How the steel beam calculator works
This free steel beam calculator analyzes and checks a steel beam with any shape from the AISC Shapes Database v16.0: W, M, S and HP shapes, C and MC channels, single and double angles, WT, MT and ST tees, rectangular and round HSS, and pipe. Enter one to five spans with pinned, fixed or free supports, add uniform, trapezoidal and point loads by load case, and choose the lateral bracing. The calculator draws the shear, moment and deflection diagrams and checks flexure and shear to AISC 360-22 in LRFD or ASD.
What it calculates
- Support reactions, shear and moment envelopes and service deflections from a stiffness-method analysis of simple, continuous, fixed, cantilever and overhanging beams
- ASCE 7-22 strength (LRFD) or allowable stress (ASD) load combinations for dead, live, roof live, snow and wind loads, with pattern live loading on continuous spans
- Flexural strength by AISC 360-22 Chapter F for every shape family: yielding, lateral-torsional buckling with Cb from the moment diagram of each unbraced segment, and flange, web, stem or leg local buckling
- Shear strength by AISC 360-22 Chapter G, including φv = 1.0 for rolled I-shape webs
- Live and total load deflection against L/360 and L/240, or any limits you enter, with twice the length for cantilevers
Chapter F sections used
- W, M, S and HP shapes and channels about the strong axis: §F2 and §F3; about the weak axis: §F6
- Rectangular and square HSS: §F7, with the effective section modulus for slender flanges
- Round HSS and pipe: §F8
- Tees and double angles loaded in the plane of symmetry: §F9, with the stem or web legs in tension or compression depending on the sign of the moment
- Single angles bent about a geometric axis: §F10
Assumptions and limitations
- Loads act through the shear center and the beam carries no axial load or torsion. Bearing, web crippling, connections, vibration and ponding are not checked.
- Unequal-leg single angles are checked only with continuous lateral-torsional restraint, because the principal-axis check of §F10 is not included.
- HSS properties use the A500 design wall thickness of 0.93 times the nominal thickness.
- Pinned and fixed supports are treated as braced points that prevent twist. A free end is unbraced.
Frequently asked questions
How is the unbraced length Lb set?
Pinned and fixed supports always brace the beam. You can add bracing at a regular spacing, such as joists or purlins, or at listed points, or make it continuous. Each length between brace points is checked as its own segment with its own Cb. If a deck braces the top flange, tick the deck option so positive moment is not checked for lateral-torsional buckling, while negative moment over supports still is.
Why does the calculator check pattern live loads?
In a continuous beam, the largest positive moment in a span occurs when live load is on that span and off the next one. ASCE 7-22 §4.3.3 requires these partial loadings, so the calculator runs every combination of loaded spans and keeps the worst result.
Can I design a lintel angle or an HSS beam?
Yes. Choose the L family for a single angle and set which leg is vertical and whether the horizontal leg is at the top or bottom. Rectangular and round HSS and pipe are checked with AISC §F7 and §F8.
Where do the section properties come from?
All 2,299 shapes and their properties come from the AISC Shapes Database v16.0 published by the American Institute of Steel Construction, which matches the 16th Edition Steel Construction Manual.
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For educational and preliminary design purposes only. Always verify results with a licensed PE.