Slender Beam-Column

Nonsway moment magnification (delta_ns) then P-M interaction (ACI 6.6.4).

Strength design (LRFD): enter factored demands (Pu, Mu, Vu from your load combinations). Results follow ACI 318-19; bar areas use standard ASTM sizes. Confirm detailing (development, spacing, ties) separately.

Design diagram — updates live with your inputs

Section

Width b (in)i

Depth h (in)i Bending direction

Materials

Concrete f'c (psi)i

Steel fy (psi)i

Reinforcement

Cover to bar c.l. (in)i

Longitudinal bari

Number of barsi

Slenderness

Effective length ki Nonsway: <=1.0

Unbraced length lu (ft)i

beta_dnsi Sustained-to-total factored axial ratio

Factored Demands

Factored axial Pu (kip)i

Smaller end moment M1 (kip-ft)i Same sign = single curvature

Larger end moment M2 (kip-ft)i

ACI 318-19

Validation, assumptions & limitations Download validation report (PDF) ↗

This calculator is verified by 4 independent tests comparing its output against closed-form statics, NDS/SDPWS design-standard values and published worked examples. Full case-by-case results are in the PDF report.

Assumptions

Nonsway (braced) frame; k <= 1.0.
EI = 0.4 Ec Ig/(1+beta_dns); Ec = 57000 sqrt(f'c).
Cm = 0.6 - 0.4 M1/M2 >= 0.4 (no transverse load).

Limitations

Sway (P-Delta) magnification not included.
Single-axis bending only.

Results are for preliminary design and must be confirmed by a licensed engineer against the current adopted code and project-specific conditions.