Service life prediction for steel wires in hangers of a newly built suspension bridge considering corrosion fatigue and traffic growth

As the critical load-carrying components, hangers of long-span suspension bridges are exposed to the combined actions of corrosive environment and cyclic stresses. Service life evaluation of hangers is an important issue for bridge maintenance and safety. In this study, a service life prediction framework is presented by establishing a direct link between site-specific traffic loads and corrosion fatigue processes of hangers' steel wires. The cyclic stress responses of hangers are firstly obtained by inputting the weigh-in-motion (WIM)-based reconstructed vehicular loads to the refined finite element model. The fatigue loading effects, that is, equivalent stress ranges and corresponding number of cycles extracted from cyclic stresses, are explicitly expressed as functions of the bridge-site traffic loads. Then, the service lives of steel wires can be predicted based on the corrosion fatigue analysis with traffic growth. The proposed framework is applied to a newly built suspension bridge in China. Ninety-day bridge-site WIM data are utilized. It is indicated that the growing traffic density would greatly shorten the pitting corrosion time and accelerate the fatigue crack propagation of the steel wires, resulting in a dramatic decrease of the service lives of the hangers' steel wires.