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

Buildings and other structures shall be designed using the provisions of either Section 2.3 or 2.4. Where elements of a structure are designed by a particular material standard or specification, they shall be designed exclusively by either Section 2.3 or 2.4.
Ak = load or load effect arising from extra ordinary event A
D = dead load
Di = weight of ice
E = earthquake load
F = load due to fluids with well-defined pressures and maximum heights
Fa = flood load
H = load due to lateral earth pressure, ground water pressure , or pressure of bulk materials
L = live load
Lr = roof live load
R = rain load
S = snow load
T = self-straining load
W = wind load
Wi = wind-on-ice determined in accordance with Chapter 10
The load combinations and load factors given in Section 2.3.2 shall be used only in those cases in which they are specifically authorized by the applicable material design standard.
Structures, components, and foundations shall be designed so that their design strength equals or exceeds the effects of the factored loads in the following combinations:
  1. 1.4D
  2. 1.2D + 1.6L + 0.5(Lr or S or R)
  3. 1.2D + 1.6(Lr or S or R) + (L or 0.5W)
  4. 1.2D + 1.0W + L + 0.5(Lr or S or R)
  5. 1.2D + 1.0E + L + 0.2S
  6. 0.9D + 1.0W
  7. 0.9D + 1.0E
EXCEPTIONS:
  1. The load factor on L in combinations 3, 4, and 5 is permitted to equal 0.5 for all occupancies in which L0 in Table 4-1 is less than or equal to 100 psf, with the exception of garages or areas occupied as places of public assembly.
  2. In combinations 2, 4, and 5, the companion load S shall be taken as either the flat roof snow load (pf) or the sloped roof snow load (ps) .
   Where fluid loads F are present, they shall be included with the same load factor as dead load D in combinations 1 through 5 and 7.

   Where loads H are present, they shall be included as follows:
  1. where the effect of H adds to the primary variable load effect, include H with a load factor of 1.6;
  2. where the effect of H resists the primary variable load effect, include H with a load factor of 0.9 where the load is permanent or a load factor of 0 for all other conditions.
   Effects of one or more loads not acting shall be investigated. The most unfavorable effects from both wind and earthquake loads shall be investigated, where appropriate, but they need not be considered to act simultaneously. Refer to Section 12.4 for specific definition of the earthquake load effect E.1
   Each relevant strength limit state shall be investigated.


1The same E from Section 12.4 is used for both Sections 2.3.2 and 2.4.1. Refer to the Chapter 11 Commentary for the seismic provisions .
When a structure is located in a flood zone (Section 5.3.1), the following load combinations shall be considered in addition to the basic combinations in Section 2.3.2:
  1. In V-Zones or Coastal A-Zones, 1.0W in combinations 4 and 6 shall be replaced by 1.0W + 2.0Fa.
  2. In noncoastal A-Zones, 1.0W in combinations 4 and 6 shall be replaced by 0.5W + 1.0Fa.
When a structure is subjected to atmospheric ice and wind-on-ice loads, the following load combinations shall be considered:
  1. 0.5(Lr or S or R) in combination 2 shall be replaced by 0.2Di + 0.5S.
  2. 1.0W + 0.5(Lr or S or R) in combination 4 shall be replaced by Di + Wi + 0.5S.
  3. 1.0W in combination 6 shall be replaced by Di + Wi.
Where applicable, the structural effects of load T shall be considered in combination with other loads. The load factor on load T shall be established considering the uncertainty associated with the likely magnitude of the load, the probability that the maximum effect of T will occur simultaneously with other applied loadings, and the potential adverse consequences if the effect of T is greater than assumed. The load factor on T shall not have a value less than 1.0.
Where approved by the authority having jurisdiction, the registered design professional is permitted to determine the combined load effect for strength design using a method that is consistent with the method on which the load combination requirements in Section 2.3.2 are based. Such a method must be probability based and must be accompanied by documentation regarding the analysis and collection of supporting data that is acceptable to the authority having jurisdiction.
Loads listed herein shall be considered to act in the following combinations; whichever produces the most unfavorable effect in the building, foundation, or structural member shall be considered. Effects of one or more loads not acting shall be considered.
  1. 1.   D
  2. 2.   D + L
  3. 3.   D + (Lr or S or R)
  4. 4.   D + 0.75L + 0.75(Lr or S or R)
  5. 5.   D + (0.6W or 0.7E)
  6. 6a.  D + 0.75L + 0.75(0.6W) + 0.75(Lr or S or R)
  7. 6b.  D + 0.75L + 0.75(0.7E) + 0.75S
  8. 7.   0.6D + 0.6W
  9. 8.   0.6D + 0.7E
EXCEPTIONS:
  1. In combinations 4 and 6, the companion load S shall be taken as either the flat roof snow load (pf) or the sloped roof snow load (ps).
  2. For nonbuilding structures, in which the wind load is determined from force coefficients, Cf, identified in Figures 29.5-1, 29.5-2 and 29.5-3 and the projected area contributing wind force to a foundation element exceeds 1,000 square feet on either a vertical or a horizontal plane, it shall be permitted to replace W with 0.9W in combination 7 for design of the foundation, excluding anchorage of the structure to the foundation.
  3. It shall be permitted to replace 0.6D with 0.9D in combination 8 for the design of special reinforced masonry shear walls, where the walls satisfy the requirement of Section 14.4.2.
Where fluid loads F are present, they shall be included in combinations 1 through 6 and 8 with the same factor as that used for dead load D.

Where loads H are present, they shall be included as follows:
  1. where the effect of H adds to the primary variable load effect, include H with a load factor of 1.0;
  2. where the effect of H resists the primary variable load effect, include H with a load factor of 0.6 where the load is permanent or a load factor of 0 for all other conditions.
   The most unfavorable effects from both wind and earthquake loads shall be considered, where appropriate, but they need not be assumed to act simultaneously. Refer to Sections 1.4 and 12.4 for the specific definition of the earthquake load effect E.2

   Increases in allowable stress shall not be used with the loads or load combinations given in this standard unless it can be demonstrated that such an increase is justified by structural behavior caused by rate or duration of load .
2The same E from Section 12.4 is used for both Sections 2.3.2 and 2.4.1. Refer to the Chapter 11 Commentary for the seismic provisions.
When a structure is located in a flood zone, the following load combinations shall be considered in addition to the basic combinations in Section 2.4.1:
  1. In V-Zones or Coastal A-Zones (Section 5.3.1), 1.5Fa shall be added to other loads in combinations 5, 6, and 7, and E shall be set equal to zero in 5 and 6.
  2. In noncoastal A-Zones, 0.75Fa shall be added to combinations 5, 6, and 7, and E shall be set equal to zero in 5 and 6.
When a structure is subjected to atmospheric ice and wind-on-ice loads, the following load combinations shall be considered:
  1. 0.7Di shall be added to combination 2.
  2. (Lr or S or R) in combination 3 shall be replaced by 0.7Di + 0.7Wi + S.
  3. 0.6W in combination 7 shall be replaced by 0.7Di + 0.7Wi.
Where applicable, the structural effects of load T  shall be considered in combination with other loads. Where the maximum effect of load T  is unlikely to occur simultaneously with the maximum effects of other variable loads, it shall be permitted to reduce the magnitude of T   considered in combination with these other loads. The fraction of T  considered in combination with other loads shall not be less than 0.75.
Where required by the owner or applicable code, strength and stability shall be checked to ensure that structures are capable of withstanding the effects of extraordinary (i.e., low-probability) events, such as fires, explosions, and vehicular impact without disproportionate collapse.
For checking the capacity of a structure or structural element to withstand the effect of an extraordinary event, the following gravity load combination shall be considered:

(0.9 or 1.2)D + Ak + 0.5L + 0.2S (2.5-1)

in which Ak = the load or load effect resulting from extraordinary event A.
For checking the residual load-carrying capacity of a structure or structural element following the occurrence of a damaging event, selected load-bearing elements identified by the registered design professional shall be notionally removed, and the capacity of the damaged structure shall be evaluated using the following gravity load combination:

(0.9 or 1.2)D + 0.5L + 0.2(Lr or S or R) (2.5-2)
Stability shall be provided for the structure as a whole and for each of its elements. Any method that considers the influence of second-order effects is permitted.
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