Corrosion Fatigue Evaluation of Suspender Cables in Railway Bridges Considering the Effect of Train-Induced Flexural Vibration

An increasing number of arch and suspension bridges have been built in railway networks. Suspender cables serve as the critical load-transmitting component in these cable-supported bridges, which are subjected to a combination of the adverse impacts of train-induced fatigue stress and a corrosive environment. However, little research effort has been made on the corrosion fatigue performance of railway bridge suspender cables. This paper proposes an approach for the corrosion fatigue evaluation of the suspenders that integrates a sophisticated fatigue stress computational model and an enhanced corrosion fatigue model. The dynamic stresses of the suspenders are computed using a three-dimensional (3D) train-bridge interaction (TBI) model, which is established to consider the train-induced flexural vibrations on the suspender. Then, the corrosion fatigue damage of steel wires is characterized by a continuum damage mechanics-based model. The condition for the transition from pitting to fatigue crack is derived. Based on this, the corrosion fatigue assessment framework for suspenders is formulated, which can describe the time-dependent damage evolution that considers significant effects. A tied-arch railway bridge is investigated to showcase the effectiveness of the proposed approach and gain insights into the corrosion fatigue performance of the suspender cables in railway bridges. The field test data are employed to validate the stress computational model. In addition, the time-dependent corrosion fatigue evolution and service life of the suspenders are obtained. The results show that the suspender flexural vibrations cause considerable variations in the equivalent stress range and number of stress cycles. The corrosion fatigue life (CFL) of the critical suspender is reduced by 25% on average due to train-induced flexural vibrations.