Home / Tools / ACI 318-19 Punching Shear C · Concrete

ACI 318-19 Two-Way (Punching) Shear — Slabs and Footings

Two-way shear at the critical section d/2 from the column, without shear reinforcement: the three concrete strength expressions of Table 22.6.5.2 with the size-effect factor λ_s, and shear stress from unbalanced moment transfer (γ_v, J_c) for interior and edge columns.

Geometry and materials

Member

Column location

Column shape

c₁ (span direction; ⟂ edge) in.

c₂ in.

Diameter (circular) in.

Effective depth d in.

f′c psi

λ (lightweight)

Footing: apply λ_s anyway

Factored loads

V_u kip

M_sc (unbalanced) kip-ft

Results

b_o · β · λ_s—

v_c: (a) · (b) · (c) → governs—

γ_v · J_c · M_u at centroid—

v_u = V_u/(b_od) + γ_vM_uc/J_c—

v_u / φv_c—

ACI 318-19Table 22.6.5.2 (a)–(c); 22.6.5.3 (α_s); 22.5.5.1.3 (λ_s); 22.6.3.1 (√f′c ≤ 100 psi); 22.6.4.1 (d/2); 8.4.2.2.2 and 8.4.4.2.2 (γ_f, γ_v); R8.4.4.2.3 (J_c); 13.2.6.2 (λ_s in footings); φ = 0.75. Clause numbers only.

VerifiedStructurePoint worked example (interior and edge columns with moment transfer) reproduced exactly; CSI ETABS/SAFE verification RC-PN Example 002 (circular column, λ_s); Dlubal footing example (λ_s = 0.755). Two published discrepancies are recorded in the engine source.

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).