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ACI 318-19 One-Way Slab — 12-in Strip Check

Minimum thickness (Table 7.3.1.1), tension-controlled flexure (§7.3.3.1, ε_t ≥ ε_ty + 0.003), A_s,min = 0.0018A_g (ACI 318-19 removed the f_y-based reduction), bar spacing incl. crack control (Table 24.3.2), one-way shear without stirrups with the size-effect factor λ_s (Table 22.5.5.1c), shrinkage & temperature steel.

Geometry & Materials

Span ℓ ft

Support

h in

Clear cover in

f′c psi

f_y

Lightweight concrete w_c pcf

Main Reinforcement

Bar

Spacing in

S&T bar (other direction)

S&T spacing in

Demand per foot of width

M_u kip-ft/ft

V_u at d kip/ft

Results

h_min Table 7.3.1.1—

d · A_s · A_s,min—

φM_n kip-ft/ft—

ε_t (≥ ε_ty + 0.003)—

φV_c kip/ft—

λ_s · ρ_w—

s_max (flexure · crack control)—

Table 7.3.1.1ℓ/20, ℓ/24, ℓ/28, ℓ/10 for normalweight concrete and Grade 60; × (0.4 + fy/100 000) for other grades; × max(1.65 − 0.005wc, 1.09) for wc = 90–115 pcf

§7.6.1.1 · §24.4.3.2As,min = 0.0018Ag; shrinkage & temperature ρ ≥ 0.0018 for all deformed reinforcement — ACI 318-19 removed the earlier reduction for fy > 60 ksi

§7.3.3.1Nonprestressed slabs must be tension-controlled (Table 21.2.2: εt ≥ εty + 0.003)

§7.7.2.3 · Table 24.3.2s ≤ min(3h, 18 in) and ≤ min(15(40 000/fs) − 2.5cc, 12(40 000/fs)), fs = ⅔fy permitted

Table 22.5.5.1(c)No stirrups → Vc = 8λsλ(ρw)^⅓√f′c·b·d, √f′c ≤ 100 psi, Vc ≤ 5λ√f′c·b·d; Av,min only where Vu > φVc for slabs (§7.6.3.1)

VerifyNo independent published ACI 318-19 one-way slab example was used. The flexure and shear parts are cross-checked against this site's beam-flexure and shear engines (each verified against published sources) and against hand calculation (regression test).

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).