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ASCE 7-22 Live Load Reduction

§4.7.2 influence-area reduction L = L₀(0.25 + 15/√(K_LLA_T)) with the Table 4.7-1 element factors, the 0.50L₀ / 0.40L₀ floors and every exception: heavy loads over 100 psf (§4.7.3), passenger vehicle garages (§4.7.4), assembly uses (§4.7.5) and the one-way slab area limit (§4.7.6).

Member

Element (Table 4.7-1)

L₀ (Table 4.3-1) psf

A_T per floor ft²

Floors supported

Use

One-way slab span ℓ ft

Results

K_LL · K_LLA_T ft²—

Reduced live load L psf—

L / L₀—

Governing provision—

§4.7.2L = L₀(0.25 + 15/√(K_LLA_T)) where K_LLA_T ≥ 400 ft²; L ≥ 0.50L₀ (one floor), ≥ 0.40L₀ (two or more floors)

§4.7.3 · §4.7.4L₀ exceeding 100 psf, and passenger vehicle garages: not reduced, except members supporting two or more floors — at most 20%, not less than §4.7.2. A load of exactly 100 psf is reducible.

§4.7.5 · §4.7.6Assembly uses are not reduced; for one-way slabs A_T ≤ ℓ × 1.5ℓ

VerifyL₀ = 40 psf, interior column, A_T = 900 ft² → 20 psf (LibreTexts worked example); 50 psf, K_LLA_T = 1,600 → 31.25 psf. A published garage example that reduces a multistory garage column to 20 psf is wrong: §4.7.4 allows at most 20% → 32 psf.

ScopeFloor live loads only. Roof live load reduction (§4.8) is not included. L₀ is entered from Table 4.3-1.

Preliminary calculation tool. Final design requires the full text of the referenced standard (see the sources on this page) and review by a licensed PE.