Free Steel Deck Design Calculator — Composite Deck
Design steel deck floor and roof systems with composite concrete topping. The calculator checks the deck in two stages: construction phase (unshored, fresh concrete weight, deflection limits) and composite phase (positive moment capacity, shear stud strength, negative moment at supports). Covers SDI (Steel Deck Institute) standards, AISC 360-22 Section I3, EN 1994-1-1, AS 2327, and CSA S16 Section 17.
Deck types: composite floor deck (1.5 to 3-inch rib height), roof deck (1.5-inch standard), deep deck (4.5 to 7.5-inch cellular), and form deck (non-composite).
How to Use
- Select deck profile: rib height (1.5, 2, 3 inch), gage (22-16 ga), yield strength.
- Define concrete slab: total thickness, f'c, normal-weight or lightweight.
- Specify construction loads: fresh concrete, construction live load, deck weight.
- Enter superimposed loads: partition, ceiling, mechanical, live load.
- Design shear studs: diameter, number per rib, layout for composite action.
- Review results: deck flexure in both stages, stud capacity, deflection.
Design Code Requirements
| Check | SDI/SJI | AISC 360 I3 | EN 1994-1-1 | AS 2327 |
|---|---|---|---|---|
| Deck flexure (construction) | SDI C3.3 | N/A (temp condition) | Cl 9.6 | Cl 4.2 |
| Composite flexure | SDI C4.1 | I3.2 | Cl 6.2.1 | Cl 4.3 |
| Shear stud capacity | SDI C5 | I3.5 (Eq I3-3) | Cl 6.6.3 | Cl 5.2 |
| Deflection (composite) | SDI C7 | I3.6 | Cl 7.2 | Cl 7.1 |
| Diaphragm shear | SDI D1 | N/A | EN 1993-1-3 | Cl 8 |
Frequently Asked Questions
What is the difference between shored and unshored construction? In unshored construction (most common), the steel deck acts as a form and must carry the wet concrete weight without temporary supports. The deck must be checked for construction-phase stresses and deflections. In shored construction, temporary supports are used, so the deck only carries superimposed loads after concrete cures. Unshored is preferred for speed and cost but limits span-to-depth ratios.
How do shear studs achieve composite action in steel deck? Shear studs welded through the deck to the steel beam below resist horizontal shear at the steel-concrete interface, preventing slip and creating composite action. The studs transfer the horizontal shear force between the steel beam and concrete slab, which allows the slab to act as the compression flange of a composite beam. Stud capacity is reduced when deck ribs are perpendicular to the beam.
What are the minimum concrete cover requirements for steel deck? SDI requires a minimum of 2 inches of concrete above the top of the deck flute. For fire ratings, this may increase to 2.5-3 inches. The total slab depth (deck rib height + topping) is typically 4.5 to 6.5 inches for floor decks. Lighter toppings (3.5-4 inches total) are possible with form deck but are less common in structural applications.
Which standards cover steel deck design? SDI (Steel Deck Institute) provides the primary design standard in the US, cited by AISC and IBC. EN 1994-1-1 covers composite steel-concrete structures in Europe. AS 2327 covers composite beams in Australia. CSA S16 Section 17 covers composite construction in Canada.
Is this steel deck calculator free? Yes, completely free with unlimited calculations.
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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.