The complete set of LRFD load combinations from ASCE 7-22 §2.3, when each combination governs, the seismic load effect E decomposition, special overstrength combinations, and the notational differences between ASCE 7 and ACI 318-25.
| Symbol | Load Type | ASCE 7-22 Reference |
|---|---|---|
| D | Dead load — weight of structure and permanent attachments | §3.1 |
| L | Live load — occupancy, moveable equipment (after any reduction) | §4.3 |
| Lr | Roof live load (not snow) | §4.5 |
| S | Snow load | Ch.7 |
| R | Rain load (ponding) | Ch.8 |
| W | Wind load | Ch.26–31 |
| E | Seismic load effect (horizontal + vertical components) | §12.4 |
| F | Fluid load with well-defined pressure and height | §3.4 |
| H | Load due to lateral earth pressure, groundwater, or bulk materials | §3.5 |
| T | Self-straining load effects (temperature, creep, shrinkage) | §2.3.5 |
Every structural member must be checked under each applicable combination. The one producing the largest demand (moment, shear, axial) governs.
In combinations 3 and 4, when L arises from a parking garage, place of public assembly, or occupancies with Lo ≥ 100 psf (4.79 kN/m²), the L factor remains 1.0, not 0.5. Otherwise L may use the 0.5 factor when wind or snow governs.
| # | Governs When… | Typical Application |
|---|---|---|
| 1 (1.4D) | Dead load is very large relative to live load; ratio D/L > 8. Rare in ordinary buildings. | Massive concrete retaining walls, large water tanks, heavily loaded foundations |
| 2 (1.2D+1.6L) | Gravity loads dominate; no significant wind, snow, or seismic. The most common governing combination for interior beams and columns of low-rise buildings. | Interior beams, interior columns, slabs in non-seismic, low-wind regions |
| 3 (1.2D+1.6S) | Heavy snow region; S > L. Often governs roof beams in northern climates. | Roof beams and purlins in regions where pg > ~30 psf (1.44 kN/m²) |
| 4 (1.2D+W+L) | Wind governs over seismic; columns on windward side of lateral system. Check alongside combination 5. | Lateral system columns, moment frame connections, braced frame diagonals |
| 5 (0.9D+W) | Wind uplift or overturning (reduced dead works against resistance). Always check when combination 4 governs. | Leeward columns, anchorage in uplift, cantilevered walls, cladding connections |
| 6 (1.2D+E+L) | Seismic governs over wind. Compressive columns in seismic frames, tension foundations. | SDC C–F lateral columns, concrete shear walls in compression, seismic regions |
| 7 (0.9D+E) | Seismic overturning / uplift. Critical for uplift on foundation bolts and hold-down anchors. | Tension connections, overturning of shear walls, column base plates in seismic zones |
In combinations 6 and 7, the letter E expands into a horizontal component (Eh) and a vertical component (Ev). The sign of Ev depends on whether it adds to or reduces the effect of gravity.
| ρ = 1.0 when… | ρ = 1.3 when… |
|---|---|
| SDC B or C (always) Structures with regular geometry and sufficient redundancy per §12.3.4 Drift and deformation checks Nonlinear analyses |
SDC D–F structures that do NOT meet the redundancy criteria of §12.3.4.2 ρ = 1.3 applies to members of the seismic force-resisting system only |
Certain structural elements — transfer elements, columns below discontinuities, collectors, connections — must be designed for the full expected overstrength of the SFRS. These combinations use Emh (with Ωo) instead of Eh.
ACI 318-25 §5.3 lists the same load combinations as ASCE 7-22 but with different notation. The load factors are identical — only the symbols and variable names differ.
| ASCE 7-22 Combination | ACI 318-25 §5.3 Notation | Notes |
|---|---|---|
| 1.4D | U = 1.4D | Identical |
| 1.2D + 1.6L + 0.5(Lr or S or R) | U = 1.2D + 1.6L + 0.5(Lr or S or R) | Identical; ACI uses U for factored demand |
| 1.2D + 1.6(Lr or S or R) + (L or 0.5W) | U = 1.2D + 1.6(Lr or S or R) + (L or 0.5W) | Identical |
| 1.2D + 1.0W + L + 0.5(Lr or S or R) | U = 1.2D + 1.0W + L + 0.5(Lr or S or R) | ACI: W is already factored wind from ASCE 7 |
| 0.9D + 1.0W | U = 0.9D + 1.0W | Identical |
| 1.2D + 1.0E + L + 0.2S | U = 1.2D + 1.0E + L + 0.2S | E = ρQE ± 0.2SDS×D per §12.4 |
| 0.9D + 1.0E | U = 0.9D + 1.0E | Identical |
| Combination | Factored Moment (kip-ft) | Governs? |
|---|---|---|
| 1 (1.4D): 1.4×60 = 84 | 84 | No |
| 2 (1.2D+1.6L): 1.2×60 + 1.6×50 = 152 | 152 | Yes |
| 3 (1.2D+1.6S+L): 1.2×60 + 1.6×20 + 50 = 154 | 154 | Yes (barely) |
| 4 (1.2D+W+L): 1.2×60 + 10 + 50 = 132 | 132 | No |
Combination 3 governs if snow load S = 20 psf is present. Design moment = 154 kip-ft.
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