Analysis of the Failure of High-Strength Steel Wires in Suspension Bridge Hangers under the Coupling Effect of Corrosion Fatigue after Prefatigue Load

Abstract

Corrosion fatigue coupling failure of high-strength steel wires in suspension bridge hangers is a common failure mode. However, corrosion and fatigue do not occur simultaneously due to the presence of protective sheaths. Furthermore, an analysis of fatigue crack propagation in steel wires based on damage mechanics is complex and not conducive to engineering applications, while fracture mechanics–based methods require the assumption of pre-existing cracks. Addressing the current research gaps, this study first calculates the fatigue damage of steel wires under undamaged conditions of the protective sheath using the S-N curve of high-strength steel wires without corrosion. Secondly, this paper employs corrosion kinetics to calculate the number of fatigue cycles when surface corrosion pits grow on the steel wire and reach the corrosion pit-crack transition after the protective sheath is damaged. Then, fracture mechanics are utilized to calculate crack propagation and determine its fatigue life. Finally, by designing corrosion fatigue coupling experiments on prefatigued high-strength steel wires, theoretical calculation parameters are provided, and the entire theoretical calculation process is realized. The research findings indicate that the theoretical calculation proposed in this paper is simple and convenient, with relatively small errors compared with experiments, providing a reference for the design, operation, and maintenance of cable-supported bridges represented by suspension bridges.