United StatesAISC 360-22
Member reactions link to connected column or footing calculations automatically, change a load and everything downstream updates. Design steel members to the current AISC 360-22 specification using Allowable Strength Design, with combined axial and bending interaction, LTB, and flexural buckling checks for W-shapes, HSS, pipes, and channels.
Method & scope
Calculation method
The Steel Member (Design Only, ASD) calculator to AISC 360-22 applies Allowable Strength Design safety factors to check all member capacity limit states using service-level (unfactored) design forces.ASD safety factors
AISC 360-22 ASD derives available strengths by dividing nominal strengths by Omega safety factors. For flexure Omega_b = 1.67, for compression Omega_c = 1.67, for shear Omega_v = 1.67, and for tension yielding Omega_t = 1.67 (rupture Omega_t = 2.00). All interaction equations and capacity ratios use these ASD allowable values, so the demand-to-capacity format is directly comparable to service loads.Section classification
Plate element slenderness ratios are compared to the limits from AISC 360-22 Table B4.1a and B4.1b to classify elements as compact, non-compact, or slender. Slender elements reduce the effective area for compression and modify the flexural strength equations for bending.Flexural capacity and lateral-torsional buckling
Chapter F provisions determine Mn. For W-shapes and doubly-symmetric I-sections, the plastic moment Mp sets the upper bound. LTB reduces capacity when Lb exceeds Lp. The boundary conditions are:- Lb ≤ Lp: no LTB, Mn = Mp
- Lp < Lb ≤ Lr: linearly reduced by LTB
- Lb > Lr: elastic LTB, Mn = Fcr × Sx
Compression and column buckling
Chapter E covers flexural buckling about strong and weak axes and, for asymmetric sections, torsional or flexural-torsional buckling. The critical stress Fcr is derived from the governing slenderness ratio KL/r. The ASD allowable compression capacity is: Pc = Pn / Omega_c = Fcr × Ag / 1.67 For slender element sections, an effective area Aeff reduces Pn. Torsional and flexural-torsional buckling provisions apply for sections with open thin-walled geometry.Combined actions interaction
Chapter H ASD interaction equations are the key output. For Pa/Pc ≥ 0.2: interaction ratio = Pa/Pc + (8/9)(Max/Mcx + May/Mcy) ≤ 1.0 For Pa/Pc < 0.2: interaction ratio = Pa/(2Pc) + (Max/Mcx + May/Mcy) ≤ 1.0 Available flexural strength Mcx includes LTB reductions where applicable. Both required and available strengths are shown for each term, and the code equation number is cited for the controlling interaction check.P-delta and stability
A first-order moment amplification factor accounts for P-little delta effects within the member. The member is assumed to be part of a braced frame. Frame-level second-order effects should be addressed before applying this calculator to sway-sensitive structures.Shear
Chapter G shear provisions compute Vn using the shear area and shear coefficient Cv2. The ASD allowable shear is Vc = Vn / 1.67. For compact webs Cv2 = 1.0 and the full shear area is available. For slender webs the coefficient is reduced.How to use it
1
Open the calculator
Open it from Run calc in the About this calculator panel above. To start from a typical setup, choose one of the presets listed there.
2
Enter your inputs
Work through the input sections from top to bottom. Click any input label to see its reference explanation, clause, conditions and assumptions. See Checks, References, Conditions and Assumptions.
3
Review the results and export
Check the utilization of each governing check in the summary, then export a PDF report. See Views and Export.
Available presets
Each preset opens the calculator with a typical setup already entered.Common questions
What design method and code does this calculator use?
What design method and code does this calculator use?
This calculator uses Allowable Strength Design (ASD) to AISC 360-22, the current 2022 edition of the AISC Specification for Structural Steel Buildings. It is the recommended version for new US projects using ASD. For LRFD design to the same code, use the steelMemberAISC360-22 calculator.
What are the key inputs?
What are the key inputs?
You provide the steel section, member length, effective length factors or unbraced lengths for each axis, and the unfactored (ASD service-level) design forces, axial load, major- and minor-axis bending moments, and shear. Forces can be manually entered or linked from an upstream analysis calculator.
What limit states does it check?
What limit states does it check?
The calculator checks yielding and lateral-torsional buckling for flexure (Chapter F), flexural and torsional buckling for compression (Chapter E), tensile yielding and rupture (Chapter D), shear (Chapter G), and combined axial plus bending interaction from AISC 360-22 Chapter H, using ASD Omega safety factors throughout.
Can it handle combined axial load and biaxial bending?
Can it handle combined axial load and biaxial bending?
Yes. Chapter H ASD interaction equations handle members under combined axial force and bending about one or both axes. The calculator evaluates both the high-axial and low-axial forms and reports the controlling interaction ratio with the code equation reference.
How do I set the effective length and unbraced length?
How do I set the effective length and unbraced length?
You enter K factors for strong- and weak-axis buckling and set the unbraced length Lb for lateral-torsional buckling. The calculator derives Lp and Lr automatically from section properties. A first-order moment amplification factor is applied for P-delta effects within the member, consistent with the braced-frame assumption.
Can this member calculation link to beam and footing calculations?
Can this member calculation link to beam and footing calculations?
Yes, the member calc receives reactions from upstream calculations (e.g. frame analysis) and passes base reactions to footing or base plate calculations. Changes propagate automatically through the load path.
Next steps
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