Steel Beam Web Shear Capacity (AISC 360 Ch. G)
The web shear a steel beam carries at its ends, where the reaction is highest and the moment is zero.
Example
You enter
- Yield stress Fy (ksi) 50
- Section depth d (in) 17.99
- Web thickness tw (in) 0.355
- Web shear coefficient Cv1 1
- ASD safety factor Omega_v (1.50 or 1.67) 1.5
You get
- Web area Aw 6.39 in^2
- Nominal Vn 191.6 kips
- ASD allowable Vn/Omega 127.7 kips
- LRFD design phi_v*Vn 191.6 kips
Details, formula, and sources
Vn = 0.6 x Fy x Aw x Cv1 with Aw = d x tw. For a rolled I-shape with a stocky web (h/tw under ~53.9 at Fy 50), Cv1 = 1.0 and the factors are Omega 1.50 / phi 1.00. A W18x50 carries 192 kips nominal, 128 allowable. Short heavily-loaded spans and coped ends are governed by the web, not the flange. Block shear at a coped end is a separate check. A design aid, not a substitute for the engineer of record.
Aw = d x tw; Vn = 0.6 x Fy x Aw x Cv1; Va = Vn / Omega_v; phi_v Vn (phi_v paired to Omega_v: 1.50/1.00 or 1.67/0.90); util = Vu / Va.
AISC 360-22 Chapter G (G2.1) and §B3.1 / §B3.2, by name; d and tw are read from the AISC Manual for the actual shape.
The Vn = 0.6 Fy Aw Cv1 web-shear relation and the paired safety / resistance factors are stated in AISC 360; d and tw come from the AISC Manual.
Estimate. AHJ and licensed professional govern.
Field names used by the API: fy, d, tw, cv1, omega_v, aw, vn, va, phi_vn
- Rolled I-shape factor Cv1 = 1.0 and Omega_v = 1.50 / phi_v = 1.00 apply where h/tw <= 2.24 sqrt(E/Fy); slenderer webs use the general 1.67 / 0.90 pairingAISC 360-22 G2.1
- Web area Aw = d x tw (overall depth times web thickness) from the AISC ManualAISC 360-22 G2.1
- Block shear separate block shear at a coped or bolted end is a distinct limit state (J4.3), not covered hereAISC 360-22 J4.3