What it checks
The module designs W-shape steel columns for combined compression and biaxial flexure. It applies the AISC 360-16 strength design method, calculating nominal strengths for compression and flexure before applying resistance factors. The sequence of checks begins with determining the critical stress for compression, accounting for flexural buckling in both axes. It then evaluates strong-axis flexure, considering yielding and lateral-torsional buckling, and weak-axis flexure based on yielding. Finally, the module runs interaction checks against project-level load combinations to verify the member's capacity under combined loads.Inputs
- Geometry - AISC designation (e.g., "W12x40"), depth (in), flange width (in), flange thickness (in), web thickness (in).
- Material - Yield strength Fy (psi), Modulus of elasticity E (psi).
- Slenderness - Strong-axis (x-x) and weak-axis (y-y) slenderness parameters, including effective length factors and unbraced lengths (ft).
- Loads - Axial compression (kips), load combinations for interaction checks.
- Flexure - Cb factor for lateral-torsional buckling (dimensionless).
What it reports
- Compression Capacity - ϕcPn (kips), the design compressive strength compared against the applied axial load.
- Strong-Axis Flexure - ϕbMnx (kip·ft), the design moment strength about the strong axis.
- Weak-Axis Flexure - ϕbMny (kip·ft), the design moment strength about the weak axis.
- Governing Equation - The specific interaction equation used, identified as "H1-1a" or "H1-1b".
- Calculation Trace - An ordered list of calculation steps with substituted values, including section headers.
- LTB Region - The lateral-torsional buckling regime, such as "no LTB," "inelastic LTB," or "elastic LTB".
- Flange Region - The flange classification, such as "compact," "noncompact," or "slender".
Code references
The engine cites AISC 360-16 Ch.E / Ch.H. Specific clauses referenced include E.3 for compression, F.2 for strong-axis flexure, F.6 for weak-axis flexure, and H1.1 for combined compression and biaxial flexure. The module also references §E7-2/E7-3 for slender elements and §F2/§F3 for lateral-torsional buckling limits.