Cover [PDF]

Standards [PDF]

Foreword [PDF]

Acknowledgements [PDF]

Dedication [PDF]

Contents [PDF]

Chapter 1 General

Chapter 2 Combinations of Loads

Chapter 3 Dead Loads, Soil Loads, and Hydrostatic Pressure

Chapter 4 Live Loads

Chapter 5 Flood Loads

Chapter 6 Reserved for Future Provisions

Chapter 7 Snow Loads

Chapter 8 Rain Loads

Chapter 9 Reserved for Future Provisions

Chapter 10 Ice Loads - Atmospheric Icing

Chapter 11 Seismic Design Criteria

Chapter 12 Seismic Design Requirements for Building Structures

Chapter 13 Seismic Design Requirements for Nonstructural Components

Chapter 14 Material Specific Seismic Design and Detailing Requirements

Chapter 15 Seismic Design Requirements for Nonbuilding Structures

Chapter 16 Seismic Response History Procedures

Chapter 17 Seismic Design Requirements for Seismically Isolated Structures

Chapter 18 Seismic Design Requirements for Structures with Damping Systems

Chapter 19 Soil-Structure Interaction for Seismic Design

Chapter 20 Site Classification Procedure for Seismic Design

Chapter 21 Site-Specific Ground Motion Procedures for Seismic Design

Chapter 22 Seismic Ground Motion Long-Period Transition and Risk Coefficient Maps

Chapter 23 Seismic Design Reference Documents

Chapter 24

Chapter 25

Chapter 26 Wind Loads: General Requirements

Chapter 27 Wind Loads on Buildings‒MWFRS (Directional Procedure)

Chapter 28 Wind Loads on Buildings‒MWFRS (Envelope Procedure)

Chapter 29 Wind Loads on Other Structures and Building Appurtenances‒MWFRS

Chapter 30 Wind Loads ‒ Components and Cladding (C&C)

Chapter 31 Wind Tunnel Procedure

Appendix 11A Quality Assurance Provisions

Appendix 11B Existing Building Provisions

Appendix C Serviceability Considerations

Appendix D Buildings Exempted from Torisional Wind Load Cases

The torsional load cases in Fig. 27.4-8 (Case 2 and Case 4) need not be considered for a building meeting the conditions of Sections D1.1, D1.2, D1.3, D1.4, or D1.5, if it can be shown by other means that the torsional load cases of Fig. 27.4-8 do not control the design.
One-story buildings with h less than or equal to 30 ft, buildings two stories or less framed with light-frame construction, and buildings two stories or less designed with flexible diaphragms.
Building structures that are regular (as defined in Section 12.3.2) and conform to the following:
  1. The eccentricity between the center of mass and the geometric centroid of the building at that level shall not exceed 15 % of the overall building width along each principal axis considered at each level and,
  2. The design story shear determined for earthquake load as specified in Chapter 12 at each floor level shall be at least 1.5 times the design story shear determined for wind loads as specified herein.
The design earthquake and wind load cases considered when evaluating this exception shall be the load cases without torsion.
Building structures that are regular (as defined in Section 12.3.2) and conform to the following:
  1. The design earthquake shear forces resolved to the vertical elements of the lateral-load-resisting system shall be at least 1.5 times the corresponding design wind shear forces resisted by those elements.
The design earthquake and wind load cases considered when evaluating this exception shall be the load cases without torsion.
Buildings meeting the definition of a torsionally regular buildings contained in Section 26.2.
     EXCEPTION: If a building does not qualify as being torsionally regular under wind load, it is permissible to base the design on the basic wind load Case 1 that is proportionally increased so that the maximum displacement at each level is not less than the maximum displacement for the torsional load Case 2.
The torsional wind load cases need not be considered if the wind force in each vertical MWFRS element of a building is scaled to be 1.5 times the wind force calculated in the same element under the basic wind load.
Square buildings with L/B = 1.0, where all the following conditions are satisfied:
  1. The combined stiffness of the MWFRS in each principal axis direction shall be equal, and
  2. The individual stiffness of each of the MWFRS in each principal axis direction shall be equal and symmetrically placed about the center of application of the wind load along the principal axis under consideration, and
  3. The combined stiffness of the two most separated lines of the MWFRS in each principal axis direction shall be 100% of the total stiffness in each principal axis direction, and
  4. The distance between the two most separated lines of the MWFRS in each principal axis direction shall be at least 45% of the effective building width perpendicular to the axis under consideration.
Square buildings with L/B = 1.0, where all the following conditions are satisfied:
  1. The combined stiffness of the MWFRS in each principal axis direction shall be equal, and
  2. The individual stiffness of the two most separated lines of the MWFRS in each principal axis direction shall be equal with all lines of the MWFRS symmetrically placed about the center of application of the wind load along the principal axis under consideration, and
  3. The combined stiffness of the two most separated lines of the MWFRS in each principal axis direction shall be at least 66% of the total stiffness in each principal axis direction, and
  4. The distance between the two most separated lines of the MWFRS in each principal axis direction shall be at least 66% of the effective building width perpendicular to the axis under consideration.
Rectangular buildings with L/B equal to 0.5 or 2.0 (L/B = 0.5, L/B = 2.0), where all the following conditions are satisfied:
  1. The combined stiffness of the MWFRS in each principal axis direction shall be proportional to the width of the sides perpendicular to the axis under consideration,
  2. The individual stiffness of each of the MWFRS in each principal axis direction shall be equal and symmetrically placed about the center of application of the wind load along the principal axis under consideration,
  3. The combined stiffness of the two most separated lines of the MWFRS in each principal axis direction shall be 100% of the total stiffness in each principal axis direction,
  4. The distance between the two most separated lines of the MWFRS in each principal axis direction shall be at least 80% of the effective building width perpendicular to the axis under consideration.
Rectangular buildings with L/B equal to 0.5 or 2.0 (L/B = 0.5, L/B = 2.0), where all the following conditions are satisfied:
  1. The combined stiffness of the MWFRS in each principal axis direction shall be proportional to the width of the sides perpendicular to the axis under consideration,
  2. The individual stiffness of the most separated lines of the MWFRS in each principal axis direction shall be equal with all lines of the MWFRS symmetrically placed about the center of application of the wind load along the principal axis under consideration,
  3. The combined stiffness of the two most separated lines of the MWFRS in each principal axis direction shall be at least 80% of the total stiffness in each principal axis direction, and
  4. The distance between the two most separated lines of the MWFRS in each principal axis direction shall be 100% of the effective building width perpendicular to the axis under consideration.
Rectangular buildings having L/B between 0.5 and 1.0 (0.5 < L/B < 1.0) or between 1.0 and 2.0 (1.0 < L/B < 2.0), the stiffness requirements and the separation distances between the two most separated lines of the MWFRS in each direction shall be interpolated between Case A and Case C and between Case B and Case D, respectively (see Fig. D1.5-1).

Main Wind Force Resisting Systems - Appendix D h ≤ 160 ft.
Figure D1.5-1 Case E MWFRS - Requirements of Case E Wind Torsion Exclusion
See Figure 27.4-8
Enclosed Simple Diaphragm Buildings
Rectangular buildings having L/B between 0.2 and 0.5 (0.2 ≤ L/B < 0.5) or between 2.0 and 5.0 (2.0 < L/B ≤ 5.0), see Fig. D1.5-2, where all of the following conditions are satisfied:
  1. There shall be at least two lines of resistance in each principal axis direction,
  2. All lines of the MWFRS shall be symmetrically placed about the center of application of the wind load along the principal axis under consideration,
  3. The distance between each line of resistance of the MWFRS in the principal axis direction shall not exceed 2 times the least effective building width in a principal axis direction, and
  4. The individual stiffness of the most separated lines of the MWFRS in each principal axis direction shall be equal and not less than (25 + 50/n) % of the total stiffness where n is the required number of lines of resistance in the principal axis direction as required by conditions 1 and 3 of this section. The value of n shall be 2, 3, or 4.

Main Wind Force Resisting Systems - Appendix D h ≤ 160 ft.
Figure D1.5-2 Case F MWFRS - Requirements of Case F Wind Torsion Exclusion
See Figure 27.4-8
Enclosed Simple Diaphragm Buildings
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