Australian Shear Tab — AS 4100 Single Plate Connection
Quick access: [[Australian Steel Grades|/reference/australian-steel-grades/]] | [[Australian Steel Properties|/reference/australian-steel-properties/]] | [[Australian Beam Sizes|/reference/au-beam-sizes/]] | [[Australian Bolt Capacity|/reference/australian-bolt-capacity/]] | [[AS 4100 Beam Design|/reference/as4100-beam-design-example/]] | [[All Australian References|/reference/]]
Reference for shear tab (single plate) connection design per AS 4100:2020 Clause 9. A single plate welded to the support and bolted to the beam web. Covers bolt shear, plate bending, weld, and block shear checks.
Shear Tab Components
| Element | Check | AS 4100 Reference |
|---|---|---|
| Bolts (beam web) | Shear, bearing, tearout | Clause 9.3 |
| Plate | Block shear, bending, gross/yield | Clause 9.2 |
| Weld (plate to support) | Fillet weld capacity | Clause 9.7 |
| Support (column/beam) | Local bending, web crippling | Clause 5.9 |
| Bolt group | Eccentricity from weld line | Clause 9.3 |
Standard Shear Tab Sizes
| Beam Range | Plate Size (mm) | No. Bolts | Bolt Size |
|---|---|---|---|
| 250UB | 150×180×8 | 3 | M20 8.8/S |
| 310UB | 150×230×10 | 4 | M20 8.8/S |
| 360UB | 150×280×10 | 5 | M20 8.8/S |
| 410UB | 150×330×10 | 6 | M20 8.8/S |
| 530UB | 150×380×12 | 7 | M20 8.8/S |
| 610UB | 150×430×12 | 8 | M20 8.8/S |
Plate length ≈ 2.5 × beam depth. Min 3 bolts per AS 4100.
Design Checks
Bolt shear: φVfn per bolt × n ≥ V*
Plate block shear (Clause 9.2.4): φVb = φ × 0.5 × fu × Ant + φ × 0.6 × fy × Agv ≤ φ × 0.5 × fu × Ant + φ × 0.6 × fu × Anv
Plate bending (eccentricity e = s/2 + gap from weld): Mpl* = V* × e (eccentricity causes plate rotation) tp ≥ √(6Mpl* / (φ × fy × Lp))
Weld: φvw × Lw ≥ V* (fillet weld along plate edges)
Worked Example
Problem: Design shear tab for 310UB46.2 (V*=200 kN). Plate: Grade 300. Bolts: M20 8.8/S.
Solution:
- Plate size: 150×230×10 mm, 4-M20 bolts
- Bolt shear: φVfn = 107 kN per M20 8.8/S. 4 × 107 = 428 > 200 OK
- Plate block shear (critical path): Ant=900 mm², Agv=3,450 mm²
- φVb = 0.90×0.5×440×900 + 0.90×0.6×300×3450 = 178 + 559 = 737 kN > 200 OK
- Weld: 6 mm FW fillet each side, capacity = 0.90 × 0.6 × 490 × 6/√2 × 230 × 2 = 517 kN > 200 OK
Design Resources
- [[Australian Steel Grades|/reference/australian-steel-grades/]] | [[Australian Steel Properties|/reference/australian-steel-properties/]] | [[Australian Beam Sizes|/reference/au-beam-sizes/]] | [[Australian Bolt Capacity|/reference/australian-bolt-capacity/]] | [[AS 4100 Beam Design|/reference/as4100-beam-design-example/]] | [[All Australian References|/reference/]]
FAQ
What is the minimum shear tab thickness? 8 mm minimum. Typically 10 mm for standard beams. Governed by plate bending from bolt eccentricity.
How many bolts minimum for a shear tab? 3 bolts minimum per AS 4100. Most common: 4-6 bolts depending on beam depth and shear force.
Does shear tab have eccentricity? Yes. The bolt line is offset from the weld line (typically 50-80 mm), creating a moment in the plate. Must be checked for combined shear + bending.
Educational Use Only — This reference is for educational and preliminary design purposes only. All structural designs must be independently verified by a licensed Professional Engineer (PE) or Structural Engineer (SE) in accordance with AS 4100:2020 and all applicable Australian Standards. Results are not for construction.