Failure analysis of connecting bolts in collapsed tower crane

The use of tower cranes can cause critical accidents during large building construction projects. Failure of the tower crane results in critical injuries to crane operators and other workers at the construction site. Issues that often cause the fatal collapse of tower cranes include the damage and fracture of the mast (or tower) and turntable parts, and the tower crane slewing‐unit‐support fleeing. Without systematic investigations and proper prevention procedures in place, this type of crane accident, which often leads to worker fatalities, will continue to occur. Therefore, more proactive, specialized and systematic research needs to be performed in terms of forensic engineering to minimize the occurrence of similar disasters. In this research, the tower crane collapse accidents are thoroughly investigated and the exact cause of the damaged crane parts is also identified using fractography and mechanical/chemical characterizations techniques, including visual inspections, field research, scanning electron microscopes and optical microscopes. Specifically, instrumented indentation technique is employed to evaluate the material properties, and energy spectrum analysis is used to determine the chemical characteristics. Based on thorough investigations, it has been identified that the connecting bolts of the tower crane are very vulnerable. It is recommended to improve the reliability of the bolts and to implement additional regulations to check their maintenance and safety. This research clearly provides guidance for investigating crane collapse accidents and contributes to the prevention of similar types of accidents. Several corrective actions and recommendations are suggested to reduce the risk of the tower crane failures.