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Calcs.com
United States
AISC 360-22AISC 360-16

Steel Beam (LRFD)

Beam reactions link to your column and footing calculations automatically - change a load once and everything downstream updates. For US structural engineers designing hot-rolled steel floor and roof beams to the current AISC 360-22 edition using LRFD. Checks bending, shear, and three deflection limits with the governing load combination identified for each.

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What it calculates

Beam reactions link to the columns and footings below, so load changes propagate downstream automatically. Design hot-rolled steel beams to AISC 360-22 LRFD with multiple spans and loads. Checks bending (Chapter F), shear (Chapter G), and three deflection limits with the governing ASCE 7 combination identified for each.

Code standards

  • AISC 360-22 (LRFD)

How it calculates

The Steel Beam (LRFD, AISC 360-22) calculator performs a full strength and serviceability check per the current AISC Specification on hot-rolled steel beams with any number of spans and loads.

Section classification (AISC 360-22 B4)

Flanges and webs are classified as compact, noncompact, or slender by comparing width-to-thickness ratios to lambda_p and lambda_r limits. The classification governs which capacity equations are used in Chapter F and determines whether reduction factors for FLB or WLB apply.

Flexural capacity - AISC 360-22 Chapter F

Positive and negative bending are checked independently. For compact sections: utilization = Mu / (phi × Mp) ≤ 1.0. For sections with noncompact or slender elements, flange local buckling and web local buckling reductions reduce the available strength. Lateral-torsional buckling is evaluated using the unbraced length Lb, limiting lengths Lp and Lr, and the Cb moment gradient factor. The governing flexural capacity is the minimum from all applicable limit states.

Shear capacity - AISC 360-22 Chapter G

Web shear capacity uses: utilization = Vu / (phi × 0.6 Fy Aw Cv1) ≤ 1.0. For standard W-shapes with h/tw ≤ 2.24√(E/Fy), phi = 1.0 and Cv1 = 1.0. For deeper webs or non-standard sections, phi = 0.9 and Cv1 is calculated from web slenderness.

Load combination analysis

All ASCE 7-22 LRFD strength combinations are evaluated with FEA. The calculator identifies the governing combination for moment and for shear separately. Unfactored load cases are also run for deflection calculations.

Deflection checks

Three deflection limits are tracked independently:

  • Instantaneous deflection - compared to L/n span ratio or absolute limit (typically L/360 for live load)
  • Long-term deflection - includes sustained load creep effect; typically L/240
  • Simplified DL+(LL or SL) deflection - combined loading for total deflection assessment

utilization = delta / delta_allow ≤ 1.0 for each criterion. The critical (worst-case) result across all load cases is shown in the summary.

Inputs summary

Geometry: section designation, yield strength Fy (ksi), plan length, span lengths, support types, incline pitch, tributary spacing. Loads: dead, live, roof live, snow, wind as uniform, partial, point, or moment loads at any position. Design criteria: separate deflection limits for each of the three serviceability checks.

Outputs summary

Summary outputs include critical moment demand and capacity, governing load combination for moment and shear, shear demand and capacity, maximum factored reactions (vertical and horizontal), and deflection ratios for all three criteria. Reactions are structured for automatic load linking to connected column and footing calculations.

Related calculators

Steel Beam (LRFD, AISC 360-16)→Steel Beam (ASD, AISC 360-22)→Steel Beam Torsion (ASD, AISC 360-22)→Steel Composite Beam (LRFD)→

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Frequently asked questions

What design method and code standard does this calculator use?
This calculator uses the Load and Resistance Factor Design (LRFD) method per AISC 360-22, the current edition of the AISC Specification for Structural Steel Buildings. Factored strength demands are compared to phiRn resistance values per Chapters F and G.
What are the key inputs?
Key inputs include the steel section (W, S, C, HSS, angle, or custom), yield strength Fy, span lengths and support conditions, applied loads (dead, live, snow, wind) with tributary widths, unbraced length for LTB, and deflection limit criteria for live load, total, and DL+(LL or SL) checks.
What does it check or output?
The calculator checks factored moment demand versus capacity (AISC 360-22 Chapter F), factored shear versus capacity (Chapter G), and three deflection limits. The summary shows the governing ASCE 7 load combination for moment and shear, support reactions for load linking, and deflection ratios for all three serviceability criteria.
Can it handle continuous spans and multiple load types?
Yes - the calculator supports simple spans, continuous spans, and cantilevers with unlimited supports and loads. Point loads, uniform loads, partial uniform loads, and moment loads can all be applied. All ASCE 7 LRFD combinations are evaluated and the governing case is identified automatically.
When should I use this versus the ASD version (steelBeamASDAISC360-22)?
Use this calculator when your project uses strength-based LRFD load combinations per ASCE 7 (1.2D+1.6L etc.). Use steelBeamASDAISC360-22 if your project uses allowable stress design with service-level ASD combinations (D+L etc.). Both calculators reference AISC 360-22 - only the design philosophy and load factors differ.
Does this calculator support load linking with column and footing calculations?
Yes - beam reactions at supports link directly to connected column and footing calculations in the same project. When span length, loads, or member size changes, all connected calculations update automatically - no manual re-entry.

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