UK Shear Stud Design — EN 1994-1-1 Headed Stud Capacity Table
Design resistance of headed shear studs for composite steel-concrete beams per BS EN 1994-1-1:2004 Clause 6.6 with UK National Annex. Capacity tables (PRd) for standard 19 mm and 22 mm diameter studs in solid slabs and composite decks, reduction factors for profiled steel sheeting, and a design example for a UK composite beam.
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Shear Stud Design per EN 1994-1-1 Clause 6.6
The design shear resistance of a headed stud in a solid slab is the lesser of:
Stud failure (steel): PRd = 0.8 × fu × π × d²/4 / γVs
Concrete failure (crushing): PRd = 0.29 × α × d² × √(fck × Ecm) / γVs
Where:
- fu = ultimate tensile strength of stud (typically 450 MPa for standard EN ISO 13918 studs)
- d = stud shank diameter (19 mm or 22 mm standard)
- hsc = stud height (typically 100 mm or 125 mm)
- α = 1.0 for hsc/d ≥ 4 (most UK studs satisfy this)
- fck = concrete cylinder strength
- Ecm = secant modulus of concrete = 22 × (fcm/10)^0.3
- γVs = 1.25 (UK NA value)
Stud Capacity Table — Solid Slab
| Stud Diameter | Stud Height (mm) | Steel Grade | fu (MPa) | PRd — Steel (kN) | PRd — C30/37 (kN) | PRd — Design (kN) |
|---|---|---|---|---|---|---|
| 19 mm | 100 | S235J2+C450 | 450 | 81.6 | 79.3 | 79.3 |
| 19 mm | 100 | S235J2+C450 | 450 | 81.6 | 86.8 (C40/50) | 81.6 (stud governs) |
| 19 mm | 125 | S235J2+C450 | 450 | 81.6 | 79.3 | 79.3 |
| 22 mm | 100 | S235J2+C450 | 450 | 109.4 | 106.3 | 106.3 |
| 22 mm | 125 | S235J2+C450 | 450 | 109.4 | 106.3 | 106.3 |
| 22 mm | 150 | S235J2+C450 | 450 | 109.4 | 106.3 | 106.3 |
Reduction Factor for Profiled Steel Sheeting
For composite slabs with profiled steel decking, the stud capacity is reduced by factor kt:
Ribs perpendicular to beam: kt = 0.6 × (b0/hp) × (hsc/hp − 1) ≤ 1.0
Ribs parallel to beam: kt = 0.6 × (b0/hp) × (hsc/hp − 1) ≤ 1.0 (similar expression with different geometry)
Where:
- b0 = mean width of concrete rib
- hp = depth of profiled steel sheeting
- hsc = stud height
Typical Reduction Factors for UK Composite Deck Profiles
| Deck Profile | hp (mm) | b0 (mm) | 19×100 mm Stud kt | 19×125 mm Stud kt |
|---|---|---|---|---|
| 50 mm trapezoidal | 50 | 90 | 0.96 | 1.0 |
| 60 mm trapezoidal | 60 | 90 | 0.86 | 1.0 |
| 80 mm re-entrant | 80 | 120 | 0.60 | 0.86 |
| 100 mm deep deck | 100 | 130 | — | 0.78 |
Worked Example — Composite Beam with 19 mm Studs
Beam details:
- 533UB in S355, span 8.0 m
- Composite slab: 130 mm deep (60 mm deck + 70 mm topping), C30/37
- Deck: 60 mm trapezoidal, ribs perpendicular to beam, b0 = 90 mm
- Studs: 19 mm × 100 mm, 2 studs per rib (pair), spacing 300 mm
Step 1 — Stud Capacity
PRd (solid slab) = 79.3 kN (governed by concrete for C30/37) kt = 0.6 × (90/60) × (100/60 − 1) = 0.6 × 1.5 × 0.667 = 0.60 (≤ 1.0)
PRd (deck) = 0.60 × 79.3 = 47.6 kN per stud
Step 2 — Number of Studs Required
Assume total longitudinal shear force: VL = min(0.85 × Ac × fck/γc, Aa × fy/γMa) = between concrete crushing and steel yielding.
For full shear connection:
VL = Aa × fy/γMa = 131 × 10² × 355 / 1.0 = 4,651 kN (steel governs)
Number of studs required each side of midspan: n = VL / (2 × PRd per stud) = 4,651 / (2 × 47.6) = 48.9 ≈ 50 studs
With 2 studs per rib at 300 mm spacing: 2 × (8,000/300) = 53 studs — adequate (with 2 per side for end detailing).
Step 3 — Degree of Shear Connection
η = n_actual / n_full = 53/50 = 1.06 ≥ 1.0 → Full shear connection.
For partial shear connection (< 1.0), the moment resistance is reduced per EN 1994-1-1 Clause 6.2.1.3.
Design Guidance
- UK standard: 19 mm × 100 mm headed studs (hsc/d = 5.3 ≥ 4)
- Spacing: Minimum 5d (≈ 100 mm), maximum 600 mm
- Edge distance: ≥ 25 mm to any concrete edge
- Welding: Through-deck welding is standard for UK composite construction
Design Resources
- UK Steel Grades Reference — EN 10025-2 grade selection for UK projects
- UK Steel Mechanical Properties — fy, fu, and elongation tables
- UK Universal Beam and Column Sizes — UB/UC section dimensions and properties
- UK Bolt Capacity Tables — Class 8.8 and 10.9 bolt resistance
- UK Beam Design Guide — EN 1993-1-1 flexure, shear, and LTB
- UK Connection Design Guide — EN 1993-1-8 bolted and welded joints
- All UK Steel Design References — complete library
Frequently Asked Questions
What is the design resistance of a 19 mm shear stud in a solid C30/37 slab?
The design resistance PRd for a 19 mm headed stud (fu = 450 MPa, hsc ≥ 4d = 76 mm) in a solid C30/37 slab is: minimum of steel failure (0.8 × 450 × π × 19²/4 / 1.25 = 81.6 kN) and concrete failure (0.29 × 1.0 × 19² × √(30 × 33,000) / 1.25 = 79.3 kN). The design resistance is PRd = 79.3 kN (governed by concrete crushing). For C40/50 concrete, PRd = 86.8 kN (governed by stud strength at 81.6 kN).
What is the reduction factor for studs in profiled steel decking?
The reduction factor kt per EN 1994-1-1 Clause 6.6.4 accounts for the reduced concrete confinement in profiled deck ribs. For 19 × 100 mm studs in a 60 mm trapezoidal deck (b0 = 90 mm): kt = 0.6 × (90/60) × (100/60 − 1) = 0.60. The stud capacity reduces from 79.3 kN to 47.6 kN. For 19 × 125 mm studs in the same deck: kt = 0.6 × (90/60) × (125/60 − 1) = 0.975 ≈ 1.0 (full capacity achieved). Longer studs significantly improve efficiency in profiled decks.
What γVs value does the UK NA specify for shear studs?
The UK NA to BS EN 1994-1-1 specifies γVs = 1.25 for shear studs. This is the same as the recommended value. The factor applies to both the stud steel failure and concrete failure terms in the PRd formula. The UK NA also confirms that the limiting tensile strength fu = 450 MPa for standard EN ISO 13918 studs (type SD1).
What is the standard shear stud specification for UK composite beams?
The standard UK specification for shear studs is: 19 mm diameter × 100 mm long, grade S235J2+C450 per EN ISO 13918 (type SD1, fu = 450 MPa minimum, Charpy 27 J at -20°C). For deeper composite slabs or where higher capacity is needed, 22 mm × 125 mm studs are used. Studs are through-deck welded to the beam top flange using a drawn-arc welding process per BS EN 1090-2. The minimum flange thickness for 19 mm stud welding is 8 mm.
Related Pages
- EN 1993 Steel Design Overview
- European Steel Properties
- EN 1993 Beam Design Guide
- EN 1993 Column Buckling
- EN 1990 Load Combinations
- UK Steel Chemical Composition
- UK Steel Charpy Values
Educational reference only. All design values are per BS EN 1993-1-1:2005 + UK National Annex and BS EN 10025-2:2019. Verify all values against the current editions of the standards and the applicable National Annex for your project jurisdiction. Designs must be independently verified by a Chartered Structural Engineer registered with the Institution of Structural Engineers (IStructE) or the Institution of Civil Engineers (ICE). Results are PRELIMINARY — NOT FOR CONSTRUCTION without independent professional verification.