AISC 360-16 Steel Member Design
Evaluate structural steel members using the AISC 360-16 calculator. This tool checks member stability, local buckling, shear, and combined actions within its stated scope. Review any incomplete or excluded checks before accepting the member design.
Core Design Methodology
The calculator implements the Specification for Structural Steel Buildings (AISC 360-16), covering both LRFD (Load and Resistance Factor Design) and ASD (Allowable Strength Design). Select the method that matches the load combinations used to obtain the entered actions.
The calculator handles geometric classification of sections into Compact, Noncompact, or Slender categories, which is essential for determining bending and compression capacities. The unbraced length (Lb) - the distance between points braced against lateral displacement or twist - is a key input that directly affects bending capacity through Lateral-Torsional Buckling provisions.
Clause Compliance Coverage:
- Section classification (Table B4.1): Compression and flexural element classes are reported separately where they affect member checks.
- Tension (D2/D3): Gross yielding and effective-net-section rupture are checked; detailed bolt-hole paths are not inferred. Channels require an entered shear-lag factor U; without it, rupture and dependent tension interactions are INCOMPLETE. Confirm assumed shear-lag factors against the actual connection; defaults are not universally conservative. A valid tensile strength is required for rupture and dependent tension interactions.
- Compression (E3/E4/E5/E7): Single angles use the E5 eccentricity treatment when the leg ratio is below 1.7, and are additionally checked to E4 when the longest full leg b/t exceeds 0.71√(E/Fy), using E7 effective area where required. For I-sections that need an E4 check, missing or invalid torsional or warping properties leave compression resistance unresolved, and the dependent compression-bending checks are not reported.
- Flexure (F2-F12): Flexural paths follow section family and axis. Channel major-axis bending requires compact webs and flanges; noncompact or slender channels have no major-axis resistance or dependent H1 interaction. Unequal-I major bending uses conservative F5 only where the compression flange is braced (continuous top-flange restraint under sagging moment, or both flanges braced), including both flange yielding limits, flange local buckling and web reduction. Other unequal-I major-axis flexure is not checked; the remaining checks are still reported.
- Shear (G2-G6): Web, flange, HSS, tee-stem, and single-angle shear rows report the applicable local shear path.
- Combined actions (App. 8 / H1/H2): Entered moments are treated as first-order. Compression-bending interactions apply Appendix 8 B1 amplification for local member (P-δ) effects. Frame sway effects (B2, or a Chapter C / Appendix 7 second-order analysis) are not calculated here and must be included in the entered moments. Invalid amplification prevents completion of the affected interaction. Torsion is not an input and is not checked.
Supported Section Types
I-Shapes - W, S, M, HP
Channels - C, MC
Tees - WT, ST, MT
HSS Rect / Sq
HSS Round / Pipe
Single Angles - L
Current Limitations
- Tension rupture follows D2/D3 using the entered net area and shear-lag factor U. Blank net area defaults to gross area. Channels require an entered U; without it, rupture and dependent tension interactions are INCOMPLETE. Other families use assumed defaults that must be checked against the actual connection; they are not universally conservative. For HSS, U = 0.75 is an assumed value that requires verification for the actual connection.
- Channel major-axis bending requires compact webs and flanges. Noncompact or slender channels have no major-axis bending resistance or dependent H1 interaction; check those limit states separately. Independent axial, shear and minor-axis checks remain available.
- For I-sections that need a Chapter E4 check, missing or invalid torsional or warping properties leave compression resistance unresolved, and the dependent compression-bending interactions are not reported. Passing individual flexural-buckling checks does not complete the member assessment.
- Single member analysis only: no automatic frame buckling analysis or system-level effects.
- The standalone calculator does not run a frame analysis. Enter first-order moments: compression-bending checks apply Appendix 8 B1 amplification (Eq. A-8-3), so entering moments that already include local second-order effects applies amplification again. Frame sway effects (B2, or a Chapter C second-order analysis) are not calculated here and must be included in the entered moments. Invalid amplification prevents completion of the affected interaction.
- No connection design, no composite construction, and no seismic provisions (AISC 341).
- AISC J10 local checks are not performed or derived from point loads, reactions, or connection forces. Check flange local bending, web local yielding, web crippling, web sidesway buckling, bearing stiffeners, and doubler plates separately.
- Effective buckling lengths and unbraced length must be user-specified.
- The calculator assumes the default section orientation shown in the preview. Major and minor axis inputs are relative to that orientation. Rotated or sideways mono-symmetric members, such as channels, tees, and angles, should be checked in the FEA workflow.
- Angle compression includes E4 coupled buckling when the full longest-leg b/t exceeds 0.71 sqrt(E/Fy); equality permits omission. This check uses independent principal effective lengths and Lcz, and its governing capacity enters H2. With Cw = 0, the coupled elastic load is independent of Lcz.
- Single angle moments are evaluated in the section principal axes. Standalone compression uses E5 when the leg ratio is below 1.7; verify its connection, loading, and slenderness prerequisites separately. Angles outside the leg-ratio limit need a Chapter H check with moments that include connection eccentricity. For equal-leg angles with bending that resolves to one leg-parallel geometric axis and no axial compression, the results also include the applicable F10 geometric-axis LTB and yielding rows.
- Applied torsion is not an input in the standalone calculator, so H3 torsion checks run in the FEA tool only. Compression-member E4 torsional buckling is still checked for supported section families. Warping resistance for applied open-section torsion is not calculated and requires separate verification.
Verification: 55 published comparisons, 0.19% average numerical difference
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