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ASCE 7-22 load combination calculator

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Enter your unfactored loads once. calcnote generates every applicable LRFD (Sec 2.3.1) and ASD (Sec 2.4.1) combination, including both wind directions and both seismic directions, and highlights the largest and smallest results. Free, no signup.

Code and method
Edition
Method
Gravity and roof loads

Enter unfactored service loads as positive magnitudes, all in one consistent unit and all the same effect type (for example all axial force in kip). Results come back in that unit. Leave a load blank or 0 if it does not apply.

Required, greater than 0. Include self-weight; it is not added automatically.

Floor live load.

Live load occupancy

Sets the live load factor in companion-load positions: 0.5 for standard occupancies, 1.0 (LRFD) for garages, places of public assembly and areas above 100 psf.

Roof live load.

Snow load.

Rain load.

Wind and seismic

Strength-level wind load per ASCE 7-22. Used directly in LRFD; the ASD equations apply the 0.6 factor for you. Both directions are generated.

Horizontal seismic force effect, before the redundancy factor. Both directions are generated. A value above 0 opens the seismic parameters below.

Additional loads (F, H, T; optional)

Load from fluids with well-defined pressures and maximum heights.

Lateral earth, groundwater or bulk material load.

The self-straining force effect (temperature, shrinkage, settlement), not a load factor.

T applies to ASD combinations per ASCE 7-22 Sec 2.4.1. LRFD combinations do not include T; for LRFD, Sec 2.3.5 requires project-specific determination.

How the combinations work

LRFD equations (ASCE 7-22 Sec 2.3.1)

Strength design. In every equation, "roof" means one of Lr, S or R, and the page expands each roof equation into one row per active roof load. W and QE act in both directions, so each wind or seismic equation produces a row for each sign.

LRFD load combination equations
Eq. Combination Notes
11.4(D + F)Always generated. Governs for heavy dead load.
21.2(D + F) + 1.6(L + H) + 0.5 roofLive load primary; roof load is the companion.
31.2(D + F) + 1.6 roof + (f1L or 0.5W)Roof load primary; live load or wind is the companion, generated as separate rows.
41.2(D + F) ± W + f1L + 0.5 roofWind primary, both directions.
5(1.2 + 0.2SDS)D + 1.2F ± ρQE + f1L + 0.2SSeismic, both directions. With Ω0, ρQE is replaced by Ω0QE in extra rows. F is included only when entered.
60.9D ± WWind uplift or overturning check. H and F are left out because they would not reduce the effect.
7(0.9 − 0.2SDS)D ± ρQESeismic uplift or overturning check, with the Ω0 variant when given.

ASD equations (ASCE 7-22 Sec 2.4.1)

Service-level combinations. Seismic effect E is resolved into its horizontal and vertical parts (see below), so each seismic row appears for both Ev signs and both QE directions.

ASD load combination equations
Eq. Combination Notes
1D + FAlways generated.
2D + H + F + L + TFull live load. This is the only combination in which T carries a factor of 1.0.
3D + H + F + roofOne row per active roof load.
4D + H + F + f2L + 0.75T + 0.75 roofCompanion loads reduced; f2 is the live load factor described below.
5D + H + F + (0.6W or 0.7E)Wind in both directions, or resolved seismic.
6aD + H + F + 0.75(0.6W) + f2L + 0.75 roofWind with companion loads.
6bD + H + F + 0.75(0.7E) + f2L + 0.75 roofSeismic with companion loads.
70.6D + 0.6WWind uplift or overturning, both directions. H and F are left out.
80.6D + 0.7ESeismic uplift or overturning, resolved. H and F are left out.

The live load factor exception

Where live load is a companion load in an LRFD equation (Eq. 3, 4 and 5), its factor f1 is 1.0 for garages, places of public assembly and areas where the live load exceeds 100 psf, and 0.5 for every other occupancy. The occupancy selector above sets f1. Where L is the primary load (Eq. 2) it is always 1.6.

In the ASD companion positions (Eq. 4 and 6a/6b) calcnote uses f2 = 0.5 for standard occupancies and 0.75 for the garage, assembly and high live load group. The calcnote column calculator has no occupancy selector and always uses the conservative values (f1 = 1.0).

Seismic effect: Eh and Ev

The seismic load effect is E = Eh + Ev. The horizontal part is Eh = ρQE, or Emh = Ω0QE when overstrength applies. The vertical part is Ev = 0.2 SDS D, which is why SDS changes the dead load factor.

  • LRFD Eq. 5: Ev adds to gravity, so D is factored by 1.2 + 0.2SDS. With SDS = 0.5 that is 1.3.
  • LRFD Eq. 7: Ev counteracts gravity, so D is factored by 0.9 − 0.2SDS. With SDS = 0.5 that is 0.8.
  • ASD Eq. 5 and 8: 0.7E gives D a factor change of ±0.14 SDS and QE a factor of 0.7ρ, so Eq. 5 uses 1.0 ± 0.14SDS and Eq. 8 uses 0.6 ± 0.14SDS.
  • ASD Eq. 6b: 0.75(0.7E) gives D a factor of 1.0 ± 0.105SDS and QE a factor of 0.525ρ.

Worked example

Loads: D = 100, L = 50, S = 20, W = 30. Method LRFD, standard occupancy (f1 = 0.5), no seismic. calcnote generates 12 combinations:

Worked example results
Equation Label Value
ASCE 7-22 Eq. 1 1.4D 140
ASCE 7-22 Eq. 2 1.2D+1.6L 200
ASCE 7-22 Eq. 2 1.2D+1.6L+0.5S 210
ASCE 7-22 Eq. 3 1.2D+0.5L+1.6S 177
ASCE 7-22 Eq. 3 1.2D+0.5W+1.6S 167
ASCE 7-22 Eq. 3 1.2D-0.5W+1.6S 137
ASCE 7-22 Eq. 4 1.2D+W+0.5L 175
ASCE 7-22 Eq. 4 1.2D+W+0.5L+0.5S 185
ASCE 7-22 Eq. 4 1.2D-W+0.5L 115
ASCE 7-22 Eq. 4 1.2D-W+0.5L+0.5S 125
ASCE 7-22 Eq. 6 0.9D+W 120
ASCE 7-22 Eq. 6 0.9D-W 60

The largest value, 210, comes from Eq. 2 with the snow companion: 1.2(100) + 1.6(50) + 0.5(20) = 120 + 80 + 10 = 210. The smallest, 60, is the Eq. 6 wind-reversal check, 0.9(100) − 30 = 60. That case is an uplift check, so the minimum is not a value to size the member for.

Results are for the loads you enter, treated as one effect type in one consistent unit. They are not a substitute for engineering judgment on which combinations apply to your structure.