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ACI 318-19 Beam Shear Design

Concrete shear capacity per Table 22.5.5.1 (ρw-dependent, with mandatory size-effect factor λs when Av<Av,min) · Required stirrup spacing · Steel shear Vs = Av·fy·d/s · φVn ≥ Vu check

⚠ Corrected 2026-07-19: This tool previously used the ACI 318-14 simplified Vc=2λ√f'c form. It now implements ACI 318-19 Table 22.5.5.1, cross-verified against two independent published sources (an Eng-Tips practitioner worked example and Dlubal's published crossover-point check) — see engine/us-codes.js test suite for the numeric cross-check.

Input Parameters

At distance d from face of support [§9.4.3.2]
Governs ρw in Table 22.5.5.1 Eq.(b)/(c). Set to 0 for a nominal 0.01 placeholder (not recommended for final design).

Shear Design Results

ρw = As/(bw·d)—
λs (size-effect factor)—
Vc, Eq.(a) 2λ√f'c·bw·d kip—
Vc, Eq.(b) 8λ(ρw)^⅓√f'c·bw·d kip—
Vc, Eq.(c) with λs kip—
Vc governing () kip—
φVc kip—
Vs,required kip—
Vs,max = 8√f'c·bw·d kip—
Required spacing s in.—
Max spacing s_max §9.7.6.2.2 in.—
Design spacing in.—
φVn kip—
DCR = Vu/φVn—

Code References

Table 22.5.5.1Vc from Eq.(a)/(b) when Av≥Av,min; mandatory Eq.(c) with λs when Av<Av,min
§22.5.5.1.3λs = √(2/(1+0.004·d[mm])) ≤ 1.0 — size-effect factor
§22.5.10.5.3Vs = Av·fy·d/s
§22.5.1.2Vs ≤ 8√f'c·bw·d (maximum steel shear)
§9.7.6.2.2s ≤ d/2 (or 24 in.) when Vs ≤ 4√f'c·bw·d; s ≤ d/4 (or 12 in.) otherwise
Table 21.2.1φ = 0.75 for shear
Cross-verified12in footing, f'c=3000psi, As=0.31in², d=8in, Av<Av,min → ρw=0.00323, λs=1.0, Vc(c)=6.20kip ✓ (independent Eng-Tips + Dlubal sources)

Engine: us-codes.js · US-ACI318-19.v1 ·

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Step-by-Step Solution

Preliminary calculation tool. Final design requires the full text of ACI 318 and review by a licensed PE. This tool follows ACI 318-19, the edition referenced by the 2021 and 2024 IBC; ACI CODE-318-25 was published in January 2025 and is expected in the 2027 IBC (changes include development length equations and seismic provisions).