| 16 | 201 | 25 | 57.8 | 41.8 | 49.2 | | 16 | 201 | 30 | 63.3 | 45.8 | 53.8 | | 19 | 284 | 25 | 81.7 | 59.1 | 69.4 | | 19 | 284 | 30 | 89.5 | 64.7 | 76.1 | | 19 | 284 | 35 | 96.7 | 69.9 | 82.2 | | 22 | 380 | 25 | 109.3 | 79.0 | 92.9 | | 22 | 380 | 30 | 119.8 | 86.6 | 101.8 |

Stud Capacity per Clause 17.7

For 19 mm stud, f'c = 30 MPa, solid slab: Asc = pi × 19^2 / 4 = 283.5 mm^2 Ec = 4500 × sqrt(30) = 24,650 MPa qr = 0.5 × 0.80 × 283.5 × sqrt(30 × 24,650) × 1.0 × 1.0 / 1000 = 89.5 kN

Metal Deck Effects

Deck Rib Orientation

Deck Rib Geometry Limits

Per CSA S16 Clause 17.7.3:

Stud Layout Requirements

Per CSA S16 Clause 17.7.3:

Longitudinal Spacing

Transverse Placement

For beams in metal deck:

• One stud per rib: For decks with 50-75 mm rib width, small beams
• Two studs per rib (staggered): For decks with 75-150 mm rib width, high shear demand
• Three studs per rib: Rare — requires rib width > 150 mm

Degree of Shear Connection

Per CSA S16 Clause 17.7.1:

Full shear connection: The number of studs provided develops the full plastic moment of the composite section.

N_full = C_f / qr

Where:

• C_f = total compressive force at full composite action = min(As × Fy, 0.85 × f'c × b_eff × t_slab)
• As = steel beam area
• b_eff = effective slab width
• t_slab = slab thickness

Partial Shear Connection

Per CSA S16 Clause 17.7.4, partial shear connection is permitted provided:

• Degree of connection ≥ 40% for beams with span ≤ 10 m
• Degree of connection ≥ 50% for beams with span > 10 m
• The reduced moment capacity M_r_partial is calculated from the available shear connection force: M_r_partial = M_s + (M_r_full - M_s) × N_studs / N_full

Where M_s = moment resistance of steel section alone.

Worked Example — Composite Floor Beam

Given: W410×60 beam, 350W steel. Span = 9.0 m. Solid slab 150 mm thick, f'c = 30 MPa, normal-weight concrete. Effective width b_eff = 2.25 m. Factored moment Mf = 600 kN·m.

Step 1 — Full Shear Connection: As = 7,550 mm^2 (W410×60) C_f_steel = As × Fy = 7,550 × 350 / 1000 = 2,643 kN C_f_concrete = 0.85 × 30 × 2,250 × 150 / 1000 = 8,606 kN C_f = min(2643, 8606) = 2,643 kN (steel governs — neutral axis in slab)

Step 2 — Studs Required (Full Connection): qr = 89.5 kN per stud (19 mm dia, f'c = 30 MPa, solid slab) N_full = 2,643 / 89.5 = 29.5 → 30 studs (15 each side of midspan, for each half-span)

Step 3 — Check Partial Connection: 40% minimum: N_min = 0.40 × 30 = 12 studs total 60% partial: N = 18 studs (9 per side) Shear force: C_actual = 18 × 89.5 = 1,611 kN

Step 4 — Reduced Moment Capacity (Partial Connection): Steel section alone: Mr_s = phi × Zx × Fy = 0.90 × 1,060 × 350 / 10^6 = 334 kN·m Full composite: Mr_full (from section analysis) ≈ 850 kN·m (typical for W410×60 with 150 mm slab) Mr_partial = 334 + (850 - 334) × 18/30 = 334 + 516 × 0.60 = 334 + 310 = 644 kN·m

Step 5 — Check: Mf = 600 kN·m ≤ Mr_partial = 644 kN·m. Ratio = 0.93. OK.

Result: 18-19 mm diameter headed studs (9 per side of midspan), full span. Partial shear connection at 60%.

Stud Welding Requirements

Per CSA W59 Clause 5.20, shear studs must be welded with:

1. Stud welding gun: Automatic arc stud welding, ferrule-contained
2. Weld qualification: 3 bend tests per CWB W47.1 procedures
3. Daily testing: 2 stud bend tests at start of each shift
4. Production testing: 10% of studs (min 2) bent 30° from vertical after installation — if no failure, all studs are acceptable. If failure occurs, double the test frequency.

Frequently Asked Questions

What is the shear capacity of a 19 mm headed stud in 30 MPa concrete? Per CSA S16 Clause 17.7: qr = 0.5 × phi_sc × Asc × sqrt(f'c × Ec) × R_g × R_p. For solid slab: qr = 89.5 kN. For metal deck perpendicular: qr = 0.5 × 0.80 × 284 × sqrt(30 × 24,650) × 0.85 × 0.75 / 1000 = 64.7 kN (28% reduction from solid slab).

What is the minimum stud spacing for composite beams per CSA S16? 6 × stud diameter in the longitudinal direction (114 mm for 19 mm studs). 4 × stud diameter in the transverse direction (76 mm for 19 mm). Minimum edge distance from the beam flange edge: 25 mm. Maximum spacing: 900 mm or 4 × slab thickness, whichever is less.

What is partial shear connection in composite beams? Partial shear connection means fewer studs are provided than required for full composite action. The degree of shear connection (N/N_full) ranges from 40-100%. The moment resistance is reduced proportionally: Mr_partial = Mr_steel + (Mr_full - Mr_steel) × N/N_full. Partial connection is economical for beams where the moment demand is less than the full composite capacity.

Does the metal deck orientation affect stud capacity? Yes. Per CSA S16 Clause 17.7, the stud reduction factors depend on deck orientation. For beams perpendicular to deck span: R_g = 0.85, R_p = 0.75 (overall factor 0.64). For beams parallel to deck span: R_g = 1.0, R_p = 0.75 (overall factor 0.75). Solid slab (no deck): R_g = 1.0, R_p = 1.0. Beams perpendicular to deck have 15% less capacity than parallel beams due to non-uniform concrete confinement in the deck ribs.

Related Pages

• Canadian Composite Column Design
• CSA S16 Beam Design
• Canadian HSS Section Properties
• CSA S16 Lateral-Torsional Buckling
• Beam Capacity Calculator
• All Canadian References

This page is for educational reference. Shear stud design per CSA S16:24 Clause 17 and CSA W59 Clause 5.20. Verify stud welding procedure qualification per CWB. Results are PRELIMINARY — NOT FOR CONSTRUCTION without independent PE/SE verification.

Design Resources

Calculator tools

• Composite Beam Design Calculator
• Composite Beam Calculator
• Steel Deck Design Calculator

Reference pages

• CA Shear Stud