Free Composite Beam Calculator — Steel-Concrete Design

Q: How does metal deck orientation affect shear stud strength?

Deck ribs perpendicular to the beam require stud capacity reduction. Per AISC 360 Table I3.2, when ribs are parallel to the beam, Rp = 1.0, Rg = 1.0 (no reduction). For perpendicular ribs with one stud per rib: Rp = 0.6, Rg = 1.0.

Q: What is the minimum slab thickness for composite beams?

AISC 360 requires minimum 2 inches of concrete above the top of metal deck. For 3/4-inch and smaller studs, the stud must extend at least 1-1/2 inches above the deck. For 7/8-inch and larger studs, minimum 3-inch cover is required.

Q: Which design codes cover composite steel-concrete beams?

AISC 360-22 Section I3 in the US, EN 1994-1-1 in Europe (the only dedicated steel-concrete composite code), AS 2327 in Australia, CSA S16 Section 17 in Canada.

Design composite steel-concrete beams for floor systems. The calculator checks full and partial composite action, shear stud strength, transformed section properties, flexural capacity, and deflection per AISC 360-22 Section I3, EN 1994-1-1, AS 2327, and CSA S16 Section 17.

Typical applications: office and commercial floor framing with metal deck and concrete topping, parking structure beams, bridge girders with cast-in-place decks, and composite beam retrofit designs.

How to Use

Select steel beam section (W-shape or built-up).
Define concrete slab: thickness, f'c, normal-weight or lightweight.
Select metal deck profile: rib height, flute width, orientation.
Specify shear studs: diameter, length, number per rib, spacing.
Enter loads: construction (unshored), superimposed dead, live load.
Review composite capacity, stud count, deflection reduction.

Design Code Requirements

Check	AISC 360 I3	EN 1994-1-1	AS 2327	CSA S16
Composite flexure	I3.2	Cl 6.2.1.2	Cl 4.3	Cl 17.2
Shear stud strength	I3.5 (Eq I3-3)	Cl 6.6.3.2	Cl 5.2	Cl 17.7
Partial composite action	I3.2 (25% min)	Cl 6.6.1.2	Cl 4.7	Cl 17.3
Deflection (composite)	I3.6	Cl 7.2	Cl 7.1	Cl 17.8
Longitudinal shear	I3.3	Cl 6.6.4	Cl 5.5	Cl 17.6

Shear Stud Capacities (AISC 360-22 Eq I3-3)

Qn = 0.5 _ Asc _ sqrt(f'c _ Ec) ≤ Rg _ Rp _ Asc _ Fu

For a 3/4-inch stud (Asc = 0.442 in^2) in 4,000 psi normal-weight concrete: Qn = 0.5 _ 0.442 _ sqrt(4000 * 57,000*√4000/1000) = 0.5 _ 0.442 _ sqrt(4000 _ 3605) = 0.5 _ 0.442 _ 3796 = 839 lb = 21.4 kips Upper bound: 1.0 _ 1.0 _ 0.442 _ 65 = 28.7 kips Governing Qn = 21.4 kips

Frequently Asked Questions

What is partial composite action? Partial composite action means fewer shear studs than required for full composite action are used. AISC 360 allows a minimum of 25% composite action. Using fewer studs reduces flexural capacity proportionally but saves on stud installation cost. The neutral axis shifts upward in partial composite beams, and deflections increase — so serviceability often governs the minimum stud count.

How does metal deck orientation affect shear stud strength? Deck ribs perpendicular to the beam axis require stud capacity reduction factors (Rp and Rg). Per AISC 360 Table I3.2, when the deck ribs are parallel to the beam and the studs are placed through the deck, Rp = 1.0 and Rg = 1.0 (no reduction). For perpendicular ribs with one stud per rib: Rp = 0.6, Rg = 1.0 — a 40% capacity reduction.

What is the minimum slab thickness for composite beams? AISC 360 requires a minimum slab thickness of 2 inches above the top of the metal deck for composite action. For studs 3/4 inch and smaller, the stud length must extend at least 1-1/2 inches above the top of the deck. For 7/8-inch and larger studs, a minimum 3-inch cover above the deck is required.

Which design codes cover composite steel-concrete beams? AISC 360-22 Section I3 in the US. EN 1994-1-1 in Europe (the only dedicated steel-concrete composite code). AS 2327 in Australia. CSA S16 Section 17 in Canada.

Disclaimer (educational use only)

This page is provided for general technical information and educational use only. It does not constitute professional engineering advice. All structural designs must be verified by a licensed Professional Engineer (PE) or Structural Engineer (SE). The site operator disclaims liability for any loss or damage arising from the use of this page.