EN 1994 Shear Stud Design — Headed Stud Capacity per Eurocode 4

Q: What is the design shear resistance of a 19 mm headed stud in C30/37 concrete per EN 1994-1-1?

The design resistance of a 19 mm × 100 mm headed stud in C30/37 concrete is P_Rd = 69.5 kN. This is governed by the concrete failure mode (0.29 × α × d² × √(f_ck × E_cm) / γ_V = 69.5 kN) rather than the steel shank failure mode (81.4 kN).

Q: What is the minimum degree of shear connection for composite beams per EN 1994-1-1?

Per Clause 6.6.1.2, the minimum degree of shear connection η depends on the span. For spans ≤ 5 m, η_min = 0.40. For spans > 25 m, η_min = 0.55. Between 5 and 25 m, linear interpolation applies: η = 0.40 + 0.03 × (L - 5). For an 8 m span, η_min = 0.49 (49% of full shear connection).

Complete guide to headed shear stud (shear connector) design per EN 1994-1-1:2004 Clause 6.6. Design shear resistance P_Rd, degree of shear connection for composite beams, stud diameters 19 mm, 22 mm, and 25 mm, transverse spacing, and longitudinal arrangement.

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Design Shear Resistance — Clause 6.6.3.1

The design shear resistance of a headed stud is the minimum of:

P_Rd = min(0.8 × f_u × π × d² / 4 / γ_V, 0.29 × α × d² × √(f_ck × E_cm) / γ_V)

Where:

f_u = ultimate tensile strength of the stud (≤ 500 MPa)
d = nominal shank diameter of the stud
γ_V = 1.25 (partial factor for shear connectors)
f_ck = characteristic cylinder compressive strength of concrete
E_cm = secant modulus of elasticity of concrete
α = correction factor = 0.2 × (h_sc / d + 1) for h_sc/d ≥ 4, or = 1.0 for h_sc/d < 4

The first term represents stud shank failure. The second term represents concrete cone failure.

Stud Resistance Table

Stud Grade — EN ISO 13918 (f_u = 450 MPa typical)

Stud Diameter	h_sc (mm)	h_sc/d	α	Steel Failure	Concrete Failure (C30/37)	P_Rd (kN)
19 mm	100	5.3	1.0	81.4 kN	69.5 kN	69.5
19 mm	125	6.6	1.0	81.4 kN	69.5 kN	69.5
22 mm	100	4.5	1.0	109.1 kN	93.2 kN	93.2
22 mm	125	5.7	1.0	109.1 kN	93.2 kN	93.2
25 mm	100	4.0	1.0	141.4 kN	120.3 kN	120.3
25 mm	125	5.0	1.0	141.4 kN	120.3 kN	120.3

For h_sc/d ≥ 4, h_sc ≥ 4d, α = 1.0 (applies to all standard studs). The concrete failure mode governs for all C30/37 concrete.

Effect of Concrete Grade (22 mm stud, h_sc = 100 mm)

Concrete Grade	f_ck (MPa)	E_cm (GPa)	P_Rd (kN)
C25/30	25	31.0	80.7
C30/37	30	33.0	93.2
C35/45	35	34.0	104.2
C40/50	40	35.0	114.3
C50/60	50	37.0	133.8

Degree of Shear Connection — Clause 6.6.1.2

The degree of shear connection η is:

η = N_c / N_c,f

Where N_c is the compressive force in the concrete (from the number of shear connectors) and N_c,f is the compressive force at full shear connection (concrete or steel section capacity, whichever is less).

Minimum Degree of Shear Connection

For steel sections with equal flanges and L ≤ 25 m:

Span L	Minimum η
L ≤ 5 m	0.40
5 < L ≤ 10 m	0.40 + 0.03 × (L - 5)
10 < L ≤ 25 m	0.55

For L = 8 m: minimum η = 0.40 + 0.03 × 3 = 0.49.

Worked Example — IPE 300 Composite Beam

Parameter	Value
Beam	IPE 300, S355
Concrete slab	150 mm deep, C30/37
Effective width	1500 mm
Span	8.0 m
Studs	19 mm × 100 mm

Shear Connection Design

Parameter	Value
P_Rd (19 mm, C30/37)	69.5 kN
N_c,f (full connection)	min(A_a × f_y / γ_M0, b_eff × h_c × 0.85 × f_ck / γ_c)
A_a × f_y / γ_M0	5380 × 355 / 1.00 = 1910 kN
b_eff × h_c × 0.85 f_ck / γ_c	1500 × 100 × 0.85 × 30 / 1.50 = 2550 kN
N_c,f	1910 kN (steel governs)
Studs for full connection	1910 / 69.5 = 27.5 ≈ 28 studs
Minimum η (L = 8 m)	0.49
Minimum studs	0.49 × 28 = 14 studs
Provide	20 studs (2 rows of 10, 200 mm spacing)

Detailing Requirements — Clause 6.6.5

Parameter	Requirement
Stud height h_sc	h_sc ≥ 4d (≥ 76 mm for 19 mm stud)
Stud spacing long.	min 5d, max 6 × slab depth or 800 mm
Stud spacing trans.	min 4d, max 600 mm
Cover to stud edge	min 20 mm in solid slab
Stud head diameter	≥ 1.5d
Stud head height	≥ 0.4d

Frequently Asked Questions

What is the design shear resistance of a 19 mm headed stud in C30/37 concrete per EN 1994-1-1?