Steel I-Beam Design
Flexure, shear, deflection and lateral-torsional buckling for hot-rolled I-sections per AISC 360-16 (LRFD). Pick a W or S shape and grade, set the unbraced length Lb, Cb and factored demands, and read every limit-state strength, utilisation and governing clause — with the design-moment vs unbraced-length curve. US units (kips, kip·ft, ksi, in).
Section classification Table B4.1b
| Flange bf/2tf | 6.6 | compact (λp 9.2 · λr 24.1) |
| Web h/tw | 45.2 | compact (λp 90.6 · λr 137.3) |
| Overall | compact | Mp attainable |
Flexural strength Ch. F2/F3
| Mp = Zx·Fy | 421 kip·ft | |
| Lp | 5.83 ft | F2-5 |
| Lr | 16.96 ft | F2-6 |
| Governing mode | Inelastic LTB (F2-2) | |
| φMn | 377 kip·ft | φb = 0.90 |
| Demand Mu | 200 kip·ft |
Shear strength Ch. G2
| h/tw | 45.2 | Cv1 = 1.00, φv = 1.00 |
| Aw = d·tw | 6.39 in² | |
| Vn = 0.6FyAwCv1 | 192 kips | |
| φVn | 192 kips | |
| Demand Vu | 40 kips |
Serviceability deflection SLS
| δ (service loads) | 0.76 in | 5wL⁴/384EI |
| Limit L/ | 360 = 0.83 in | |
| Span / δ | 396 | ≥ 360 |
Design moment vs unbraced length Ch. F2 · LTB
AISC 360-16 (LRFD). Hot-rolled doubly-symmetric W and S shapes in major-axis bending — flexural yielding / lateral-torsional buckling (Ch. F2) with flange local buckling (F3), shear (Ch. G2.1 with the AISC-tabulated h/tw), and elastic serviceability deflection. Lb, Cb and factored demands are user inputs — verify bracing, load combinations, web local yielding/crippling and biaxial or combined effects independently. A licensed P.E. review remains required.