Load effects
Any consistent unit: kips, kip-ft, lb, psf, kN. Every load below must be in it.
Service-level (unfactored) effects, signed: positive acts with gravity, negative against it (wind uplift, for instance). Lr, S and R are alternatives: enter the one that applies to your roof; the rows for the others show what they would give. S is the 7-22 strength-level snow load (from the reliability-targeted pg), as the factors below assume.
Options
Exception 1 changes only the LRFD rows that carry 1.0L; the ASD rows already use 0.75L and are left as they are.
Governing
LRFD strength ASCE 7-22 §2.3.1
Seismic rows (Eq. 6 and 7) are the basic combinations with seismic load effects, §2.3.6, with E = Eh only here (Ev is not applied).
ASD allowable stress ASCE 7-22 §2.4.1
Seismic rows (Eq. 8 to 10) are the basic combinations with seismic load effects, §2.4.5, with Eh only. Faded rows carry a load entered as zero.
How it works
Each row is one combination from the ASCE 7-22 set the StructuralClaw desktop app ships with (§2.3.1 strength, §2.4.1 allowable stress): the page multiplies each load effect by its factor and adds them. Nothing is enveloped along a member here; you enter the effect at one point and get the combined effect at that point.
- Max is the largest combined effect, the design value for a member loaded in the gravity sense. Min is the smallest: when it is negative the member sees a net reversal (uplift, tension in a hold-down), usually from 0.9D + 1.0W or 0.6D + 0.6W.
- With the ± option on, every row that carries W or Eh is evaluated twice, once with the load as entered and once reversed.
- The factors come straight from the combination set the beam calculator uses; this page keeps no copy of its own.
To carry these combinations along a whole beam (moment, shear and deflection at every point, per load case), use the free beam calculator: it applies this same set.