Section 2.3.1/Load Combinations Using Strength Design
ASCE 7-22 Section 2.3.1 defines the LRFD load combinations establishing how dead, live, wind, seismic, snow, and other loads are combined for structural analysis.
Structures must be designed so that their strength equals or exceeds the effects of the factored loads in seven basic combinations. The combinations apply load factors to dead load (D), live load (L), roof live load (Lr), snow (S), rain (R), wind (W), and earthquake (E). Key combinations include 1.2D + 1.6L, 1.2D + 1.0W + L, and 1.2D + 1.0E + L. Load factors reflect the statistical variability and consequences of each load type.
Why this section exists
No building experiences all maximum loads simultaneously. Load combinations represent realistic worst-case scenarios by applying full factors to the dominant load and reduced factors to companion loads that are statistically unlikely to peak at the same time. Using the wrong combination or omitting a relevant load type can produce an unconservative design that does not meet the intended reliability level.
What plan reviewers look for
Plan reviewers verify that the structural general notes list the applicable load combinations and that the design criteria sheet identifies all load types present on the project. They check that the controlling combination is identified for key members, especially where wind or seismic loads govern. Reviewers also verify that the correct edition of ASCE 7 is referenced, since load factors changed between editions.
Common violations
Related ASCE 7 requirements
Section 2.3.6 covers load combinations including flood loads. Section 2.4 provides load combinations for allowable stress design (ASD). Chapter 4 covers live loads, Chapter 7 covers snow loads, and Chapters 26-31 cover wind loads that feed into these combinations.