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502.2 Loads and Load Combinations
The loads and load combinations shall be as stipulated by this chapter. In the absence of a building code, the loads and load combinations shall be those stipulated in Chapter 2. For design purposes, the nominal loads shall be taken as the loads stipulated by this chapter.
203 Combination of Loads
203.1 General
Buildings, towers and other vertical structures and all portions thereof shall be designed to resist the load combinations specified in Section 203.3, 203.4 and 203.5.
The most critical effect can occur when one or more of the contributing loads are not acting. All applicable loads shall be considered, including both earthquake and wind, accordance with the specified load combinations.
203.2 Symbols and Notations
D = dead load
E = earthquake load set fo1th in Section 208.6.1
Em = estimated maximum earthquake force that can be developed in the structure as set forth in Section 208.6.1
F = load due to fluids with well-defined pressures and maximum heights
H = load due to lateral pressure of soil and water in soil
L = live load, except roof live load, including any permitted live load reduction
Lr = roof live load, including any permitted live load reduction
P = ponding load
R = rain load on the undeflected roof
T = self-straining force and effects arising from contraction or expansion resulting from temperature change, shrinkage, moisture change, creep in component materials, movement due to differential settlement, or combinations thereof
W = load due to wind pressure
203.1 Basic Load Combinations (LRFD)
Where strength design or load and resistance factor design is used, structures and all portions thereof shall resist the most critical effects from the following combinations of factored loads:
203.3.2 Other Loads
Where P (Ponding load) is to be considered in design, the applicable load hall be added to Section 203 .3 .1 factored as 1. 2 P.
203.4 Load Combinations Using Allowable Stress or Allowable Strength Design (ASD)
203.4.1 Basic Load Combinations
Where allowable stress or allowable strength design is used, structures and all portions thereof shall resist the most critical effects resulting from the following combinations of loads:
No increase in allowable stresses shall be used with these load combinations except as specifically permitted by Section 203.4.2.
203.4.2 Alternate Basic Load Combinations
In lieu of the basic load combinations specified in Section 203.4.1, structures and portions thereof shall be permitted to be designed for the most critical effects resulting from the following load combinations. When using these alternate basic load combinations, a one-third increase shall be permitted in allowable stresses for all combinations, including W or E.
Exception: Crane hook loads need not be combined with roof five load or with more than one-half of the wind load.
203.4.3 Other Loads
Where P is to be considered in design, each applicable load shall be added to the combinations specified in Sections 203.4.1 and 203.4.2.
203.5 Special Seismic Load Combinations
For both allowable stress design and strength design for concrete, and Load and Resistance Factor Design (LRFD) and Allowable Strength Design (ASD) for steel, the following special load combinations for seismic design shall be used as specifically required by Section 208, or by Chapters 3 through 7.
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