Failure analysis of high-strength bolts in steel truss bridges

Recent high-profile failures of high-strength bolts – including the fatal Vivekananda Flyover collapse in Kolkata in 2016 – serve to highlight the ongoing risk of failure of such bolts. Based on investigations into continual high-strength bolt failures on steel truss bridges in China, this paper discusses and summarises the typical reasons for failure and what can be done to prevent it. Bolt quality defects, over-tightening during assembly, fatigue loads and environmental corrosion are identified as the main causes. The characteristics of bolt failure damage are highlighted and preventative measures to help reduce the risk of failure are proposed.