Corrosion-Fatigue Analysis of Wires in Bridge Cables Considering Time-Dependent Electrochemical Corrosion Process

Environmental corrosion and cyclic dynamic loadings are the main causes of cable failures. In the degradation process of cables, the effects of corrosion and cyclic loading are coupled and the corrosion rate is time dependent. To consider the time-variant properties of the electrochemical corrosion process, the evolution curve of corrosion current density was proposed and introduced into a corrosion-fatigue model. Based on the model, we extracted in situ wires from a tied-arch bridge for the corrosion-fatigue analysis. The surface profiles of the wires from midregion and the anchored region were measured. We found that the corrosions in the anchored region of the wires distribute more uniformly than those in the midregion due to the different contact patterns among wires. And the corrosion characteristics of salt spray-corroded wires are close to those of wires from the anchored region. The corrosion-fatigue simulations considering the effect of environments, loadings, and contact patterns of wires show that the failure modes of wires are greatly affected by loadings; the lifetimes of wires and cables are particularly sensitive to environmental corrosivity; and due to different contact patterns, the lifetimes of cables from the midregion are shorter than those from the anchored region by 30%. The research on corrosion fatigue of cables provides a rational basis for the operation and maintenance of cable-supported bridges.