Failure analysis of the suspender fracture in a railway self-anchored suspension bridge: Damage identification, fatigue mechanism and remaining life prediction

Abstract

A suspender fracture accident was reported in a railway self-anchored suspension bridge, arousing intensive concern to fatigue issue in the suspender end connector area which is exposed to complex stress states and cyclic traffic loads. Some critical issues involving the fatigue mechanism, the damage identification, and the remaining life prediction were investigated on the basis of on-site and lab tests, numerical simulations, and theoretical analyses. It was found that the root of an ear-plate screw with threads becomes the fatigue-prone detail since action of stress concentration and the unexpected cyclic bending. Also, an effective crack identification scheme by the ultrasonic phased array inspection as well as a verified prediction method for remaining life were proposed. Short suspenders in the main span are significantly affected by the cyclic bending, resulting in the extremely lower fatigue life than that of a long or side-span suspender. Suggestions for a classified disposal plan are provided based on fatigue risk for individual suspender.