Evaluation of Safety Performance of Fractured Joints in Steel Truss Bridge

Abstract

This study aims to evaluate safety performance of fractured joints and failure mechanisms of high-strength friction-grip (HSFG) bolted connections in steel bridge. As a case study, the bolted connections on the Ayeyarwady Bridge (Yadanarbon) in Myanmar have been investigated. Initial inspection of the bridge found that a number of bolts were loosened, missing or had already fractured and most were heavily corroded. The original fractured bolts have been replaced with the new ones as remedial work. The safety performance of fractured joints were evaluated based on simulation results of existing bridge by Midas Civil in accordance with AASHTO standards. The failure mechanisms of the fractured bolts were investigated by analyzing through optical and scanned electron microscopy. The main factors contributed to the failure of the bolted connections at the Ayeyarwady Bridge (Yadanarbon) include delayed fracture, stress corrosion cracking, the fluctuating loads, and the corrosive environment it was subjected to. The failure mechanisms of the fractured bolts were mainly due to pitting corrosion and fretting fatigue.