Steel Column Calculator
Compressive strength of W-shape columns — concentric load, flexural buckling per §E3. Get an answer in five seconds, then watch the buckling-branch logic work below.
Every equation verified against the AISC 360-22 registry · No account required
The full calculation, spelled out
Below is the live CalcPackage editor in public view — the same worksheet an engineer would stamp: slenderness, Euler stress, the piecewise critical-stress block, and the strength check in sequence.
Change any input — every dependent block recomputes. Stretch the column to 30 ft and watch F_cr switch from the inelastic (Eq. E3-2) to the elastic (Eq. E3-3) branch live. Click ✦ Explain on any block and the AI walks you through it.
With a free account you get full authoring control: different bracing about each axis, slender-element sections, combined loading. You can change any number — sign up free to change the math.
Live worksheetMake it yours
A free account turns this calculator into your worksheet — your edits in this tab carry over when you sign up.
Edit the math, not just the numbers
Add blocks, change equations, rename variables, restructure sections. The full editor with 3 worksheets, no card required.
FREESave versions & export PDF
Submittal-ready calc packages with title blocks, page numbers, and revision history. Watermark removed on Pro.
FREE · PROAI that you can verify
Describe a problem; get a complete scaffold built only from pre-verified code equations. Every block carries its chain of custody — you stay the author of record.
DEMOS FREE · FULL ON PROPick up exactly where you left off
Sign up free and this worksheet — with the inputs you just changed — becomes the first one in your account. No credit card.
How this calculator works
The calculator checks a concentrically loaded W-shape column using LRFD per AISC 360-22 §E3. The factored load is Pᵤ = 1.2P_D + 1.6P_L (ASCE 7-22 load combination 2). With equal unbraced lengths about both axes, weak-axis slenderness L_c/r = KL/r_y governs. The elastic buckling stress is F_e = π²E/(L_c/r)², and the critical stress follows the §E3 branch: F_cr = 0.658^(F_y/F_e) F_y when L_c/r ≤ 4.71√(E/F_y) (inelastic), otherwise F_cr = 0.877F_e (elastic). Design strength is φ_c P_n = 0.90 · F_cr · A_g.
Assumptions and limitations
Concentric axial load (no moments), the same effective length about both axes, nonslender rolled W-shapes per §B4.1, and E = 29,000 ksi. Combined axial + bending (Chapter H), slender elements (§E7), and torsional buckling are covered in the full editor templates. This calculator is a design aid — engineering judgment and final responsibility rest with the licensed engineer of record.
Frequently asked questions
Which K value should I use?
K = 1.0 (pinned-pinned) is the safe default for braced frames. The 0.65 and 0.80 options are the AISC Appendix 7 design recommendations for fixed end conditions; K = 2.0 covers flagpole cantilevers. When in doubt, use the larger K.
Why doesn't higher-strength steel help my long column?
Past the slenderness limit 4.71√(E/F_y) the capacity is elastic-buckling-controlled — it depends on E, which is the same for all steel grades. Try it: set L to 30 ft and switch F_y between 36 and 50 ksi.
Is the calculation verified?
Yes. Every equation is matched against CalcPackage's AISC 360-22 equation registry and dimension-checked on every recomputation. The chain-of-custody rail records the history.