 -27.8 -42.6 -38.0 -31.2 -32.0 -32.2 -49.4 -44.1 -36.2 -36.7 -37.0 -56.8 -50.6 -41.5
2 15.8 -13.3 0.0 0.0 0.0 18.4 -15.4 0.0 0.0 0.0 21.1 -17.7 0.0 0.0 0.0
6:12 (26.6 deg) 1 -22.2 -27.8 -42.6 -38.0 -31.2 -25.7 -32.2 -49.4 -44.1 -36.2 -29.5 -37.0 -56.8 -50.6 -41.5
2 17.5 -13.3 0.0 0.0 0.0 20.3 -15.4 0.0 0.0 0.0 23.3 -17.7 0.0 0.0 0.0
9:12 (36.9 deg) 1 -12.8 -27.8 -42.6 -38.0 -31.2 -14.9 -32.2 -49.4 -44.1 -36.2 -17.1 -37.0 -56.8 -50.6 -41.5
2 20.9 -13.3 0.0 0.0 0.0 24.3 -15.4 0.0 0.0 0.0 8.9 -17.7 0.0 0.0 0.0
12:12 (45.0 deg) 1 -7.2 -27.8 -42.6 -38.0 -31.2 -8.4 -32.2 -49.4 -44.1 -36.2 -9.6 -37.0 -56.8 -50.6 -41.5
2 20.9 -13.3 0.0 0.0 0.0 24.3 -15.4 0.0 0.0 0.0 27.8 -17.7 0.0 0.0 0.0
Table 27.6-2
MWFRS- Part 2: Wind Loads - Roof
Exposure C
MWFRS – Roof
V = 130–150 mph
h = 50–80 ft.
c27.indd 288 4/14/2010 11:04:45 AM
MINIMUM DESIGN LOADS
289
V (MPH) 160 180 200
Load Zone Zone Zone
h (ft) Roof Slope Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat < 2:12 (9.46 deg) 1 NA NA -71.3 -63.6 -52.1 NA NA -90.2 -80.5 -66.0 NA NA -111.4 -99.3 -81.5
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -70.0 -50.4 -71.3 -63.6 -52.1 -88.5 -60.2 -90.2 -80.5 -66.0 -109.3 -74.3 -111.4 -99.3 -81.5
2 10.1 -14.2 0.0 0.0 0.0 12.8 -18.0 0.0 0.0 0.0 15.8 -22.2 0.0 0.0 0.0
4:12 (18.4 deg) 1 -57.5 -46.4 -71.3 -63.6 -52.1 -72.8 -58.7 -90.2 -80.5 -66.0 -89.9 -72.5 -111.4 -99.3 -81.5
2 19.9 -20.4 0.0 0.0 0.0 25.2 -25.8 0.0 0.0 0.0 31.1 -31.8 0.0 0.0 0.0
80 5:12 (22.6 deg) 1 -46.1 -46.4 -71.3 -63.6 -52.1 -58.4 -58.7 -90.2 -80.5 -66.0 -72.1 -72.5 -111.4 -99.3 -81.5
2 26.5 -22.2 0.0 0.0 0.0 33.5 -28.1 0.0 0.0 0.0 41.4 -34.7 0.0 0.0 0.0
6:12 (26.6 deg) 1 -37.1 -46.4 -71.3 -63.6 -52.1 -46.9 -58.7 -90.2 -80.5 -66.0 -57.9 -72.5 -111.4 -99.3 -81.5
2 29.3 -22.2 0.0 0.0 0.0 37.0 -28.1 0.0 0.0 0.0 45.7 -34.7 0.0 0.0 0.0
9:12 (36.9 deg) 1 -21.5 -46.4 -71.3 -63.6 -52.1 -27.2 -58.7 -90.2 -80.5 -66.0 -33.5 -72.5 -111.4 -99.3 -81.5
2 35.0 -22.2 0.0 0.0 0.0 44.3 -28.1 0.0 0.0 0.0 54.7 -34.7 0.0 0.0 0.0
12:12 (45.0 deg) 1 -12.1 -46.4 -71.3 -63.6 -52.1 -15.3 -58.7 -90.2 -80.5 -66.0 -18.9 -72.5 -111.4 -99.3 -81.5
2 35.0 -22.2 0.0 0.0 0.0 44.3 -28.1 0.0 0.0 0.0 54.7 -34.7 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -69.3 -61.8 -50.7 NA NA -87.7 -78.2 -64.2 NA NA -108.3 -96.6 -79.2
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -68.0 -49.0 -69.3 -61.8 -50.7 -86.1 -58.5 -87.7 -78.2 -64.2 -106.3 -72.2 -108.3 -96.6 -79.2
2 9.8 -13.8 0.0 0.0 0.0 12.4 -17.5 0.0 0.0 0.0 15.3 -21.6 0.0 0.0 0.0
4:12 (18.4 deg) 1 -55.9 -45.1 -69.3 -61.8 -50.7 -70.8 -57.1 -87.7 -78.2 -64.2 -87.4 -70.5 -108.3 -96.6 -79.2
2 19.4 -19.8 0.0 0.0 0.0 24.5 -25.1 0.0 0.0 0.0 30.2 -31.0 0.0 0.0 0.0
70 5:12 (22.6 deg) 1 -44.9 -45.1 -69.3 -61.8 -50.7 -56.8 -57.1 -87.7 -78.2 -64.2 -70.1 -70.5 -108.3 -96.6 -79.2
2 25.8 -21.6 0.0 0.0 0.0 32.6 -27.3 0.0 0.0 0.0 40.3 -33.7 0.0 0.0 0.0
6:12 (26.6 deg) 1 -36.0 -45.1 -69.3 -61.8 -50.7 -45.6 -57.1 -87.7 -78.2 -64.2 -56.3 -70.5 -108.3 -96.6 -79.2
2 28.4 -21.6 0.0 0.0 0.0 36.0 -27.3 0.0 0.0 0.0 44.5 -33.7 0.0 0.0 0.0
9:12 (36.9 deg) 1 -20.9 -45.1 -69.3 -61.8 -50.7 -26.4 -57.1 -87.7 -78.2 -64.2 -32.6 -70.5 -108.3 -96.6 -79.2
2 34.0 -21.6 0.0 0.0 0.0 43.0 -27.3 0.0 0.0 0.0 53.1 -33.7 0.0 0.0 0.0
12:12 (45.0 deg) 1 -11.8 -45.1 -69.3 -61.8 -50.7 -14.9 -57.1 -87.7 -78.2 -64.2 -18.4 -70.5 -108.3 -96.6 -79.2
2 34.0 -21.6 0.0 0.0 0.0 43.0 -27.3 0.0 0.0 0.0 53.1 -33.7 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -67.1 -59.8 -49.1 NA NA -84.9 -75.7 -62.1 NA NA -104.9 -93.5 -76.7
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -65.8 -47.4 -67.1 -59.8 -49.1 -83.3 -56.7 -84.9 -75.7 -62.1 -102.9 -69.9 -104.9 -93.5 -76.7
2 9.5 -13.4 0.0 0.0 0.0 12.0 -16.9 0.0 0.0 0.0 14.8 -20.9 0.0 0.0 0.0
4:12 (18.4 deg) 1 -54.1 -43.7 -67.1 -59.8 -49.1 -68.5 -55.3 -84.9 -75.7 -62.1 -84.6 -68.3 -104.9 -93.5 -76.7
2 18.7 -19.2 0.0 0.0 0.0 23.7 -24.3 0.0 0.0 0.0 29.3 -30.0 0.0 0.0 0.0
60 5:12 (22.6 deg) 1 -43.4 -43.7 -67.1 -59.8 -49.1 -55.0 -55.3 -84.9 -75.7 -62.1 -67.9 -68.3 -104.9 -93.5 -76.7
2 24.9 -20.9 0.0 0.0 0.0 31.6 -26.4 0.0 0.0 0.0 39.0 -32.6 0.0 0.0 0.0
6:12 (26.6 deg) 1 -34.9 -43.7 -67.1 -59.8 -49.1 -44.2 -55.3 -84.9 -75.7 -62.1 -54.5 -68.3 -104.9 -93.5 -76.7
2 27.5 -20.9 0.0 0.0 0.0 34.9 -26.4 0.0 0.0 0.0 43.0 -32.6 0.0 0.0 0.0
9:12 (36.9 deg) 1 -20.2 -43.7 -67.1 -59.8 -49.1 -25.6 -55.3 -84.9 -75.7 -62.1 -31.6 -68.3 -104.9 -93.5 -76.7
2 32.9 -20.9 0.0 0.0 0.0 41.7 -26.4 0.0 0.0 0.0 51.4 -32.6 0.0 0.0 0.0
12:12 (45.0 deg) 1 -11.4 -43.7 -67.1 -59.8 -49.1 -14.4 -55.3 -84.9 -75.7 -62.1 -17.8 -68.3 -104.9 -93.5 -76.7
2 32.9 -20.9 0.0 0.0 0.0 41.7 -26.4 0.0 0.0 0.0 51.4 -32.6 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -64.6 -57.6 -47.2 NA NA -81.7 -72.9 -59.8 NA NA -100.9 -90.0 -73.8
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -63.4 -45.6 -64.6 -57.6 -47.2 -80.2 -54.5 -81.7 -72.9 -59.8 -99.0 -67.3 -100.9 -90.0 -73.8
2 9.1 -12.9 0.0 0.0 0.0 11.6 -16.3 0.0 0.0 0.0 14.3 -20.1 0.0 0.0 0.0
4:12 (18.4 deg) 1 -52.1 -42.0 -64.6 -57.6 -47.2 -65.9 -53.2 -81.7 -72.9 -59.8 -81.4 -65.7 -100.9 -90.0 -73.8
2 18.0 -18.5 0.0 0.0 0.0 22.8 -23.4 0.0 0.0 0.0 28.2 -28.8 0.0 0.0 0.0
50 5:12 (22.6 deg) 1 -41.8 -42.0 -64.6 -57.6 -47.2 -52.9 -53.2 -81.7 -72.9 -59.8 -65.3 -65.7 -100.9 -90.0 -73.8
2 24.0 -20.1 0.0 0.0 0.0 30.4 -25.4 0.0 0.0 0.0 37.5 -31.4 0.0 0.0 0.0
6:12 (26.6 deg) 1 -33.6 -42.0 -64.6 -57.6 -47.2 -42.5 -53.2 -81.7 -72.9 -59.8 -52.5 -65.7 -100.9 -90.0 -73.8
2 26.5 -20.1 0.0 0.0 0.0 33.5 -25.4 0.0 0.0 0.0 41.4 -31.4 0.0 0.0 0.0
9:12 (36.9 deg) 1 -19.4 -42.0 -64.6 -57.6 -47.2 -24.6 -53.2 -81.7 -72.9 -59.8 -30.4 -65.7 -100.9 -90.0 -73.8
2 31.7 -20.1 0.0 0.0 0.0 40.1 -25.4 0.0 0.0 0.0 49.5 -31.4 0.0 0.0 0.0
12:12 (45.0 deg) 1 -11.0 -42.0 -64.6 -57.6 -47.2 -13.9 -53.2 -81.7 -72.9 -59.8 -17.1 -65.7 -100.9 -90.0 -73.8
2 31.7 -20.1 0.0 0.0 0.0 40.1 -25.4 0.0 0.0 0.0 49.5 -31.4 0.0 0.0 0.0
Table 27.6-2
MWFRS- Part 2: Wind Loads - Roof
Exposure C
MWFRS – Roof
V = 160–200 mph
h = 50–80 ft.
c27.indd 289 4/14/2010 11:04:46 AM
CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
290
V (MPH) 110 115 120
Load Zone Zone Zone
h (ft) Roof Slope Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat < 2:12 (9.46 deg) 1 NA NA -36.7 -32.7 -26.8 NA NA -40.1 -35.8 -29.3 NA NA -43.7 -38.9 -31.9
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -36.0 -24.5 -36.7 -32.7 -26.8 -39.4 -28.3 -40.1 -35.8 -29.3 -42.9 -29.1 -43.7 -38.9 -31.9
2 5.2 -7.3 0.0 0.0 0.0 5.7 -8.0 0.0 0.0 0.0 6.2 -8.7 0.0 0.0 0.0
4:12 (18.4 deg) 1 -29.6 -23.9 -36.7 -32.7 -26.8 -32.4 -26.1 -40.1 -35.8 -29.3 -35.2 -28.4 -43.7 -38.9 -31.9
2 10.2 -10.5 0.0 0.0 0.0 11.2 -11.5 0.0 0.0 0.0 12.2 -12.5 0.0 0.0 0.0
120 5:12 (22.6 deg) 1 -23.8 -23.9 -36.7 -32.7 -26.8 -26.0 -26.1 -40.1 -35.8 -29.3 -28.3 -28.4 -43.7 -38.9 -31.9
2 13.6 -11.4 0.0 0.0 0.0 14.9 -12.5 0.0 0.0 0.0 16.2 -13.6 0.0 0.0 0.0
6:12 (26.6 deg) 1 -19.1 -23.9 -36.7 -32.7 -26.8 -20.9 -26.1 -40.1 -35.8 -29.3 -22.7 -28.4 -43.7 -38.9 -31.9
2 15.1 -11.4 0.0 0.0 0.0 16.5 -12.5 0.0 0.0 0.0 17.9 -13.6 0.0 0.0 0.0
9:12 (36.9 deg) 1 -11.0 -23.9 -36.7 -32.7 -26.8 -12.1 -26.1 -40.1 -35.8 -29.3 -13.1 -28.4 -43.7 -38.9 -31.9
2 18.0 -11.4 0.0 0.0 0.0 19.7 -12.5 0.0 0.0 0.0 21.4 -13.6 0.0 0.0 0.0
12:12 (45.0 deg) 1 -6.2 -23.9 -36.7 -32.7 -26.8 -6.8 -26.1 -40.1 -35.8 -29.3 -7.4 -28.4 -43.7 -38.9 -31.9
2 18.0 -11.4 0.0 0.0 0.0 19.7 -12.5 0.0 0.0 0.0 21.4 -13.6 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -36.0 -32.1 -26.3 NA NA -39.4 -35.1 -28.8 NA NA -42.9 -38.2 -31.4
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -35.4 -24.0 -36.0 -32.1 -26.3 -38.6 -27.8 -39.4 -35.1 -28.8 -42.1 -28.6 -42.9 -38.2 -31.4
2 5.1 -7.2 0.0 0.0 0.0 5.6 -7.8 0.0 0.0 0.0 6.1 -8.5 0.0 0.0 0.0
4:12 (18.4 deg) 1 -29.1 -23.5 -36.0 -32.1 -26.3 -31.8 -25.6 -39.4 -35.1 -28.8 -34.6 -27.9 -42.9 -38.2 -31.4
2 10.1 -10.3 0.0 0.0 0.0 11.0 -11.3 0.0 0.0 0.0 12.0 -12.3 0.0 0.0 0.0
110 5:12 (22.6 deg) 1 -23.3 -23.5 -36.0 -32.1 -26.3 -25.5 -25.6 -39.4 -35.1 -28.8 -27.8 -27.9 -42.9 -38.2 -31.4
2 13.4 -11.2 0.0 0.0 0.0 14.6 -12.3 0.0 0.0 0.0 15.9 -13.4 0.0 0.0 0.0
6:12 (26.6 deg) 1 -18.7 -23.5 -36.0 -32.1 -26.3 -20.5 -25.6 -39.4 -35.1 -28.8 -22.3 -27.9 -42.9 -38.2 -31.4
2 14.8 -11.2 0.0 0.0 0.0 16.2 -12.3 0.0 0.0 0.0 17.6 -13.4 0.0 0.0 0.0
9:12 (36.9 deg) 1 -10.8 -23.5 -36.0 -32.1 -26.3 -11.9 -25.6 -39.4 -35.1 -28.8 -12.9 -27.9 -42.9 -38.2 -31.4
2 17.7 -11.2 0.0 0.0 0.0 19.3 -12.3 0.0 0.0 0.0 21.0 -13.4 0.0 0.0 0.0
12:12 (45.0 deg) 1 -6.1 -23.5 -36.0 -32.1 -26.3 -6.7 -25.6 -39.4 -35.1 -28.8 -7.3 -27.9 -42.9 -38.2 -31.4
2 17.7 -11.2 0.0 0.0 0.0 19.3 -12.3 0.0 0.0 0.0 21.0 -13.4 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -35.3 -31.5 -25.8 NA NA -38.6 -34.4 -28.2 NA NA -42.0 -37.5 -30.7
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -34.7 -23.6 -35.3 -31.5 -25.8 -37.9 -27.3 -38.6 -34.4 -28.2 -41.2 -28.0 -42.0 -37.5 -30.7
2 5.0 -7.0 0.0 0.0 0.0 5.5 -7.7 0.0 0.0 0.0 5.9 -8.4 0.0 0.0 0.0
4:12 (18.4 deg) 1 -28.5 -23.0 -35.3 -31.5 -25.8 -31.1 -25.1 -38.6 -34.4 -28.2 -33.9 -27.4 -42.0 -37.5 -30.7
2 9.9 -10.1 0.0 0.0 0.0 10.8 -11.0 0.0 0.0 0.0 11.7 -12.0 0.0 0.0 0.0
100 5:12 (22.6 deg) 1 -22.9 -23.0 -35.3 -31.5 -25.8 -25.0 -25.1 -38.6 -34.4 -28.2 -27.2 -27.4 -42.0 -37.5 -30.7
2 13.1 -11.0 0.0 0.0 0.0 14.4 -12.0 0.0 0.0 0.0 15.6 -13.1 0.0 0.0 0.0
6:12 (26.6 deg) 1 -18.4 -23.0 -35.3 -31.5 -25.8 -20.1 -25.1 -38.6 -34.4 -28.2 -21.9 -27.4 -42.0 -37.5 -30.7
2 14.5 -11.0 0.0 0.0 0.0 15.8 -12.0 0.0 0.0 0.0 17.3 -13.1 0.0 0.0 0.0
9:12 (36.9 deg) 1 -10.6 -23.0 -35.3 -31.5 -25.8 -11.6 -25.1 -38.6 -34.4 -28.2 -12.7 -27.4 -42.0 -37.5 -30.7
2 17.3 -11.0 0.0 0.0 0.0 18.9 -12.0 0.0 0.0 0.0 20.6 -13.1 0.0 0.0 0.0
12:12 (45.0 deg) 1 -6.0 -23.0 -35.3 -31.5 -25.8 -6.6 -25.1 -38.6 -34.4 -28.2 -7.1 -27.4 -42.0 -37.5 -30.7
2 17.3 -11.0 0.0 0.0 0.0 18.9 -12.0 0.0 0.0 0.0 20.6 -13.1 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -34.5 -30.8 -25.3 NA NA -37.8 -33.7 -27.6 NA NA -41.1 -36.7 -30.1
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -33.9 -23.0 -34.5 -30.8 -25.3 -37.0 -26.7 -37.8 -33.7 -27.6 -40.3 -27.4 -41.1 -36.7 -30.1
2 4.9 -6.9 0.0 0.0 0.0 5.3 -7.5 0.0 0.0 0.0 5.8 -8.2 0.0 0.0 0.0
4:12 (18.4 deg) 1 -27.9 -22.5 -34.5 -30.8 -25.3 -30.5 -24.6 -37.8 -33.7 -27.6 -33.2 -26.8 -41.1 -36.7 -30.1
2 9.6 -9.9 0.0 0.0 0.0 10.5 -10.8 0.0 0.0 0.0 11.5 -11.8 0.0 0.0 0.0
90 5:12 (22.6 deg) 1 -22.4 -22.5 -34.5 -30.8 -25.3 -24.4 -24.6 -37.8 -33.7 -27.6 -26.6 -26.8 -41.1 -36.7 -30.1
2 12.8 -10.8 0.0 0.0 0.0 14.0 -11.8 0.0 0.0 0.0 15.3 -12.8 0.0 0.0 0.0
6:12 (26.6 deg) 1 -18.0 -22.5 -34.5 -30.8 -25.3 -19.6 -24.6 -37.8 -33.7 -27.6 -21.4 -26.8 -41.1 -36.7 -30.1
2 14.2 -10.8 0.0 0.0 0.0 15.5 -11.8 0.0 0.0 0.0 16.9 -12.8 0.0 0.0 0.0
9:12 (36.9 deg) 1 -10.4 -22.5 -34.5 -30.8 -25.3 -11.4 -24.6 -37.8 -33.7 -27.6 -12.4 -26.8 -41.1 -36.7 -30.1
2 16.9 -10.8 0.0 0.0 0.0 18.5 -11.8 0.0 0.0 0.0 20.2 -12.8 0.0 0.0 0.0
12:12 (45.0 deg) 1 -5.9 -22.5 -34.5 -30.8 -25.3 -6.4 -24.6 -37.8 -33.7 -27.6 -7.0 -26.8 -41.1 -36.7 -30.1
2 16.9 -10.8 0.0 0.0 0.0 18.5 -11.8 0.0 0.0 0.0 20.2 -12.8 0.0 0.0 0.0
Table 27.6-2
MWFRS- Part 2: Wind Loads - Roof
Exposure C
MWFRS – Roof
V = 110–120 mph
h = 90–120 ft.
c27.indd 290 4/14/2010 11:04:46 AM
MINIMUM DESIGN LOADS
291
V (MPH) 130 140 150
Load Zone Zone Zone
h (ft) Roof Slope Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat < 2:12 (9.46 deg) 1 NA NA -51.3 -45.7 -37.5 NA NA -59.5 -53.0 -43.5 NA NA -36.7 -32.7 -26.8
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -50.3 -34.2 -51.3 -45.7 -37.5 -58.3 -39.7 -59.5 -53.0 -43.5 -36.0 -24.5 -36.7 -32.7 -26.8
2 7.3 -10.2 0.0 0.0 0.0 8.4 -11.8 0.0 0.0 0.0 5.2 -7.3 0.0 0.0 0.0
4:12 (18.4 deg) 1 -41.4 -33.4 -51.3 -45.7 -37.5 -48.0 -38.7 -59.5 -53.0 -43.5 -29.6 -23.9 -36.7 -32.7 -26.8
2 14.3 -14.7 0.0 0.0 0.0 16.6 -17.0 0.0 0.0 0.0 10.2 -10.5 0.0 0.0 0.0
120 5:12 (22.6 deg) 1 -33.2 -33.4 -51.3 -45.7 -37.5 -38.5 -38.7 -59.5 -53.0 -43.5 -23.8 -23.9 -36.7 -32.7 -26.8
2 19.1 -16.0 0.0 0.0 0.0 22.1 -18.5 0.0 0.0 0.0 13.6 -11.4 0.0 0.0 0.0
6:12 (26.6 deg) 1 -26.6 -33.4 -51.3 -45.7 -37.5 -30.9 -38.7 -59.5 -53.0 -43.5 -19.1 -23.9 -36.7 -32.7 -26.8
2 21.0 -16.0 0.0 0.0 0.0 24.4 -18.5 0.0 0.0 0.0 15.1 -11.4 0.0 0.0 0.0
9:12 (36.9 deg) 1 -15.4 -33.4 -51.3 -45.7 -37.5 -17.9 -38.7 -59.5 -53.0 -43.5 -11.0 -23.9 -36.7 -32.7 -26.8
2 25.1 -16.0 0.0 0.0 0.0 29.2 -18.5 0.0 0.0 0.0 18.0 -11.4 0.0 0.0 0.0
12:12 (45.0 deg) 1 -8.7 -33.4 -51.3 -45.7 -37.5 -10.1 -38.7 -59.5 -53.0 -43.5 -6.2 -23.9 -36.7 -32.7 -26.8
2 25.1 -16.0 0.0 0.0 0.0 29.2 -18.5 0.0 0.0 0.0 18.0 -11.4 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -50.3 -44.9 -36.8 NA NA -58.4 -52.0 -42.7 NA NA -36.0 -32.1 -26.3
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -49.4 -33.6 -50.3 -44.9 -36.8 -57.3 -38.9 -58.4 -52.0 -42.7 -35.4 -24.0 -36.0 -32.1 -26.3
2 7.1 -10.0 0.0 0.0 0.0 8.3 -11.6 0.0 0.0 0.0 5.1 -7.2 0.0 0.0 0.0
4:12 (18.4 deg) 1 -40.6 -32.8 -50.3 -44.9 -36.8 -47.1 -38.0 -58.4 -52.0 -42.7 -29.1 -23.5 -36.0 -32.1 -26.3
2 14.1 -14.4 0.0 0.0 0.0 16.3 -16.7 0.0 0.0 0.0 10.1 -10.3 0.0 0.0 0.0
110 5:12 (22.6 deg) 1 -32.6 -32.8 -50.3 -44.9 -36.8 -37.8 -38.0 -58.4 -52.0 -42.7 -23.3 -23.5 -36.0 -32.1 -26.3
2 18.7 -15.7 0.0 0.0 0.0 21.7 -18.2 0.0 0.0 0.0 13.4 -11.2 0.0 0.0 0.0
6:12 (26.6 deg) 1 -26.2 -32.8 -50.3 -44.9 -36.8 -30.3 -38.0 -58.4 -52.0 -42.7 -18.7 -23.5 -36.0 -32.1 -26.3
2 20.7 -15.7 0.0 0.0 0.0 24.0 -18.2 0.0 0.0 0.0 14.8 -11.2 0.0 0.0 0.0
9:12 (36.9 deg) 1 -15.1 -32.8 -50.3 -44.9 -36.8 -17.6 -38.0 -58.4 -52.0 -42.7 -10.8 -23.5 -36.0 -32.1 -26.3
2 24.7 -15.7 0.0 0.0 0.0 28.6 -18.2 0.0 0.0 0.0 17.7 -11.2 0.0 0.0 0.0
12:12 (45.0 deg) 1 -8.5 -32.8 -50.3 -44.9 -36.8 -9.9 -38.0 -58.4 -52.0 -42.7 -6.1 -23.5 -36.0 -32.1 -26.3
2 24.7 -15.7 0.0 0.0 0.0 28.6 -18.2 0.0 0.0 0.0 17.7 -11.2 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -49.3 -44.0 -36.1 NA NA -57.2 -51.0 -41.8 NA NA -35.3 -31.5 -25.8
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -48.4 -32.9 -49.3 -44.0 -36.1 -56.1 -38.2 -57.2 -51.0 -41.8 -34.7 -23.6 -35.3 -31.5 -25.8
2 7.0 -9.8 0.0 0.0 0.0 8.1 -11.4 0.0 0.0 0.0 5.0 -7.0 0.0 0.0 0.0
4:12 (18.4 deg) 1 -39.8 -32.1 -49.3 -44.0 -36.1 -46.2 -37.2 -57.2 -51.0 -41.8 -28.5 -23.0 -35.3 -31.5 -25.8
2 13.8 -14.1 0.0 0.0 0.0 16.0 -16.4 0.0 0.0 0.0 9.9 -10.1 0.0 0.0 0.0
100 5:12 (22.6 deg) 1 -31.9 -32.1 -49.3 -44.0 -36.1 -37.0 -37.2 -57.2 -51.0 -41.8 -22.9 -23.0 -35.3 -31.5 -25.8
2 18.3 -15.4 0.0 0.0 0.0 21.3 -17.8 0.0 0.0 0.0 13.1 -11.0 0.0 0.0 0.0
6:12 (26.6 deg) 1 -25.6 -32.1 -49.3 -44.0 -36.1 -29.7 -37.2 -57.2 -51.0 -41.8 -18.4 -23.0 -35.3 -31.5 -25.8
2 20.2 -15.4 0.0 0.0 0.0 23.5 -17.8 0.0 0.0 0.0 14.5 -11.0 0.0 0.0 0.0
9:12 (36.9 deg) 1 -14.8 -32.1 -49.3 -44.0 -36.1 -17.2 -37.2 -57.2 -51.0 -41.8 -10.6 -23.0 -35.3 -31.5 -25.8
2 24.2 -15.4 0.0 0.0 0.0 28.1 -17.8 0.0 0.0 0.0 17.3 -11.0 0.0 0.0 0.0
12:12 (45.0 deg) 1 -8.4 -32.1 -49.3 -44.0 -36.1 -9.7 -37.2 -57.2 -51.0 -41.8 -6.0 -23.0 -35.3 -31.5 -25.8
2 24.2 -15.4 0.0 0.0 0.0 28.1 -17.8 0.0 0.0 0.0 17.3 -11.0 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -48.3 -43.0 -35.3 NA NA -56.0 -49.9 -40.9 NA NA -34.5 -30.8 -25.3
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -47.3 -32.2 -48.3 -43.0 -35.3 -54.9 -37.3 -56.0 -49.9 -40.9 -33.9 -23.0 -34.5 -30.8 -25.3
2 6.8 -9.6 0.0 0.0 0.0 7.9 -11.1 0.0 0.0 0.0 4.9 -6.9 0.0 0.0 0.0
4:12 (18.4 deg) 1 -38.9 -31.4 -48.3 -43.0 -35.3 -45.1 -36.4 -56.0 -49.9 -40.9 -27.9 -22.5 -34.5 -30.8 -25.3
2 13.5 -13.8 0.0 0.0 0.0 15.6 -16.0 0.0 0.0 0.0 9.6 -9.9 0.0 0.0 0.0
90 5:12 (22.6 deg) 1 -31.2 -31.4 -48.3 -43.0 -35.3 -36.2 -36.4 -56.0 -49.9 -40.9 -22.4 -22.5 -34.5 -30.8 -25.3
2 17.9 -15.0 0.0 0.0 0.0 20.8 -17.4 0.0 0.0 0.0 12.8 -10.8 0.0 0.0 0.0
6:12 (26.6 deg) 1 -25.1 -31.4 -48.3 -43.0 -35.3 -29.1 -36.4 -56.0 -49.9 -40.9 -18.0 -22.5 -34.5 -30.8 -25.3
2 19.8 -15.0 0.0 0.0 0.0 23.0 -17.4 0.0 0.0 0.0 14.2 -10.8 0.0 0.0 0.0
9:12 (36.9 deg) 1 -14.5 -31.4 -48.3 -43.0 -35.3 -16.8 -36.4 -56.0 -49.9 -40.9 -10.4 -22.5 -34.5 -30.8 -25.3
2 23.7 -15.0 0.0 0.0 0.0 27.5 -17.4 0.0 0.0 0.0 16.9 -10.8 0.0 0.0 0.0
12:12 (45.0 deg) 1 -8.2 -31.4 -48.3 -43.0 -35.3 -9.5 -36.4 -56.0 -49.9 -40.9 -5.9 -22.5 -34.5 -30.8 -25.3
2 23.7 -15.0 0.0 0.0 0.0 27.5 -17.4 0.0 0.0 0.0 16.9 -10.8 0.0 0.0 0.0
Table 27.6-2
MWFRS- Part 2: Wind Loads - Roof
Exposure C
MWFRS – Roof
V = 130–150 mph
h = 90–120 ft.
c27.indd 291 4/14/2010 11:04:46 AM
CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
292
V (MPH) 160 180 200
Load Zone Zone Zone
h (ft) Roof Slope Case 1 2 3 4 5 1 2 34512345
Flat < 2:12 (9.46 deg) 1 NA NA -77.7 -69.2 -56.8 NA NA -98.3 -87.6 -71.9 NA NA -121.3 -108.2 -88.7
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -76.2 -54.8 -77.7 -69.2 -56.8 -96.4 -65.6 -98.3 -87.6 -71.9 -119.0 -80.9 -121.3 -108.2 -88.7
2 11.0 -15.5 0.0 0.0 0.0 13.9 -19.6 0.0 0.0 0.0 17.2 -24.2 0.0 0.0 0.0
4:12 (18.4 deg) 1 -62.6 -50.5 -77.7 -69.2 -56.8 -79.3 -64.0 -98.3 -87.6 -71.9 -97.9 -79.0 -121.3 -108.2 -88.7
2 21.7 -22.2 0.0 0.0 0.0 27.4 -28.1 0.0 0.0 0.0 33.9 -34.7 0.0 0.0 0.0
120 5:12 (22.6 deg) 1 -50.3 -50.5 -77.7 -69.2 -56.8 -63.6 -64.0 -98.3 -87.6 -71.9 -78.5 -79.0 -121.3 -108.2 -88.7
2 28.9 -24.2 0.0 0.0 0.0 36.5 -30.6 0.0 0.0 0.0 45.1 -37.8 0.0 0.0 0.0
6:12 (26.6 deg) 1 -40.4 -50.5 -77.7 -69.2 -56.8 -51.1 -64.0 -98.3 -87.6 -71.9 -63.1 -79.0 -121.3 -108.2 -88.7
2 31.9 -24.2 0.0 0.0 0.0 40.3 -30.6 0.0 0.0 0.0 49.8 -37.8 0.0 0.0 0.0
9:12 (36.9 deg) 1 -23.4 -50.5 -77.7 -69.2 -56.8 -29.6 -64.0 -98.3 -87.6 -71.9 -36.5 -79.0 -121.3 -108.2 -88.7
2 38.1 -24.2 0.0 0.0 0.0 48.2 -30.6 0.0 0.0 0.0 59.5 -37.8 0.0 0.0 0.0
12:12 (45.0 deg) 1 -13.2 -50.5 -77.7 -69.2 -56.8 -16.7 -64.0 -98.3 -87.6 -71.9 -20.6 -79.0 -121.3 -108.2 -88.7
2 38.1 -24.2 0.0 0.0 0.0 48.2 -30.6 0.0 0.0 0.0 59.5 -37.8 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -76.2 -68.0 -55.7 NA NA -96.5 -86.0 -70.6 NA NA -119.1 -106.2 -87.1
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -74.8 -53.8 -76.2 -68.0 -55.7 -94.7 -64.4 -96.5 -86.0 -70.6 -116.9 -79.5 -119.1 -106.2 -87.1
2 10.8 -15.2 0.0 0.0 0.0 13.7 -19.2 0.0 0.0 0.0 16.9 -23.7 0.0 0.0 0.0
4:12 (18.4 deg) 1 -61.5 -49.6 -76.2 -68.0 -55.7 -77.8 -62.8 -96.5 -86.0 -70.6 -96.1 -77.6 -119.1 -106.2 -87.1
2 21.3 -21.8 0.0 0.0 0.0 26.9 -27.6 0.0 0.0 0.0 33.3 -34.1 0.0 0.0 0.0
110 5:12 (22.6 deg) 1 -49.3 -49.6 -76.2 -68.0 -55.7 -62.5 -62.8 -96.5 -86.0 -70.6 -77.1 -77.6 -119.1 -106.2 -87.1
2 28.3 -23.7 0.0 0.0 0.0 35.9 -30.0 0.0 0.0 0.0 44.3 -37.1 0.0 0.0 0.0
6:12 (26.6 deg) 1 -39.6 -49.6 -76.2 -68.0 -55.7 -50.2 -62.8 -96.5 -86.0 -70.6 -61.9 -77.6 -119.1 -106.2 -87.1
2 31.3 -23.7 0.0 0.0 0.0 39.6 -30.0 0.0 0.0 0.0 48.9 -37.1 0.0 0.0 0.0
9:12 (36.9 deg) 1 -22.9 -49.6 -76.2 -68.0 -55.7 -29.0 -62.8 -96.5 -86.0 -70.6 -35.9 -77.6 -119.1 -106.2 -87.1
2 37.4 -23.7 0.0 0.0 0.0 47.3 -30.0 0.0 0.0 0.0 58.4 -37.1 0.0 0.0 0.0
12:12 (45.0 deg) 1 -12.9 -49.6 -76.2 -68.0 -55.7 -16.4 -62.8 -96.5 -86.0 -70.6 -20.2 -77.6 -119.1 -106.2 -87.1
2 37.4 -23.7 0.0 0.0 0.0 47.3 -30.0 0.0 0.0 0.0 58.4 -37.1 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -74.7 -66.6 -54.6 NA NA -94.6 -84.3 -69.2 NA NA -116.8 -104.1 -85.4
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -73.3 -52.8 -74.7 -66.6 -54.6 -92.8 -63.1 -94.6 -84.3 -69.2 -114.6 -77.9 -116.8 -104.1 -85.4
2 10.6 -14.9 0.0 0.0 0.0 13.4 -18.8 0.0 0.0 0.0 16.5 -23.2 0.0 0.0 0.0
4:12 (18.4 deg) 1 -60.3 -48.6 -74.7 -66.6 -54.6 -76.3 -61.6 -94.6 -84.3 -69.2 -94.2 -76.0 -116.8 -104.1 -85.4
2 20.9 -21.4 0.0 0.0 0.0 26.4 -27.0 0.0 0.0 0.0 32.6 -33.4 0.0 0.0 0.0
100 5:12 (22.6 deg) 1 -48.4 -48.6 -74.7 -66.6 -54.6 -61.2 -61.6 -94.6 -84.3 -69.2 -75.6 -76.0 -116.8 -104.1 -85.4
2 27.8 -23.3 0.0 0.0 0.0 35.2 -29.4 0.0 0.0 0.0 43.4 -36.4 0.0 0.0 0.0
6:12 (26.6 deg) 1 -38.8 -48.6 -74.7 -66.6 -54.6 -49.2 -61.6 -94.6 -84.3 -69.2 -60.7 -76.0 -116.8 -104.1 -85.4
2 30.7 -23.3 0.0 0.0 0.0 38.8 -29.4 0.0 0.0 0.0 47.9 -36.4 0.0 0.0 0.0
9:12 (36.9 deg) 1 -22.5 -48.6 -74.7 -66.6 -54.6 -28.5 -61.6 -94.6 -84.3 -69.2 -35.1 -76.0 -116.8 -104.1 -85.4
2 36.7 -23.3 0.0 0.0 0.0 46.4 -29.4 0.0 0.0 0.0 57.3 -36.4 0.0 0.0 0.0
12:12 (45.0 deg) 1 -12.7 -48.6 -74.7 -66.6 -54.6 -16.1 -61.6 -94.6 -84.3 -69.2 -19.8 -76.0 -116.8 -104.1 -85.4
2 36.7 -23.3 0.0 0.0 0.0 46.4 -29.4 0.0 0.0 0.0 57.3 -36.4 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -73.1 -65.2 -53.4 NA NA -92.5 -82.5 -67.6 NA NA -114.2 -101.8 -83.5
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -71.7 -51.6 -73.1 -65.2 -53.4 -90.8 -61.7 -92.5 -82.5 -67.6 -112.1 -76.2 -114.2 -101.8 -83.5
2 10.3 -14.5 0.0 0.0 0.0 13.1 -18.4 0.0 0.0 0.0 16.2 -22.7 0.0 0.0 0.0
4:12 (18.4 deg) 1 -59.0 -47.6 -73.1 -65.2 -53.4 -74.6 -60.2 -92.5 -82.5 -67.6 -92.1 -74.3 -114.2 -101.8 -83.5
2 20.4 -20.9 0.0 0.0 0.0 25.8 -26.4 0.0 0.0 0.0 31.9 -32.6 0.0 0.0 0.0
90 5:12 (22.6 deg) 1 -47.3 -47.6 -73.1 -65.2 -53.4 -59.9 -60.2 -92.5 -82.5 -67.6 -73.9 -74.3 -114.2 -101.8 -83.5
2 27.2 -22.8 0.0 0.0 0.0 34.4 -28.8 0.0 0.0 0.0 42.5 -35.6 0.0 0.0 0.0
6:12 (26.6 deg) 1 -38.0 -47.6 -73.1 -65.2 -53.4 -48.1 -60.2 -92.5 -82.5 -67.6 -59.4 -74.3 -114.2 -101.8 -83.5
2 30.0 -22.8 0.0 0.0 0.0 38.0 -28.8 0.0 0.0 0.0 46.9 -35.6 0.0 0.0 0.0
9:12 (36.9 deg) 1 -22.0 -47.6 -73.1 -65.2 -53.4 -27.8 -60.2 -92.5 -82.5 -67.6 -34.4 -74.3 -114.2 -101.8 -83.5
2 35.9 -22.8 0.0 0.0 0.0 45.4 -28.8 0.0 0.0 0.0 56.0 -35.6 0.0 0.0 0.0
12:12 (45.0 deg) 1 -12.4 -47.6 -73.1 -65.2 -53.4 -15.7 -60.2 -92.5 -82.5 -67.6 -19.4 -74.3 -114.2 -101.8 -83.5
2 35.9 -22.8 0.0 0.0 0.0 45.4 -28.8 0.0 0.0 0.0 56.0 -35.6 0.0 0.0 0.0
Table 27.6-2
MWFRS- Part 2: Wind Loads - Roof
Exposure C
MWFRS – Roof
V = 160–200 mph
h = 90–120 ft.
c27.indd 292 4/14/2010 11:04:46 AM
MINIMUM DESIGN LOADS
293
V (MPH) 110 115 120
Load Zone Zone Zone
h (ft) Roof Slope Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat < 2:12 (9.46 deg) 1 NA NA -39.0 -34.8 -28.5 NA NA -42.6 -38.0 -31.2 NA NA -46.4 -41.4 -33.9
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -38.3 -26.0 -39.0 -34.8 -28.5 -41.8 -30.1 -42.6 -38.0 -31.2 -45.5 -31.0 -46.4 -41.4 -33.9
2 5.5 -7.8 0.0 0.0 0.0 6.0 -8.5 0.0 0.0 0.0 6.6 -9.2 0.0 0.0 0.0
4:12 (18.4 deg) 1 -31.5 -25.4 -39.0 -34.8 -28.5 -34.4 -27.7 -42.6 -38.0 -31.2 -37.4 -30.2 -46.4 -41.4 -33.9
2 10.9 -11.1 0.0 0.0 0.0 11.9 -12.2 0.0 0.0 0.0 13.0 -13.3 0.0 0.0 0.0
160 5:12 (22.6 deg) 1 -25.2 -25.4 -39.0 -34.8 -28.5 -27.6 -27.7 -42.6 -38.0 -31.2 -30.0 -30.2 -46.4 -41.4 -33.9
2 14.5 -12.1 0.0 0.0 0.0 15.8 -13.3 0.0 0.0 0.0 17.3 -14.4 0.0 0.0 0.0
6:12 (26.6 deg) 1 -20.3 -25.4 -39.0 -34.8 -28.5 -22.2 -27.7 -42.6 -38.0 -31.2 -24.1 -30.2 -46.4 -41.4 -33.9
2 16.0 -12.1 0.0 0.0 0.0 17.5 -13.3 0.0 0.0 0.0 19.0 -14.4 0.0 0.0 0.0
9:12 (36.9 deg) 1 -11.7 -25.4 -39.0 -34.8 -28.5 -12.8 -27.7 -42.6 -38.0 -31.2 -14.0 -30.2 -46.4 -41.4 -33.9
2 19.1 -12.1 0.0 0.0 0.0 20.9 -13.3 0.0 0.0 0.0 22.8 -14.4 0.0 0.0 0.0
12:12 (45.0 deg) 1 -6.6 -25.4 -39.0 -34.8 -28.5 -7.2 -27.7 -42.6 -38.0 -31.2 -7.9 -30.2 -46.4 -41.4 -33.9
2 19.1 -12.1 0.0 0.0 0.0 20.9 -13.3 0.0 0.0 0.0 22.8 -14.4 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -38.5 -34.3 -28.1 NA NA -42.0 -37.5 -30.7 NA NA -45.8 -40.8 -33.5
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -37.7 -25.7 -38.5 -34.3 -28.1 -41.3 -29.7 -42.0 -37.5 -30.7 -44.9 -30.5 -45.8 -40.8 -33.5
2 5.4 -7.7 0.0 0.0 0.0 6.0 -8.4 0.0 0.0 0.0 6.5 -9.1 0.0 0.0 0.0
4:12 (18.4 deg) 1 -31.0 -25.0 -38.5 -34.3 -28.1 -33.9 -27.4 -42.0 -37.5 -30.7 -36.9 -29.8 -45.8 -40.8 -33.5
2 10.7 -11.0 0.0 0.0 0.0 11.7 -12.0 0.0 0.0 0.0 12.8 -13.1 0.0 0.0 0.0
150 5:12 (22.6 deg) 1 -24.9 -25.0 -38.5 -34.3 -28.1 -27.2 -27.4 -42.0 -37.5 -30.7 -29.6 -29.8 -45.8 -40.8 -33.5
2 14.3 -12.0 0.0 0.0 0.0 15.6 -13.1 0.0 0.0 0.0 17.0 -14.3 0.0 0.0 0.0
6:12 (26.6 deg) 1 -20.0 -25.0 -38.5 -34.3 -28.1 -21.9 -27.4 -42.0 -37.5 -30.7 -23.8 -29.8 -45.8 -40.8 -33.5
2 15.8 -12.0 0.0 0.0 0.0 17.3 -13.1 0.0 0.0 0.0 18.8 -14.3 0.0 0.0 0.0
9:12 (36.9 deg) 1 -11.6 -25.0 -38.5 -34.3 -28.1 -12.7 -27.4 -42.0 -37.5 -30.7 -13.8 -29.8 -45.8 -40.8 -33.5
2 18.9 -12.0 0.0 0.0 0.0 20.6 -13.1 0.0 0.0 0.0 22.5 -14.3 0.0 0.0 0.0
12:12 (45.0 deg) 1 -6.5 -25.0 -38.5 -34.3 -28.1 -7.1 -27.4 -42.0 -37.5 -30.7 -7.8 -29.8 -45.8 -40.8 -33.5
2 18.9 -12.0 0.0 0.0 0.0 20.6 -13.1 0.0 0.0 0.0 22.5 -14.3 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -37.9 -33.8 -27.7 NA NA -41.4 -36.9 -30.3 NA NA -45.1 -40.2 -33.0
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -37.2 -25.3 -37.9 -33.8 -27.7 -40.7 -29.3 -41.4 -36.9 -30.3 -44.3 -30.1 -45.1 -40.2 -33.0
2 5.4 -7.5 0.0 0.0 0.0 5.9 -8.2 0.0 0.0 0.0 6.4 -9.0 0.0 0.0 0.0
4:12 (18.4 deg) 1 -30.6 -24.7 -37.9 -33.8 -27.7 -33.4 -27.0 -41.4 -36.9 -30.3 -36.4 -29.4 -45.1 -40.2 -33.0
2 10.6 -10.8 0.0 0.0 0.0 11.6 -11.8 0.0 0.0 0.0 12.6 -12.9 0.0 0.0 0.0
140 5:12 (22.6 deg) 1 -24.5 -24.7 -37.9 -33.8 -27.7 -26.8 -27.0 -41.4 -36.9 -30.3 -29.2 -29.4 -45.1 -40.2 -33.0
2 14.1 -11.8 0.0 0.0 0.0 15.4 -12.9 0.0 0.0 0.0 16.8 -14.0 0.0 0.0 0.0
6:12 (26.6 deg) 1 -19.7 -24.7 -37.9 -33.8 -27.7 -21.5 -27.0 -41.4 -36.9 -30.3 -23.5 -29.4 -45.1 -40.2 -33.0
2 15.6 -11.8 0.0 0.0 0.0 17.0 -12.9 0.0 0.0 0.0 18.5 -14.0 0.0 0.0 0.0
9:12 (36.9 deg) 1 -11.4 -24.7 -37.9 -33.8 -27.7 -12.5 -27.0 -41.4 -36.9 -30.3 -13.6 -29.4 -45.1 -40.2 -33.0
2 18.6 -11.8 0.0 0.0 0.0 20.3 -12.9 0.0 0.0 0.0 22.1 -14.0 0.0 0.0 0.0
12:12 (45.0 deg) 1 -6.4 -24.7 -37.9 -33.8 -27.7 -7.0 -27.0 -41.4 -36.9 -30.3 -7.7 -29.4 -45.1 -40.2 -33.0
2 18.6 -11.8 0.0 0.0 0.0 20.3 -12.9 0.0 0.0 0.0 22.1 -14.0 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -37.3 -33.3 -27.3 NA NA -40.8 -36.4 -29.8 NA NA -44.4 -39.6 -32.5
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -36.6 -24.9 -37.3 -33.3 -27.3 -40.0 -28.8 -40.8 -36.4 -29.8 -43.6 -29.6 -44.4 -39.6 -32.5
2 5.3 -7.4 0.0 0.0 0.0 5.8 -8.1 0.0 0.0 0.0 6.3 -8.8 0.0 0.0 0.0
4:12 (18.4 deg) 1 -30.1 -24.3 -37.3 -33.3 -27.3 -32.9 -26.6 -40.8 -36.4 -29.8 -35.8 -28.9 -44.4 -39.6 -32.5
2 10.4 -10.7 0.0 0.0 0.0 11.4 -11.7 0.0 0.0 0.0 12.4 -12.7 0.0 0.0 0.0
130 5:12 (22.6 deg) 1 -24.2 -24.3 -37.3 -33.3 -27.3 -26.4 -26.6 -40.8 -36.4 -29.8 -28.7 -28.9 -44.4 -39.6 -32.5
2 13.9 -11.6 0.0 0.0 0.0 15.2 -12.7 0.0 0.0 0.0 16.5 -13.8 0.0 0.0 0.0
6:12 (26.6 deg) 1 -19.4 -24.3 -37.3 -33.3 -27.3 -21.2 -26.6 -40.8 -36.4 -29.8 -23.1 -28.9 -44.4 -39.6 -32.5
2 15.3 -11.6 0.0 0.0 0.0 16.7 -12.7 0.0 0.0 0.0 18.2 -13.8 0.0 0.0 0.0
9:12 (36.9 deg) 1 -11.2 -24.3 -37.3 -33.3 -27.3 -12.3 -26.6 -40.8 -36.4 -29.8 -13.4 -28.9 -44.4 -39.6 -32.5
2 18.3 -11.6 0.0 0.0 0.0 20.0 -12.7 0.0 0.0 0.0 21.8 -13.8 0.0 0.0 0.0
12:12 (45.0 deg) 1 -6.3 -24.3 -37.3 -33.3 -27.3 -6.9 -26.6 -40.8 -36.4 -29.8 -7.5 -28.9 -44.4 -39.6 -32.5
2 18.3 -11.6 0.0 0.0 0.0 20.0 -12.7 0.0 0.0 0.0 21.8 -13.8 0.0 0.0 0.0
Table 27.6-2
MWFRS- Part 2: Wind Loads - Roof
Exposure C
MWFRS – Roof
V = 110–120 mph
h = 130–160 ft.
c27.indd 293 4/14/2010 11:04:46 AM
CHAPTER 27 WIND LOADS ON BUILDINGS—MWFRS (DIRECTIONAL PROCEDURE)
294
V (MPH) 130 140 150
Load Zone Zone Zone
h (ft) Roof Slope Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat < 2:12 (9.46 deg) 1 NA NA -54.5 -48.6 -39.8 NA NA -63.2 -56.3 -46.2 NA NA -72.5 -64.6 -53.0
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -53.4 -36.3 -54.5 -48.6 -39.8 -62.0 -42.1 -63.2 -56.3 -46.2 -71.1 -48.4 -72.5 -64.6 -53.0
2 7.7 -10.8 0.0 0.0 0.0 8.9 -12.6 0.0 0.0 0.0 10.3 -14.4 0.0 0.0 0.0
4:12 (18.4 deg) 1 -43.9 -35.5 -54.5 -48.6 -39.8 -51.0 -41.1 -63.2 -56.3 -46.2 -58.5 -47.2 -72.5 -64.6 -53.0
2 15.2 -15.6 0.0 0.0 0.0 17.6 -18.1 0.0 0.0 0.0 20.2 -20.7 0.0 0.0 0.0
160 5:12 (22.6 deg) 1 -35.2 -35.5 -54.5 -48.6 -39.8 -40.9 -41.1 -63.2 -56.3 -46.2 -46.9 -47.2 -72.5 -64.6 -53.0
2 20.2 -17.0 0.0 0.0 0.0 23.5 -19.7 0.0 0.0 0.0 27.0 -22.6 0.0 0.0 0.0
6:12 (26.6 deg) 1 -28.3 -35.5 -54.5 -48.6 -39.8 -32.8 -41.1 -63.2 -56.3 -46.2 -37.7 -47.2 -72.5 -64.6 -53.0
2 22.4 -17.0 0.0 0.0 0.0 25.9 -19.7 0.0 0.0 0.0 29.8 -22.6 0.0 0.0 0.0
9:12 (36.9 deg) 1 -16.4 -35.5 -54.5 -48.6 -39.8 -19.0 -41.1 -63.2 -56.3 -46.2 -21.8 -47.2 -72.5 -64.6 -53.0
2 26.7 -17.0 0.0 0.0 0.0 31.0 -19.7 0.0 0.0 0.0 11.4 -22.6 0.0 0.0 0.0
12:12 (45.0 deg) 1 -9.2 -35.5 -54.5 -48.6 -39.8 -10.7 -41.1 -63.2 -56.3 -46.2 -12.3 -47.2 -72.5 -64.6 -53.0
2 26.7 -17.0 0.0 0.0 0.0 31.0 -19.7 0.0 0.0 0.0 35.6 -22.6 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -53.7 -47.9 -39.3 NA NA -62.3 -55.6 -45.6 NA NA -71.5 -63.8 -52.3
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -52.7 -35.8 -53.7 -47.9 -39.3 -61.1 -41.6 -62.3 -55.6 -45.6 -70.2 -47.7 -71.5 -63.8 -52.3
2 7.6 -10.7 0.0 0.0 0.0 8.8 -12.4 0.0 0.0 0.0 10.1 -14.2 0.0 0.0 0.0
4:12 (18.4 deg) 1 -43.3 -35.0 -53.7 -47.9 -39.3 -50.3 -40.6 -62.3 -55.6 -45.6 -57.7 -46.6 -71.5 -63.8 -52.3
2 15.0 -15.4 0.0 0.0 0.0 17.4 -17.8 0.0 0.0 0.0 20.0 -20.4 0.0 0.0 0.0
150 5:12 (22.6 deg) 1 -34.8 -35.0 -53.7 -47.9 -39.3 -40.3 -40.6 -62.3 -55.6 -45.6 -46.3 -46.6 -71.5 -63.8 -52.3
2 20.0 -16.7 0.0 0.0 0.0 23.2 -19.4 0.0 0.0 0.0 26.6 -22.3 0.0 0.0 0.0
6:12 (26.6 deg) 1 -27.9 -35.0 -53.7 -47.9 -39.3 -32.4 -40.6 -62.3 -55.6 -45.6 -37.2 -46.6 -71.5 -63.8 -52.3
2 22.1 -16.7 0.0 0.0 0.0 25.6 -19.4 0.0 0.0 0.0 29.4 -22.3 0.0 0.0 0.0
9:12 (36.9 deg) 1 -16.2 -35.0 -53.7 -47.9 -39.3 -18.8 -40.6 -62.3 -55.6 -45.6 -21.5 -46.6 -71.5 -63.8 -52.3
2 26.4 -16.7 0.0 0.0 0.0 30.6 -19.4 0.0 0.0 0.0 11.3 -22.3 0.0 0.0 0.0
12:12 (45.0 deg) 1 -9.1 -35.0 -53.7 -47.9 -39.3 -10.6 -40.6 -62.3 -55.6 -45.6 -12.1 -46.6 -71.5 -63.8 -52.3
2 26.4 -16.7 0.0 0.0 0.0 30.6 -19.4 0.0 0.0 0.0 35.1 -22.3 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -53.0 -47.2 -38.7 NA NA -61.4 -54.8 -44.9 NA NA -70.5 -62.9 -51.5
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -52.0 -35.3 -53.0 -47.2 -38.7 -60.3 -41.0 -61.4 -54.8 -44.9 -69.2 -47.0 -70.5 -62.9 -51.5
2 7.5 -10.5 0.0 0.0 0.0 8.7 -12.2 0.0 0.0 0.0 10.0 -14.0 0.0 0.0 0.0
4:12 (18.4 deg) 1 -42.7 -34.5 -53.0 -47.2 -38.7 -49.5 -40.0 -61.4 -54.8 -44.9 -56.9 -45.9 -70.5 -62.9 -51.5
2 14.8 -15.1 0.0 0.0 0.0 17.2 -17.6 0.0 0.0 0.0 19.7 -20.2 0.0 0.0 0.0
140 5:12 (22.6 deg) 1 -34.3 -34.5 -53.0 -47.2 -38.7 -39.7 -40.0 -61.4 -54.8 -44.9 -45.6 -45.9 -70.5 -62.9 -51.5
2 19.7 -16.5 0.0 0.0 0.0 22.8 -19.1 0.0 0.0 0.0 26.2 -21.9 0.0 0.0 0.0
6:12 (26.6 deg) 1 -27.5 -34.5 -53.0 -47.2 -38.7 -31.9 -40.0 -61.4 -54.8 -44.9 -36.6 -45.9 -70.5 -62.9 -51.5
2 21.7 -16.5 0.0 0.0 0.0 25.2 -19.1 0.0 0.0 0.0 28.9 -21.9 0.0 0.0 0.0
9:12 (36.9 deg) 1 -15.9 -34.5 -53.0 -47.2 -38.7 -18.5 -40.0 -61.4 -54.8 -44.9 -21.2 -45.9 -70.5 -62.9 -51.5
2 26.0 -16.5 0.0 0.0 0.0 30.1 -19.1 0.0 0.0 0.0 11.1 -21.9 0.0 0.0 0.0
12:12 (45.0 deg) 1 -9.0 -34.5 -53.0 -47.2 -38.7 -10.4 -40.0 -61.4 -54.8 -44.9 -12.0 -45.9 -70.5 -62.9 -51.5
2 26.0 -16.5 0.0 0.0 0.0 30.1 -19.1 0.0 0.0 0.0 34.6 -21.9 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -52.1 -46.5 -38.1 NA NA -60.5 -53.9 -44.2 NA NA -69.4 -61.9 -50.7
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -51.2 -34.8 -52.1 -46.5 -38.1 -59.3 -40.3 -60.5 -53.9 -44.2 -68.1 -46.3 -69.4 -61.9 -50.7
2 7.4 -10.4 0.0 0.0 0.0 8.6 -12.0 0.0 0.0 0.0 9.8 -13.8 0.0 0.0 0.0
4:12 (18.4 deg) 1 -42.1 -33.9 -52.1 -46.5 -38.1 -48.8 -39.4 -60.5 -53.9 -44.2 -56.0 -45.2 -69.4 -61.9 -50.7
2 14.6 -14.9 0.0 0.0 0.0 16.9 -17.3 0.0 0.0 0.0 19.4 -19.8 0.0 0.0 0.0
130 5:12 (22.6 deg) 1 -33.7 -33.9 -52.1 -46.5 -38.1 -39.1 -39.4 -60.5 -53.9 -44.2 -44.9 -45.2 -69.4 -61.9 -50.7
2 19.4 -16.2 0.0 0.0 0.0 22.5 -18.8 0.0 0.0 0.0 25.8 -21.6 0.0 0.0 0.0
6:12 (26.6 deg) 1 -27.1 -33.9 -52.1 -46.5 -38.1 -31.4 -39.4 -60.5 -53.9 -44.2 -36.1 -45.2 -69.4 -61.9 -50.7
2 21.4 -16.2 0.0 0.0 0.0 24.8 -18.8 0.0 0.0 0.0 28.5 -21.6 0.0 0.0 0.0
9:12 (36.9 deg) 1 -15.7 -33.9 -52.1 -46.5 -38.1 -18.2 -39.4 -60.5 -53.9 -44.2 -20.9 -45.2 -69.4 -61.9 -50.7
2 25.6 -16.2 0.0 0.0 0.0 29.7 -18.8 0.0 0.0 0.0 10.9 -21.6 0.0 0.0 0.0
12:12 (45.0 deg) 1 -8.9 -33.9 -52.1 -46.5 -38.1 -10.3 -39.4 -60.5 -53.9 -44.2 -11.8 -45.2 -69.4 -61.9 -50.7
2 15.0 -9.5 0.0 0.0 0.0 16.4 -10.4 0.0 0.0 0.0 34.1 -21.6 0.0 0.0 0.0
Table 27.6-2
MWFRS- Part 2: Wind Loads - Roof
Exposure C
MWFRS – Roof
V = 130–150 mph
h = 130–160 ft.
c27.indd 294 4/14/2010 11:04:46 AM
MINIMUM DESIGN LOADS
295
V (MPH) 160 180 200
Load Zone Zone Zone
h (ft) Roof Slope Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat < 2:12 (9.46 deg) 1 NA NA -82.5 -73.6 -60.3 NA NA -104.4 -93.1 -76.3 NA NA -128.9 -114.9 -94.3
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -80.9 -58.3 -82.5 -73.6 -60.3 -102.5 -69.6 -104.4 -93.1 -76.3 -126.5 -86.0 -128.9 -114.9 -94.3
2 11.7 -16.4 0.0 0.0 0.0 14.8 -20.8 0.0 0.0 0.0 18.2 -25.7 0.0 0.0 0.0
4:12 (18.4 deg) 1 -66.5 -53.7 -82.5 -73.6 -60.3 -84.2 -68.0 -104.4 -93.1 -76.3 -104.0 -83.9 -128.9 -114.9 -94.3
2 23.0 -23.6 0.0 0.0 0.0 29.2 -29.8 0.0 0.0 0.0 36.0 -36.8 0.0 0.0 0.0
160 5:12 (22.6 deg) 1 -53.4 -53.7 -82.5 -73.6 -60.3 -67.6 -68.0 -104.4 -93.1 -76.3 -83.4 -83.9 -128.9 -114.9 -94.3
2 30.7 -25.7 0.0 0.0 0.0 38.8 -32.5 0.0 0.0 0.0 47.9 -40.1 0.0 0.0 0.0
6:12 (26.6 deg) 1 -42.9 -53.7 -82.5 -73.6 -60.3 -54.3 -68.0 -104.4 -93.1 -76.3 -67.0 -83.9 -128.9 -114.9 -94.3
2 33.9 -25.7 0.0 0.0 0.0 42.9 -32.5 0.0 0.0 0.0 52.9 -40.1 0.0 0.0 0.0
9:12 (36.9 deg) 1 -24.8 -53.7 -82.5 -73.6 -60.3 -31.4 -68.0 -104.4 -93.1 -76.3 -38.8 -83.9 -128.9 -114.9 -94.3
2 40.5 -25.7 0.0 0.0 0.0 51.2 -32.5 0.0 0.0 0.0 63.2 -40.1 0.0 0.0 0.0
12:12 (45.0 deg) 1 -14.0 -53.7 -82.5 -73.6 -60.3 -17.7 -68.0 -104.4 -93.1 -76.3 -21.9 -83.9 -128.9 -114.9 -94.3
2 40.5 -25.7 0.0 0.0 0.0 51.2 -32.5 0.0 0.0 0.0 63.2 -40.1 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -81.4 -72.6 -59.5 NA NA -103.0 -91.8 -75.3 NA NA -127.2 -113.4 -93.0
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -79.9 -57.5 -81.4 -72.6 -59.5 -101.1 -68.7 -103.0 -91.8 -75.3 -124.8 -84.8 -127.2 -113.4 -93.0
2 11.5 -16.2 0.0 0.0 0.0 14.6 -20.5 0.0 0.0 0.0 18.0 -25.3 0.0 0.0 0.0
4:12 (18.4 deg) 1 -65.7 -53.0 -81.4 -72.6 -59.5 -83.1 -67.1 -103.0 -91.8 -75.3 -102.6 -82.8 -127.2 -113.4 -93.0
2 22.7 -23.3 0.0 0.0 0.0 28.8 -29.4 0.0 0.0 0.0 35.5 -36.4 0.0 0.0 0.0
150 5:12 (22.6 deg) 1 -52.7 -53.0 -81.4 -72.6 -59.5 -66.7 -67.1 -103.0 -91.8 -75.3 -82.3 -82.8 -127.2 -113.4 -93.0
2 30.3 -25.3 0.0 0.0 0.0 38.3 -32.1 0.0 0.0 0.0 47.3 -39.6 0.0 0.0 0.0
6:12 (26.6 deg) 1 -42.3 -53.0 -81.4 -72.6 -59.5 -53.5 -67.1 -103.0 -91.8 -75.3 -66.1 -82.8 -127.2 -113.4 -93.0
2 33.4 -25.3 0.0 0.0 0.0 42.3 -32.1 0.0 0.0 0.0 52.2 -39.6 0.0 0.0 0.0
9:12 (36.9 deg) 1 -24.5 -53.0 -81.4 -72.6 -59.5 -31.0 -67.1 -103.0 -91.8 -75.3 -38.3 -82.8 -127.2 -113.4 -93.0
2 39.9 -25.3 0.0 0.0 0.0 50.5 -32.1 0.0 0.0 0.0 62.4 -39.6 0.0 0.0 0.0
12:12 (45.0 deg) 1 -13.8 -53.0 -81.4 -72.6 -59.5 -17.5 -67.1 -103.0 -91.8 -75.3 -21.6 -82.8 -127.2 -113.4 -93.0
2 39.9 -25.3 0.0 0.0 0.0 50.5 -32.1 0.0 0.0 0.0 62.4 -39.6 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -80.2 -71.5 -58.6 NA NA -101.5 -90.5 -74.2 NA NA -125.3 -111.7 -91.6
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -78.7 -56.7 -80.2 -71.5 -58.6 -99.6 -67.7 -101.5 -90.5 -74.2 -123.0 -83.6 -125.3 -111.7 -91.6
2 11.4 -16.0 0.0 0.0 0.0 14.4 -20.2 0.0 0.0 0.0 17.7 -24.9 0.0 0.0 0.0
4:12 (18.4 deg) 1 -64.7 -52.2 -80.2 -71.5 -58.6 -81.9 -66.1 -101.5 -90.5 -74.2 -101.1 -81.6 -125.3 -111.7 -91.6
2 22.4 -22.9 0.0 0.0 0.0 28.4 -29.0 0.0 0.0 0.0 35.0 -35.8 0.0 0.0 0.0
140 5:12 (22.6 deg) 1 -51.9 -52.2 -80.2 -71.5 -58.6 -65.7 -66.1 -101.5 -90.5 -74.2 -81.1 -81.6 -125.3 -111.7 -91.6
2 29.8 -25.0 0.0 0.0 0.0 37.7 -31.6 0.0 0.0 0.0 46.6 -39.0 0.0 0.0 0.0
6:12 (26.6 deg) 1 -41.7 -52.2 -80.2 -71.5 -58.6 -52.8 -66.1 -101.5 -90.5 -74.2 -65.2 -81.6 -125.3 -111.7 -91.6
2 32.9 -25.0 0.0 0.0 0.0 41.7 -31.6 0.0 0.0 0.0 51.4 -39.0 0.0 0.0 0.0
9:12 (36.9 deg) 1 -24.1 -52.2 -80.2 -71.5 -58.6 -30.6 -66.1 -101.5 -90.5 -74.2 -37.7 -81.6 -125.3 -111.7 -91.6
2 39.4 -25.0 0.0 0.0 0.0 49.8 -31.6 0.0 0.0 0.0 61.5 -39.0 0.0 0.0 0.0
12:12 (45.0 deg) 1 -13.6 -52.2 -80.2 -71.5 -58.6 -17.2 -66.1 -101.5 -90.5 -74.2 -21.3 -81.6 -125.3 -111.7 -91.6
2 39.4 -25.0 0.0 0.0 0.0 49.8 -31.6 0.0 0.0 0.0 61.5 -39.0 0.0 0.0 0.0
Flat < 2:12 (9.46 deg) 1 NA NA -79.0 -70.4 -57.7 NA NA -100.0 -89.1 -73.1 NA NA -123.4 -110.0 -90.2
2 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0 NA NA 0.0 0.0 0.0
3:12 (14.0 deg) 1 -77.5 -55.8 -79.0 -70.4 -57.7 -98.1 -66.7 -100.0 -89.1 -73.1 -121.1 -82.3 -123.4 -110.0 -90.2
2 11.2 -15.7 0.0 0.0 0.0 14.1 -19.9 0.0 0.0 0.0 17.5 -24.6 0.0 0.0 0.0
4:12 (18.4 deg) 1 -63.7 -51.4 -79.0 -70.4 -57.7 -80.6 -65.1 -100.0 -89.1 -73.1 -99.5 -80.3 -123.4 -110.0 -90.2
2 22.1 -22.6 0.0 0.0 0.0 27.9 -28.6 0.0 0.0 0.0 34.5 -35.3 0.0 0.0 0.0
130 5:12 (22.6 deg) 1 -51.1 -51.4 -79.0 -70.4 -57.7 -64.7 -65.1 -100.0 -89.1 -73.1 -79.9 -80.3 -123.4 -110.0 -90.2
2 29.4 -24.6 0.0 0.0 0.0 37.2 -31.1 0.0 0.0 0.0 45.9 -38.4 0.0 0.0 0.0
6:12 (26.6 deg) 1 -41.1 -51.4 -79.0 -70.4 -57.7 -52.0 -65.1 -100.0 -89.1 -73.1 -64.1 -80.3 -123.4 -110.0 -90.2
2 32.4 -24.6 0.0 0.0 0.0 41.0 -31.1 0.0 0.0 0.0 50.6 -38.4 0.0 0.0 0.0
9:12 (36.9 deg) 1 -23.8 -51.4 -79.0 -70.4 -57.7 -30.1 -65.1 -100.0 -89.1 -73.1 -37.1 -80.3 -123.4 -110.0 -90.2
2 38.7 -24.6 0.0 0.0 0.0 49.0 -31.1 0.0 0.0 0.0 60.5 -38.4 0.0 0.0 0.0
12:12 (45.0 deg) 1 -13.4 -51.4 -79.0 -70.4 -57.7 -17.0 -65.1 -100.0 -89.1 -73.1 -21.0 -80.3 -123.4 -110.0 -90.2
2 38.7 -24.6 0.0 0.0 0.0 49.0 -31.1 0.0 0.0 0.0 60.5 -38.4 0.0 0.0 0.0
Table 27.6-2
MWFRS – Part 2: Wind Loads – Roof
Exposure C
MWFRS – Roof
V = 160–200 mph
h = 130–160 ft.
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297
Chapter 28
WIND LOADS ON BUILDINGS—MWFRS
(ENVELOPE PROCEDURE)
PART 1: ENCLOSED AND PARTIALLY
ENCLOSED LOW-RISE BUILDINGS
28.2 GENERAL REQUIREMENTS
The steps required for the determination of MWFRS
wind loads on low-rise buildings are shown in Table
28.2-1.
28.1 SCOPE
28.1.1 Building Types
This chapter applies to the determination of
MWFRS wind loads on low-rise buildings using the
Envelope Procedure.
1) Part 1 applies to all low-rise buildings where it is
necessary to separate applied wind loads onto the
windward, leeward, and side walls of the building
to properly assess the internal forces in the
MWFRS members.
2) Part 2 applies to a special class of low-rise buildings
designated as enclosed simple diaphragm
buildings as defi ned in Section 26.2.
28.1.2 Conditions
A building whose design wind loads are determined
in accordance with this section shall comply
with all of the following conditions:
1. The building is a regular-shaped building or
structure as defi ned in Section 26.2.
2. The building does not have response characteristics
making it subject to across wind loading, vortex
shedding, instability due to galloping or fl utter, or
it does not have a site location for which channeling
effects or buffeting in the wake of upwind
obstructions warrant special consideration.
28.1.3 Limitations
The provisions of this chapter take into consideration
the load magnifi cation effect caused by gusts in
resonance with along-wind vibrations of fl exible
buildings. Buildings not meeting the requirements of
Section 28.1.2, or having unusual shapes or response
characteristics shall be designed using recognized
literature documenting such wind load effects or
shall use the wind tunnel procedure specifi ed in
Chapter 31.
28.1.4 Shielding
There shall be no reductions in velocity pressure
due to apparent shielding afforded by buildings and
other structures or terrain features.
User Note: Use Part 1 of Chapter 28 to determine the
wind pressure on the MWFRS of enclosed, partially
enclosed or open low-rise buildings having a fl at, gable
or hip roof. These provisions utilize the Envelope
Procedure by calculating wind pressures from the
specifi c equation applicable to each building surface. For
building shapes and heights for which these provisions
are applicable this method generally yields the lowest
wind pressure of all of the analytical methods specifi ed
in this standard.
28.2.1 Wind Load Parameters Specifi ed
in Chapter 26
The following wind load parameters shall be
determined in accordance with Chapter 26:
– Basic Wind Speed V (Section 26.5)
– Wind directionality Factor Kd (Section 26.6)
– Exposure category (Section 26.7)
– Topographic factor Kzt (Section 26.8)
– Enclosure classifi cation (Section 26.10)
– Internal pressure coeffi cient (GCpi) (Section 26.11).
28.3 VELOCITY PRESSURE
28.3.1 Velocity Pressure Exposure Coeffi cient
Based on the Exposure Category determined in
Section 26.7.3, a velocity pressure exposure coeffi -
cient Kz or Kh, as applicable, shall be determined from
Table 28.3-1.
For a site located in a transition zone between
exposure categories that is near to a change in
ground surface roughness, intermediate values of
Kz or Kh, between those shown in Table 28.3-1, are
permitted, provided that they are determined by a
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298
rational analysis method defi ned in the recognized
literature.
28.3.2 Velocity Pressure
Velocity pressure, qz, evaluated at height z shall
be calculated by the following equation:
qz = 0.00256 KzKztKdV2 (lb/ft2
) (28.3-1)
[In SI: qz = 0.613 KzKztKdV2
(N/m2
); V in m/s]
where
Kd = wind directionality factor defi ned in Section 26.6
Kz = velocity pressure exposure coeffi cient defi ned in
Section 28.3.1
Kzt = topographic factor defi ned in Section 26.8.2
V = basic wind speed from Section 26.5.1
qh = velocity pressure qz calculated using Eq. 28.3-1
at mean roof height h
The numerical coeffi cient 0.00256 (0.613 in SI)
shall be used except where suffi cient climatic data are
available to justify the selection of a different value of
this factor for a design application.
28.4 WIND LOADS—MAIN WIND-FORCE
RESISTING SYSTEM
28.4.1 Design Wind Pressure for Low-Rise
Buildings
Design wind pressures for the MWFRS of
low-rise buildings shall be determined by the following
equation:
p = qh[(GCpf) – (GCpi)] (lb/ft2
) (N/m2
) (28.4-1)
where
qh = velocity pressure evaluated at mean roof
height h as defi ned in Section 26.3
(GCpf) = external pressure coeffi cient from Fig. 28.4-1
(GCpi) = internal pressure coeffi cient from Table
26.11-1
28.4.1.1 External Pressure Coeffi cients (GCpf)
The combined gust effect factor and external
pressure coeffi cients for low-rise buildings, (GCpf), are
not permitted to be separated.
28.4.2 Parapets
The design wind pressure for the effect of
parapets on MWFRS of low-rise buildings with fl at,
gable, or hip roofs shall be determined by the following
equation:
pp = qp(GCpn) (lb/ft2
) (28.4-2)
where
pp = combined net pressure on the parapet due to
the combination of the net pressures from the
front and back parapet surfaces. Plus (and
minus) signs signify net pressure acting
toward (and away from) the front (exterior)
side of the parapet
qp = velocity pressure evaluated at the top of the
parapet
GCpn = combined net pressure coeffi cient
= +1.5 for windward parapet
= –1.0 for leeward parapet
28.4.3 Roof Overhangs
The positive external pressure on the bottom
surface of windward roof overhangs shall be determined
using Cp = 0.7 in combination with the top
surface pressures determined using Fig. 28.4-1.
28.4.4 Minimum Design Wind Loads
The wind load to be used in the design of the
MWFRS for an enclosed or partially enclosed
building shall not be less than 16 lb/ft2
(0.77 kN/m2
)
Table 28.2-1 Steps to Determine Wind Loads
on MWFRS Low-Rise Buildings
Step 1: Determine risk category of building or other
structure, see Table 1.5-1
Step 2: Determine the basic wind speed, V, for applicable
risk category, see Fig. 26.5-1A, B or C
Step 3: Determine wind load parameters:
➢ Wind directionality factor, Kd , see Section
26.6 and Table 26.6-1
➢ Exposure category B, C or D, see Section
26.7
➢ Topographic factor, Kzt, see Section 26.8 and
Fig. 26.8-1
➢ Enclosure classifi cation, see Section 26.10
➢ Internal pressure coeffi cient, (GCpi), see
Section 26.11 and Table 26.11-1
Step 4: Determine velocity pressure exposure
coeffi cient, Kz or Kh, see Table 28.3-1
Step 5: Determine velocity pressure, qz or qh, Eq. 28.3-1
Step 6: Determine external pressure coeffi cient, (GCp),
using Fig. 28.4-1 for fl at and gable roofs.
Step 7: Calculate wind pressure, p, from Eq. 28.4-1
User Note: See Commentary Fig. C28.4-1 for
guidance on hip roofs.
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299
Velocity Pressure Exposure Coefficients, Kh and Kz
Table 28.3-1
Height above
ground level, z
Exposure
B C D
ft (m)
0-15 (0-4.6) 0.70 0.85 1.03
20 (6.1) 0.70 0.90 1.08
25 (7.6) 0.70 0.94 1.12
30 (9.1) 0.70 0.98 1.16
40 (12.2) 0.76 1.04 1.22
50 (15.2) 0.81 1.09 1.27
60 (18) 0.85 1.13 1.31
Notes:
1 The velocity pressure exposure coefficient Kz may be determined from the following formula:
For 15 ft. ≤ z ≤ zg For z < 15 ft.
Kz = 2.01 (z/zg)
2/α
Kz = 2.01 (15/zg)
2/α
Note: z shall not be taken less than 30 feet in exposure B.
2. α and zg are tabulated in Table 26.9-1.
3. Linear interpolation for intermediate values of height z is acceptable.
4. Exposure categories are defined in Section 26.7.
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CHAPTER 28 WIND LOADS ON BUILDINGS—MWFRS (ENVELOPE PROCEDURE)
302
multiplied by the wall area of the building and 8 lb/ft2
(0.38 kN/m2
) multiplied by the roof area of the
building projected onto a vertical plane normal to the
assumed wind direction.
PART 2: ENCLOSED SIMPLE DIAPHRAGM
LOW-RISE BUILDINGS
28.5 GENERAL REQUIREMENTS
The steps required for the determination of MWFRS
wind loads on enclosed simple diaphragm buildings
are shown in Table 28.5-1.
Table 28.5-1 Steps to Determine Wind Loads on
MWFRS Simple Diaphragm Low-Rise Buildings
Step 1: Determine risk category of building or other
structure, see Table 1.5-1
Step 2: Determine the basic wind speed, V, for applicable
risk category, see Fig. 26.5-1A, B or C
Step 3: Determine wind load parameters:
➢ Exposure category B, C or D, see Section 26.7
➢ Topographic factor, Kzt, see Section 26.8 and
Fig. 26.8-1
Step 4: Enter fi gure to determine wind pressures for
h = 30 ft (9.1 m)., pS30, see Fig. 28.6-1
Step 5: Enter fi gure to determine adjustment for
building height and exposure, λ, see Fig. 28.6-1
Step 6: Determine adjusted wind pressures, ps, see
Eq. 28.6-1
User Note: Part 2 of Chapter 28 is a simplifi ed method
to determine the wind pressure on the MWFRS of
enclosed simple diaphragm low-rise buildings having a
fl at, gable or hip roof. The wind pressures are obtained
directly from a table and applied on horizontal and
vertical projected surfaces of the building. This method
is a simplifi cation of the Envelope Procedure contained
in Part 1 of Chapter 28.
28.5.1 Wind Load Parameters Specifi ed in
Chapter 26
The following wind load parameters are specifi ed
in Chapter 26:
– Basic Wind Speed V (Section 26.5)
– Exposure category (Section 26.7)
– Topographic factor Kzt (Section 26.8)
– Enclosure classifi cation (Section 26.10)
28.6 WIND LOADS—MAIN WIND-FORCE
RESISTING SYSTEM
28.6.1 Scope
A building whose design wind loads are determined
in accordance with this section shall meet all
the conditions of Section 28.6.2. If a building does
not meet all of the conditions of Section 28.6.2, then
its MWFRS wind loads shall be determined by Part 1
of this chapter, by the Directional Procedure of
Chapter 27, or by the Wind Tunnel Procedure of
Chapter 31.
28.6.2 Conditions
For the design of MWFRS the building shall
comply with all of the following conditions:
1. The building is a simple diaphragm building as
defi ned in Section 26.2.
2. The building is a low-rise building as defi ned in
Section 26.2.
3. The building is enclosed as defi ned in Section 26.2
and conforms to the wind-borne debris provisions
of Section 26.10.3.
4. The building is a regular-shaped building or
structure as defi ned in Section 26.2.
5. The building is not classifi ed as a fl exible building
as defi ned in Section 26.2.
6. The building does not have response
characteristics making it subject to across
wind loading, vortex shedding, instability due to
galloping or fl utter; and it does not have a site
location for which channeling effects or buffeting
in the wake of upwind obstructions warrant special
consideration.
7. The building has an approximately symmetrical
cross-section in each direction with either a fl at
roof or a gable or hip roof with θ ≤ 45°.
8. The building is exempted from torsional load cases
as indicated in Note 5 of Fig. 28.4-1, or the
torsional load cases defi ned in Note 5 do not
control the design of any of the MWFRS of the
building.
28.6.3 Design Wind Loads
Simplifi ed design wind pressures, ps, for the
MWFRS of low-rise simple diaphragm buildings
represent the net pressures (sum of internal and
external) to be applied to the horizontal and vertical
projections of building surfaces as shown in Fig.
28.6-1. For the horizontal pressures (Zones A, B, C,
D), ps is the combination of the windward and
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Main Wind Force Resisting System – Method 2 h ≤ 60 ft.
Figure 28.6-1 Design Wind Pressures Walls & Roofs Enclosed Buildings
Notes:
1. Pressures shown are applied to the horizontal and vertical projections, for exposure B, at h=30 ft (9.1m). Adjust to other exposures and
heights with adjustment factor λ.
2. The load patterns shown shall be applied to each corner of the building in turn as the reference corner. (See Figure 28.4-1)
3. For Case B use θ = 0°.
4. Load cases 1 and 2 must be checked for 25° < θ ≤ 45°. Load case 2 at 25° is provided only for interpolation between 25° and 30°.
5. Plus and minus signs signify pressures acting toward and away from the projected surfaces, respectively.
6. For roof slopes other than those shown, linear interpolation is permitted.
7. The total horizontal load shall not be less than that determined by assuming pS = 0 in zones B & D.
8. Where zone E or G falls on a roof overhang on the windward side of the building, use EOH and GOH for the pressure on the horizontal
projection of the overhang. Overhangs on the leeward and side edges shall have the basic zone pressure applied.
9. Notation:
a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension
or 3 ft (0.9 m).
h: Mean roof height, in feet (meters), except that eave height shall be used for roof angles <10°.
θ: Angle of plane of roof from horizontal, in degrees.
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304
Main Wind Force Resisting System – Method 2 h ≤ 60 ft.
Figure 28.6-1 (cont’d) Design Wind Pressures Walls & Roofs Enclosed Buildings
Unit Conversions – 1.0 ft = 0.3048 m; 1.0 psf = 0.0479 kN/m2
Simplified Design Wind Pressure , pS30 (psf) (Exposure B at h = 30 ft. with I = 1.0)
ABCD E F G HEOH GOH
2 ------- ------- ------- ------- -4.1 -7.9 -1.1 -5.1 ------- -------
30 to 45 1 21.6 14.8 17.2 11.8 1.7 -13.1 0.6 -11.3 -7.6 -8.7
2 21.6 14.8 17.2 11.8 8.3 -6.5 7.2 -4.6 -7.6 -8.7
2 ------- ------- ------- ------- -4.4 -8.7 -1.2 -5.5 ------- -------
30 to 45 1 23.6 16.1 18.8 12.9 1.8 -14.3 0.6 -12.3 -8.3 -9.5
2 23.6 16.1 18.8 12.9 9.1 -7.1 7.9 -5.0 -8.3 -9.5
2 ------- ------- ------- ------- -4.8 -9.4 -1.3 -6.0 ------- -------
30 to 45 1 25.7 17.6 20.4 14.0 2.0 -15.6 0.7 -13.4 -9.0 -10.3
2 25.7 17.6 20.4 14.0 9.9 -7.7 8.6 -5.5 -9.0 -10.3
2 ------- ------- ------- ------- -5.7 -11.1 -1.5 -7.1 ------- -------
30 to 45 1 30.1 20.6 24.0 16.5 2.3 -18.3 0.8 -15.7 -10.6 -12.1
2 30.1 20.6 24.0 16.5 11.6 -9.0 10.0 -6.4 -10.6 -12.1
2 ------- ------- ------- ------- -6.6 -12.8 -1.8 -8.2 ------- -------
30 to 45 1 35.0 23.9 27.8 19.1 2.7 -21.2 0.9 -18.2 -12.3 -14.0
2 35.0 23.9 27.8 19.1 13.4 -10.5 11.7 -7.5 -12.3 -14.0
2 ------- ------- ------- ------- -7.5 -14.7 -2.1 -9.4 ------- -------
30 to 45 1 40.1 27.4 31.9 22.0 3.1 -24.4 1.0 -20.9 -14.1 -16.1
2 40.1 27.4 31.9 22.0 15.4 -12.0 13.4 -8.6 -14.1 -16.1
Basic Wind
Speed
(mph)
Roof
Angle
(degrees)
Load Case
Horizontal Pressures Vertical Pressures Overhangs
Zones
110
115
120
130
140
150
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Main Wind Force Resisting System – Method 2 h ≤ 60 ft.
Figure 28.6-1 (cont’d) Design Wind Pressures Walls & Roofs Enclosed Buildings
Unit Conversions – 1.0 ft = 0.3048 m; 1.0 psf = 0.0479 kN/m2
Simplified Design Wind Pressure , pS30 (psf) (Exposure B at h = 30 ft.)
ABCD E F G HEOH GOH
2 ------- ------- ------- ------- -8.6 -16.8 -2.3 -10.7 ------- -------
30 to 45 1 45.7 31.2 36.3 25.0 3.5 -27.7 1.2 -23.8 -16.0 -18.3
2 45.7 31.2 36.3 25.0 17.6 -13.7 15.2 -9.8 -16.0 -18.3
2 ------- ------- ------- ------- -10.9 -21.2 -3.0 -13.6 ------- -------
30 to 45 1 57.8 39.5 45.9 31.6 4.4 -35.1 1.5 -30.1 -20.3 -23.2
2 57.8 39.5 45.9 31.6 22.2 -17.3 19.3 -12.3 -20.3 -23.2
2 ------- ------- ------- ------- -13.4 -26.2 -3.7 -16.8 ------- -------
30 to 45 1 71.3 48.8 56.7 39.0 5.5 -43.3 1.8 -37.2 -25.0 -28.7
2 71.3 48.8 56.7 39.0 27.4 -21.3 23.8 -15.2 -25.0 -28.7
Basic Wind
Speed
(mph)
Roof
Angle
(degrees)
Load Case
Horizontal Pressures Vertical Pressures Overhangs
Zones
160
200
180
Exposure
BCD
15 1.00 1.21 1.47
20 1.00 1.29 1.55
25 1.00 1.35 1.61
30 1.00 1.40 1.66
35 1.05 1.45 1.70
40 1.09 1.49 1.74
45 1.12 1.53 1.78
50 1.16 1.56 1.81
55 1.19 1.59 1.84
60 1.22 1.62 1.87
for Building Height and Exposure, λ
Adjustment Factor
Mean roof
height (ft)
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CHAPTER 28 WIND LOADS ON BUILDINGS—MWFRS (ENVELOPE PROCEDURE)
306
leeward net pressures. ps shall be determined by the
following equation:
ps = λ Kzt pS30 (28.6-1)
where
λ = adjustment factor for building height and
exposure from Fig. 28.6-1
Kzt = topographic factor as defi ned in Section 26.8
evaluated at mean roof height, h
pS30 = simplifi ed design wind pressure for Exposure B,
at h = 30 ft (9.1 m) from Fig. 28.6-1
28.6.4 Minimum Design Wind Loads
The load effects of the design wind pressures
from Section 28.6.3 shall not be less than a minimum
load defi ned by assuming the pressures, ps, for zones
A and C equal to +16 psf, Zones B and D equal to +8
psf, while assuming ps for Zones E, F, G, and H are
equal to 0 psf.
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307
Chapter 29
WIND LOADS ON OTHER STRUCTURES AND
BUILDING APPURTENANCES—MWFRS
29.1.4 Shielding
There shall be no reductions in velocity pressure
due to apparent shielding afforded by buildings and
other structures or terrain features.
29.2 GENERAL REQUIREMENTS
29.2.1 Wind Load Parameters Specifi ed in
Chapter 26
The following wind load parameters shall be
determined in accordance with Chapter 26:
– Basic Wind Speed V (Section 26.5)
– Wind directionality Factor Kd (Section 26.6)
– Exposure category (Section 26.7)
– Topographic factor Kzt (Section 26.8)
– Enclosure classifi cation (Section 26.10)
29.3 VELOCITY PRESSURE
29.3.1 Velocity Pressure Exposure Coeffi cient
Based on the exposure category determined in
Section 26.7.3, a velocity pressure exposure coeffi -
cient Kz or Kh, as applicable, shall be determined from
Table 29.3-1.
For a site located in a transition zone between
exposure categories that is near to a change in ground
surface roughness, intermediate values of Kz or Kh,
between those shown in Table 29.3-1, are permitted,
provided that they are determined by a rational
analysis method defi ned in the recognized literature.
29.3.2 Velocity Pressure
Velocity pressure, qz, evaluated at height z shall
be calculated by the following equation:
qz = 0.00256 KzKztKdV2
(lb/ft2
) (29.3-1)
[In SI: qz = 0.613 KzKztKdV2 (N/m2
); V in m/s]
where
Kd = wind directionality factor defi ned in Section 26.6
Kz = velocity pressure exposure coeffi cient defi ned in
Section 29.3.1
Kzt = topographic factor defi ned in Section 26.8.2
V = basic wind speed from Section 26.5
29.1 SCOPE
29.1.1 Structure Types
This chapter applies to the determination of wind
loads on building appurtenances (such as rooftop
structures and rooftop equipment) and other structures
of all heights (such as solid freestanding walls and
freestanding solid signs, chimneys, tanks, open signs,
lattice frameworks, and trussed towers) using the
Directional Procedure.
The steps required for the determination of wind
loads on building appurtenances and other structures
are shown in Table 29.1-1.
User Note: Use Chapter 29 to determine wind pressures
on the MWFRS of solid freestanding walls, freestanding
solid signs, chimneys, tanks, open signs, lattice frameworks
and trussed towers. Wind loads on rooftop
structures and equipment may be determined from the
provisions of this chapter. The wind pressures are
calculated using specifi c equations based upon the
Directional Procedure.
29.1.2 Conditions
A structure whose design wind loads are determined
in accordance with this section shall comply
with all of the following conditions:
1. The structure is a regular-shaped structure as
defi ned in Section 26.2.
2. The structure does not have response characteristics
making it subject to across-wind loading,
vortex shedding, or instability due to galloping or
fl utter; or it does not have a site location for which
channeling effects or buffeting in the wake of
upwind obstructions warrant special consideration.
29.1.3 Limitations
The provisions of this chapter take into consideration
the load magnifi cation effect caused by gusts in
resonance with along-wind vibrations of fl exible
structures. Structures not meeting the requirements of
Section 29.1.2, or having unusual shapes or response
characteristics, shall be designed using recognized
literature documenting such wind load effects or shall
use the Wind Tunnel Procedure specifi ed in Chapter 31.
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308
qh = velocity pressure calculated using Eq. 29.3-1 at
height h
The numerical coeffi cient 0.00256 (0.613 in SI)
shall be used except where suffi cient climatic data are
available to justify the selection of a different value of
this factor for a design application.
29.4 DESIGN WIND LOADS—SOLID
FREESTANDING WALLS AND SOLID SIGNS
29.4.1 Solid Freestanding Walls and Solid
Freestanding Signs
The design wind force for solid freestanding
walls and solid freestanding signs shall be determined
by the following formula:
F = qhGCfAs (lb) (N) (29.4-1)
where
qh = the velocity pressure evaluated at height h
(defi ned in Fig. 29.4-1) as determined in accordance
with Section 29.3.2
G = gust-effect factor from Section 26.9
Cf = net force coeffi cient from Fig. 29.4-1
As = the gross area of the solid freestanding wall or
freestanding solid sign, in ft2
(m2
)
29.4.2 Solid Attached Signs
The design wind pressure on a solid sign attached
to the wall of a building, where the plane of the sign
is parallel to and in contact with the plane of the wall,
and the sign does not extend beyond the side or top
edges of the wall, shall be determined using procedures
for wind pressures on walls in accordance with
Chapter 30, and setting the internal pressure coeffi -
cient (GCpi) equal to 0.
This procedure shall also be applicable to solid
signs attached to but not in direct contact with the
wall, provided the gap between the sign and wall is
no more than 3 ft (0.9 m) and the edge of the sign is
at least 3 ft (0.9 m) in from free edges of the wall,
i.e., side and top edges and bottom edges of elevated
walls.
29.5 DESIGN WIND LOADS—
OTHER STRUCTURES
The design wind force for other structures (chimneys,
tanks, rooftop equipment for h > 60°, and similar
structures, open signs, lattice frameworks, and trussed
towers) shall be determined by the following equation:
F = qzGCfAf (lb) (N) (29.5-1)
where
qz = velocity pressure evaluated at height z as defi ned
in Section 29.3, of the centroid of area Af
G = gust-effect factor from Section 26.9
Cf = force coeffi cients from Figs. 29.5-1 through
29.5-3
Af = projected area normal to the wind except where
Cf is specifi ed for the actual surface area,
in ft2
(m2
)
29.5.1 ROOFTOP STRUCTURES AND
EQUIPMENT FOR BUILDINGS WITH
h ≤ 60 ft (18.3 m)
The lateral force Fh on rooftop structures and
equipment located on buildings with a mean roof
height h ≤ 60 ft (18.3 m) shall be determined from
Eq. 29.5-2.
Fh = qh(GCr)Af (lb) (N) (29.5-2)
Table 29.1-1 Steps to Determine Wind Loads
on MWFRS Rooftop Equipment and
Other Structures
Step 1: Determine risk category of building or other
structure, see Table 1.5-1
Step 2: Determine the basic wind speed, V, for applicable
risk category, see Figure 26.5-1A, B or C
Step 3: Determine wind load parameters:
➢ Wind directionality factor, Kd, see Section
26.6 and Table 26.6-1
➢ Exposure category B, C or D, see Section 26.7
➢ Topographic factor, Kzt, see Section 26.8 and
Figure 26.8-1
➢ Gust Effect Factor, G, see Section 26.9
Step 4: Determine velocity pressure exposure
coeffi cient, Kz or Kh, see Table 29.2-1
Step 5: Determine velocity pressure qz or qh, see
Eq. 29.3-1
Step 6: Determine force coeffi cient, Cf:
➢ Solid freestanding signs or solid freestanding
walls, Fig. 29.4-1
➢ Chimneys, tanks, rooftop equipment Fig. 29.5-1
➢ Open signs, lattice frameworks Fig. 29.5-2
➢ Trussed towers Fig. 29.4-3
Step 7: Calculate wind force, F:
➢ Eq. 29.4-1 for signs and walls
➢ Eq. 29-6-1 and Eq. 29.6-2 for rooftop
structures and equipment
➢ Eq. 29.5-1 for other structures
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MINIMUM DESIGN LOADS
309
where
(GCr) = 1.9 for rooftop structures and equipment with
Af less than (0.1Bh). (GCr) shall be permitted
to be reduced linearly from 1.9 to 1.0 as the
value of Af is increased from (0.1Bh) to (Bh)
qh = velocity pressure evaluated at mean roof
height of the building
Af = vertical projected area of the rooftop structure
or equipment on a plane normal to the
direction of wind, in ft2
(m2
)
The vertical uplift force, Fv, on rooftop structures
and equipment shall be determined from Eq. 29.5-3.
Fv = qh(GCr)Ar (lb) (N) (29.5-3)
where
(GCr) = 1.5 for rooftop structures and equipment with
Ar less than (0.1BL). (GCr) shall be permitted
to be reduced linearly from 1.5 to 1.0 as the
value of Ar is increased from (0.1BL) to (BL)
qh = velocity pressure evaluated at the mean roof
height of the building
Ar = horizontal projected area of rooftop structure
or equipment, in ft2
(m2
)
29.6 PARAPETS
Wind loads on parapets are specifi ed in Section 27.4.5
for buildings of all heights designed using the
Directional Procedure and in Section 28.4.2 for
low-rise buildings designed using the Envelope
Procedure.
29.7 ROOF OVERHANGS
Wind loads on roof overhangs are specifi ed in Section
27.4.4 for buildings of all heights designed using the
Directional Procedure and in Section 28.4.3 for
low-rise buildings designed using the Envelope
Procedure.
29.8 MINIMUM DESIGN WIND LOADING
The design wind force for other structures shall be
not less than 16 lb/ft2
(0.77 kN/m2
) multiplied by the
area Af.
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310
Velocity Pressure Exposure Coefficients, Kh and Kz
Table 29.3-1
Height above
ground level, z
Exposure
B C D
ft (m)
0-15 (0-4.6) 0.57 0.85 1.03
20 (6.1) 0.62 0.90 1.08
25 (7.6) 0.66 0.94 1.12
30 (9.1) 0.70 0.98 1.16
40 (12.2) 0.76 1.04 1.22
50 (15.2) 0.81 1.09 1.27
60 (18) 0.85 1.13 1.31
70 (21.3) 0.89 1.17 1.34
80 (24.4) 0.93 1.21 1.38
90 (27.4) 0.96 1.24 1.40
100 (30.5) 0.99 1.26 1.43
120 (36.6) 1.04 1.31 1.48
140 (42.7) 1.09 1.36 1.52
160 (48.8) 1.13 1.39 1.55
180 (54.9) 1.17 1.43 1.58
200 (61.0) 1.20 1.46 1.61
250 (76.2) 1.28 1.53 1.68
300 (91.4) 1.35 1.59 1.73
350 (106.7) 1.41 1.64 1.78
400 (121.9) 1.47 1.69 1.82
450 (137.2) 1.52 1.73 1.86
500 (152.4) 1.56 1.77 1.89
Notes:
1. The velocity pressure exposure coefficient Kz may be determined from the following
formula:
For 15 ft. ≤ z ≤ zg For z < 15 ft.
Kz = 2.01 (z/zg)
2/α
Kz = 2.01 (15/zg)
2/α
2. α and zg are tabulated in Table 26.9.1.
3. Linear interpolation for intermediate values of height z is acceptable.
4. Exposure categories are defined in Section 26.7.
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311
Design Wind Loads All Heights
Figure 29.4-1 Force Coefficients, Cf Solid Freestanding Walls
Other Structures & Solid Freestanding Signs
≤ 0.05 0.1 0.2 0.5 1 2 4 5 10 20 30 ≥ 45
1 1.80 1.70 1.65 1.55 1.45 1.40 1.35 1.35 1.30 1.30 1.30 1.30
0.9 1.85 1.75 1.70 1.60 1.55 1.50 1.45 1.45 1.40 1.40 1.40 1.40
0.7 1.90 1.85 1.75 1.70 1.65 1.60 1.60 1.55 1.55 1.55 1.55 1.55
0.5 1.95 1.85 1.80 1.75 1.75 1.70 1.70 1.70 1.70 1.70 1.70 1.75
0.3 1.95 1.90 1.85 1.80 1.80 1.80 1.80 1.80 1.80 1.85 1.85 1.85
0.2 1.95 1.90 1.85 1.80 1.80 1.80 1.80 1.80 1.85 1.90 1.90 1.95
≤ 0.16 1.95 1.90 1.85 1.85 1.80 1.80 1.85 1.85 1.85 1.90 1.90 1.95
Region Region
2 3 4 5 6 7 8 9 10 13 ≥ 45
0 to s 2.25 2.60 2.90 3.10* 3.30* 3.40* 3.55* 3.65* 3.75* 0 to s 4.00* 4.30*
s to 2s 1.50 1.70 1.90 2.00 2.15 2.25 2.30 2.35 2.45 s to 2s 2.60 2.55
2s to 3s 1.15 1.30 1.45 1.55 1.65 1.70 1.75 1.85 2s to 3s 2.00 1.95
3s to 10s 1.10 1.05 1.05 1.05 1.05 1.00 0.95 3s to 4s 1.50 1.85
4s to 5s 1.35 1.85
5s to 10s 0.90 1.10
>10s 0.55 0.55
Notes:
ELEVATION VIEW
Cf, CASE A & CASE B
Clearance
Ratio, s/h
Aspect Ratio, B/s
CROSS-SECTION VIEW PLAN VIEWS
CASE A: resultant force acts normal to the face of the sign through the geometric center.
toward the windward edge equal to 0.2 times the average width of the sign.
For B/s ≥ 2, CASE C must also be considered:
5. Linear interpolation is permitted for values of s/h, B/s and Lr/s other than shown.
6. Notation:
B: horizontal dimension of sign, in feet (meters);
h: height of the sign, in feet (meters);
ε: ratio of solid area to gross area;
For s/h = 1:
The same cases as above except that the vertical locations of the resultant forces occur at a distance above
3. To allow for both normal and oblique wind directions, the following cases shall be considered:
For s/h < 1:
CASE B: resultant force acts normal to the face of the sign at a distance from the geometric center
the geometric center equal to 0.05 times the average height of the sign.
CASE C: resultant forces act normal to the face of the sign through the geometric centers of each region.
Cf, CASE C
Lr: horizontal dimension of return corner, in feet (meters)
s: vertical dimension of the sign, in feet (meters);
Aspect Ratio, B/s
4. For CASE C where s/h > 0.8, force coefficients shall be multiplied by the reduction factor (1.8 - s/h).
Aspect Ratio, B/s
shall be permitted to be multiplied by the reduction factor (1 - (1 - ε)
1.5).
1. The term "signs" in notes below also applies to "freestanding walls".
2. Signs with openings comprising less than 30% of the gross area are classified as solid signs. Force coefficients for solid signs with openings
s
B
h
SOLID SIGN OR
FREESTANDING WALL
GROUND SURFACE
CASE C
CASE A
F
s
F F F F
WIND
WIND
s s Balance
F
F F F
0.2B
F WIND
RANGE
CASE B
F
WIND
RANGE
0.2B
s s s
WIND
s
h
GROUND SURFACE s/h < 1 s/h = 1
F s/2
s/2
s=h
F h/2
h/2
0.05h
B
Lr
WIND
PLAN VIEW OF WALL OR SIGN WITH
A RETURN CORNER
*Values shall be multiplied
by the following reduction
factor when a return
corner is present:
Lr / s Reduction Factor
0.3
1.0
≥ 2
0.90
0.75
0.60
(horizontal
distance from
windward edge)
(horizontal
distance from
windward edge)
Balance
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CHAPTER 29 WIND LOADS ON OTHER STRUCTURES AND BUILDING APPURTENANCES—MWFRS
312
Other Structures All Heights
Figure 29.5-1 Force Coefficients, Cf Chimneys, Tanks, Rooftop
Equipment, & Similar Structures
Cross-Section Type of Surface h/D
1 7 25
Square (wind normal to face) All 1.3 1.4 2.0
Square (wind along diagonal) All 1.0 1.1 1.5
Hexagonal or octagonal All 1.0 1.2 1.4
Round ( > 2.5) D qz
( 5.3, in m, in N/m ) 2
z z D q > D q
Moderately smooth 0.5 0.6 0.7
Rough (D'/D = 0.02) 0.7 0.8 0.9
Very rough (D'/D = 0.08) 0.8 1.0 1.2
Round ( £ 2.5) D qz
( 5.3, in m, in N/m ) 2 D qz £ D qz
All 0.7 0.8 1.2
Notes:
1. The design wind force shall be calculated based on the area of the structure projected on a plane
normal to the wind direction. The force shall be assumed to act parallel to the wind direction.
2. Linear interpolation is permitted for h/D values other than shown.
3. Notation:
4. For rooftop equipment on buildings with a mean roof height of h ≤ 60 ft, use Section 29.5.1.
D: diameter of circular cross-section and least horizontal dimension of square, hexagonal or
octagonal cross-sections at elevation under consideration, in feet (meters);
D': depth of protruding elements such as ribs and spoilers, in feet (meters); and
h: height of structure, in feet (meters); and
qz: velocity pressure evaluated at height z above ground, in pounds per square foot (N/m2
).
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MINIMUM DESIGN LOADS
313
Other Structures All Heights
Figure 29.5-2 Force Coefficients, Cf Open Signs &
Lattice Frameworks
∈ Flat-Sided
Members
Rounded Members
(D q 5.3)
2.5
z ≤
D qz ≤
(D q 5.3)
2.5
z >
D qz >
< 0.1 2.0 1.2 0.8
0.1 to 0.29 1.8 1.3 0.9
0.3 to 0.7 1.6 1.5 1.1
Notes:
1. Signs with openings comprising 30% or more of the gross area are
classified as open signs.
2. The calculation of the design wind forces shall be based on the area of
all exposed members and elements projected on a plane normal to the
wind direction. Forces shall be assumed to act parallel to the wind
direction.
3. The area Af consistent with these force coefficients is the solid area
projected normal to the wind direction.
4. Notation:
∈: ratio of solid area to gross area;
D: diameter of a typical round member, in feet (meters);
qz: velocity pressure evaluated at height z above ground in pounds
per square foot (N/m2
).
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CHAPTER 29 WIND LOADS ON OTHER STRUCTURES AND BUILDING APPURTENANCES—MWFRS
314
Other Structures All Heights
Figure 29.5-3 Force Coefficients, Cf
Trussed Towers Open Structures
Tower Cross Section Cf
Square 4.0 ∈2
- 5.9 ∈ + 4.0
Triangle 3.4 ∈2
- 4.7 ∈ + 3.4
Notes:
1. For all wind directions considered, the area Af consistent with the specified force
coefficients shall be the solid area of a tower face projected on the plane of that
face for the tower segment under consideration.
2. The specified force coefficients are for towers with structural angles or similar flatsided
members.
3. For towers containing rounded members, it is acceptable to multiply the specified
force coefficients by the following factor when determining wind forces on such
members:
0.51 ∈2
+ 0.57, but not > 1.0
4. Wind forces shall be applied in the directions resulting in maximum member forces
and reactions. For towers with square cross-sections, wind forces shall be
multiplied by the following factor when the wind is directed along a tower
diagonal:
1 + 0.75 ∈, but not > 1.2
5. Wind forces on tower appurtenances such as ladders, conduits, lights, elevators,
etc., shall be calculated using appropriate force coefficients for these elements.
6. Loads due to ice accretion as described in Chapter 10 shall be accounted for.
7. Notation:
∈: ratio of solid area to gross area of one tower face for the segment under
consideration.
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315
Chapter 30
WIND LOADS – COMPONENTS AND CLADDING (C&C)
30.1.2 Conditions
A building whose design wind loads are determined
in accordance with this chapter shall comply
with all of the following conditions:
1. The building is a regular-shaped building as
defi ned in Section 26.2.
2. The building does not have response characteristics
making it subject to across wind loading, vortex
shedding, or instability due to galloping or fl utter;
or it does not have a site location for which
channeling effects or buffeting in the wake of
upwind obstructions warrant special consideration.
30.1.3 Limitations
The provisions of this chapter take into consideration
the load magnifi cation effect caused by gusts in
resonance with along-wind vibrations of fl exible
buildings. The loads on buildings not meeting the
requirements of Section 30.1.2, or having unusual
shapes or response characteristics, shall be determined
using recognized literature documenting such wind
load effects or shall use the wind tunnel procedure
specifi ed in Chapter 31.
30.1.4 Shielding
There shall be no reductions in velocity pressure
due to apparent shielding afforded by buildings and
other structures or terrain features.
30.1.5 Air-Permeable Cladding
Design wind loads determined from Chapter 30
shall be used for air-permeable cladding unless
approved test data or recognized literature demonstrates
lower loads for the type of air-permeable
cladding being considered.
30.2 GENERAL REQUIREMENTS
30.2.1 Wind Load Parameters Specifi ed
in Chapter 26
The following wind load parameters are specifi ed
in Chapter 26:
– Basic Wind Speed V (Section 26.5)
– Wind directionality factor Kd (Section 26.6)
– Exposure category (Section 26.7)
– Topographic factor Kzt (Section 26.8)
30.1 SCOPE
30.1.1 Building Types
This chapter applies to the determination of wind
pressures on components and cladding (C&C) on
buildings.
1) Part 1 is applicable to an enclosed or partially
enclosed:
– Low-rise building (see defi nition in Section 26.2)
– Building with h ≤ 60 ft (18.3 m)
The building has a fl at roof, gable roof,
multispan gable roof, hip roof, monoslope roof,
stepped roof, or sawtooth roof and the wind
pressures are calculated from a wind pressure
equation.
2) Part 2 is a simplifi ed approach and is applicable to
an enclosed:
– Low-rise building (see defi nition in Section 26.2)
– Building with h ≤ 60 ft (18.3 m)
The building has a fl at roof, gable roof, or hip roof
and the wind pressures are determined directly
from a table.
3) Part 3 is applicable to an enclosed or partially
enclosed:
– Building with h > 60 ft (18.3 m)
The building has a fl at roof, pitched roof, gable
roof, hip roof, mansard roof, arched roof, or domed
roof and the wind pressures are calculated from a
wind pressure equation.
4) Part 4 is a simplifi ed approach and is applicable to
an enclosed
– Building with h ≤ 160 ft (48.8 m)
The building has a fl at roof, gable roof, hip
roof, monoslope roof, or mansard roof and the
wind pressures are determined directly from a
table.
5) Part 5 is applicable to an open building of all
heights having a pitched free roof, monoslope free
roof, or trough free roof.
6) Part 6 is applicable to building appurtenances such
as roof overhangs and parapets and rooftop
equipment.
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CHAPTER 30 WIND LOADS – COMPONENTS AND CLADDING
316
– Gust Effect Factor (Section 26.9)
– Enclosure classifi cation (Section 26.10)
– Internal pressure coeffi cient (GCpi) (Section 26.11).
30.2.2 Minimum Design Wind Pressures
The design wind pressure for components and
cladding of buildings shall not be less than a net
pressure of 16 lb/ft2
(0.77 kN/m2
) acting in either
direction normal to the surface.
30.2.3 Tributary Areas Greater than 700 ft2
(65 m2
)
Component and cladding elements with tributary
areas greater than 700 ft2
(65 m2
) shall be permitted to
be designed using the provisions for MWFRS.
30.2.4 External Pressure Coeffi cients
Combined gust effect factor and external pressure
coeffi cients for components and cladding, (GCp), are
given in the fi gures associated with this chapter. The
pressure coeffi cient values and gust effect factor shall
not be separated.
30.3 VELOCITY PRESSURE
30.3.1 Velocity Pressure Exposure Coeffi cient
Based on the exposure category determined in
Section 26.7.3, a velocity pressure exposure coeffi -
cient Kz or Kh, as applicable, shall be determined from
Table 30.3-1. For a site located in a transition zone
between exposure categories, that is, near to a change
in ground surface roughness, intermediate values of Kz
or Kh, between those shown in Table 30.3-1, are
permitted, provided that they are determined by a
rational analysis method defi ned in the recognized
literature.
30.3.2 Velocity Pressure
Velocity pressure, qz, evaluated at height z shall
be calculated by the following equation:
qz = 0.00256 KzKztKdV2 (lb/ft2
) (30.3-1)
[In SI: qz = 0.613 KzKztKdV2 (N/m2
); V in m/s]
where
Kd = wind directionality factor defi ned in Section 26.6
Kz = velocity pressure exposure coeffi cient defi ned in
Section 30.3.1
Kzt = topographic factor defi ned in Section 26.8
V = basic wind speed from Section 26.5
qh = velocity pressure calculated using Eq. 30.3-1 at
height h
The numerical coeffi cient 0.00256 (0.613 in SI)
shall be used except where suffi cient climatic data are
available to justify the selection of a different value of
this factor for a design application.
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MINIMUM DESIGN LOADS
317
Velocity Pressure Exposure Coefficients, Kh and Kz
Table 30.3-1
Exposure Height above
ground level, z
ft (m)
B C D
0-15 (0-4.6) 0.70 0.85 1.03
20 (6.1) 0.70 0.90 1.08
25 (7.6) 0.70 0.94 1.12
30 (9.1) 0.70 0.98 1.16
40 (12.2) 0.76 1.04 1.22
50 (15.2) 0.81 1.09 1.27
60 (18) 0.85 1.13 1.31
70 (21.3) 0.89 1.17 1.34
80 (24.4) 0.93 1.21 1.38
90 (27.4) 0.96 1.24 1.40
100 (30.5) 0.99 1.26 1.43
120 (36.6) 1.04 1.31 1.48
140 (42.7) 1.09 1.36 1.52
160 (48.8) 1.13 1.39 1.55
180 (54.9) 1.17 1.43 1.58
200 (61.0) 1.20 1.46 1.61
250 (76.2) 1.28 1.53 1.68
300 (91.4) 1.35 1.59 1.73
350 (106.7) 1.41 1.64 1.78
400 (121.9) 1.47 1.69 1.82
450 (137.2) 1.52 1.73 1.86
500 (152.4) 1.56 1.77 1.89
Notes:
1. The velocity pressure exposure coefficient Kz may be determined from the following formula:
For 15 ft. ≤ z ≤ zg For z < 15 ft.
Kz = 2.01 (z/zg)
2/α
Kz = 2.01 (15/zg)
2/α
Note: z shall not be taken less than 30 feet in exposure B.
2. α and zg are tabulated in Table 26.9.1.
3. Linear interpolation for intermediate values of height z is acceptable.
4. Exposure categories are defined in Section 26.7.
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CHAPTER 30 WIND LOADS – COMPONENTS AND CLADDING
318
PART 1: LOW-RISE BUILDINGS
30.4 BUILDING TYPES
The provisions of Section 30.4 are applicable to an
enclosed and partially enclosed:
– Low-rise building (see defi nition in Section 26.2)
– Building with h ≤ 60 ft (18.3 m)
The building has a fl at roof, gable roof, multispan
gable roof, hip roof, monoslope roof, stepped roof, or
sawtooth roof. The steps required for the determination
of wind loads on components and cladding for
these building types are shown in Table 30.4-1.
30.4.1 Conditions
For the determination of the design wind pressures on
the components and claddings using the provisions of
Section 30.4.2 the conditions indicated on the selected
fi gure(s) shall be applicable to the building under
consideration.
30.4.2 Design Wind Pressures
Design wind pressures on component and
cladding elements of low-rise buildings and buildings
with h ≤ 60 ft (18.3 m) shall be determined from the
following equation:
p = qh[(GCp) – (GCpi)] (lb/ft2
) (N/m2
) (30.4-1)
where
qh = velocity pressure evaluated at mean roof
height h as defi ned in Section 30.3
(GCp) = external pressure coeffi cients given in:
– Figure 30.4-1 (walls)
– Figures. 30.4-2A to 30.4-2C (fl at roofs,
gable roofs, and hip roofs)
– Figure 30.4-3 (stepped roofs)
– Figure 30.4-4 (multispan gable roofs)
– Figures. 30.4-5A and 30.4-5B (monoslope
roofs)
– Figure 30.4-6 (sawtooth roofs)
– Fig. 30.4-7 (domed roofs)
– Fig. 27.4-3, footnote 4 (arched roofs)
(GCpi) = internal pressure coeffi cient given in Table
26.11-1
User Note: Use Part 1 of Chapter 30 to determine wind
pressures on C&C of enclosed and partially enclosed
low-rise buildings having roof shapes as specifi ed in the
applicable fi gures. The provisions in Part 1 are based on
the Envelope Procedure with wind pressures calculated
using the specifi ed equation as applicable to each
building surface. For buildings for which these provisions
are applicable this method generally yields the
lowest wind pressures of all analytical methods
contained in this standard.
Table 30.4-1 Steps to Determine C&C Wind
Loads Enclosed and Partially Enclosed
Low-rise Buildings
Step 1: Determine risk category, see Table 1.5-1
Step 2: Determine the basic wind speed, V, for
applicable risk category, see Fig. 26.5-1A,
B or C
Step 3: Determine wind load parameters:
➢ Wind directionality factor, Kd , see Section
26.6 and Table 26.6-1
➢ Exposure category B, C or D, see Section
26.7
➢ Topographic factor, Kzt, see Section 26.8 and
Fig. 26.8-1
➢ Enclosure classifi cation, see Section 26.10
➢ Internal pressure coeffi cient, (GCpi), see
Section 26.11 and Table 26.11-1
Step 4: Determine velocity pressure exposure
coeffi cient, Kz or Kh, see Table 30.3-1
Step 5: Determine velocity pressure, qh, Eq. 30.3-1
Step 6: Determine external pressure coeffi cient, (GCp)
➢ Walls, see Fig. 30.4-1
➢ Flat roofs, gable roofs, hip roofs, see
Fig. 30.4-2
➢ Stepped roofs, see Fig. 30.4-3
➢ Multispan gable roofs, see Fig. 30.4-4
➢ Monoslope roofs, see Fig. 30.4-5
➢ Sawtooth roofs, see Fig. 30.4-6
➢ Domed roofs, see Fig. 30.4-7
➢ Arched roofs, see Fig. 27.4-3 footnote 4
Step 7: Calculate wind pressure, p, Eq. 30.4-1
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MINIMUM DESIGN LOADS
319
PART 2: LOW-RISE BUILDINGS
(SIMPLIFIED)
30.5 BUILDING TYPES
The provisions of Section 30.5 are applicable to an
enclosed:
– Low-rise building (see defi nition in Section 26.2)
– Building with h ≤ 60 ft (18.3 m)
The building has a fl at roof, gable roof, or hip roof.
The steps required for the determination of wind loads
on components and cladding for these building types
are shown in Table 30.5-1.
30.5.1 Conditions
For the design of components and cladding the
building shall comply with all the following
conditions:
1. The mean roof height h must be less than or equal
to 60 ft (18.3 m) (h ≤ 60 ft (18.3 m)).
2. The building is enclosed as defi ned in Section 26.2
and conforms to the wind-borne debris provisions
of Section 26.10.3.
3. The building is a regular-shaped building or
structure as defi ned in Section 26.2.
4. The building does not have response characteristics
making it subject to across wind loading, vortex
shedding, or instability due to galloping or fl utter;
and it does not have a site location for which
channeling effects or buffeting in the wake of
upwind obstructions warrant special consideration.
5. The building has either a fl at roof, a gable roof
with θ ≤ 45º, or a hip roof with θ ≤ 27º.
30.5.2 Design Wind Pressures
Net design wind pressures, pnet, for component
and cladding of buildings designed using the procedure
specifi ed herein represent the net pressures (sum
of internal and external) that shall be applied normal
to each building surface as shown in Fig. 30.5-1. pnet
shall be determined by the following equation:
pnet = λKzt pnet30 (30.5-1)
where
λ = adjustment factor for building height and exposure
from Fig. 30.5-1
Kzt = topographic factor as defi ned in Section 26.8
evaluated at 0.33 mean roof height, 0.33h
pnet30 = net design wind pressure for Exposure B, at h
= 30 ft (9.1 m), from Fig. 30.5-1
User Note: Part 2 of Chapter 30 is a simplifi ed method
to determine wind pressures on C&C of enclosed
low-rise buildings having fl at, gable or hip roof shapes.
The provisions of Part 2 are based on the Envelope
Procedure of Part 1 with wind pressures determined
from a table and adjusted as appropriate.
Table 30.5-1 Steps to Determine C&C
Wind Loads Enclosed Low-rise Buildings
(Simplifi ed Method)
Step 1: Determine risk category, see Table 1.5-1
Step 2: Determine the basic wind speed, V, for
applicable risk category see Figure 26.5-1A,
B or C
Step 3: Determine wind load parameters:
➢ Exposure category B, C or D, see
Section 26.7
➢ Topographic factor, Kzt, see Section 26.8 and
Figure 26.8-1
Step 4: Enter fi gure to determine wind pressures at
h = 30 ft., pnet30, see Fig. 30.5-1
Step 5: Enter fi gure to determine adjustment for building
height and exposure, λ, see Fig. 30.5-1
Step 6: Determine adjusted wind pressures, pnet, see
Eq. 30.5-1.
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CHAPTER 30 WIND LOADS – COMPONENTS AND CLADDING
320
PART 3: BUILDINGS WITH h > 60 ft
(18.3 m)
30.6 BUILDING TYPES
The provisions of Section 30.6 are applicable to an
enclosed or partially enclosed building with a mean
roof height h > 60 ft. (18.3 m) with a fl at roof,
pitched roof, gable roof, hip roof, mansard roof,
arched roof, or domed roof. The steps required for the
determination of wind loads on components and
cladding for these building types are shown in
Table 30.6-1.
30.6.1 Conditions
For the determination of the design wind pressures
on the component and cladding using the
provisions of Section 30.6.2, the conditions indicated
on the selected fi gure(s) shall be applicable to the
building under consideration.
30.6.2 Design Wind Pressures
Design wind pressures on component and
cladding for all buildings with h > 60 ft (18.3 m) shall
be determined from the following equation:
p = q(GCp) – qi(GCpi) (lb/ft2
) (N/m2
) (30.6-1)
where
q = qz for windward walls calculated at height z
above the ground
q = qh for leeward walls, side walls, and roofs
evaluated at height h
qi = qh for windward walls, side walls, leeward
walls, and roofs of enclosed buildings and
for negative internal pressure evaluation in
partially enclosed buildings
qi = qz for positive internal pressure evaluation in
partially enclosed buildings where height z is
defi ned as the level of the highest opening in
the building that could affect the positive
internal pressure. For positive internal
pressure evaluation, qi may conservatively be
evaluated at height h (qi = qh)
(GCp) = external pressure coeffi cients given in:
– Fig. 30.6-1 for walls and fl at roofs
– Fig. 27.4-3, footnote 4, for arched roofs
– Fig. 30.4-7 for domed roofs
– Note 6 of Fig. 30.6-1 for other roof angles
and geometries
(GCpi) = internal pressure coeffi cient given in Table
26.11-1
q and qi shall be evaluated using exposure
defi ned in Section 26.7.3.
User Note: Use Part 3 of Chapter 30 for determining
wind pressures for C&C of enclosed and partially
enclosed buildings with h > 60 ft. having roof shapes as
specifi ed in the applicable fi gures. These provisions are
based on the Directional Procedure with wind pressures
calculated from the specifi ed equation applicable to each
building surface.
Table 30.6-1 Steps to Determine C&C Wind
Loads Enclosed or Partially Enclosed Building
with h > 60 ft
Step 1: Determine risk category, see Table 1.5-1
Step 2: Determine the basic wind speed, V, for
applicable risk category, see Figure 26.5-1A,
B or C
Step 3: Determine wind load parameters:
➢ Wind directionality factor, Kd , see
Section 26.6 and Table 26.6-1
➢ Exposure category B, C or D, see
Section 26.7
➢ Topographic factor, Kzt, see Section 26.8 and
Fig. 26.8-1
➢ Enclosure classifi cation, see Section 26.10
➢ Internal pressure coeffi cient, (GCpi), see
Section 26.11 and Table 26.11-1
Step 4: Determine velocity pressure exposure
coeffi cient, Kz or Kh, see Table 30.3-1
Step 5: Determine velocity pressure, qh, Eq. 30.3-1
Step 6: Determine external pressure coeffi cient, (GCp)
➢ Walls and fl at roofs (θ < 10 deg), see
Fig. 30.6-1
➢ Gable and hip roofs, see Fig. 30.4-2 per
Note 6 of Fig. 30.6-1
➢ Arched roofs, see Fig. 27.4-3, footnote 4
➢ Domed roofs, see Fig. 30.4-7
Step 7: Calculate wind pressure, p, Eq. 30.6-1
EXCEPTION: In buildings with a mean roof
height h greater than 60 ft (18.3 m) and less than
90 ft (27.4 m), (GCp) values from Figs. 30.4-1
through 30.4-6 shall be permitted to be used if
the height to width ratio is one or less.
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MINIMUM DESIGN LOADS
321
PART 4: BUILDINGS WITH h ≤ 160 ft
(48.8 m) (SIMPLIFIED)
30.7 BUILDING TYPES
The provisions of Section 30.7 are applicable to an
enclosed building having a mean roof height h ≤ 160
ft. (48.8 m) with a fl at roof, gable roof, hip roof,
monoslope roof, or mansard roof. The steps required
for the determination of wind loads on components
and cladding for these building types are shown in
Table 30.7-1.
30.7.1 Wind Loads—Components And Cladding
30.7.1.1 Wall and Roof Surfaces
Design wind pressures on the designated zones of
walls and roofs surfaces shall be determined from
Table 30.7-2 based on the applicable basic wind speed
V, mean roof height h, and roof slope θ. Tabulated
pressures shall be multiplied by the exposure adjustment
factor (EAF) shown in the table if exposure is
different than Exposure C. Pressures in Table 30.7-2
are based on an effective wind area of 10 ft2
(0.93
m2
). Reductions in wind pressure for larger effective
wind areas may be taken based on the reduction
multipliers (RF) shown in the table. Pressures are to
be applied over the entire zone shown in the fi gures.
Final design wind pressure shall be determined
from the following equation:
p = ptable(EAF)(RF)Kzt (30.7-1)
where:
RF = effective area reduction factor from Table
30.7-2
EAF = Exposure adjustment factor from Table 30.7-2
Kzt = topographic factor as defi ned in Section 26.8
30.7.1.2 Parapets
Design wind pressures on parapet surfaces shall
be based on wind pressures for the applicable edge
and corner zones in which the parapet is located, as
shown in Table 30.7-2, modifi ed based on the
following two load cases:
– Load Case A shall consist of applying the applicable
positive wall pressure from the table to the
front surface of the parapet while applying the
applicable negative edge or corner zone roof
pressure from the table to the back surface.
– Load Case B shall consist of applying the applicable
positive wall pressure from the table to the
back of the parapet surface and applying the
applicable negative wall pressure from the table to
the front surface.
Pressures in Table 30.7-2 are based on an
effective wind area of 10 sf. Reduction in wind
pressure for larger effective wind area may be taken
based on the reduction factor shown in the table.
Pressures are to be applied to the parapet in
accordance with Fig. 30.7-1. The height h to be used
with Fig. 30.7-1 to determine the pressures shall be
the height to the top of the parapet. Determine fi nal
pressure from Equation 30.7-1.
30.7.1.3 Roof Overhangs
Design wind pressures on roof overhangs shall be
based on wind pressures shown for the applicable zones
in Table 30.7-2 modifi ed as described herein. For Zones
1 and 2, a multiplier of 1.0 shall be used on pressures
shown in Table 30.7-2. For Zone 3, a multiplier of 1.15
shall be used on pressures shown in Table 30.7-2.
Pressures in Table 30.7-2 are based on an effective
wind area of 10 sf. Reductions in wind pressure for
larger effective wind areas may be taken based on the
reduction multiplier shown in Table 30.7-2. Pressures
on roof overhangs include the pressure from the top and
bottom surface of overhang. Pressures on the underside
of the overhangs are equal to the adjacent wall pressures.
Refer to the overhang drawing shown in Fig.
30.7-2. Determine fi nal pressure from Equation 30.7-1.
Table 30.7-1 Steps to Determine C&C Wind
Loads Enclosed Building with h ≤ 160 ft
Step 1: Determine risk category of building, see
Table 1.5-1
Step 2: Determine the basic wind speed, V, for applicable
risk category, see Figure 26.5-1A, B or C
Step 3: Determine wind load parameters:
➢ Exposure category B, C or D, see Section 26.7
Step 4: Enter Table 30.7-2 to determine pressure on walls
and roof, p, using Eq. 30.7-1. Roof types are:
➢ Flat roof (θ < 10 deg)
➢ Gable roof
➢ Hip roof
➢ Monoslope roof
➢ Mansard roof
Step 5: Determine topographic factors, Kzt, and apply
factor to pressures determined from tables (if
applicable), see Section 26.8.
User Note: Part 4 of Chapter 30 is a simplifi ed method
for determining wind pressures for C&C of enclosed and
partially enclosed buildings with h ≤ 160 ft. having roof
shapes as specifi ed in the applicable fi gures. These
provisions are based on the Directional Procedure from
Part 3 with wind pressures selected directly from a table
and adjusted as applicable.
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CHAPTER 30 WIND LOADS – COMPONENTS AND CLADDING
322
Components and Cladding – Part 4 h £ 160 ft.
Table 30.7-2 C & C Zones
Enclosed Buildings
C&C
Wall and Roof Pressures
3
2
5
4
1
2 2
3
4
3
5
2a a
2a
2a
4a
a
Flat Roof
θ < 10 deg
Gable Roof
Monoslope Roof Hip Roof
Mansard Roof
1
2
3
4
5
2
4
3
a a
a
a
3
3
5
1
2
1
4
5
2 4
a
a a
3
5 3 5
1
2
3
3
4
5
1
4 3
2
2
a a
a
3
3
1
3
2
5
2
3
5
2
3
1
2a
a
a
2a
a
4 4
5
2 2
3 3
2
5 5
3
c30.indd 322 4/14/2010 11:05:01 AM
MINIMUM DESIGN LOADS
323
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25
Building height h (ft.)
Exposure Adjustment Factor
Roof and Wall Pressures - Components and Cladding
Exposure Adjustment Factor
Exposure B Exposure D
Exposure Adjustment Factor
h (ft.) Exp B Exp D
160 0.809 1.113
150 0.805 1.116
140 0.801 1.118
130 0.796 1.121
120 0.792 1.125
110 0.786 1.128
100 0.781 1.132
90 0.775 1.137
80 0.768 1.141
70 0.760 1.147
60 0.751 1.154
50 0.741 1.161
40 0.729 1.171
30 0.713 1.183
20 0.692 1.201
15 0.677 1.214
Components and Cladding – Part 4 h £ 160 ft.
Table 30.7-2 C & C Notes
Enclosed Buildings
C&C
Wall and Roof Pressures
Notes to Component and Cladding Wind Pressure Table:
1. For each roof form, Exposure C, V and h determine roof and wall cladding pressures for the applicable
zone from tables below. For other exposures B or D, multiply pressures from table by the appropriate
exposure adjustment factor determined from figure below.
2. Interpolation between h values is permitted. For pressures at other V values than shown in the table,
multiply table value for any given V’ in the table as shown below:
Pressure at desired V = pressure from table at V’ x [V desired / V’]2
3. Where two load cases are shown, both positive and negative pressures shall be considered.
4. Pressures are shown for an effective wind area = 10 sf (0.93 m2
). For larger effective wind areas, the
pressure shown may be reduced by the reduction coefficient applicable to each zone.
Notation:
h = mean roof height (ft)
V = Basic wind speed (mph)
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CHAPTER 30 WIND LOADS – COMPONENTS AND CLADDING
324
0.5
0.6
0.7
0.8
0.9
1
1.1
1 10 100 1000
Reduction Factor
Effective Wind Area (sf)
Reduction Factors
Effective Wind Area
20 50 200 500
0.8
0.7
0.6
1.0
0.9
A
B
C
D
E
Components and Cladding – Part 4 h £ 160 ft.
Table 30.7-2 C & C Effective Wind Area
Enclosed Buildings
C&C
Wall and Roof Pressures
Roof Form Sign Pressure Zone 1 Zone 2 Zone 3 Zone 4 Zone 5
Flat Minus D D D C E
Flat Plus NA NA NA D D
Gable, Mansard Minus B C C C E
Gable, Mansard Plus B B B D D
Hip Minus B C C C E
Hip Plus B B B D D
Monoslope Plus A B D C E
Monoslope Minus C C C D D
Overhangs All A A B NA NA
Reduction Factors
Effective Wind Area
c30.indd 324 4/14/2010 11:05:01 AM
MINIMUM DESIGN LOADS
325
V (MPH) 110 115 120
Load Zone Zone Zone
h (ft) Roof Form Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat Roof 1 -50.2 -78.8 -107.5 -34.3 -63.0 -54.9 -86.2 -117.5 -37.5 -68.8 -59.8 -93.8 -127.9 -40.9 -74.9
2 NA NA NA 34.3 34.3 NA NA NA 37.5 37.5 NA NA NA 40.9 40.9
Gable Roof 1 -37.5 -63.0 -94.7 -40.7 -63.0 -41.0 -68.8 -103.6 -44.5 -68.8 -44.6 -74.9 -112.8 -48.4 -74.9
80 Mansard Roof 2 21.6 21.6 21.6 37.5 34.3 23.6 23.6 23.6 41.0 37.5 25.7 25.7 25.7 44.6 40.9
Hip Roof 1 -34.3 -59.8 -88.4 -40.7 -63.0 -37.5 -65.3 -96.6 -44.5 -68.8 -40.9 -71.1 -105.2 -48.4 -74.9
2 21.6 21.6 21.6 37.5 34.3 23.6 23.6 23.6 41.0 37.5 25.7 25.7 25.7 44.6 40.9
Monoslope Roof 1 -43.9 -56.6 -97.9 -40.7 -63.0 -48.0 -61.9 -107.0 -44.5 -68.8 -52.2 -67.4 -116.5 -48.4 -74.9
2 18.4 18.4 18.4 37.5 37.5 20.2 20.2 20.2 41.0 41.0 21.9 21.9 21.9 44.6 44.6
Flat Roof 1 -48.8 -76.7 -104.5 -33.4 -61.2 -53.4 -83.8 -114.2 -36.5 -66.9 -58.1 -91.2 -124.3 -39.7 -72.8
2 NA NA NA 33.4 33.4 NA NA NA 36.5 36.5 NA NA NA 39.7 39.7
Gable Roof 1 -36.5 -61.2 -92.1 -39.6 -61.2 -39.9 -66.9 -100.7 -43.2 -66.9 -43.4 -72.8 -109.6 -47.1 -72.8
70 Mansard Roof 2 21.0 21.0 21.0 36.5 33.4 23.0 23.0 23.0 39.9 36.5 25.0 25.0 25.0 43.4 39.7
Hip Roof 1 -33.4 -58.1 -85.9 -39.6 -61.2 -36.5 -63.5 -93.9 -43.2 -66.9 -39.7 -69.2 -102.3 -47.1 -72.8
2 21.0 21.0 21.0 36.5 33.4 23.0 23.0 23.0 39.9 36.5 25.0 25.0 25.0 43.4 39.7
Monoslope Roof 1 -42.7 -55.0 -95.2 -39.6 -61.2 -46.6 -60.1 -104.1 -43.2 -66.9 -50.8 -65.5 -113.3 -47.1 -72.8
2 17.9 17.9 17.9 36.5 36.5 19.6 19.6 19.6 39.9 39.9 21.3 21.3 21.3 43.4 43.4
Flat Roof 1 -47.3 -74.2 -101.1 -32.3 -59.3 -51.7 -81.1 -110.6 -35.3 -64.8 -56.3 -88.3 -120.4 -38.5 -70.5
2 NA NA NA 32.3 32.3 NA NA NA 35.3 35.3 NA NA NA 38.5 38.5
Gable Roof 1 -35.3 -59.3 -89.2 -38.3 -59.3 -38.6 -64.8 -97.5 -41.9 -64.8 -42.0 -70.5 -106.1 -45.6 -70.5
60 Mansard Roof 2 20.3 20.3 20.3 35.3 32.3 22.2 22.2 22.2 38.6 35.3 24.2 24.2 24.2 42.0 38.5
Hip Roof 1 -32.3 -56.3 -83.2 -38.3 -59.3 -35.3 -61.5 -90.9 -41.9 -64.8 -38.5 -67.0 -99.0 -45.6 -70.5
2 20.3 20.3 20.3 35.3 32.3 22.2 22.2 22.2 38.6 35.3 24.2 24.2 24.2 42.0 38.5
Monoslope Roof 1 -41.3 -53.3 -92.2 -38.3 -59.3 -45.1 -58.2 -100.7 -41.9 -64.8 -49.1 -63.4 -109.7 -45.6 -70.5
2 17.4 17.4 17.4 35.3 35.3 19.0 19.0 19.0 38.6 38.6 20.7 20.7 20.7 42.0 42.0
Flat Roof 1 -45.5 -71.4 -97.3 -31.1 -57.0 -49.7 -78.1 -106.4 -34.0 -62.3 -54.2 -85.0 -115.8 -37.0 -67.9
2 NA NA NA 31.1 31.1 NA NA NA 34.0 34.0 NA NA NA 37.0 37.0
Gable Roof 1 -34.0 -57.0 -85.8 -36.9 -57.0 -37.1 -62.3 -93.8 -40.3 -62.3 -40.4 -67.9 -102.1 -43.9 -67.9
50 Mansard Roof 2 19.6 19.6 19.6 34.0 31.1 21.4 21.4 21.4 37.1 34.0 23.3 23.3 23.3 40.4 37.0
Hip Roof 1 -31.1 -54.1 -80.1 -36.9 -57.0 -34.0 -59.2 -87.5 -40.3 -62.3 -37.0 -64.4 -95.3 -43.9 -67.9
2 19.6 19.6 19.6 34.0 31.1 21.4 21.4 21.4 37.1 34.0 23.3 23.3 23.3 40.4 37.0
Monoslope Roof 1 -39.7 -51.3 -88.7 -36.9 -57.0 -43.4 -56.0 -96.9 -40.3 -62.3 -47.3 -61.0 -105.6 -43.9 -67.9
2 16.7 16.7 16.7 34.0 34.0 18.3 18.3 18.3 37.1 37.1 19.9 19.9 19.9 40.4 40.4
Flat Roof 1 -43.4 -68.1 -92.9 -29.7 -54.4 -47.5 -74.5 -101.5 -32.4 -59.5 -51.7 -81.1 -110.5 -35.3 -64.7
2 NA NA NA 29.7 29.7 NA NA NA 32.4 32.4 NA NA NA 35.3 35.3
Gable Roof 1 -32.4 -54.4 -81.9 -35.2 -54.4 -35.4 -59.5 -89.5 -38.4 -59.5 -38.6 -64.7 -97.4 -41.9 -64.7
40 Mansard Roof 2 18.7 18.7 18.7 32.4 29.7 20.4 20.4 20.4 35.4 32.4 22.2 22.2 22.2 38.6 35.3
Hip Roof 1 -29.7 -51.7 -76.4 -35.2 -54.4 -32.4 -56.5 -83.5 -38.4 -59.5 -35.3 -61.5 -90.9 -41.9 -64.7
2 18.7 18.7 18.7 32.4 29.7 20.4 20.4 20.4 35.4 32.4 22.2 22.2 22.2 38.6 35.3
Monoslope Roof 1 -37.9 -48.9 -84.6 -35.2 -54.4 -41.4 -53.5 -92.5 -38.4 -59.5 -45.1 -58.2 -100.7 -41.9 -64.7
2 15.9 15.9 15.9 32.4 32.4 17.4 17.4 17.4 35.4 35.4 19.0 19.0 19.0 38.6 38.6
Flat Roof 1 -40.9 -64.1 -87.4 -27.9 -51.2 -44.7 -70.1 -95.5 -30.5 -56.0 -48.6 -76.3 -104.0 -33.2 -60.9
2 NA NA NA 27.9 27.9 NA NA NA 30.5 30.5 NA NA NA 33.2 33.2
Gable Roof 1 -30.5 -51.2 -77.1 -33.1 -51.2 -33.4 -56.0 -84.2 -36.2 -56.0 -36.3 -60.9 -91.7 -39.4 -60.9
30 Mansard Roof 2 17.6 17.6 17.6 30.5 27.9 19.2 19.2 19.2 33.4 30.5 20.9 20.9 20.9 36.3 33.2
Hip Roof 1 -27.9 -48.6 -71.9 -33.1 -51.2 -30.5 -53.1 -78.6 -36.2 -56.0 -33.2 -57.9 -85.6 -39.4 -60.9
2 17.6 17.6 17.6 30.5 27.9 19.2 19.2 19.2 33.4 30.5 20.9 20.9 20.9 36.3 33.2
Monoslope Roof 1 -35.7 -46.0 -79.7 -33.1 -51.2 -39.0 -50.3 -87.1 -36.2 -56.0 -42.5 -54.8 -94.8 -39.4 -60.9
2 15.0 15.0 15.0 30.5 30.5 16.4 16.4 16.4 33.4 33.4 17.9 17.9 17.9 36.3 36.3
Flat Roof 1 -37.5 -58.9 -80.3 -25.6 -47.0 -41.0 -64.4 -87.7 -28.0 -51.4 -44.7 -70.1 -95.5 -30.5 -56.0
2 NA NA NA 25.6 25.6 NA NA NA 28.0 28.0 NA NA NA 30.5 30.5
Gable Roof 1 -28.0 -47.0 -70.8 -30.4 -47.0 -30.6 -51.4 -77.3 -33.2 -51.4 -33.3 -56.0 -84.2 -36.2 -56.0
20 Mansard Roof 2 16.1 16.1 16.1 28.0 25.6 17.6 17.6 17.6 30.6 28.0 19.2 19.2 19.2 33.3 30.5
Hip Roof 1 -25.6 -44.6 -66.0 -30.4 -47.0 -28.0 -48.8 -72.2 -33.2 -51.4 -30.5 -53.1 -78.6 -36.2 -56.0
2 16.1 16.1 16.1 28.0 25.6 17.6 17.6 17.6 30.6 28.0 19.2 19.2 19.2 33.3 30.5
Monoslope Roof 1 -32.8 -42.3 -73.1 -30.4 -47.0 -35.8 -46.2 -79.9 -33.2 -51.4 -39.0 -50.3 -87.0 -36.2 -56.0
2 13.8 13.8 13.8 28.0 28.0 15.1 15.1 15.1 30.6 30.6 16.4 16.4 16.4 33.3 33.3
Flat Roof 1 -35.3 -55.4 -75.5 -24.1 -44.3 -38.6 -60.6 -82.6 -26.4 -48.4 -42.0 -66.0 -89.9 -28.7 -52.7
2 NA NA NA 24.1 24.1 NA NA NA 26.4 26.4 NA NA NA 28.7 28.7
Gable Roof 1 -26.4 -44.3 -66.6 -28.6 -44.3 -28.8 -48.4 -72.8 -31.3 -48.4 -31.4 -52.7 -79.3 -34.0 -52.7
15 Mansard Roof 2 15.2 15.2 15.2 26.4 24.1 16.6 16.6 16.6 28.8 26.4 18.1 18.1 18.1 31.4 28.7
Hip Roof 1 -24.1 -42.0 -62.1 -28.6 -44.3 -26.4 -45.9 -67.9 -31.3 -48.4 -28.7 -50.0 -73.9 -34.0 -52.7
2 15.2 15.2 15.2 26.4 24.1 16.6 16.6 16.6 28.8 26.4 18.1 18.1 18.1 31.4 28.7
Monoslope Roof 1 -30.8 -39.8 -68.8 -28.6 -44.3 -33.7 -43.5 -75.2 -31.3 -48.4 -36.7 -47.3 -81.9 -34.0 -52.7
2 13.0 13.0 13.0 26.4 26.4 14.2 14.2 14.2 28.8 28.8 15.4 15.4 15.4 31.4 31.4
Table 30.7-2
Components and Cladding – Part 4
Exposure C
C & C
V = 110-120 mph
h = 15-80 ft.
c30.indd 325 4/14/2010 11:05:01 AM
CHAPTER 30 WIND LOADS – COMPONENTS AND CLADDING
326
V (MPH) 130 140 150
Load Zone Zone Zone
h (ft) Roof Form Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat Roof 1 -70.2 -110.1 -150.1 -48.0 -87.9 -81.4 -127.7 -174.1 -55.6 -102.0 -93.4 -146.6 -199.8 -63.9 -117.1
2 NA NA NA 48.0 48.0 NA NA NA 55.6 55.6 NA NA NA 63.9 63.9
Gable Roof 1 -52.4 -87.9 -132.3 -56.8 -87.9 -60.8 -102.0 -153.5 -65.9 -102.0 -69.8 -117.1 -176.2 -75.7 -117.1
80 Mansard Roof 2 30.2 30.2 30.2 52.4 48.0 35.0 35.0 35.0 60.8 55.6 40.2 40.2 40.2 69.8 63.9
Hip Roof 1 -48.0 -83.5 -123.5 -56.8 -87.9 -55.6 -96.8 -143.2 -65.9 -102.0 -63.9 -111.1 -164.4 -75.7 -117.1
2 30.2 30.2 30.2 52.4 48.0 35.0 35.0 35.0 60.8 55.6 40.2 40.2 40.2 69.8 63.9
Monoslope Roof 1 -61.3 -79.0 -136.8 -56.8 -87.9 -71.1 -91.7 -158.6 -65.9 -102.0 -81.6 -105.2 -182.1 -75.7 -117.1
2 25.8 25.8 25.8 52.4 52.4 29.9 29.9 29.9 60.8 60.8 34.3 34.3 34.3 69.8 69.8
Flat Roof 1 -68.2 -107.1 -145.9 -46.6 -85.5 -79.1 -124.2 -169.2 -54.1 -99.1 -90.8 -142.6 -194.3 -62.1 -113.8
2 NA NA NA 46.6 46.6 NA NA NA 54.1 54.1 NA NA NA 62.1 62.1
Gable Roof 1 -50.9 -85.5 -128.7 -55.3 -85.5 -59.1 -99.1 -149.2 -64.1 -99.1 -67.8 -113.8 -171.3 -73.6 -113.8
70 Mansard Roof 2 29.4 29.4 29.4 50.9 46.6 34.0 34.0 34.0 59.1 54.1 39.1 39.1 39.1 67.8 62.1
Hip Roof 1 -46.6 -81.2 -120.0 -55.3 -85.5 -54.1 -94.1 -139.2 -64.1 -99.1 -62.1 -108.1 -159.8 -73.6 -113.8
2 29.4 29.4 29.4 50.9 46.6 34.0 34.0 34.0 59.1 54.1 39.1 39.1 39.1 67.8 62.1
Monoslope Roof 1 -59.6 -76.9 -133.0 -55.3 -85.5 -69.1 -89.1 -154.2 -64.1 -99.1 -79.3 -102.3 -177.0 -73.6 -113.8
2 25.0 25.0 25.0 50.9 50.9 29.0 29.0 29.0 59.1 59.1 33.3 33.3 33.3 67.8 67.8
Flat Roof 1 -66.0 -103.7 -141.3 -45.1 -82.8 -76.6 -120.2 -163.8 -52.4 -96.0 -87.9 -138.0 -188.1 -60.1 -110.2
2 NA NA NA 45.1 45.1 NA NA NA 52.4 52.4 NA NA NA 60.1 60.1
Gable Roof 1 -49.3 -82.8 -124.6 -53.5 -82.8 -57.2 -96.0 -144.5 -62.0 -96.0 -65.7 -110.2 -165.8 -71.2 -110.2
60 Mansard Roof 2 28.4 28.4 28.4 49.3 45.1 33.0 33.0 33.0 57.2 52.4 37.8 37.8 37.8 65.7 60.1
Hip Roof 1 -45.1 -78.6 -116.2 -53.5 -82.8 -52.4 -91.1 -134.8 -62.0 -96.0 -60.1 -104.6 -154.7 -71.2 -110.2
2 28.4 28.4 28.4 49.3 45.1 33.0 33.0 33.0 57.2 52.4 37.8 37.8 37.8 65.7 60.1
Monoslope Roof 1 -57.7 -74.4 -128.7 -53.5 -82.8 -66.9 -86.3 -149.3 -62.0 -96.0 -76.8 -99.1 -171.4 -71.2 -110.2
2 24.2 24.2 24.2 49.3 49.3 28.1 28.1 28.1 57.2 57.2 32.3 32.3 32.3 65.7 65.7
Flat Roof 1 -63.6 -99.8 -136.0 -43.4 -79.6 -73.7 -115.7 -157.7 -50.4 -92.4 -84.6 -132.8 -181.0 -57.8 -106.0
2 NA NA NA 43.4 43.4 NA NA NA 50.4 50.4 NA NA NA 57.8 57.8
Gable Roof 1 -47.5 -79.6 -119.9 -51.5 -79.6 -55.0 -92.4 -139.0 -59.7 -92.4 -63.2 -106.0 -159.6 -68.5 -106.0
50 Mansard Roof 2 27.4 27.4 27.4 47.5 43.4 31.7 31.7 31.7 55.0 50.4 36.4 36.4 36.4 63.2 57.8
Hip Roof 1 -43.4 -75.6 -111.8 -51.5 -79.6 -50.4 -87.7 -129.7 -59.7 -92.4 -57.8 -100.7 -148.9 -68.5 -106.0
2 27.4 27.4 27.4 47.5 43.4 31.7 31.7 31.7 55.0 50.4 36.4 36.4 36.4 63.2 57.8
Monoslope Roof 1 -55.5 -71.6 -123.9 -51.5 -79.6 -64.4 -83.0 -143.7 -59.7 -92.4 -73.9 -95.3 -164.9 -68.5 -106.0
2 23.3 23.3 23.3 47.5 47.5 27.1 27.1 27.1 55.0 55.0 31.1 31.1 31.1 63.2 63.2
Flat Roof 1 -60.6 -95.2 -129.7 -41.4 -76.0 -70.3 -110.4 -150.4 -48.1 -88.1 -80.7 -126.7 -172.7 -55.2 -101.2
2 NA NA NA 41.4 41.4 NA NA NA 48.1 48.1 NA NA NA 55.2 55.2
Gable Roof 1 -45.3 -76.0 -114.4 -49.1 -76.0 -52.5 -88.1 -132.6 -57.0 -88.1 -60.3 -101.2 -152.3 -65.4 -101.2
40 Mansard Roof 2 26.1 26.1 26.1 45.3 41.4 30.3 30.3 30.3 52.5 48.1 34.7 34.7 34.7 60.3 55.2
Hip Roof 1 -41.4 -72.1 -106.7 -49.1 -76.0 -48.1 -83.7 -123.7 -57.0 -88.1 -55.2 -96.1 -142.0 -65.4 -101.2
2 26.1 26.1 26.1 45.3 41.4 30.3 30.3 30.3 52.5 48.1 34.7 34.7 34.7 60.3 55.2
Monoslope Roof 1 -53.0 -68.3 -118.2 -49.1 -76.0 -61.4 -79.2 -137.1 -57.0 -88.1 -70.5 -90.9 -157.4 -65.4 -101.2
2 22.3 22.3 22.3 45.3 45.3 25.8 25.8 25.8 52.5 52.5 29.6 29.6 29.6 60.3 60.3
Flat Roof 1 -57.1 -89.6 -122.1 -39.0 -71.5 -66.2 -103.9 -141.6 -45.2 -82.9 -76.0 -119.3 -162.5 -51.9 -95.2
2 NA NA NA 39.0 39.0 NA NA NA 45.2 45.2 NA NA NA 51.9 51.9
Gable Roof 1 -42.6 -71.5 -107.6 -46.2 -71.5 -49.4 -82.9 -124.8 -53.6 -82.9 -56.7 -95.2 -143.3 -61.6 -95.2
30 Mansard Roof 2 24.6 24.6 24.6 42.6 39.0 28.5 28.5 28.5 49.4 45.2 32.7 32.7 32.7 56.7 51.9
Hip Roof 1 -39.0 -67.9 -100.4 -46.2 -71.5 -45.2 -78.8 -116.5 -53.6 -82.9 -51.9 -90.4 -133.7 -61.6 -95.2
2 24.6 24.6 24.6 42.6 39.0 28.5 28.5 28.5 49.4 45.2 32.7 32.7 32.7 56.7 51.9
Monoslope Roof 1 -49.8 -64.3 -111.3 -46.2 -71.5 -57.8 -74.6 -129.0 -53.6 -82.9 -66.4 -85.6 -148.1 -61.6 -95.2
2 21.0 21.0 21.0 42.6 42.6 24.3 24.3 24.3 49.4 49.4 27.9 27.9 27.9 56.7 56.7
Flat Roof 1 -52.4 -82.3 -112.1 -35.8 -65.7 -60.8 -95.4 -130.0 -41.5 -76.2 -69.8 -109.5 -149.2 -47.7 -87.4
2 NA NA NA 35.8 35.8 NA NA NA 41.5 41.5 NA NA NA 47.7 47.7
Gable Roof 1 -39.1 -65.7 -98.8 -42.5 -65.7 -45.4 -76.2 -114.6 -49.2 -76.2 -52.1 -87.4 -131.6 -56.5 -87.4
20 Mansard Roof 2 22.6 22.6 22.6 39.1 35.8 26.2 26.2 26.2 45.4 41.5 30.0 30.0 30.0 52.1 47.7
Hip Roof 1 -35.8 -62.4 -92.2 -42.5 -65.7 -41.5 -72.3 -106.9 -49.2 -76.2 -47.7 -83.0 -122.8 -56.5 -87.4
2 22.6 22.6 22.6 39.1 35.8 26.2 26.2 26.2 45.4 41.5 30.0 30.0 30.0 52.1 47.7
Monoslope Roof 1 -45.8 -59.0 -102.2 -42.5 -65.7 -53.1 -68.5 -118.5 -49.2 -76.2 -60.9 -78.6 -136.0 -56.5 -87.4
2 19.2 19.2 19.2 39.1 39.1 22.3 22.3 22.3 45.4 45.4 25.6 25.6 25.6 52.1 52.1
Flat Roof 1 -49.3 -77.4 -105.5 -33.7 -61.8 -57.2 -89.8 -122.4 -39.1 -71.7 -65.7 -103.1 -140.5 -44.9 -82.3
2 NA NA NA 33.7 33.7 NA NA NA 39.1 39.1 NA NA NA 44.9 44.9
Gable Roof 1 -36.8 -61.8 -93.0 -40.0 -61.8 -42.7 -71.7 -107.9 -46.3 -71.7 -49.0 -82.3 -123.9 -53.2 -82.3
15 Mansard Roof 2 21.2 21.2 21.2 36.8 33.7 24.6 24.6 24.6 42.7 39.1 28.3 28.3 28.3 49.0 44.9
Hip Roof 1 -33.7 -58.7 -86.8 -40.0 -61.8 -39.1 -68.1 -100.6 -46.3 -71.7 -44.9 -78.1 -115.5 -53.2 -82.3
2 21.2 21.2 21.2 36.8 33.7 24.6 24.6 24.6 42.7 39.1 28.3 28.3 28.3 49.0 44.9
Monoslope Roof 1 -43.1 -55.6 -96.1 -40.0 -61.8 -50.0 -64.4 -111.5 -46.3 -71.7 -57.4 -74.0 -128.0 -53.2 -82.3
2 18.1 18.1 18.1 36.8 36.8 21.0 21.0 21.0 42.7 42.7 24.1 24.1 24.1 49.0 49.0
Table 30.7-2
Components and Cladding – Part 4
Exposure C
C & C
V = 130-150 mph
h = 15-80 ft.
c30.indd 326 4/14/2010 11:05:01 AM
MINIMUM DESIGN LOADS
327
V (MPH) 160 180 200
Load Zone Zone Zone
h (ft) Roof Form Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat Roof 1 -106.3 -166.8 -227.4 -72.6 -133.2 -134.5 -211.1 -287.8 -91.9 -168.6 -166.1 -260.7 -355.3 -113.5 -208.1
2 NA NA NA 72.6 72.6 NA NA NA 91.9 91.9 NA NA NA 113.5 113.5
Gable Roof 1 -79.4 -133.2 -200.5 -86.1 -133.2 -100.5 -168.6 -253.7 -109.0 -168.6 -124.0 -208.1 -313.2 -134.5 -208.1
80 Mansard Roof 2 45.7 45.7 45.7 79.4 72.6 57.9 57.9 57.9 100.5 91.9 71.5 71.5 71.5 124.0 113.5
Hip Roof 1 -72.6 -126.5 -187.0 -86.1 -133.2 -91.9 -160.1 -236.7 -109.0 -168.6 -113.5 -197.6 -292.2 -134.5 -208.1
2 45.7 45.7 45.7 79.4 72.6 57.9 57.9 57.9 100.5 91.9 71.5 71.5 71.5 124.0 113.5
Monoslope Roof 1 -92.8 -119.7 -207.2 -86.1 -133.2 -117.5 -151.5 -262.2 -109.0 -168.6 -145.0 -187.1 -323.7 -134.5 -208.1
2 39.0 39.0 39.0 79.4 79.4 49.4 49.4 49.4 100.5 100.5 61.0 61.0 61.0 124.0 113.5
Flat Roof 1 -103.3 -162.2 -221.1 -70.6 -129.5 -130.8 -205.3 -279.8 -89.4 -163.9 -161.5 -253.4 -345.4 -110.4 -202.3
2 NA NA NA 70.6 70.6 NA NA NA 89.4 89.4 NA NA NA 110.4 110.4
Gable Roof 1 -77.2 -129.5 -194.9 -83.7 -129.5 -97.7 -163.9 -246.7 -106.0 -163.9 -120.6 -202.3 -304.5 -130.8 -202.3
70 Mansard Roof 2 44.5 44.5 44.5 77.2 70.6 56.3 56.3 56.3 97.7 89.4 69.5 69.5 69.5 120.6 110.4
Hip Roof 1 -70.6 -123.0 -181.8 -83.7 -129.5 -89.4 -155.6 -230.1 -106.0 -163.9 -110.4 -192.1 -284.1 -130.8 -202.3
2 44.5 44.5 44.5 77.2 70.6 56.3 56.3 56.3 97.7 89.4 69.5 69.5 69.5 120.6 110.4
Monoslope Roof 1 -90.3 -116.4 -201.4 -83.7 -129.5 -114.2 -147.3 -254.9 -106.0 -163.9 -141.0 -181.9 -314.7 -130.8 -202.3
2 37.9 37.9 37.9 77.2 77.2 48.0 48.0 48.0 97.7 97.7 59.3 59.3 59.3 120.6 110.4
Flat Roof 1 -100.0 -157.0 -214.0 -68.4 -125.4 -126.6 -198.7 -270.8 -86.5 -158.7 -156.3 -245.3 -334.4 -106.8 -195.9
2 NA NA NA 68.4 68.4 NA NA NA 86.5 86.5 NA NA NA 106.8 106.8
Gable Roof 1 -74.7 -125.4 -188.7 -81.0 -125.4 -94.6 -158.7 -238.8 -102.6 -158.7 -116.7 -195.9 -294.8 -126.6 -195.9
60 Mansard Roof 2 43.1 43.1 43.1 74.7 68.4 54.5 54.5 54.5 94.6 86.5 67.3 67.3 67.3 116.7 106.8
Hip Roof 1 -68.4 -119.0 -176.0 -81.0 -125.4 -86.5 -150.6 -222.8 -102.6 -158.7 -106.8 -186.0 -275.0 -126.6 -195.9
2 43.1 43.1 43.1 74.7 68.4 54.5 54.5 54.5 94.6 86.5 67.3 67.3 67.3 116.7 106.8
Monoslope Roof 1 -87.4 -112.7 -195.0 -81.0 -125.4 -110.6 -142.6 -246.8 -102.6 -158.7 -136.5 -176.1 -304.7 -126.6 -195.9
2 36.7 36.7 36.7 74.7 74.7 46.5 46.5 46.5 94.6 94.6 57.4 57.4 57.4 116.7 106.8
Flat Roof 1 -96.3 -151.1 -205.9 -65.8 -120.6 -121.8 -191.2 -260.6 -83.3 -152.7 -150.4 -236.1 -321.8 -102.8 -188.5
2 NA NA NA 65.8 65.8 NA NA NA 83.3 83.3 NA NA NA 102.8 102.8
Gable Roof 1 -71.9 -120.6 -181.6 -78.0 -120.6 -91.0 -152.7 -229.8 -98.7 -152.7 -112.3 -188.5 -283.7 -121.9 -188.5
50 Mansard Roof 2 41.4 41.4 41.4 71.9 65.8 52.4 52.4 52.4 91.0 83.3 64.7 64.7 64.7 112.3 102.8
Hip Roof 1 -65.8 -114.5 -169.4 -78.0 -120.6 -83.3 -145.0 -214.4 -98.7 -152.7 -102.8 -179.0 -264.7 -121.9 -188.5
2 41.4 41.4 41.4 71.9 65.8 52.4 52.4 52.4 91.0 83.3 64.7 64.7 64.7 112.3 102.8
Monoslope Roof 1 -84.1 -108.5 -187.7 -78.0 -120.6 -106.4 -137.3 -237.5 -98.7 -152.7 -131.4 -169.5 -293.2 -121.9 -188.5
2 35.3 35.3 35.3 71.9 71.9 44.7 44.7 44.7 91.0 91.0 55.2 55.2 55.2 112.3 102.8
Flat Roof 1 -91.9 -144.2 -196.5 -62.8 -115.1 -116.2 -182.5 -248.7 -79.5 -145.7 -143.5 -225.3 -307.0 -98.1 -179.8
2 NA NA NA 62.8 62.8 NA NA NA 79.5 79.5 NA NA NA 98.1 98.1
Gable Roof 1 -68.6 -115.1 -173.2 -74.4 -115.1 -86.8 -145.7 -219.3 -94.2 -145.7 -107.2 -179.8 -270.7 -116.3 -179.8
40 Mansard Roof 2 39.5 39.5 39.5 68.6 62.8 50.0 50.0 50.0 86.8 79.5 61.8 61.8 61.8 107.2 98.1
Hip Roof 1 -62.8 -109.3 -161.6 -74.4 -115.1 -79.5 -138.3 -204.5 -94.2 -145.7 -98.1 -170.8 -252.5 -116.3 -179.8
2 39.5 39.5 39.5 68.6 62.8 50.0 50.0 50.0 86.8 79.5 61.8 61.8 61.8 107.2 98.1
Monoslope Roof 1 -80.2 -103.5 -179.1 -74.4 -115.1 -101.5 -131.0 -226.6 -94.2 -145.7 -125.3 -161.7 -279.8 -116.3 -179.8
2 33.7 33.7 33.7 68.6 68.6 42.7 42.7 42.7 86.8 86.8 52.7 52.7 52.7 107.2 98.1
Flat Roof 1 -86.5 -135.7 -184.9 -59.1 -108.3 -109.4 -171.7 -234.1 -74.8 -137.1 -135.1 -212.0 -289.0 -92.3 -169.3
2 NA NA NA 59.1 59.1 NA NA NA 74.8 74.8 NA NA NA 92.3 92.3
Gable Roof 1 -64.6 -108.3 -163.1 -70.0 -108.3 -81.7 -137.1 -206.4 -88.6 -137.1 -100.9 -169.3 -254.8 -109.4 -169.3
30 Mansard Roof 2 37.2 37.2 37.2 64.6 59.1 47.1 47.1 47.1 81.7 74.8 58.1 58.1 58.1 100.9 92.3
Hip Roof 1 -59.1 -102.9 -152.1 -70.0 -108.3 -74.8 -130.2 -192.5 -88.6 -137.1 -92.3 -160.7 -237.7 -109.4 -169.3
2 37.2 37.2 37.2 64.6 59.1 47.1 47.1 47.1 81.7 74.8 58.1 58.1 58.1 100.9 92.3
Monoslope Roof 1 -75.5 -97.4 -168.5 -70.0 -108.3 -95.6 -123.3 -213.3 -88.6 -137.1 -118.0 -152.2 -263.3 -109.4 -169.3
2 31.7 31.7 31.7 64.6 64.6 40.2 40.2 40.2 81.7 81.7 49.6 49.6 49.6 100.9 92.3
Flat Roof 1 -79.4 -124.6 -169.8 -54.3 -99.5 -100.5 -157.7 -214.9 -68.7 -125.9 -124.0 -194.7 -265.3 -84.8 -155.4
2 NA NA NA 54.3 54.3 NA NA NA 68.7 68.7 NA NA NA 84.8 84.8
Gable Roof 1 -59.3 -99.5 -149.7 -64.3 -99.5 -75.0 -125.9 -189.5 -81.4 -125.9 -92.6 -155.4 -233.9 -100.5 -155.4
20 Mansard Roof 2 34.2 34.2 34.2 59.3 54.3 43.2 43.2 43.2 75.0 68.7 53.4 53.4 53.4 92.6 84.8
Hip Roof 1 -54.3 -94.5 -139.7 -64.3 -99.5 -68.7 -119.5 -176.8 -81.4 -125.9 -84.8 -147.6 -218.2 -100.5 -155.4
2 34.2 34.2 34.2 59.3 54.3 43.2 43.2 43.2 75.0 68.7 53.4 53.4 53.4 92.6 84.8
Monoslope Roof 1 -69.3 -89.4 -154.7 -64.3 -99.5 -87.7 -113.2 -195.8 -81.4 -125.9 -108.3 -139.7 -241.8 -100.5 -155.4
2 29.1 29.1 29.1 59.3 59.3 36.9 36.9 36.9 75.0 75.0 45.5 45.5 45.5 92.6 84.8
Flat Roof 1 -74.7 -117.3 -159.8 -51.1 -93.6 -94.6 -148.4 -202.3 -64.6 -118.5 -116.7 -183.2 -249.7 -79.8 -146.3
2 NA NA NA 51.1 51.1 NA NA NA 64.6 64.6 NA NA NA 79.8 79.8
Gable Roof 1 -55.8 -93.6 -140.9 -60.5 -93.6 -70.6 -118.5 -178.3 -76.6 -118.5 -87.2 -146.3 -220.2 -94.6 -146.3
15 Mansard Roof 2 32.2 32.2 32.2 55.8 51.1 40.7 40.7 40.7 70.6 64.6 50.2 50.2 50.2 87.2 79.8
Hip Roof 1 -51.1 -88.9 -131.5 -60.5 -93.6 -64.6 -112.5 -166.4 -76.6 -118.5 -79.8 -138.9 -205.4 -94.6 -146.3
2 32.2 32.2 32.2 55.8 51.1 40.7 40.7 40.7 70.6 64.6 50.2 50.2 50.2 87.2 79.8
Monoslope Roof 1 -65.3 -84.2 -145.6 -60.5 -93.6 -82.6 -106.5 -184.3 -76.6 -118.5 -102.0 -131.5 -227.6 -94.6 -146.3
2 27.4 27.4 27.4 55.8 55.8 34.7 34.7 34.7 70.6 70.6 42.9 42.9 42.9 87.2 79.8
Table 30.7-2
Components and Cladding – Part 4
Exposure C
C & C
V = 160-200 mph
h = 15-80 ft.
c30.indd 327 4/14/2010 11:05:02 AM
CHAPTER 30 WIND LOADS – COMPONENTS AND CLADDING
328
V (MPH) 110 115 120
Load Zone Zone Zone
h (ft) Roof Form Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat Roof 1 -58.1 -91.2 -124.3 -39.7 -72.8 -63.5 -99.7 -135.9 -43.4 -79.6 -69.2 -108.6 -148.0 -47.3 -86.7
2 NA NA NA 39.7 39.7 NA NA NA 43.4 43.4 NA NA NA 47.3 47.3
Gable Roof 1 -43.4 -72.8 -109.6 -47.1 -72.8 -47.4 -79.6 -119.8 -51.5 -79.6 -51.7 -86.7 -130.5 -56.0 -86.7
160 Mansard Roof 2 25.0 25.0 25.0 43.4 39.7 27.3 27.3 27.3 47.4 43.4 29.8 29.8 29.8 51.7 47.3
Hip Roof 1 -39.7 -69.2 -102.3 -47.1 -72.8 -43.4 -75.6 -111.8 -51.5 -79.6 -47.3 -82.3 -121.7 -56.0 -86.7
2 25.0 25.0 25.0 43.4 39.7 27.3 27.3 27.3 47.4 43.4 29.8 29.8 29.8 51.7 47.3
Monoslope Roof 1 -50.8 -65.5 -113.3 -47.1 -72.8 -55.5 -71.6 -123.8 -51.5 -79.6 -60.4 -77.9 -134.8 -56.0 -86.7
2 21.3 21.3 21.3 43.4 43.4 23.3 23.3 23.3 47.4 47.4 25.4 25.4 25.4 51.7 51.7
Flat Roof 1 -57.3 -90.0 -122.7 -39.2 -71.9 -62.7 -98.4 -134.1 -42.8 -78.5 -68.2 -107.1 -146.0 -46.6 -85.5
2 NA NA NA 39.2 39.2 NA NA NA 42.8 42.8 NA NA NA 46.6 46.6
Gable Roof 1 -42.8 -71.9 -108.2 -46.5 -71.9 -46.8 -78.5 -118.2 -50.8 -78.5 -51.0 -85.5 -128.7 -55.3 -85.5
150 Mansard Roof 2 24.7 24.7 24.7 42.8 39.2 27.0 27.0 27.0 46.8 42.8 29.4 29.4 29.4 51.0 46.6
Hip Roof 1 -39.2 -68.2 -100.9 -46.5 -71.9 -42.8 -74.6 -110.3 -50.8 -78.5 -46.6 -81.2 -120.1 -55.3 -85.5
2 24.7 24.7 24.7 42.8 39.2 27.0 27.0 27.0 46.8 42.8 29.4 29.4 29.4 51.0 46.6
Monoslope Roof 1 -50.1 -64.6 -111.8 -46.5 -71.9 -54.7 -70.6 -122.2 -50.8 -78.5 -59.6 -76.9 -133.0 -55.3 -85.5
2 21.0 21.0 21.0 42.8 42.8 23.0 23.0 23.0 46.8 46.8 25.1 25.1 25.1 51.0 51.0
Flat Roof 1 -56.5 -88.7 -120.9 -38.6 -70.8 -61.8 -97.0 -132.1 -42.2 -77.4 -67.3 -105.6 -143.9 -46.0 -84.3
2 NA NA NA 38.6 38.6 NA NA NA 42.2 42.2 NA NA NA 46.0 46.0
Gable Roof 1 -42.2 -70.8 -106.6 -45.8 -70.8 -46.1 -77.4 -116.5 -50.0 -77.4 -50.2 -84.3 -126.9 -54.5 -84.3
140 Mansard Roof 2 24.3 24.3 24.3 42.2 38.6 26.6 26.6 26.6 46.1 42.2 28.9 28.9 28.9 50.2 46.0
Hip Roof 1 -38.6 -67.2 -99.4 -45.8 -70.8 -42.2 -73.5 -108.7 -50.0 -77.4 -46.0 -80.0 -118.3 -54.5 -84.3
2 24.3 24.3 24.3 42.2 38.6 26.6 26.6 26.6 46.1 42.2 28.9 28.9 28.9 50.2 46.0
Monoslope Roof 1 -49.4 -63.7 -110.2 -45.8 -70.8 -54.0 -69.6 -120.4 -50.0 -77.4 -58.7 -75.8 -131.1 -54.5 -84.3
2 20.7 20.7 20.7 42.2 42.2 22.7 22.7 22.7 46.1 46.1 24.7 24.7 24.7 50.2 50.2
Flat Roof 1 -55.6 -87.3 -119.0 -38.0 -69.7 -60.8 -95.5 -130.1 -41.6 -76.2 -66.2 -103.9 -141.7 -45.3 -83.0
2 NA NA NA 38.0 38.0 NA NA NA 41.6 41.6 NA NA NA 45.3 45.3
Gable Roof 1 -41.6 -69.7 -104.9 -45.1 -69.7 -45.4 -76.2 -114.7 -49.3 -76.2 -49.5 -83.0 -124.9 -53.6 -83.0
130 Mansard Roof 2 23.9 23.9 23.9 41.6 38.0 26.2 26.2 26.2 45.4 41.6 28.5 28.5 28.5 49.5 45.3
Hip Roof 1 -38.0 -66.2 -97.9 -45.1 -69.7 -41.6 -72.4 -107.0 -49.3 -76.2 -45.3 -78.8 -116.5 -53.6 -83.0
2 23.9 23.9 23.9 41.6 38.0 26.2 26.2 26.2 45.4 41.6 28.5 28.5 28.5 49.5 45.3
Monoslope Roof 1 -48.6 -62.7 -108.5 -45.1 -69.7 -53.1 -68.5 -118.5 -49.3 -76.2 -57.8 -74.6 -129.1 -53.6 -83.0
2 20.4 20.4 20.4 41.6 41.6 22.3 22.3 22.3 45.4 45.4 24.3 24.3 24.3 49.5 49.5
Flat Roof 1 -54.7 -85.9 -117.0 -37.4 -68.6 -59.8 -93.9 -127.9 -40.9 -74.9 -65.1 -102.2 -139.3 -44.5 -81.6
2 NA NA NA 37.4 37.4 NA NA NA 40.9 40.9 NA NA NA 44.5 44.5
Gable Roof 1 -40.9 -68.6 -103.2 -44.3 -68.6 -44.7 -74.9 -112.8 -48.4 -74.9 -48.6 -81.6 -122.8 -52.7 -81.6
120 Mansard Roof 2 23.5 23.5 23.5 40.9 37.4 25.7 25.7 25.7 44.7 40.9 28.0 28.0 28.0 48.6 44.5
Hip Roof 1 -37.4 -65.1 -96.3 -44.3 -68.6 -40.9 -71.2 -105.2 -48.4 -74.9 -44.5 -77.5 -114.6 -52.7 -81.6
2 23.5 23.5 23.5 40.9 37.4 25.7 25.7 25.7 44.7 40.9 28.0 28.0 28.0 48.6 44.5
Monoslope Roof 1 -47.8 -61.6 -106.7 -44.3 -68.6 -52.2 -67.4 -116.6 -48.4 -74.9 -56.9 -73.4 -126.9 -52.7 -81.6
2 20.1 20.1 20.1 40.9 40.9 22.0 22.0 22.0 44.7 44.7 23.9 23.9 23.9 48.6 48.6
Flat Roof 1 -53.7 -84.3 -114.9 -36.7 -67.3 -58.7 -92.2 -125.6 -40.1 -73.6 -63.9 -100.3 -136.8 -43.7 -80.1
2 NA NA NA 36.7 36.7 NA NA NA 40.1 40.1 NA NA NA 43.7 43.7
Gable Roof 1 -40.1 -67.3 -101.3 -43.5 -67.3 -43.8 -73.6 -110.7 -47.6 -73.6 -47.7 -80.1 -120.6 -51.8 -80.1
110 Mansard Roof 2 23.1 23.1 23.1 40.1 36.7 25.3 25.3 25.3 43.8 40.1 27.5 27.5 27.5 47.7 43.7
Hip Roof 1 -36.7 -63.9 -94.5 -43.5 -67.3 -40.1 -69.9 -103.3 -47.6 -73.6 -43.7 -76.1 -112.5 -51.8 -80.1
2 23.1 23.1 23.1 40.1 36.7 25.3 25.3 25.3 43.8 40.1 27.5 27.5 27.5 47.7 43.7
Monoslope Roof 1 -46.9 -60.5 -104.7 -43.5 -67.3 -51.3 -66.1 -114.5 -47.6 -73.6 -55.8 -72.0 -124.6 -51.8 -80.1
2 19.7 19.7 19.7 40.1 40.1 21.6 21.6 21.6 43.8 43.8 23.5 23.5 23.5 47.7 47.7
Flat Roof 1 -52.7 -82.6 -112.6 -36.0 -66.0 -57.5 -90.3 -123.1 -39.3 -72.1 -62.7 -98.4 -134.0 -42.8 -78.5
2 NA NA NA 36.0 36.0 NA NA NA 39.3 39.3 NA NA NA 42.8 42.8
Gable Roof 1 -39.3 -66.0 -99.3 -42.7 -66.0 -43.0 -72.1 -108.5 -46.6 -72.1 -46.8 -78.5 -118.2 -50.8 -78.5
100 Mansard Roof 2 22.7 22.7 22.7 39.3 36.0 24.8 24.8 24.8 43.0 39.3 27.0 27.0 27.0 46.8 42.8
Hip Roof 1 -36.0 -62.6 -92.6 -42.7 -66.0 -39.3 -68.5 -101.3 -46.6 -72.1 -42.8 -74.6 -110.2 -50.8 -78.5
2 22.7 22.7 22.7 39.3 36.0 24.8 24.8 24.8 43.0 39.3 27.0 27.0 27.0 46.8 42.8
Monoslope Roof 1 -46.0 -59.3 -102.6 -42.7 -66.0 -50.3 -64.8 -112.2 -46.6 -72.1 -54.7 -70.6 -122.1 -50.8 -78.5
2 19.3 19.3 19.3 39.3 39.3 21.1 21.1 21.1 43.0 43.0 23.0 23.0 23.0 46.8 46.8
Flat Roof 1 -51.5 -80.8 -110.2 -35.2 -64.5 -56.3 -88.3 -120.4 -38.5 -70.5 -61.3 -96.2 -131.1 -41.9 -76.8
2 NA NA NA 35.2 35.2 NA NA NA 38.5 38.5 NA NA NA 41.9 41.9
Gable Roof 1 -38.5 -64.5 -97.1 -41.7 -64.5 -42.0 -70.5 -106.2 -45.6 -70.5 -45.8 -76.8 -115.6 -49.6 -76.8
90 Mansard Roof 2 22.2 22.2 22.2 38.5 35.2 24.2 24.2 24.2 42.0 38.5 26.4 26.4 26.4 45.8 41.9
Hip Roof 1 -35.2 -61.3 -90.6 -41.7 -64.5 -38.5 -67.0 -99.0 -45.6 -70.5 -41.9 -72.9 -107.8 -49.6 -76.8
2 22.2 22.2 22.2 38.5 35.2 24.2 24.2 24.2 42.0 38.5 26.4 26.4 26.4 45.8 41.9
Monoslope Roof 1 -45.0 -58.0 -100.4 -41.7 -64.5 -49.2 -63.4 -109.7 -45.6 -70.5 -53.5 -69.0 -119.5 -49.6 -76.8
2 18.9 18.9 18.9 38.5 38.5 20.7 20.7 20.7 42.0 42.0 22.5 22.5 22.5 45.8 45.8
Table 30.7-2
Components and Cladding – Part 4
Exposure C
C & C
V = 110-120 mph
h = 90-160 ft.
c30.indd 328 4/14/2010 11:05:02 AM
MINIMUM DESIGN LOADS
329
V (MPH) 130 140 150
Load Zone Zone Zone
h (ft) Roof Form Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat Roof 1 -81.2 -127.4 -173.7 -55.5 -101.7 -94.2 -147.8 -201.4 -64.4 -118.0 -108.1 -169.7 -231.2 -73.9 -135.5
2 NA NA NA 55.5 55.5 NA NA NA 64.4 64.4 NA NA NA 73.9 73.9
Gable Roof 1 -60.6 -101.7 -153.1 -65.8 -101.7 -70.3 -118.0 -177.6 -76.3 -118.0 -80.7 -135.5 -203.9 -87.6 -135.5
160 Mansard Roof 2 34.9 34.9 34.9 60.6 55.5 40.5 40.5 40.5 70.3 64.4 46.5 46.5 46.5 80.7 73.9
Hip Roof 1 -55.5 -96.6 -142.8 -65.8 -101.7 -64.4 -112.0 -165.7 -76.3 -118.0 -73.9 -128.6 -190.2 -87.6 -135.5
2 34.9 34.9 34.9 60.6 55.5 40.5 40.5 40.5 70.3 64.4 46.5 46.5 46.5 80.7 73.9
Monoslope Roof 1 -70.9 -91.5 -158.3 -65.8 -101.7 -82.2 -106.1 -183.5 -76.3 -118.0 -94.4 -121.8 -210.7 -87.6 -135.5
2 29.8 29.8 29.8 60.6 60.6 34.6 34.6 34.6 70.3 70.3 39.7 39.7 39.7 80.7 80.7
Flat Roof 1 -80.1 -125.7 -171.3 -54.7 -100.4 -92.9 -145.8 -198.7 -63.5 -116.4 -106.6 -167.4 -228.1 -72.9 -133.6
2 NA NA NA 54.7 54.7 NA NA NA 63.5 63.5 NA NA NA 72.9 72.9
Gable Roof 1 -59.8 -100.4 -151.1 -64.9 -100.4 -69.4 -116.4 -175.2 -75.2 -116.4 -79.6 -133.6 -201.1 -86.4 -133.6
150 Mansard Roof 2 34.5 34.5 34.5 59.8 54.7 40.0 40.0 40.0 69.4 63.5 45.9 45.9 45.9 79.6 72.9
Hip Roof 1 -54.7 -95.3 -140.9 -64.9 -100.4 -63.5 -110.5 -163.4 -75.2 -116.4 -72.9 -126.9 -187.6 -86.4 -133.6
2 34.5 34.5 34.5 59.8 54.7 40.0 40.0 40.0 69.4 63.5 45.9 45.9 45.9 79.6 72.9
Monoslope Roof 1 -70.0 -90.2 -156.1 -64.9 -100.4 -81.1 -104.6 -181.1 -75.2 -116.4 -93.1 -120.1 -207.9 -86.4 -133.6
2 29.4 29.4 29.4 59.8 59.8 34.1 34.1 34.1 69.4 69.4 39.1 39.1 39.1 79.6 79.6
Flat Roof 1 -78.9 -123.9 -168.9 -54.0 -98.9 -91.5 -143.7 -195.8 -62.6 -114.7 -105.1 -165.0 -224.8 -71.8 -131.7
2 NA NA NA 54.0 54.0 NA NA NA 62.6 62.6 NA NA NA 71.8 71.8
Gable Roof 1 -59.0 -98.9 -148.9 -63.9 -98.9 -68.4 -114.7 -172.7 -74.2 -114.7 -78.5 -131.7 -198.2 -85.1 -131.7
140 Mansard Roof 2 34.0 34.0 34.0 59.0 54.0 39.4 39.4 39.4 68.4 62.6 45.2 45.2 45.2 78.5 71.8
Hip Roof 1 -54.0 -93.9 -138.9 -63.9 -98.9 -62.6 -108.9 -161.1 -74.2 -114.7 -71.8 -125.0 -184.9 -85.1 -131.7
2 34.0 34.0 34.0 59.0 54.0 39.4 39.4 39.4 68.4 62.6 45.2 45.2 45.2 78.5 71.8
Monoslope Roof 1 -68.9 -88.9 -153.9 -63.9 -98.9 -80.0 -103.1 -178.5 -74.2 -114.7 -91.8 -118.4 -204.9 -85.1 -131.7
2 29.0 29.0 29.0 59.0 59.0 33.6 33.6 33.6 68.4 68.4 38.6 38.6 38.6 78.5 78.5
Flat Roof 1 -77.7 -122.0 -166.2 -53.1 -97.4 -90.1 -141.5 -192.8 -61.6 -112.9 -103.5 -162.4 -221.3 -70.7 -129.7
2 NA NA NA 53.1 53.1 NA NA NA 61.6 61.6 NA NA NA 70.7 70.7
Gable Roof 1 -58.0 -97.4 -146.6 -63.0 -97.4 -67.3 -112.9 -170.0 -73.0 -112.9 -77.3 -129.7 -195.1 -83.8 -129.7
130 Mansard Roof 2 33.4 33.4 33.4 58.0 53.1 38.8 38.8 38.8 67.3 61.6 44.5 44.5 44.5 77.3 70.7
Hip Roof 1 -53.1 -92.5 -136.7 -63.0 -97.4 -61.6 -107.2 -158.6 -73.0 -112.9 -70.7 -123.1 -182.0 -83.8 -129.7
2 33.4 33.4 33.4 58.0 53.1 38.8 38.8 38.8 67.3 61.6 44.5 44.5 44.5 77.3 70.7
Monoslope Roof 1 -67.9 -87.6 -151.5 -63.0 -97.4 -78.7 -101.5 -175.7 -73.0 -112.9 -90.4 -116.6 -201.7 -83.8 -129.7
2 28.5 28.5 28.5 58.0 58.0 33.1 33.1 33.1 67.3 67.3 38.0 38.0 38.0 77.3 77.3
Flat Roof 1 -76.4 -119.9 -163.5 -52.2 -95.8 -88.6 -139.1 -189.6 -60.6 -111.1 -101.7 -159.7 -217.6 -69.5 -127.5
2 NA NA NA 52.2 52.2 NA NA NA 60.6 60.6 NA NA NA 69.5 69.5
Gable Roof 1 -57.1 -95.8 -144.1 -61.9 -95.8 -66.2 -111.1 -167.1 -71.8 -111.1 -76.0 -127.5 -191.9 -82.4 -127.5
120 Mansard Roof 2 32.9 32.9 32.9 57.1 52.2 38.1 38.1 38.1 66.2 60.6 43.8 43.8 43.8 76.0 69.5
Hip Roof 1 -52.2 -90.9 -134.5 -61.9 -95.8 -60.6 -105.4 -155.9 -71.8 -111.1 -69.5 -121.1 -179.0 -82.4 -127.5
2 32.9 32.9 32.9 57.1 52.2 38.1 38.1 38.1 66.2 60.6 43.8 43.8 43.8 76.0 69.5
Monoslope Roof 1 -66.7 -86.1 -149.0 -61.9 -95.8 -77.4 -99.8 -172.8 -71.8 -111.1 -88.9 -114.6 -198.3 -82.4 -127.5
2 28.1 28.1 28.1 57.1 57.1 32.5 32.5 32.5 66.2 66.2 37.3 37.3 37.3 76.0 76.0
Flat Roof 1 -75.0 -117.8 -160.5 -51.3 -94.0 -87.0 -136.6 -186.1 -59.5 -109.0 -99.9 -156.8 -213.7 -68.3 -125.2
2 NA NA NA 51.3 51.3 NA NA NA 59.5 59.5 NA NA NA 68.3 68.3
Gable Roof 1 -56.0 -94.0 -141.5 -60.8 -94.0 -65.0 -109.0 -164.1 -70.5 -109.0 -74.6 -125.2 -188.4 -80.9 -125.2
110 Mansard Roof 2 32.3 32.3 32.3 56.0 51.3 37.4 37.4 37.4 65.0 59.5 43.0 43.0 43.0 74.6 68.3
Hip Roof 1 -51.3 -89.3 -132.0 -60.8 -94.0 -59.5 -103.5 -153.1 -70.5 -109.0 -68.3 -118.9 -175.8 -80.9 -125.2
2 32.3 32.3 32.3 56.0 51.3 37.4 37.4 37.4 65.0 59.5 43.0 43.0 43.0 74.6 68.3
Monoslope Roof 1 -65.5 -84.5 -146.3 -60.8 -94.0 -76.0 -98.0 -169.6 -70.5 -109.0 -87.2 -112.5 -194.7 -80.9 -125.2
2 27.5 27.5 27.5 56.0 56.0 31.9 31.9 31.9 65.0 65.0 36.7 36.7 36.7 74.6 74.6
Flat Roof 1 -73.5 -115.4 -157.3 -50.3 -92.2 -85.3 -133.9 -182.4 -58.3 -106.9 -97.9 -153.7 -209.4 -66.9 -122.7
2 NA NA NA 50.3 50.3 NA NA NA 58.3 58.3 NA NA NA 66.9 66.9
Gable Roof 1 -54.9 -92.2 -138.7 -59.6 -92.2 -63.7 -106.9 -160.9 -69.1 -106.9 -73.1 -122.7 -184.7 -79.3 -122.7
100 Mansard Roof 2 31.6 31.6 31.6 54.9 50.3 36.7 36.7 36.7 63.7 58.3 42.1 42.1 42.1 73.1 66.9
Hip Roof 1 -50.3 -87.5 -129.4 -59.6 -92.2 -58.3 -101.5 -150.1 -69.1 -106.9 -66.9 -116.5 -172.3 -79.3 -122.7
2 31.6 31.6 31.6 54.9 50.3 36.7 36.7 36.7 63.7 58.3 42.1 42.1 42.1 73.1 66.9
Monoslope Roof 1 -64.2 -82.8 -143.4 -59.6 -92.2 -74.5 -96.1 -166.3 -69.1 -106.9 -85.5 -110.3 -190.9 -79.3 -122.7
2 27.0 27.0 27.0 54.9 54.9 31.3 31.3 31.3 63.7 63.7 35.9 35.9 35.9 73.1 73.1
Flat Roof 1 -71.9 -112.9 -153.9 -49.2 -90.1 -83.4 -130.9 -178.4 -57.0 -104.5 -95.8 -150.3 -204.8 -65.5 -120.0
2 NA NA NA 49.2 49.2 NA NA NA 57.0 57.0 NA NA NA 65.5 65.5
Gable Roof 1 -53.7 -90.1 -135.7 -58.3 -90.1 -62.3 -104.5 -157.3 -67.6 -104.5 -71.5 -120.0 -180.6 -77.6 -120.0
90 Mansard Roof 2 31.0 31.0 31.0 53.7 49.2 35.9 35.9 35.9 62.3 57.0 41.2 41.2 41.2 71.5 65.5
Hip Roof 1 -49.2 -85.6 -126.5 -58.3 -90.1 -57.0 -99.3 -146.8 -67.6 -104.5 -65.5 -113.9 -168.5 -77.6 -120.0
2 31.0 31.0 31.0 53.7 49.2 35.9 35.9 35.9 62.3 57.0 41.2 41.2 41.2 71.5 65.5
Monoslope Roof 1 -62.8 -81.0 -140.2 -58.3 -90.1 -72.9 -94.0 -162.6 -67.6 -104.5 -83.6 -107.9 -186.7 -77.6 -120.0
2 26.4 26.4 26.4 53.7 53.7 30.6 30.6 30.6 62.3 62.3 35.2 35.2 35.2 71.5 71.5
Table 30.7-2
Components and Cladding – Part 4
Exposure C
C & C
V = 130-150 mph
h = 90-160 ft.
c30.indd 329 4/14/2010 11:05:02 AM
CHAPTER 30 WIND LOADS – COMPONENTS AND CLADDING
330
V (MPH) 160 180 200
Load Zone Zone Zone
h (ft) Roof Form Case 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Flat Roof 1 -123.0 -193.0 -263.1 -84.1 -154.1 -155.6 -244.3 -333.0 -106.4 -195.0 -192.2 -301.6 -411.1 -131.3 -240.8
2 NA NA NA 84.1 84.1 NA NA NA 106.4 106.4 NA NA NA 131.3 131.3
Gable Roof 1 -91.8 -154.1 -231.9 -99.6 -154.1 -116.2 -195.0 -293.6 -126.1 -195.0 -143.5 -240.8 -362.4 -155.7 -240.8
160 Mansard Roof 2 52.9 52.9 52.9 91.8 84.1 67.0 67.0 67.0 116.2 106.4 82.7 82.7 82.7 143.5 131.3
Hip Roof 1 -84.1 -146.3 -216.4 -99.6 -154.1 -106.4 -185.2 -273.9 -126.1 -195.0 -131.3 -228.6 -338.1 -155.7 -240.8
2 52.9 52.9 52.9 91.8 84.1 67.0 67.0 67.0 116.2 106.4 82.7 82.7 82.7 143.5 131.3
Monoslope Roof 1 -107.4 -138.5 -239.7 -99.6 -154.1 -135.9 -175.3 -303.4 -126.1 -195.0 -167.8 -216.5 -374.6 -155.7 -240.8
2 45.1 45.1 45.1 91.8 91.8 57.1 57.1 57.1 116.2 116.2 70.5 70.5 70.5 143.5 131.3
Flat Roof 1 -121.3 -190.4 -259.5 -82.9 -152.0 -153.5 -241.0 -328.5 -105.0 -192.4 -189.6 -297.5 -405.5 -129.6 -237.6
2 NA NA NA 82.9 82.9 NA NA NA 105.0 105.0 NA NA NA 129.6 129.6
Gable Roof 1 -90.6 -152.0 -228.8 -98.3 -152.0 -114.7 -192.4 -289.6 -124.4 -192.4 -141.6 -237.6 -357.5 -153.6 -237.6
150 Mansard Roof 2 52.2 52.2 52.2 90.6 82.9 66.1 66.1 66.1 114.7 105.0 81.6 81.6 81.6 141.6 129.6
Hip Roof 1 -82.9 -144.4 -213.5 -98.3 -152.0 -105.0 -182.7 -270.2 -124.4 -192.4 -129.6 -225.6 -333.5 -153.6 -237.6
2 52.2 52.2 52.2 90.6 82.9 66.1 66.1 66.1 114.7 105.0 81.6 81.6 81.6 141.6 129.6
Monoslope Roof 1 -106.0 -136.7 -236.5 -98.3 -152.0 -134.1 -173.0 -299.3 -124.4 -192.4 -165.6 -213.6 -369.5 -153.6 -237.6
2 44.5 44.5 44.5 90.6 90.6 56.4 56.4 56.4 114.7 114.7 69.6 69.6 69.6 141.6 129.6
Flat Roof 1 -119.6 -187.7 -255.8 -81.7 -149.8 -151.3 -237.5 -323.7 -103.4 -189.6 -186.8 -293.2 -399.7 -127.7 -234.1
2 NA NA NA 81.7 81.7 NA NA NA 103.4 103.4 NA NA NA 127.7 127.7
Gable Roof 1 -89.3 -149.8 -225.5 -96.9 -149.8 -113.0 -189.6 -285.4 -122.6 -189.6 -139.5 -234.1 -352.4 -151.4 -234.1
140 Mansard Roof 2 51.5 51.5 51.5 89.3 81.7 65.1 65.1 65.1 113.0 103.4 80.4 80.4 80.4 139.5 127.7
Hip Roof 1 -81.7 -142.3 -210.4 -96.9 -149.8 -103.4 -180.1 -266.3 -122.6 -189.6 -127.7 -222.3 -328.7 -151.4 -234.1
2 51.5 51.5 51.5 89.3 81.7 65.1 65.1 65.1 113.0 103.4 80.4 80.4 80.4 139.5 127.7
Monoslope Roof 1 -104.4 -134.7 -233.1 -96.9 -149.8 -132.2 -170.5 -295.0 -122.6 -189.6 -163.2 -210.5 -364.2 -151.4 -234.1
2 43.9 43.9 43.9 89.3 89.3 55.6 55.6 55.6 113.0 113.0 68.6 68.6 68.6 139.5 127.7
Flat Roof 1 -117.7 -184.8 -251.8 -80.5 -147.5 -149.0 -233.9 -318.7 -101.8 -186.7 -183.9 -288.7 -393.5 -125.7 -230.5
2 NA NA NA 80.5 80.5 NA NA NA 101.8 101.8 NA NA NA 125.7 125.7
Gable Roof 1 -87.9 -147.5 -222.0 -95.4 -147.5 -111.3 -186.7 -281.0 -120.7 -186.7 -137.4 -230.5 -346.9 -149.0 -230.5
130 Mansard Roof 2 50.7 50.7 50.7 87.9 80.5 64.1 64.1 64.1 111.3 101.8 79.2 79.2 79.2 137.4 125.7
Hip Roof 1 -80.5 -140.1 -207.1 -95.4 -147.5 -101.8 -177.3 -262.1 -120.7 -186.7 -125.7 -218.9 -323.6 -149.0 -230.5
2 50.7 50.7 50.7 87.9 80.5 64.1 64.1 64.1 111.3 101.8 79.2 79.2 79.2 137.4 125.7
Monoslope Roof 1 -102.8 -132.6 -229.5 -95.4 -147.5 -130.1 -167.8 -290.4 -120.7 -186.7 -160.7 -207.2 -358.6 -149.0 -230.5
2 43.2 43.2 43.2 87.9 87.9 54.7 54.7 54.7 111.3 111.3 67.5 67.5 67.5 137.4 125.7
Flat Roof 1 -115.8 -181.7 -247.6 -79.1 -145.1 -146.5 -229.9 -313.4 -100.1 -183.6 -180.9 -283.9 -386.9 -123.6 -226.7
2 NA NA NA 79.1 79.1 NA NA NA 100.1 100.1 NA NA NA 123.6 123.6
Gable Roof 1 -86.4 -145.1 -218.3 -93.8 -145.1 -109.4 -183.6 -276.3 -118.7 -183.6 -135.1 -226.7 -341.1 -146.5 -226.7
120 Mansard Roof 2 49.8 49.8 49.8 86.4 79.1 63.1 63.1 63.1 109.4 100.1 77.8 77.8 77.8 135.1 123.6
Hip Roof 1 -79.1 -137.7 -203.7 -93.8 -145.1 -100.1 -174.3 -257.8 -118.7 -183.6 -123.6 -215.2 -318.2 -146.5 -226.7
2 49.8 49.8 49.8 86.4 79.1 63.1 63.1 63.1 109.4 100.1 77.8 77.8 77.8 135.1 123.6
Monoslope Roof 1 -101.1 -130.4 -225.6 -93.8 -145.1 -128.0 -165.0 -285.6 -118.7 -183.6 -158.0 -203.8 -352.6 -146.5 -226.7
2 42.5 42.5 42.5 86.4 86.4 53.8 53.8 53.8 109.4 109.4 66.4 66.4 66.4 135.1 123.6
Flat Roof 1 -113.7 -178.4 -243.1 -77.7 -142.4 -143.8 -225.8 -307.7 -98.3 -180.3 -177.6 -278.7 -379.9 -121.4 -222.5
2 NA NA NA 77.7 77.7 NA NA NA 98.3 98.3 NA NA NA 121.4 121.4
Gable Roof 1 -84.9 -142.4 -214.4 -92.1 -142.4 -107.4 -180.3 -271.3 -116.5 -180.3 -132.6 -222.5 -334.9 -143.9 -222.5
110 Mansard Roof 2 48.9 48.9 48.9 84.9 77.7 61.9 61.9 61.9 107.4 98.3 76.4 76.4 76.4 132.6 121.4
Hip Roof 1 -77.7 -135.2 -200.0 -92.1 -142.4 -98.3 -171.2 -253.1 -116.5 -180.3 -121.4 -211.3 -312.5 -143.9 -222.5
2 48.9 48.9 48.9 84.9 77.7 61.9 61.9 61.9 107.4 98.3 76.4 76.4 76.4 132.6 121.4
Monoslope Roof 1 -99.3 -128.0 -221.5 -92.1 -142.4 -125.6 -162.0 -280.4 -116.5 -180.3 -155.1 -200.1 -346.2 -143.9 -222.5
2 41.7 41.7 41.7 84.9 84.9 52.8 52.8 52.8 107.4 107.4 65.2 65.2 65.2 132.6 121.4
Flat Roof 1 -111.4 -174.8 -238.3 -76.1 -139.6 -141.0 -221.3 -301.6 -96.4 -176.7 -174.1 -273.2 -372.3 -119.0 -218.1
2 NA NA NA 76.1 76.1 NA NA NA 96.4 96.4 NA NA NA 119.0 119.0
Gable Roof 1 -83.2 -139.6 -210.1 -90.2 -139.6 -105.3 -176.7 -265.9 -114.2 -176.7 -130.0 -218.1 -328.3 -141.0 -218.1
100 Mansard Roof 2 47.9 47.9 47.9 83.2 76.1 60.7 60.7 60.7 105.3 96.4 74.9 74.9 74.9 130.0 119.0
Hip Roof 1 -76.1 -132.5 -196.0 -90.2 -139.6 -96.4 -167.8 -248.1 -114.2 -176.7 -119.0 -207.1 -306.2 -141.0 -218.1
2 47.9 47.9 47.9 83.2 76.1 60.7 60.7 60.7 105.3 96.4 74.9 74.9 74.9 130.0 119.0
Monoslope Roof 1 -97.3 -125.5 -217.1 -90.2 -139.6 -123.1 -158.8 -274.8 -114.2 -176.7 -152.0 -196.1 -339.3 -141.0 -218.1
2 40.9 40.9 40.9 83.2 83.2 51.8 51.8 51.8 105.3 105.3 63.9 63.9 63.9 130.0 119.0
Flat Roof 1 -108.9 -171.0 -233.1 -74.5 -136.5 -137.9 -216.4 -295.0 -94.3 -172.8 -170.2 -267.2 -364.2 -116.4 -213.3
2 NA NA NA 74.5 74.5 NA NA NA 94.3 94.3 NA NA NA 116.4 116.4
Gable Roof 1 -81.4 -136.5 -205.5 -88.3 -136.5 -103.0 -172.8 -260.1 -111.7 -172.8 -127.1 -213.3 -321.1 -137.9 -213.3
90 Mansard Roof 2 46.9 46.9 46.9 81.4 74.5 59.3 59.3 59.3 103.0 94.3 73.3 73.3 73.3 127.1 116.4
Hip Roof 1 -74.5 -129.6 -191.7 -88.3 -136.5 -94.3 -164.1 -242.6 -111.7 -172.8 -116.4 -202.6 -299.5 -137.9 -213.3
2 46.9 46.9 46.9 81.4 74.5 59.3 59.3 59.3 103.0 94.3 73.3 73.3 73.3 127.1 116.4
Monoslope Roof 1 -95.2 -122.7 -212.4 -88.3 -136.5 -120.4 -155.3 -268.8 -111.7 -172.8 -148.7 -191.8 -331.8 -137.9 -213.3
2 40.0 40.0 40.0 81.4 81.4 50.6 50.6 50.6 103.0 103.0 62.5 62.5 62.5 127.1 116.4
Table 30.7-2
Components and Cladding – Part 4
Exposure C
C & C
V = 160-200 mph
h = 90-160 ft.
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PART 5: OPEN BUILDINGS
30.8 BUILDING TYPES
The provisions of Section 30.8 are applicable to an
open building of all heights having a pitched free
roof, monosloped free roof, or troughed free roof. The
steps required for the determination of wind loads on
components and cladding for these building types is
shown in Table 30.8-1.
30.8.1 Conditions
For the determination of the design wind pressures
on components and claddings using the provisions
of Section 30.8.2, the conditions indicated on
the selected fi gure(s) shall be applicable to the
building under consideration.
30.8.2 Design Wind Pressures
The net design wind pressure for component and
cladding elements of open buildings of all heights
with monoslope, pitched, and troughed roofs shall be
determined by the following equation:
p = qhGCN (30.8-1)
where
qh = velocity pressure evaluated at mean roof height
h using the exposure as defi ned in Section 26.7.3
that results in the highest wind loads for any
wind direction at the site
G = gust-effect factor from Section 26.9
CN = net pressure coeffi cient given in:
– Fig. 30.8-1 for monosloped roof
– Fig. 30.8-2 for pitched roof
– Fig. 30.8-3 for troughed roof
Net pressure coeffi cients CN include contributions
from top and bottom surfaces. All load cases shown
for each roof angle shall be investigated. Plus and
minus signs signify pressure acting toward and away
from the top surface of the roof, respectively.
Table 30.8-1 Steps to Determine C&C Wind
Loads Open Buildings
Step 1: Determine risk category, see Table 1.5-1
Step 2: Determine the basic wind speed, V, for
applicable risk category, see Figure 26.5-1A,
B or C
Step 3: Determine wind load parameters:
➢ Wind directionality factor, Kd , see
Section 26.6 and Table 26.6-1
➢ Exposure category B, C or D, see
Section 26.7
➢ Topographic factor, Kzt, see Section 26.8 and
Figure 26.8-1
➢ Gust effect factor, G, see Section 26.9
Step 4: Determine velocity pressure exposure
coeffi cient, Kz or Kh, see Table 30.3-1
Step 5: Determine velocity pressure, qh, Eq. 30.3-1
Step 6: Determine net pressure coeffi cients, CN
➢ Monosloped roof, see Fig. 30.8-1
➢ Pitched roof, see Fig. 30.8-2
➢ Troughed roof, see Fig. 30.8-3
Step 7: Calculate wind pressure, p, Eq. 30.8-1
User Note: Use Part 5 of Chapter 30 for determining
wind pressures for C&C of open buildings having
pitched, monoslope or troughed roofs. These provisions
are based on the Directional Procedure with wind
pressures calculated from the specifi ed equation
applicable to each roof surface.
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332
PART 6: BUILDING APPURTENANCES
AND ROOFTOP STRUCTURES
AND EQUIPMENT
30.9 PARAPETS
The design wind pressure for component and cladding
elements of parapets for all building types and
heights, except enclosed buildings with h ≤ 160 ft
(48.8 m) for which the provisions of Part 4 are used,
shall be determined from the following equation:
p = qp((GCp) – (GCpi)) (30.9-1)
where
qp = velocity pressure evaluated at the top of the
parapet
(GCp) = external pressure coeffi cient given in
– Fig. 30.4-1 for walls with h ≤ 60 ft (48.8 m)
– Figs. 30.4-2A to 30.4-2C for fl at roofs,
gable roofs, and hip roofs
– Fig. 30.4-3 for stepped roofs
– Fig. 30.4-4 for multispan gable roofs
– Figs. 30.4-5A and 30-5B for monoslope
roofs
– Fig. 30.4-6 for sawtooth roofs
– Fig. 30.4-7 for domed roofs of all heights
– Fig. 30.6-1 for walls and fl at roofs with
h > 60 ft (18.3 m)
– Fig. 27.4-3 footnote 4 for arched roofs
(GCpi) = internal pressure coeffi cient from Table
26.11-1, based on the porosity of the parapet
envelope
Two load cases, see Fig. 30.9-1, shall be
considered:
– Load Case A: Windward Parapet shall consist of
applying the applicable positive wall pressure from
Fig. 30.4-1 (h ≤ 60 ft (18.3 m)) or Fig. 30.6-1 (h >
60 ft (18.3 m)) to the windward surface of the
parapet while applying the applicable negative
edge or corner zone roof pressure from Figs.
30.4-2 (A, B or C), 30.4-3, 30.4-4, 30.4-5 (A or
B), 30.4-6, 30.4-7, Fig. 27.4-3 footnote 4, or Fig.
30.6-1 (h > 60 ft (18.3 m)) as applicable to the
leeward surface of the parapet.
– Load Case B: Leeward Parapet shall consist of
applying the applicable positive wall pressure from
Fig. 30.4-1 (h ≤ 60 ft (18.3 m)) or Fig. 30.6-1 (h >
60 ft (18.3 m)) to the windward surface of the
parapet, and applying the applicable negative wall
pressure from Fig. 30.4-1 (h ≤ 60 ft (18.3 m)) or
Fig. 30.6-1 (h > 60 ft (18.3 m)) as applicable to the
leeward surface. Edge and corner zones shall be
arranged as shown in the applicable fi gures. (GCp)
shall be determined for appropriate roof angle and
effective wind area from the applicable fi gures.
If internal pressure is present, both load cases
should be evaluated under positive and negative
internal pressure.
The steps required for the determination of wind
loads on component and cladding of parapets are
shown in Table 30.9-1.
Table 30.9-1 Steps to Determine C&C Wind
Loads Parapets
Step 1: Determine risk category of building, see
Table 1.5-1
Step 2: Determine the basic wind speed, V, for applicable
risk category, see Figure 26.5-1A, B or C
Step 3: Determine wind load parameters:
➢ Wind directionality factor, Kd , see Section
26.6 and Table 26.6-1
➢ Exposure category B, C or D, see Section 26.7
➢ Topographic factor, Kzt, see Section 26.8 and
Fig. 26.8-1
➢ Enclosure classifi cation, see Section 26.10
➢ Internal pressure coeffi cient, (GCpi), see
Section 26.11 and Table 26.11-1
Step 4: Determine velocity pressure exposure coeffi cient,
Kh, at top of the parapet see Table 30.3-1
Step 5: Determine velocity pressure, qp, at the top of the
parapet using Eq. 30.3-1
Step 6: Determine external pressure coeffi cient for wall
and roof surfaces adjacent to parapet, (GCp)
➢ Walls with h ≤ 60 ft., see Fig. 30.4-1
➢ Flat, gable and hip roofs, see Figs. 30.4-2A to
30.4-2C
➢ Stepped roofs, see Fig. 30.4-3
➢ Multispan gable roofs, see Fig. 30.4-4
➢ Monoslope roofs, see Figs. 30.4-5A and
30.4-5B
➢ Sawtooth roofs, see Fig. 30.4-6
➢ Domed roofs of all heights, see Fig. 30.4-7
➢ Walls and fl at roofs with h > 60 ft., see
Fig. 30.6-1
➢ Arched roofs, see footnote 4 of Fig. 27.4-3
Step 7: Calculate wind pressure, p, using Eq. 30.9-1 on
windward and leeward face of parapet,
considering two load cases (Case A and Case B)
as shown in Fig. 30.9-1.
User Note: Use Part 6 of Chapter 30 for determining
wind pressures for C&C on roof overhangs and parapets
of buildings. These provisions are based on the
Directional Procedure with wind pressures calculated
from the specifi ed equation applicable to each roof
overhang or parapet surface.
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30.10 ROOF OVERHANGS
The design wind pressure for roof overhangs of
enclosed and partially enclosed buildings of all
heights, except enclosed buildings with h ≤ 160 ft
(48.8 m) for which the provisions of Part 4 are used,
shall be determined from the following equation:
p = qh[(GCp) – (GCpi)] (lb/ft2
) (N/m2
) (30.10-1)
where
qh = velocity pressure from Section 30.3.2
evaluated at mean roof height h using
exposure defi ned in Section 26.7.3
(GCp) = external pressure coeffi cients for overhangs
given in Figs. 30.4-2A to 30.4-2C (fl at roofs,
gable roofs, and hip roofs), including
contributions from top and bottom surfaces
of overhang. The external pressure coeffi -
cient for the covering on the underside of the
roof overhang is the same as the external
pressure coeffi cient on the adjacent wall
surface, adjusted for effective wind area,
determined from Figure 30.4-1 or Figure
30.6-1 as applicable
(GCpi) = internal pressure coeffi cient given in Table
26.11-1
The steps required for the determination of wind
loads on components and cladding of roof overhangs
are shown in Table 30.10-1.
Table 30.10-1 Steps to Determine C&C Wind
Loads Roof Overhangs
Step 1: Determine risk category of building, see
Table 1.5-1
Step 2: Determine the basic wind speed, V, for
applicable risk category, see Figure 26.5-1A, B
or C
Step 3: Determine wind load parameters:
➢ Wind directionality factor, Kd , see Section
26.6 and Table 26.6-1
➢ Exposure category B, C or D, see Section
26.7
➢ Topographic factor, Kzt, see Section 26.8 and
Fig. 26.8-1
➢ Enclosure classifi cation, see Section 26.10
➢ Internal pressure coeffi cient, (GCpi), see
Section 26.11 and Table 26.11-1
Step 4: Determine velocity pressure exposure
coeffi cient, Kh, see Table 30.3-1
Step 5: Determine velocity pressure, qh, at mean roof
height h using Eq. 30.3-1
Step 6: Determine external pressure coeffi cient, (GCp),
using Figs. 30.4-2A through C for fl at, gabled
and hip roofs.
Step 7: Calculate wind pressure, p, using Eq. 30.10-1.
Refer to Figure 30.10-1
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334
30.11 ROOFTOP STRUCTURES AND
EQUIPMENT FOR BUILDINGS WITH
h ≤ 60 ft (18.3 m)
The components and cladding pressure on each
wall of the rooftop structure shall be equal to
the lateral force determined in accordance with
Section 29.5.1 divided by the respective wall
surface area of the rooftop structure and shall be
considered to act inward and outward. The components
and cladding pressure on the roof shall be
equal to the vertical uplift force determined in
accordance with Section 29.5.1 divided by the
horizontal projected area of the roof of the rooftop
structure and shall be considered to act in the upward
direction.
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Components and Cladding h ≤ 60 ft.
Figure 30.4-1 External Pressure Coefficients, GCp
Enclosed, Partially Enclosed Buildings Walls
Notes:
1. Vertical scale denotes GCp to be used with qh.
2. Horizontal scale denotes effective wind area, in square feet (square meters).
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. Values of GCp for walls shall be reduced by 10% when θ ≤ 10°.
6. Notation:
a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4%
of least horizontal dimension or 3 ft (0.9 m).
h: Mean roof height, in feet (meters), except that eave height shall be used for θ ≤ 10°.
θ: Angle of plane of roof from horizontal, in degrees.
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Components and Cladding h ≤ 60 ft.
Figure 30.4-2A External Pressure Coefficients, GCp
Enclosed, Partially Enclosed Buildings Gable Roofs θ ≤ 7°
Notes:
1. Vertical scale denotes GCp to be used with qh.
2. Horizontal scale denotes effective wind area, in square feet (square meters).
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. If a parapet equal to or higher than 3 ft (0.9m) is provided around the perimeter of the roof with θ ≤ 7°,
the negative values of GCp in Zone 3 shall be equal to those for Zone 2 and positive values of GCp in
Zones 2 and 3 shall be set equal to those for wall Zones 4 and 5 respectively in Figure 30.4-1.
6. Values of GCp for roof overhangs include pressure contributions from both upper and lower surfaces.
7. Notation:
a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of
least horizontal dimension or 3 ft (0.9 m).
h: Eave height shall be used for θ ≤ 10°.
θ: Angle of plane of roof from horizontal, in degrees.
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Components and Cladding h ≤ 60 ft.
Figure 30.4-2B External Pressure Coefficients, GCp
Enclosed, Partially Enclosed Buildings Gable/Hip Roofs 7°< θ ≤ 27°
Notes:
1. Vertical scale denotes GCp to be used with qh.
2. Horizontal scale denotes effective wind area, in square feet (square meters).
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. Values of GCp for roof overhangs include pressure contributions from both upper and lower surfaces.
6. For hip roofs with 7° < θ ≤ 27°, edge/ridge strips and pressure coefficients for ridges of gabled roofs shall
apply on each hip.
7. For hip roofs with θ ≤ 25°, Zone 3 shall be treated as Zone 2.
8. Notation:
a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of
least horizontal dimension or 3 ft (0.9 m).
h: Mean roof height, in feet (meters), except that eave height shall be used for θ ≤ 10°.
θ: Angle of plane of roof from horizontal, in degrees.
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Components and Cladding h ≤ 60 ft.
Figure 30.4-2C External Pressure Coefficients GCp
Enclosed, Partially Enclosed Buildings Gable Roofs 27°< θ ≤ 45°
Notes:
1. Vertical scale denotes GCp to be used with qh.
2. Horizontal scale denotes effective wind area, in square feet (square meters).
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. Values of GCp for roof overhangs include pressure contributions from both upper and lower surfaces.
6. Notation:
a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of
least horizontal dimension or 3 ft (0.9 m).
h: Mean roof height, in feet (meters).
θ: Angle of plane of roof from horizontal, in degrees.
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Components and Cladding h ≤ 60 ft.
Figure 30.4-3 External Pressure Coefficients, GCp
Enclosed, Partially Enclosed Buildings Stepped Roofs
Notes:
1. On the lower level of flat, stepped roofs shown in Fig. 30.4-3, the zone designations and pressure
coefficients shown in Fig. 30.4-2A shall apply, except that at the roof-upper wall intersection(s),
Zone 3 shall be treated as Zone 2 and Zone 2 shall be treated as Zone 1. Positive values of GCp
equal to those for walls in Fig. 30.4-1 shall apply on the cross-hatched areas shown in Fig. 30.4-3.
2. Notation:
b: 1.5h1 in Fig. 30.4-3, but not greater than 100 ft (30.5 m).
h: Mean roof height, in feet (meters).
hi: h1 or h2 in Fig. 30.4-3; h = h1 + h2; h1 ≥ 10 ft (3.1 m); hi/h = 0.3 to 0.7.
W: Building width in Fig. 30.4-3.
Wi: W1 or W2 or W3 in Fig. 30.4-3. W = W1 + W2 or W1 + W2 + W3; Wi/W = 0.25 to 0.75.
θ: Angle of plane of roof from horizontal, in degrees.
0.25 to 0.75
0.3 to 0.7
100 ft.(30.5 m)
1.5 h
10 ft.(3m)
1
1
=
=
<
=

W
W
h
h
b
b
h
i
i
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340
Components and Cladding h ≤ 60 ft.
Figure 30.4-4 External Pressure Coefficients, GCp
Enclosed, Partially Enclosed Buildings Multispan Gable Roofs
Notes:
1. Vertical scale denotes GCp to be used with qh.
2. Horizontal scale denotes effective wind area A, in square feet (square meters).
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. For θ ≤ 10°, values of GCp from Fig. 30.4-2A shall be used.
6. Notation:
a: 10 percent of least horizontal dimension of a single-span module or 0.4h, whichever is
smaller, but not less than either 4 percent of least horizontal dimension of a single-span
module or 3 ft (0.9 m).
h: Mean roof height, in feet (meters), except that eave height shall be used for θ ≤ 10°.
W: Building module width, in feet (meters).
θ: Angle of plane of roof from horizontal, in degrees.
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Components and Cladding h ≤ 60 ft.
Figure 30.4-5A External Pressure Coefficients, GCp
Enclosed, Partially Enclosed Buildings
Monoslope Roofs
3°< θ ≤ 10°
Notes:
1. Vertical scale denotes GCp to be used with qh.
2. Horizontal scale denotes effective wind area A, in square feet (square meters).
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. For θ ≤ 3°, values of GCp from Fig. 30.4-2A shall be used.
6. Notation:
a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than
either 4 percent of least horizontal dimension or 3 ft (0.9 m).
h: Eave height shall be used for θ ≤ 10°.
W: Building width, in feet (meters).
θ: Angle of plane of roof from horizontal, in degrees.
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Components and Cladding h ≤ 60 ft.
Figure 30.4-5B External Pressure Coefficients, GCp
Enclosed, Partially Enclosed Buildings
Monoslope Roofs
10°< θ ≤ 30°
Notes:
1. Vertical scale denotes GCp to be used with qh.
2. Horizontal scale denotes effective wind area A, in square feet (square meters).
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. Notation:
a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than
either 4 percent of least horizontal dimension or 3 ft (0.9 m).
h: Mean roof height, in feet (meters).
W: Building width, in feet (meters).
θ: Angle of plane of roof from horizontal, in degrees.
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Components and Cladding h ≤ 60 ft.
Figure 30.4-6 External Pressure Coefficients, GCp
Enclosed, Partially Enclosed Buildings Sawtooth Roofs
Notes:
1. Vertical scale denotes GCp to be used with qh.
2. Horizontal scale denotes effective wind area A, in square feet (square meters).
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Each component shall be designed for maximum positive and negative pressures.
5. For θ ≤ 10°, values of GCp from Fig. 30.4-2A shall be used.
6. Notation:
a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either
4 percent of least horizontal dimension or 3 ft (0.9 m).
h: Mean roof height, in feet (meters), except that eave height shall be used for θ ≤ 10°.
W: Building module width, in feet (meters).
θ: Angle of plane of roof from horizontal, in degrees.
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Components and Cladding All Heights
Figure 30.4-7 External Pressure Coefficients, GCp
Enclosed, Partially Enclosed Buildings and Structures Domed Roofs
D
h
f
Wind
Wind
External Pressure Coefficients for Domes with a Circular Base
Negative
Pressures
Positive
Pressures
Positive
Pressures
θ, degrees 0 – 90 0 – 60 61 – 90
GCp -0.9 +0.9 +0.5
Notes:
1. Values denote GCp to be used with q(hD+f) where hD + f is the height at the top of the dome.
2. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
3. Each component shall be designed for the maximum positive and negative pressures.
4. Values apply to 0 ≤ hD/D ≤ 0.5, 0.2 ≤ f/D ≤ 0.5.
5. θ = 0 degrees on dome springline, θ = 90 degrees at dome center top point. f is measured from
springline to top.
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Components and Cladding – Method 1 h ≤ 60 ft.
Figure30.5-1 Design Wind Pressures
Enclosed Buildings Walls & Roofs
Notes:
1. Pressures shown are applied normal to the surface, for exposure B, at h=30 ft (9.1m). Adjust to other conditions using Equation
30.5-1.
2. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
3. For hip roofs with θ ≤ 25°, Zone 3 shall be treated as Zone 2.
4. For effective wind areas between those given, value may be interpolated, otherwise use the value associated with the lower
effective wind area.
5. Notation:
a: 10 percent of least horizontal dimension or 0.4h, whichever is smaller, but not less than either 4% of least horizontal dimension
or 3 ft (0.9 m).
h: Mean roof height, in feet (meters), except that eave height shall be used for roof angles <10°.
θ: Angle of plane of roof from horizontal, in degrees.
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IP Zone Basic Wind Speed V (mph)
0.18 110 115 120 130 140 150 160 180 200
1 10 8.9 -21.8 9.7 -23.8 10.5 -25.9 12.4 -30.4 14.3 -35.3 16.5 -40.5 18.7 -46.1 23.7 -58.3 29.3 -72.0
1 20 8.3 -21.2 9.1 -23.2 9.9 -25.2 11.6 -29.6 13.4 -34.4 15.4 -39.4 17.6 -44.9 22.2 -56.8 27.4 -70.1
1 50 7.6 -20.5 8.3 -22.4 9.0 -24.4 10.6 -28.6 12.3 -33.2 14.1 -38.1 16.0 -43.3 20.3 -54.8 25.0 -67.7
1 100 7.0 -19.9 7.7 -21.8 8.3 -23.7 9.8 -27.8 11.4 -32.3 13.0 -37.0 14.8 -42.1 18.8 -53.3 23.2 -65.9
2 10 8.9 -36.5 9.7 -39.9 10.5 -43.5 12.4 -51.0 14.3 -59.2 16.5 -67.9 18.7 -77.3 23.7 -97.8 29.3 -120.7
2 20 8.3 -32.6 9.1 -35.7 9.9 -38.8 11.6 -45.6 13.4 -52.9 15.4 -60.7 17.6 -69.0 22.2 -87.4 27.4 -107.9
2 50 7.6 -27.5 8.3 -30.1 9.0 -32.7 10.6 -38.4 12.3 -44.5 14.1 -51.1 16.0 -58.2 20.3 -73.6 25.0 -90.9
2 100 7.0 -23.6 7.7 -25.8 8.3 -28.1 9.8 -33.0 11.4 -38.2 13.0 -43.9 14.8 -50.0 18.8 -63.2 23.2 -78.1
3 10 8.9 -55.0 9.7 -60.1 10.5 -65.4 12.4 -76.8 14.3 -89.0 16.5 -102.2 18.7 -116.3 23.7 -147.2 29.3 -181.7
3 20 8.3 -45.5 9.1 -49.8 9.9 -54.2 11.6 -63.6 13.4 -73.8 15.4 -84.7 17.6 -96.3 22.2 -121.9 27.4 -150.5
3 50 7.6 -33.1 8.3 -36.1 9.0 -39.3 10.6 -46.2 12.3 -53.5 14.1 -61.5 16.0 -69.9 20.3 -88.5 25.0 -109.3
3 100 7.0 -23.6 7.7 -25.8 8.3 -28.1 9.8 -33.0 11.4 -38.2 13.0 -43.9 14.8 -50.0 18.8 -63.2 23.2 -78.1
1 10 12.5 -19.9 13.7 -21.8 14.9 -23.7 17.5 -27.8 20.3 -32.3 23.3 -37.0 26.5 -42.1 33.6 -53.3 41.5 -65.9
1 20 11.4 -19.4 12.5 -21.2 13.6 -23.0 16.0 -27.0 18.5 -31.4 21.3 -36.0 24.2 -41.0 30.6 -51.9 37.8 -64.0
1 50 10.0 -18.6 10.9 -20.4 11.9 -22.2 13.9 -26.0 16.1 -30.2 18.5 -34.6 21.1 -39.4 26.7 -49.9 32.9 -61.6
1 100 8.9 -18.1 9.7 -19.8 10.5 -21.5 12.4 -25.2 14.3 -29.3 16.5 -33.6 18.7 -38.2 23.7 -48.4 29.3 -59.8
2 10 12.5 -34.7 13.7 -37.9 14.9 -41.3 17.5 -48.4 20.3 -56.2 23.3 -64.5 26.5 -73.4 33.6 -92.9 41.5 -114.6
2 20 11.4 -31.9 12.5 -34.9 13.6 -38.0 16.0 -44.6 18.5 -51.7 21.3 -59.3 24.2 -67.5 30.6 -85.4 37.8 -105.5
2 50 10.0 -28.2 10.9 -30.9 11.9 -33.6 13.9 -39.4 16.1 -45.7 18.5 -52.5 21.1 -59.7 26.7 -75.6 32.9 -93.3
2 100 8.9 -25.5 9.7 -27.8 10.5 -30.3 12.4 -35.6 14.3 -41.2 16.5 -47.3 18.7 -53.9 23.7 -68.2 29.3 -84.2
3 10 12.5 -51.3 13.7 -56.0 14.9 -61.0 17.5 -71.6 20.3 -83.1 23.3 -95.4 26.5 -108.5 33.6 -137.3 41.5 -169.5
3 20 11.4 -47.9 12.5 -52.4 13.6 -57.1 16.0 -67.0 18.5 -77.7 21.3 -89.2 24.2 -101.4 30.6 -128.4 37.8 -158.5
3 50 10.0 -43.5 10.9 -47.6 11.9 -51.8 13.9 -60.8 16.1 -70.5 18.5 -81.0 21.1 -92.1 26.7 -116.6 32.9 -143.9
3 100 8.9 -40.2 9.7 -44.0 10.5 -47.9 12.4 -56.2 14.3 -65.1 16.5 -74.8 18.7 -85.1 23.7 -107.7 29.3 -132.9
1 10 19.9 -21.8 21.8 -23.8 23.7 -25.9 27.8 -30.4 32.3 -35.3 37.0 -40.5 42.1 -46.1 53.3 -58.3 65.9 -72.0
1 20 19.4 -20.7 21.2 -22.6 23.0 -24.6 27.0 -28.9 31.4 -33.5 36.0 -38.4 41.0 -43.7 51.9 -55.3 64.0 -68.3
1 50 18.6 -19.2 20.4 -21.0 22.2 -22.8 26.0 -26.8 30.2 -31.1 34.6 -35.7 39.4 -40.6 49.9 -51.4 61.6 -63.4
1 100 18.1 -18.1 19.8 -19.8 21.5 -21.5 25.2 -25.2 29.3 -29.3 33.6 -33.6 38.2 -38.2 48.4 -48.4 59.8 -59.8
2 10 19.9 -25.5 21.8 -27.8 23.7 -30.3 27.8 -35.6 32.3 -41.2 37.0 -47.3 42.1 -53.9 53.3 -68.2 65.9 -84.2
2 20 19.4 -24.3 21.2 -26.6 23.0 -29.0 27.0 -34.0 31.4 -39.4 36.0 -45.3 41.0 -51.5 51.9 -65.2 64.0 -80.5
2 50 18.6 -22.9 20.4 -25.0 22.2 -27.2 26.0 -32.0 30.2 -37.1 34.6 -42.5 39.4 -48.4 49.9 -61.3 61.6 -75.6
2 100 18.1 -21.8 19.8 -23.8 21.5 -25.9 25.2 -30.4 29.3 -35.3 33.6 -40.5 38.2 -46.1 48.4 -58.3 59.8 -72.0
3 10 19.9 -25.5 21.8 -27.8 23.7 -30.3 27.8 -35.6 32.3 -41.2 37.0 -47.3 42.1 -53.9 53.3 -68.2 65.9 -84.2
3 20 19.4 -24.3 21.2 -26.6 23.0 -29.0 27.0 -34.0 31.4 -39.4 36.0 -45.3 41.0 -51.5 51.9 -65.2 64.0 -80.5
3 50 18.6 -22.9 20.4 -25.0 22.2 -27.2 26.0 -32.0 30.2 -37.1 34.6 -42.5 39.4 -48.4 49.9 -61.3 61.6 -75.6
3 100 18.1 -21.8 19.8 -23.8 21.5 -25.9 25.2 -30.4 29.3 -35.3 33.6 -40.5 38.2 -46.1 48.4 -58.3 59.8 -72.0
4 10 21.8 -23.6 23.8 -25.8 25.9 -28.1 30.4 -33.0 35.3 -38.2 40.5 -43.9 46.1 -50.0 58.3 -63.2 72.0 -78.1
4 20 20.8 -22.6 22.7 -24.7 24.7 -26.9 29.0 -31.6 33.7 -36.7 38.7 -42.1 44.0 -47.9 55.7 -60.6 68.7 -74.8
4 50 19.5 -21.3 21.3 -23.3 23.2 -25.4 27.2 -29.8 31.6 -34.6 36.2 -39.7 41.2 -45.1 52.2 -57.1 64.4 -70.5
4 100 18.5 -20.4 20.2 -22.2 22.0 -24.2 25.9 -28.4 30.0 -33.0 34.4 -37.8 39.2 -43.1 49.6 -54.5 61.2 -67.3
4 500 16.2 -18.1 17.7 -19.8 19.3 -21.5 22.7 -25.2 26.3 -29.3 30.2 -33.6 34.3 -38.2 43.5 -48.4 53.7 -59.8
5 10 21.8 -29.1 23.8 -31.9 25.9 -34.7 30.4 -40.7 35.3 -47.2 40.5 -54.2 46.1 -61.7 58.3 -78.0 72.0 -96.3
5 20 20.8 -27.2 22.7 -29.7 24.7 -32.4 29.0 -38.0 33.7 -44.0 38.7 -50.5 44.0 -57.5 55.7 -72.8 68.7 -89.9
5 50 19.5 -24.6 21.3 -26.9 23.2 -29.3 27.2 -34.3 31.6 -39.8 36.2 -45.7 41.2 -52.0 52.2 -65.8 64.4 -81.3
5 100 18.5 -22.6 20.2 -24.7 22.0 -26.9 25.9 -31.6 30.0 -36.7 34.4 -42.1 39.2 -47.9 49.6 -60.6 61.2 -74.8
5 500 16.2 -18.1 17.7 -19.8 19.3 -21.5 22.7 -25.2 26.3 -29.3 30.2 -33.6 34.3 -38.2 43.5 -48.4 53.7 -59.8
Note: For effective areas between the those given above the load may be interpolated, otherwise use the load associated with the lower effective area.
The final value, including all permitted reductions, used in the design shll not be less than that required by Section 30.2.2.
Net Design Wind Pressure, pnet30 (psf) (Exposure B at h = 30 ft.)
Components and Cladding – Method 1 h ≤ 60 ft.
Figure 30.5-1 (cont’d) Design Wind Pressures
Enclosed Buildings Walls & Roofs
Unit Conversions – 1.0 ft = 0.3048 m; 1.0 sf = 0.0929 m2
; 1.0 psf = 0.0479 kN/m2
Effective
wind area
(sf)
Roof > 27 to 45 degrees Wall Roof 0 to 7 degrees Roof > 7 to 27 degrees
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Components and Cladding – Method 1 h ≤ 60 ft.
Figure 30.5-1 (cont’d) Design Wind Pressures
Enclosed Buildings Walls & Roofs
Unit Conversions – 1.0 ft = 0.3048 m; 1.0 sf = 0.0929 m2
; 1.0 psf = 0.0479 kN/m2
Basic Wind Speed V (mph)
110 115 130 140 150 160 180 200
2 10 -31.4 -34.3 -43.8 -50.8 -58.3 -66.3 -84.0 -103.7
2 20 -30.8 -33.7 -43.0 -49.9 -57.3 -65.2 -82.5 -101.8
2 50 -30.1 -32.9 -42.0 -48.7 -55.9 -63.6 -80.5 -99.4
2 100 -29.5 -32.3 -41.2 -47.8 -54.9 -62.4 -79.0 -97.6
3 10 -51.6 -56.5 -72.1 -83.7 -96.0 -109.3 -138.3 -170.7
3 20 -40.5 -44.3 -56.6 -65.7 -75.4 -85.8 -108.6 -134.0
3 50 -25.9 -28.3 -36.1 -41.9 -48.1 -54.7 -69.3 -85.5
3 100 -14.8 -16.1 -20.6 -23.9 -27.4 -31.2 -39.5 -48.8
2 10 -40.6 -44.4 -56.7 -65.7 -75.5 -85.9 -108.7 -134.2
2 20 -40.6 -44.4 -56.7 -65.7 -75.5 -85.9 -108.7 -134.2
2 50 -40.6 -44.4 -56.7 -65.7 -75.5 -85.9 -108.7 -134.2
2 100 -40.6 -44.4 -56.7 -65.7 -75.5 -85.9 -108.7 -134.2
3 10 -68.3 -74.6 -95.3 -110.6 -126.9 -144.4 -182.8 -225.6
3 20 -61.6 -67.3 -86.0 -99.8 -114.5 -130.3 -164.9 -203.6
3 50 -52.8 -57.7 -73.7 -85.5 -98.1 -111.7 -141.3 -174.5
3 100 -46.1 -50.4 -64.4 -74.7 -85.8 -97.6 -123.5 -152.4
2 10 -36.9 -40.3 -51.5 -59.8 -68.6 -78.1 -98.8 -122.0
2 20 -35.8 -39.1 -50.0 -58.0 -66.5 -75.7 -95.8 -118.3
2 50 -34.3 -37.5 -47.9 -55.6 -63.8 -72.6 -91.9 -113.4
2 100 -33.2 -36.3 -46.4 -53.8 -61.7 -70.2 -88.9 -109.8
3 10 -36.9 -40.3 -51.5 -59.8 -68.6 -78.1 -98.8 -122.0
3 20 -35.8 -39.1 -50.0 -58.0 -66.5 -75.7 -95.8 -118.3
3 50 -34.3 -37.5 -47.9 -55.6 -63.8 -72.6 -91.9 -113.4
3 100 -33.2 -36.3 -46.4 -53.8 -61.7 -70.2 -88.9 -109.8
Roof Overhang Net Design Wind Pressure , pnet30 (psf)
Roof 0 to 7 degrees Roof > 7 to 27 degrees Roof > 27 to 45 degrees
Zone
Effective
Wind Area
(sf)
(Exposure B at h = 30 ft.)
Exposure
BCD
15 1.00 1.21 1.47
20 1.00 1.29 1.55
25 1.00 1.35 1.61
30 1.00 1.40 1.66
35 1.05 1.45 1.70
40 1.09 1.49 1.74
45 1.12 1.53 1.78
50 1.16 1.56 1.81
55 1.19 1.59 1.84
60 1.22 1.62 1.87
for Building Height and Exposure, l
Adjustment Factor
Mean roof
height (ft)
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Components and Cladding h > 60 ft.
Figure 30.6-1 External Pressure Coefficients, GCp
Enclosed, Partially Enclosed Buildings Walls & Roofs
Notes:
1. Vertical scale denotes GCp to be used with appropriate qz or qh.
2. Horizontal scale denotes effective wind area A, in square feet (square meters).
3. Plus and minus signs signify pressures acting toward and away from the surfaces, respectively.
4. Use qz with positive values of GCp and qh with negative values of GCp.
5. Each component shall be designed for maximum positive and negative pressures.
6. Coefficients are for roofs with angle θ ≤ 10°. For other roof angles and geometry, use GCp values
from Fig. 30.4-2A, B and C and attendant qh based on exposure defined in Section 26.7.
7. If a parapet equal to or higher than 3 ft (0.9m) is provided around the perimeter of the roof with θ ≤
10°, Zone 3 shall be treated as Zone 2.
8. Notation:
a: 10 percent of least horizontal dimension, but not less than 3 ft (0.9 m).
h: Mean roof height, in feet (meters), except that eave height shall be used for θ ≤ 10°.
z: height above ground, in feet (meters).
θ: Angle of plane of roof from horizontal, in degrees.
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Components and Cladding – Part 4 h £ 160 ft.
Figure 30.7-1 Parapet Wind Loads
Enclosed Simple Diaphragm Building
Application of Parapet Wind
Loads
Windward Parapet
Load Case A
1. Windward parapet pressure (p1) is determined using the positive wall pressure (p5) zones 4 or 5 from
Table 30.7-2.
Leeward parapet pressure (p2) is determined using the negative roof pressure (p7) zones 2 or 3 from Table
30.7-2.
Leeward Parapet
Load Case B
1. Windward parapet pressure (p3) is determined using the positive wall pressure (p5) zones 4 or 5 from
Table 30.7-2.
2. Leeward parapet pressure (p4) is determined using the negative wall pressure (p6) zones 4 or 5 from Table
30.7-2.
p1
p5
p2 p3
p7
p4
p6
Windward parapet
Load Case A
Leeward parapet
Load Case B Top of parapet
hp
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Components and Cladding – Part 4 h £ 160 ft.
Figure 30.7-2 Roof Overhang Wind Loads
Enclosed Simple Diaphragm Building
Application of Overhang Wind
Loads

povh
ps
pw
povh = 1.0 x roof pressure p from tables for edge Zones 1, 2
povh = 1.15 x roof pressure p from tables for corner Zone 3
Notes:
1. povh = roof pressure at overhang for edge or corner zone as applicable
from figures in roof pressure table.
2. povh from figures includes load from both top and bottom surface of
overhang.
3. Pressure ps at soffit of overhang can be assumed same as wall pressure pw.
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Components and Cladding 0.25 £ h/L £ 1.0
Figure 30.8-1 Net Pressure Coefficient, CN
Open Buildings
Monoslope Free Roofs
q £ 45°
Roof Effective
Angle Wind Area
θ
< a2 2.4 -3.3 1.8 -1.7 1.2 -1.1 1 -3.6 0.8 -1.8 0.5 -1.2
> a2
, < 4.0a2 1.8 -1.7 1.8 -1.7 1.2 -1.1 0.8 -1.8 0.8 -1.8 0.5 -1.2
> 4.0a2 1.2 -1.1 1.2 -1.1 1.2 -1.1 0.5 -1.2 0.5 -1.2 0.5 -1.2
< a2 3.2 -4.2 2.4 -2.1 1.6 -1.4 1.6 -5.1 1.2 -2.6 0.8 -1.7
> a2
, < 4.0a2 2.4 -2.1 2.4 -2.1 1.6 -1.4 1.2 -2.6 1.2 -2.6 0.8 -1.7
> 4.0a2 1.6 -1.4 1.6 -1.4 1.6 -1.4 0.8 -1.7 0.8 -1.7 0.8 -1.7
< a2 3.6 -3.8 2.7 -2.9 1.8 -1.9 2.4 -4.2 1.8 -3.2 1.2 -2.1
> a2
, < 4.0a2 2.7 -2.9 2.7 -2.9 1.8 -1.9 1.8 -3.2 1.8 -3.2 1.2 -2.1
> 4.0a2 1.8 -1.9 1.8 -1.9 1.8 -1.9 1.2 -2.1 1.2 -2.1 1.2 -2.1
< a2 5.2 -5 3.9 -3.8 2.6 -2.5 3.2 -4.6 2.4 -3.5 1.6 -2.3
> a2
, < 4.0a2 3.9 -3.8 3.9 -3.8 2.6 -2.5 2.4 -3.5 2.4 -3.5 1.6 -2.3
> 4.0a2 2.6 -2.5 2.6 -2.5 2.6 -2.5 1.6 -2.3 1.6 -2.3 1.6 -2.3
< a2 5.2 -4.6 3.9 -3.5 2.6 -2.3 4.2 -3.8 3.2 -2.9 2.1 -1.9
> a2
, < 4.0a2 3.9 -3.5 3.9 -3.5 2.6 -2.3 3.2 -2.9 3.2 -2.9 2.1 -1.9
> 4.0a2 2.6 -2.3 2.6 -2.3 2.6 -2.3 2.1 -1.9 2.1 -1.9 2.1 -1.9
CN
Clear Wind Flow Obstructed Wind Flow
Zone 3 Zone 2 Zone 1 Zone 3 Zone 2 Zone 1
45o
0
o
7.5o
15o
30o
Notes:
1. CN denotes net pressures (contributions from top and bottom surfaces).
2. Clear wind flow denotes relatively unobstructed wind flow with blockage less than or equal to 50%. Obstructed
wind flow denotes objects below roof inhibiting wind flow (>50% blockage).
3. For values of θ other than those shown, linear interpolation is permitted.
4. Plus and minus signs signify pressures acting towards and away from the top roof surface, respectively.
5. Components and cladding elements shall be designed for positive and negative pressure coefficients shown.
6. Notation:
a : 10% of least horizontal dimension or 0.4h, whichever is smaller but not less than 4% of least horizontal
dimension or 3 ft. (0.9 m)
h : mean roof height, ft. (m)
L : horizontal dimension of building, measured in along wind direction, ft. (m)
θ : angle of plane of roof from horizontal, degrees
3
3
1
2
2
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Components and Cladding 0.25 £ h/L £ 1.0
Figure 30.8-2 Net Pressure Coefficient, CN
Open Buildings
Pitched Free Roofs
q £ 45°
Roof Effective
Angle Wind Area
θ
< a2 2.4 -3.3 1.8 -1.7 1.2 -1.1 1 -3.6 0.8 -1.8 0.5 -1.2
> a2
, < 4.0a2 1.8 -1.7 1.8 -1.7 1.2 -1.1 0.8 -1.8 0.8 -1.8 0.5 -1.2
> 4.0a2 1.2 -1.1 1.2 -1.1 1.2 -1.1 0.5 -1.2 0.5 -1.2 0.5 -1.2
< a2 2.2 -3.6 1.7 -1.8 1.1 -1.2 1 -5.1 0.8 -2.6 0.5 -1.7
> a2
, < 4.0a2 1.7 -1.8 1.7 -1.8 1.1 -1.2 0.8 -2.6 0.8 -2.6 0.5 -1.7
> 4.0a2 1.1 -1.2 1.1 -1.2 1.1 -1.2 0.5 -1.7 0.5 -1.7 0.5 -1.7
< a2 2.2 -2.2 1.7 -1.7 1.1 -1.1 1 -3.2 0.8 -2.4 0.5 -1.6
> a2
, < 4.0a2 1.7 -1.7 1.7 -1.7 1.1 -1.1 0.8 -2.4 0.8 -2.4 0.5 -1.6
> 4.0a2 1.1 -1.1 1.1 -1.1 1.1 -1.1 0.5 -1.6 0.5 -1.6 0.5 -1.6
< a2 2.6 -1.8 2 -1.4 1.3 -0.9 1 -2.4 0.8 -1.8 0.5 -1.2
> a2
, < 4.0a2 2 -1.4 2 -1.4 1.3 -0.9 0.8 -1.8 0.8 -1.8 0.5 -1.2
> 4.0a2 1.3 -0.9 1.3 -0.9 1.3 -0.9 0.5 -1.2 0.5 -1.2 0.5 -1.2
< a2 2.2 -1.6 1.7 -1.2 1.1 -0.8 1 -2.4 0.8 -1.8 0.5 -1.2
> a2
, < 4.0a2 1.7 -1.2 1.7 -1.2 1.1 -0.8 0.8 -1.8 0.8 -1.8 0.5 -1.2
> 4.0a2 1.1 -0.8 1.1 -0.8 1.1 -0.8 0.5 -1.2 0.5 -1.2 0.5 -1.2
CN
Clear Wind Flow Obstructed Wind Flow
Zone 3 Zone 2 Zone 1 Zone 3 Zone 2 Zone 1
45o
0
o
7.5o
15o
30o
2
Notes:
1. CN denotes net pressures (contributions from top and bottom surfaces).
2. Clear wind flow denotes relatively unobstructed wind flow with blockage less than or equal to 50%.
Obstructed wind flow denotes objects below roof inhibiting wind flow (>50% blockage).
3. For values of θ other than those shown, linear interpolation is permitted.
4. Plus and minus signs signify pressures acting towards and away from the top roof surface, respectively.
5. Components and cladding elements shall be designed for positive and negative pressure coefficients shown.
6. Notation:
a : 10% of least horizontal dimension or 0.4h, whichever is smaller but not less than 4% of least horizontal
dimension or 3 ft. (0.9 m). Dimension “a” is as shown in Fig. 30.8-1.
h : mean roof height, ft. (m)
L : horizontal dimension of building, measured in along wind direction, ft. (m)
θ : angle of plane of roof from horizontal, degrees
3
3
2
2
1 1
2 2
1 1
3 3
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MINIMUM DESIGN LOADS
353
£ £
q £
Components and Cladding 0.25 h/L 1.0
Figure 30.8-3 Net Pressure Coefficient, CN
Open Buildings
Troughed Free Roofs
45°
Roof Effective
Angle Wind Area
θ
< a2 2.4 -3.3 1.8 -1.7 1.2 -1.1 1 -3.6 0.8 -1.8 0.5 -1.2
> a2
, < 4.0a2 1.8 -1.7 1.8 -1.7 1.2 -1.1 0.8 -1.8 0.8 -1.8 0.5 -1.2
> 4.0a2 1.2 -1.1 1.2 -1.1 1.2 -1.1 0.5 -1.2 0.5 -1.2 0.5 -1.2
< a2 2.4 -3.3 1.8 -1.7 1.2 -1.1 1 -4.8 0.8 -2.4 0.5 -1.6
> a2
, < 4.0a2 1.8 -1.7 1.8 -1.7 1.2 -1.1 0.8 -2.4 0.8 -2.4 0.5 -1.6
> 4.0a2 1.2 -1.1 1.2 -1.1 1.2 -1.1 0.5 -1.6 0.5 -1.6 0.5 -1.6
< a2 2.2 -2.2 1.7 -1.7 1.1 -1.1 1 -2.4 0.8 -1.8 0.5 -1.2
> a2
, < 4.0a2 1.7 -1.7 1.7 -1.7 1.1 -1.1 0.8 -1.8 0.8 -1.8 0.5 -1.2
> 4.0a2 1.1 -1.1 1.1 -1.1 1.1 -1.1 0.5 -1.2 0.5 -1.2 0.5 -1.2
< a2 1.8 -2.6 1.4 -2 0.9 -1.3 1 -2.8 0.8 -2.1 0.5 -1.4
> a2
, < 4.0a2 1.4 -2 1.4 -2 0.9 -1.3 0.8 -2.1 0.8 -2.1 0.5 -1.4
> 4.0a2 0.9 -1.3 0.9 -1.3 0.9 -1.3 0.5 -1.4 0.5 -1.4 0.5 -1.4
< a2 1.6 -2.2 1.2 -1.7 0.8 -1.1 1 -2.4 0.8 -1.8 0.5 -1.2
> a2
, < 4.0a2 1.2 -1.7 1.2 -1.7 0.8 -1.1 0.8 -1.8 0.8 -1.8 0.5 -1.2
> 4.0a2 0.8 -1.1 0.8 -1.1 0.8 -1.1 0.5 -1.2 0.5 -1.2 0.5 -1.2
CN
Clear Wind Flow Obstructed Wind Flow
Zone 3 Zone 2 Zone 1 Zone 3 Zone 2 Zone 1
45o
0
o
7.5o
15o
30o
3
3
2
2
1 1 2
2
1 1
3
3
Notes:
1. CN denotes net pressures (contributions from top and bottom surfaces).
2. Clear wind flow denotes relatively unobstructed wind flow with blockage less than or equal to 50%.
Obstructed wind flow denotes objects below roof inhibiting wind flow (>50% blockage).
3. For values of θ other than those shown, linear interpolation is permitted.
4. Plus and minus signs signify pressures acting towards and away from the top roof surface, respectively.
5. Components and cladding elements shall be designed for positive and negative pressure coefficients shown.
6. Notation:
a : 10% of least horizontal dimension or 0.4h, whichever is smaller but not less than 4% of least horizontal
dimension or 3 ft. (0.9 m). Dimension “a” is as shown in Fig. 30.8-1.
h : mean roof height, ft. (m)
L : horizontal dimension of building, measured in along wind direction, ft. (m)
θ : angle of plane of roof from horizontal, degrees
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CHAPTER 30 WIND LOADS – COMPONENTS AND CLADDING
354
Components and Cladding – Part 6 All Building Heights
Figure 30.9-1 Parapet Wind Loads
All Building Types
C & C
Parapet Wind Loads
Windward Parapet
Load Case A
1. Windward parapet pressure (p1) is determined using the positive wall pressure (p5) zones 4 or 5 from the
applicable figure.
2. Leeward parapet pressure (p2) is determined using the negative roof pressure (p7) zones 2 or 3 from the
applicable figure.
Leeward Parapet
Load Case B
1. Windward parapet pressure (p3) is determined using the positive wall pressure (p5) zones 4 or 5 from the
applicable figure.
2. Leeward parapet pressure (p4) is determined using the negative wall pressure (p6) zones 4 or 5 from the
applicable figure.
p1
p5
p2 p3
p7
p4
p6
Windward parapet
Load Case A
Leeward parapet
Load Case B Top of parapet
hp
User Note: See Note 5 in Fig. 30.4-2A
and Note 7 in Fig. 30.6-1 for reductions in
component and cladding roof pressures
when parapets 3 ft or higher are present.
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355
Components and Cladding All Building Heights
Figure 30.10-1 Wind Loading – Roof Overhangs
All Building Types
C & C
Wind Load on Roof Overhangs
Notes:
1. Net roof pressure povh on roof overhangs is determined from interior, edge or corner zones
as applicable from figures.
2. Net pressure povh from figures includes pressure contribution from top and bottom surfaces
of roof overhang.
3. Positive pressure at roof overhang soffit ps is the same as adjacent wall pressure pw.
povh
ps
pw
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357
Chapter 31
WIND TUNNEL PROCEDURE
percent of the test section cross-sectional area
unless correction is made for blockage.
5. The longitudinal pressure gradient in the wind
tunnel test section is accounted for.
6. Reynolds number effects on pressures and forces
are minimized.
7. Response characteristics of the wind tunnel
instrumentation are consistent with the required
measurements.
31.3 DYNAMIC RESPONSE
Tests for the purpose of determining the dynamic
response of a building or other structure shall be in
accordance with Section 31.2. The structural model
and associated analysis shall account for mass
distribution, stiffness, and damping.
31.4 LOAD EFFECTS
31.4.1 Mean Recurrence Intervals of Load Effects
The load effect required for Strength Design shall
be determined for the same mean recurrence interval
as for the Analytical Method, by using a rational
analysis method, defi ned in the recognized literature,
for combining the directional wind tunnel data with
the directional meteorological data or probabilistic
models based thereon. The load effect required for
Allowable Stress Design shall be equal to the load
effect required for Strength Design divided by 1.6.
For buildings that are sensitive to possible variations
in the values of the dynamic parameters, sensitivity
studies shall be required to provide a rational basis for
design recommendations.
31.4.2 Limitations on Wind Speeds
The wind speeds and probabilistic estimates
based thereon shall be subject to the limitations
described in Section 26.5.3.
31.4.3 Limitations on Loads
Loads for the main wind force resisting system
determined by wind tunnel testing shall be limited
such that the overall principal loads in the x and y
directions are not less than 80 percent of those that
would be obtained from Part 1 of Chapter 27 or Part 1
31.1 SCOPE
The Wind Tunnel Procedure shall be used where
required by Sections 27.1.3, 28.1.3, and 29.1.3. The
Wind Tunnel Procedure shall be permitted for any
building or structure in lieu of the design procedures
specifi ed in Chapter 27 (MWFRS for buildings of all
heights and simple diaphragm buildings with h ≤ 160
ft (48.8 m)), Chapter 28 (MWFRS of low-rise
buildings and simple diaphragm low-rise buildings),
Chapter 29 (MWFRS for all other structures), and
Chapter 30 (components and cladding for all building
types and other structures).
User Note: Chapter 31 may always be used for
determining wind pressures for the MWFRS and/or for
C&C of any building or structure. This method is
considered to produce the most accurate wind pressures
of any method specifi ed in this Standard.
31.2 TEST CONDITIONS
Wind tunnel tests, or similar tests employing fl uids
other than air, used for the determination of design
wind loads for any building or other structure, shall
be conducted in accordance with this section. Tests
for the determination of mean and fl uctuating forces
and pressures shall meet all of the following
conditions:
1. The natural atmospheric boundary layer has been
modeled to account for the variation of wind speed
with height.
2. The relevant macro- (integral) length and microlength
scales of the longitudinal component of
atmospheric turbulence are modeled to approximately
the same scale as that used to model the
building or structure.
3. The modeled building or other structure and
surrounding structures and topography are geometrically
similar to their full-scale counterparts,
except that, for low-rise buildings meeting the
requirements of Section 28.1.2, tests shall be
permitted for the modeled building in a single
exposure site as defi ned in Section 26.7.3.
4. The projected area of the modeled building or
other structure and surroundings is less than 8
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CHAPTER 31 WIND TUNNEL PROCEDURE
358
of Chapter 28. The overall principal load shall be
based on the overturning moment for fl exible buildings
and the base shear for other buildings.
Pressures for components and cladding determined
by wind tunnel testing shall be limited to not
less than 80 percent of those calculated for Zone 4 for
walls and Zone 1 for roofs using the procedure of
Chapter 30. These Zones refer to those shown in
Figs. 30.4-1, 30.4-2A, 30.4-2B, 30.4-2C, 30.4-3,
30.4-4, 30.4-5A, 30.4-5B, 30.4-6, 30.4-7, and 30.6-1.
The limiting values of 80 percent may be reduced
to 50 percent for the main wind force resisting system
and 65 percent for components and cladding if either
of the following conditions applies:
1. There were no specifi c infl uential buildings or
objects within the detailed proximity model.
2. Loads and pressures from supplemental tests for all
signifi cant wind directions in which specifi c
infl uential buildings or objects are replaced by the
roughness representative of the adjacent roughness
condition, but not rougher than exposure B, are
included in the test results.
31.5 WIND-BORNE DEBRIS
Glazing in buildings in wind-borne debris regions
shall be protected in accordance with Section 26.10.3.
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