Bolt Bearing and Tearout — AS 4100 Clause 9.3

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Reference for bolt bearing and tearout resistance per AS 4100:2020 Clause 9.3.2. Covers bearing capacity, tearout failure modes, and end distance effects for Grade 300 and 350 steel.

Bearing Capacity — Clause 9.3.2.2

φVb = φ × 3.2 × df × tp × fup (φ = 0.90)

Bolt t=8 mm t=10 mm t=12 mm t=16 mm
M16 162 kN 203 kN 243 kN 324 kN
M20 203 kN 253 kN 304 kN 405 kN
M24 243 kN 304 kN 365 kN 486 kN

(Grade 300, fup=440 MPa)

Tearout Capacity — Clause 9.3.2.3

φVb = φ × ae × tp × fup

ae t=8 mm t=10 mm t=12 mm
30 mm 95 kN 119 kN 143 kN
40 mm 127 kN 158 kN 190 kN
50 mm 158 kN 198 kN 238 kN
60 mm 190 kN 238 kN 285 kN

Worked Example

Problem: M20 bolt, 10 mm Grade 300 plate, end distance 40 mm.

Solution: Bearing: φVb = 0.90 × 3.2 × 20 × 10 × 440 = 253 kN Tearout: φVb = 0.90 × 40 × 10 × 440 = 158 kN Critical = min(253, 158) = 158 kN (tearout governs). Increase ae to 64 mm+ for bearing to govern.

Design Resources

FAQ

What governs bearing vs tearout? Tearout governs when end distance is small. For M20 in 10 mm Gr 300, tearout governs at ae < 64 mm.

Minimum end distance per AS 4100? 1.25df for sheared edges, 1.0df for rolled edges per Clause 9.5.3. Min 1.5df recommended.

How to increase bearing capacity? Increase plate thickness, bolt size, or end distance. For tearout-governed, increasing ae is most effective.

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.