Steel · Connections: bolts & welds
Bolt design & bolt group calculator
Bolt shear, tension, bearing and tear-out; eccentric bolt group by the elastic method.
Standard: AS 4100 Cl 9.3, 9.4 · AS/NZS 1252
Inputs in the worked example
The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.
| Input | Value | Unit |
|---|---|---|
| Bolt | M20 | |
| Grade | 8.8/S | |
| Shear planes through threads | 1 | |
| Shear planes through shank | 0 | |
| Lap reduction kr | 1 | |
| Ply thickness | 10 | mm |
| Ply fu | 440 | MPa |
| Edge distance (tear-out) | 35 | mm |
| Bolt rows | 3 | |
| Bolt columns | 2 | |
| Pitch (vertical) | 70 | mm |
| Gauge (horizontal) | 70 | mm |
| Shear V* | 120 | kN |
| Eccentricity of V* | 100 | mm |
| Tension N* (group) | 0 | kN |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| φVf (shear, per bolt) | 92.6 | kN |
| φVb (bearing / tear-out) | 123 | kN |
| φNtf (tension) | 163 | kN |
| Bolts in group | 6 | |
| Σr² | 26,950 | mm² |
| Critical bolt force | 47.3 | kN |
| Tension per bolt | 0.00 | kN |
| (V/φVf)² + (N/φNtf)² | 0.261 |
- ✓ Critical bolt shear ≤ φVf
- ✓ Ply bearing ≤ φVb
- ✓ Combined shear + tension ≤ 1.0
Method, formulas and assumptions
- Vf = 0.62 fuf kr (nn Ac + nx Ao), fuf = 830 MPa, φ = 0.8 (Cl 9.3.2.1)
- Ntf = As fuf (Cl 9.3.2.2); Vb = min(3.2 df tp fup, ae tp fup) (Cl 9.3.2.4)
- Elastic method: direct V/n plus V·e·r/Σr² perpendicular to r
- Combined: (V*/φVf)² + (N*/φNtf)² ≤ 1.0 (Cl 9.3.2.3)
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.