Simple Shear Connections — EN 1993-1-8 Clause 3

Simple connections transmit shear only, with negligible moment transfer (nominally pinned). EN 1993-1-8 Clause 3.5 specifies that connections classified as nominally pinned must satisfy the ductility and rotation capacity requirements of Clause 5.1.2.

Connection Types Covered

Fin Plate Connection — Design Checks

A fin plate (shear tab) consists of a single plate welded to the supporting member and bolted to the web of the supported beam. Per EN 1993-1-8, seven checks are required:

1. Bolt Shear (Clause 3.6)

F_v,Rd = α_v × f_ub × A_s / γ_M2

For single shear plane: α_v = 0.6 (grades 4.6, 5.6, 8.8) or 0.5 (grade 10.9)

2. Bolt Bearing — Supported Beam Web (Clause 3.6)

F_b,Rd = k_1 × α_b × f_u × d × t / γ_M2

The thinner of the fin plate and the beam web typically governs. For an IPE 300 in S355 (t_w = 7.1 mm), bearing resistance of the beam web is the critical check.

3. Bolt Bearing — Fin Plate (Clause 3.6)

4. Plate Gross Shear (Clause 6.2.6)

V_pl,Rd = A_v × f_y / (√3 × γ_M0)

For a 200 × 90 × 10 mm fin plate: A_v = 200 × 10 = 2000 mm² V_pl,Rd = 2000 × 355 / (√3 × 1.00) / 1000 = 410 kN

5. Plate Net Shear (Clause 6.2.2)

V_net,Rd = A_v,net × f_u / (√3 × γ_M2)

6. Block Tearing (Clause 3.10.2)

Block tearing is the combination of shear on the bolt line and tension on the transverse row:

V_eff,Rd = f_u × A_nt / γ_M2 + f_y × A_nv / (√3 × γ_M0)

7. Weld Group — Fin Plate to Support (Clause 4.5)

The fillet weld connecting the fin plate to the column flange or web is checked for the combined shear and bending moment from the eccentricity:

τ_|| = V_Ed / Σ(a × l_w) σ_⊥ = M_Ed / W_weld

Worked Example — IPE 300 Fin Plate to Column Flange

Check 1: Bolt Shear

3 bolts in single shear: V_Rd = 3 × 94.1 = 282.3 kN > 180 kN — OK

Check 2: Beam Web Bearing

k₁ = min(2.8 × e₂/d₀ - 1.7, 2.5) = min(2.8 × 35/22 - 1.7, 2.5) = min(2.76, 2.5) = 2.5 α_b = min(e₁/3d₀, p₁/3d₀ - 0.25, f_ub/f_u, 1.0) = min(35/66, 70/66 - 0.25, 1.0) = min(0.53, 0.81, 1.0) = 0.53

F_b,Rd = 2.5 × 0.53 × 490 × 20 × 7.1 / (1.25 × 1000) = 73.7 kN/bolt

3 bolts: 221.1 kN > 180 kN — OK (beam web bearing governs at 73.7 kN/bolt)

Check 3: Fin Plate Bearing

With t_p = 10 mm: F_b,Rd = 91.9 kN/bolt. 3 bolts: 275.7 kN > 180 kN — OK

Check 7: Weld Group

Fillet weld throat a = 6 mm, l_w = 200 mm. Design strength: f_vw,d = f_u / (√3 × β_w × γ_M2) = 490 / (√3 × 0.9 × 1.25) = 251.4 MPa

Weld shear: τ_v = 180,000 / (2 × 6 × 200) = 75.0 MPa

Eccentric moment: M_Ed = 180 × 0.045 = 8.1 kN·m Weld section modulus: W = 2 × 6 × 200² / 6 = 80,000 mm³ Bending stress: σ = 8.1 × 10⁶ / 80,000 = 101.3 MPa

Combined per directional method: √[(101.3/0.9)² + 3 × 75.0²] = 168.9 MPa < 251.4 MPa — OK

Web Cleat (Double Angle) Connection

For heavier shear (over 250 kN), a web cleat connection with two angles bolted to the beam web and the column face provides higher capacity:

Capacity Summary — IPE Beams with 2 × L90×90×10 Angles

Flexible End Plate Connection

A flexible end plate is a partial-depth end plate welded to the beam end and bolted to the column face. Its thin plate ensures sufficient rotation capacity for nominally pinned behaviour.

Design checks per EN 1993-1-8:

1. Bolt group shear (vertical)
2. End plate bearing on bolts
3. End plate block tearing
4. End plate shear (gross and net)
5. Weld — end plate to beam web
6. Supporting member — bolt bearing and column web shear

Typical thickness: 8-12 mm for 200-300 mm plate depth. Rotation capacity verified when t_p ≤ d/2 (where d = bolt diameter).

Frequently Asked Questions

What is the difference between a fin plate and a web cleat connection?

A fin plate uses a single plate welded to the supporting member with bolts through the beam web, providing a simple, economical shear connection. A web cleat uses two angles (one each side of the beam web) bolted through both legs, giving higher shear capacity and better rotational ductility. Fin plates suit moderate shear (50-500 kN); web cleats suit heavier shear (80-600 kN) and are preferred when accidental tie force resistance is required.

How is block tearing checked per EN 1993-1-8?

Block tearing (Clause 3.10.2) involves shear yielding/rupture along the bolt line combined with tension rupture on the perpendicular edge. The design resistance is the smaller of: (1) V_eff,1,Rd = f_u × A_nt / γ_M2 + f_y × A_nv / (√3 × γ_M0) for concentric loading, or (2) V_eff,2,Rd = 0.5 × f_u × A_nt / γ_M2 + f_y × A_nv / (√3 × γ_M0) for eccentric loading. For fin plates with eccentric bolt groups, the eccentric formula always applies.

When can a fin plate connection be classified as nominally pinned?

Per EN 1993-1-8 Clause 5.1.2, a fin plate connection can be classified as nominally pinned when its rotational stiffness S_j,ini ≤ 0.5 × EI_b / L_b, and the moment resistance M_j,Rd ≤ 25% of the beam plastic moment M_pl,Rd. The fin plate's thin plate ensures sufficient rotation through plastic deformation of the plate in bending. Additionally, the vertical distance between the bolt centreline and the weld should be limited to avoid premature weld fracture.

What partial safety factors apply to shear connection design per EN 1993-1-8?

The recommended partial safety factors are: γ_M0 = 1.00 for cross-section resistance (plate gross shear, plate bending), γ_M2 = 1.25 for bolt shear and bearing resistance, and γ_M2 = 1.25 for net section resistance (plate net shear, block tearing). The correlation factor for fillet welds β_w = 0.90 for S355 and β_w = 0.85 for S275. Check the National Annex for any country-specific modifications.

Related Pages

• EN 1993 End Plate Connection → — Moment connection per Clause 6.2
• EN 1993 Bolt Bearing → — Bearing per Clause 3.6
• EN 1993 Weld Capacity → — Fillet weld design
• EN 1993 Bolt Spacing → — Edge and end distances
• All European References →

Educational reference only. Design per EN 1993-1-8:2005 Clauses 3.6, 3.10, and 6.2. Verify bolt shear, bearing, block tearing, and weld group separately. Fin plate capacities assume S355 plate, 8.8 bolts, and standard edge distances. Results are PRELIMINARY — NOT FOR CONSTRUCTION without independent verification by a qualified structural engineer.

Design Resources

Calculator tools

• Fin Plate Shear Connection Calculator
• Bolted Connection Calculator
• Weld Capacity Calculator
• Block Tearing Calculator

Design guides

• EN 1993-1-8 Bolted Connection Worked Example
• Bolted Connection Worked Example
• Bolted Connection Checklist
• Steel Connection Calculator Guide
• Weld Design Checklist

Reference pages

• EU End Plate Connection
• EU Shear Tab
• UK Simple Connections