Steel Member (Design Only - LRFD, AISC 360-16)

Member reactions link to connected column or footing calculations automatically, change a load and everything downstream updates. Design steel members to AISC 360-16 LRFD with combined axial and bending interaction, LTB, and flexural buckling checks. For projects on the 2016 specification.

This calculator uses an earlier code edition (AISC 360-16). It stays available for existing projects. For new designs, check the [Calculator Library](/docs/calculators/us) for the current edition. ## Method & scope | Property | Detail | | ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Design standards | AISC 360-16 | | Regions | United States | | What it checks | Section classification, Flexural capacity and lateral-torsional buckling, Compression and column buckling, Combined axial and bending interaction, P-delta effects, Shear | #### Calculation method The Steel Member (Design Only, LRFD, AISC 360-16) calculator takes factored design forces from analysis and checks a selected US steel section against all member limit states defined in AISC 360-16. ##### Section classification Plate elements of the cross-section, flanges and web, are classified as compact, non-compact, or slender using the limiting width-to-thickness ratios from AISC 360-16 Table B4.1. Classification affects which capacity equations apply for flexure (Chapter F) and compression (Chapter E). Slender elements trigger effective area reductions and modified LTB provisions. ##### Flexural capacity and lateral-torsional buckling For doubly-symmetric I-shaped members, the nominal flexural strength Mn follows Chapter F. In the plastic range (Lb ≤ Lp), Mn = Mp. Between Lp and Lr, LTB reduces Mn linearly. Beyond Lr, the elastic LTB equation governs. The calculator computes Lp and Lr from the section's torsional and warping properties. The Cb factor for non-uniform moment is calculated from the moment diagram, increasing capacity where the moment is lower along the unbraced length. For HSS, pipes, channels, and other section types, the applicable Chapter F sub-provisions apply automatically, including flange local buckling and web local buckling reductions for non-compact and slender sections. ##### Compression and column buckling Chapter E compression checks cover flexural buckling about both axes, torsional buckling, and flexural-torsional buckling as applicable to the section type. The critical stress Fcr is determined from the effective slenderness ratio KL/r. The calculator uses: **φcPn = φc × Fcr × Ag** (for compact sections) For slender elements, Fcr is computed using the effective area Aeff reduced by the effective width method per Section E7. ##### Combined axial and bending interaction The Chapter H interaction equations are the primary pass/fail output: For high axial load (Pr/Pc ≥ 0.2): **interaction ratio** = Pr/Pc + (8/9)(Mrx/Mcx + Mry/Mcy) ≤ 1.0 For low axial load (Pr/Pc \< 0.2): **interaction ratio** = Pr/(2Pc) + (Mrx/Mcx + Mry/Mcy) ≤ 1.0 Where Pr is the required axial strength, Pc the available axial strength, Mrx and Mry the required flexural strengths, and Mcx and Mcy the available flexural strengths including LTB reductions. Both ratios are shown with full code references. ##### P-delta effects The calculator applies a first-order moment amplification factor to account for P-little delta effects within the member, consistent with the assumption that the member is part of a braced frame. Engineers designing sway frames should verify that second-order effects are addressed at the frame level before using this calculator. ##### Shear Chapter G shear checks determine the nominal shear strength Vn from the shear area and the web shear coefficient Cv. For compact webs Cv = 1.0 and the full plastic shear capacity is available. For slender webs, tension-field action may be considered if applicable. ## How to use it Open it from **Run calc** in the About this calculator panel above. 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](/docs/running-calculations/checking-results/checks-references-conditions-assumptions). Check the utilization of each governing check in the summary, then export a PDF report. See [Views and Export](/docs/running-calculations/exporting-reports/views-and-export). ## Common questions This calculator uses the Load and Resistance Factor Design (LRFD) method to AISC 360-16, the 2016 edition of the AISC Specification for Structural Steel Buildings. Engineers who need the newer 2022 edition should use the steelMemberAISC360-22 calculator. You provide the steel section (W, HSS, pipe, channel, angle, or built-up), member length, effective length factors or unbraced lengths, and the design forces, factored axial load, major- and minor-axis bending moments, and shear. Forces can be entered manually or linked from an upstream analysis calculator. 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 the combined axial plus bending interaction equations from Chapter H. Compact, non-compact, and slender section classifications are applied automatically. Yes. Chapter H interaction equations are evaluated for members under combined axial force and bending about one or both axes. The calculator reports the interaction ratio and indicates whether the high-axial or low-axial form of the equation governs. You enter Lc/r values or effective lengths separately for each buckling axis. For lateral-torsional buckling, you specify the unbraced length Lb and the calculator computes the LTB limit states (Lp and Lr) automatically from section properties. A first-order moment amplification factor accounts for P-delta effects, consistent with the braced-frame assumption. 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 Complete list of Calcs.com design calculators available for United States projects (AISC, ACI, NDS, ASCE 7, IBC, and related standards). Design steel members to AISC 360-22 (LRFD). Input analysis forces to check combined axial, bending, and shear for US hot-rolled and HSS sections. Design steel members to AISC 360-16 (ASD) from analysis forces. An earlier code edition, kept for existing projects. Design steel members to AISC 360-22 (ASD). Input analysis forces to check combined axial, bending, and shear interaction for US hot-rolled sections. Design steel beams to AISC 360-16 (ASD) with multiple supports and loads. An earlier code edition, kept for existing projects. Link Design Only calculators to Truss Analysis and Portal Frame Analysis results to check member capacity against the analysis forces.