What it checks
The module designs round steel pipe members, specifically Schedule 40 sizes, under combined axial compression, shear, and flexural loads. It applies the Load and Resistance Factor Design (LRFD) method, utilizing factored demands for axial force and moment. The engine calculates section properties from the outside diameter and wall thickness, then evaluates the member against AISC 360-16 provisions for compression, flexure, and combined action.
The sequence of checks begins with a compactness assessment using AISC 360-16 Table B4.1b limits for round hollow structural sections. The module then performs a flexural check per Chapter F8, accounting for the section's compactness classification. Finally, it evaluates the combined axial-flexure interaction using the H1-1a or H1-1b equations, depending on the ratio of applied axial force to the nominal compressive strength. The results include a comparison table for all ten standard Schedule 40 sizes under the same loading conditions.
Inputs
- Geometry - Outside diameter (in) and wall thickness (in), or a selection from the ten Schedule 40 size rows defined by ASME B36.10 dimensions.
- Material - Material key (A53B, A500B, or A500C), which determines the yield strength Fy (ksi) and ultimate strength Fu (ksi).
- Loads - Applied axial compression P (kips), applied moment M (kip-ft), and applied shear V (kips) at the base.
- Stability - Effective length KL (ft), where the module assumes a cantilever pole configuration with KL equal to two times the height.
What it reports
- Section Properties - Area, moment of inertia, and other geometric properties derived from the outside diameter and wall thickness.
- Compactness Classification - A verdict of "Compact," "Noncompact," or "Slender" based on the width-to-thickness ratio limits in Table B4.1b.
- Flexural Capacity - The nominal flexural strength calculated per Chapter F8, which varies based on the compactness classification.
- Compressive Capacity - The nominal compressive strength calculated per Chapter E3, considering the effective length KL.
- Interaction Equation - The specific interaction equation used, either H1-1a or H1-1b, determined by the axial load ratio.
- Interaction Check - The combined axial-flexure utilization ratio compared against the allowable limit of 1.0.
- Slenderness Badge - A boolean indicator for whether the KL/r ratio exceeds 200.
- Comparison Table - A ten-row table showing the check results for all Schedule 40 sizes at the same material and loads.
Code references
The engine cites AISC 360-16 §E3 for compression, §F8 for flexure, and §H1 for combined action. It specifically references Table B4.1b for the compactness limits of round HSS and pipe sections, and utilizes the H1-1a and H1-1b interaction equations for the combined load check. The module also references ASME B36.10 for the standard dimensions of Schedule 40 pipe.
Limits
The module is limited to round steel pipe sections, specifically Schedule 40 sizes, and does not support rectangular or square HSS tubes. It assumes a cantilever pole configuration for the effective length calculation, where KL is defined as two times the height. The shear check uses a simplified method, and the module does not account for lateral-torsional buckling modifiers other than the conservative assumption for closed sections. Results are engineering aids; the engineer of record is responsible for the design.