Ductile fracture simulation on 10.9 HP bolts under composite loading at elevated temperatures

The mechanical properties of the bolts deteriorate significantly at elevated temperatures; accurate prediction of the performance and fracture behaviour of steel bolted connections is essential for the fire safety assessment of steel structures and is a prerequisite for performance‐based fire safety design. Existing studies on the fracture mechanical properties of bolts at elevated temperatures are limited due to the difficulty and economics of testing. This paper presents the numerical analysis of combined loads on grade 10.9 high‐performance (HP) bolts. Based on the proven fracture analysis method, the fracture behaviour of HP bolts at high temperatures was investigated by fitting material parameters. Significant changes in the fracture shape of the bolts at high temperatures were found. The ultimate resistance, fracture deformation behaviour and strength reduction factors were analyzed. This study demonstrates the potential of using numerical analysis to reasonably predict the fracture behaviour of steel bolted joints at high temperatures and under complex loading conditions.