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ASCE 41-17/23 Concrete Column — Nonlinear Modeling Parameters & Acceptance Criteria

Plastic rotations a_nl (onset of lateral-strength loss) and b_nl (onset of axial failure) from the Ghannoum–Matamoros equations adopted in ASCE 41-17, with acceptance criteria IO = 0.15a ≤ 0.005, LS = 0.5b, CP = 0.7b. Verified against the provisions' author (16WCEE 2017) and a peer-reviewed paper. Turkish counterpart: TBDY Chapter 15 plastic rotation limits.

Column

Type

Ties anchored in the core?

b in

h in

d in

f′c psi

f_yt psi

A_v in²

s in

N_UD (compression) kip

V_y (shear at flexural yielding) kip

M_UD/(V_UDd) (2–4)

a_v/h (optional)

Results

ρ_t · α_Col · N/(A_gf′c)—

V₀ · V_y/V₀ (≥ 0.2)—

a_nl · b_nl rad—

Acceptance IO · LS · CP rad—

a_nlRectangular: 0.042 − 0.043N/(A_gf′c) + 0.63ρ_t − 0.023V_y/V₀ ≥ 0; spiral: 0.06 − 0.06N/(A_gf′c) + 1.3ρ_t − 0.037V_y/V₀ ≥ 0; V_y/V₀ ≥ 0.2

b_nlk/(5 + (N/(0.8A_gf′c))(1/ρ_t)(f′c/f_yt)) − 0.01 ≥ a, k = 0.5 / 0.65 (spiral); reduced linearly from N/(A_gf′c) = 0.5 to zero at 0.7

V₀α_ColA_vf_ytd/s + [6√f′c/(M/Vd)]√(1 + N/(6√f′c A_g))·0.8A_g (lb, in); M/Vd within 2–4; α_Col 1.0 (s/d ≤ 0.75) to 0 (s/d ≥ 1.0). ρ_t = A_v/(b·s) ≤ 0.0175 (≤ 0.0075 if ties are not anchored); not valid below 0.0005.

AcceptanceLS = 0.5b and CP = 0.7b are the 10th and 25th percentiles of the test data (b computed with N/(A_gf′c) ≥ 0.10); IO = 0.15a ≤ 0.005 (the cap from a single source).

VerifyW. M. Ghannoum, 16WCEE 2017, Paper 1010 (author of the provisions); Han et al., Applied Sciences 9(23):5193, 2019. Hand calculation (regression test): 18×18 in, f′c 4 ksi, #4 × 2 @ 12 in, N 200 kip, V_y 60 kip → a 0.01952, b 0.03186, CP 0.0223 rad. An open-source implementation checked during this work contained three errors (ρ_t clamp, b reduction target, end-load mix-up) — the reason code is never used as an anchor.

ScopeColumns not controlled by inadequate development or splicing. These are the ASCE 41-17 (ACI 369.1-17) equations. ASCE 41-23 changed its reference concrete and steel standards (ASCE's “ASCE 41-23 General Updates” course), so for a 41-23 evaluation confirm them against the referenced concrete standard. Short columns (a_v/h < 2) are flagged.

Preliminary calculation tool. Final design requires the full text of the referenced standard (see the sources on this page) and review by a licensed PE.