Free Web Tool · NSCP Ch. 4 / ACI 318 Ch. 18

Seismic Detailing Checker

Special moment frame ductile detailing — verifies hoop spacing in beam plastic-hinge zones, column confinement spacing s ≤ min(b/4, 6d_b, s₀), confinement length ℓ₀, and lap-splice exclusion zones per NSCP Ch. 4 / ACI 318 Ch. 18.

Member

Checks

Hinge zone length 2h (beam) / ℓ₀ (col)
Max hoop spacing s_max,hinge
Provided s vs s_max
First hoop ≤ 50 mm from face
Outside hinge: s_out limit
Lap-splice excl. zone
Min cross-section dim. (b)
Code basis

Beam SMF (ACI 18.6.4 / NSCP): Hinge zone = 2h from each face. s ≤ min(d/4, 6·d_bL, 150 mm). First hoop ≤ 50 mm. Outside hinge: s ≤ d/2. Column SMF (ACI 18.7.5): ℓ₀ = max(h, ℓn/6, 450 mm). s_max,hinge = min(b/4, 6·d_bL, s₀) where s₀ = 100 + (350 − h_x)/3, 100 ≤ s₀ ≤ 150 mm. Outside ℓ₀: s ≤ min(6·d_bL, 150 mm). Lap splices only in middle half of column. b ≥ 300 mm; aspect ≤ 0.4.