Damage Identification of Tie-Down Cables in Cable-Stayed Bridges Using Vehicle-Induced Displacement

Abstract

Tie-down cables are critical components of uplift-restraint bearings in bridges. Damage of a tie-down cable substantially affects the safety of a bridge and driving conditions. In this study, a damage identification method for the tie-down cable in cable-stayed bridges is developed by using vehicle-induced displacement. First, a vehicle-induced displacement is derived through theoretical mechanical analysis. By introducing an area reduction factor for the tie-down cable, a displacement-based damage index is proposed, and the changing regularity of the proposed damage index is comprehensively illustrated in different damage cases. Then, the numerical simulation with the corresponding area reduction of the tie-down cable is implemented for a cable-stayed bridge to validate the rationality of the damage index. The results demonstrate that the proposed damage index is not affected by the weight of the vehicles and is effective in detecting the area reduction of tie-down cables without the information of vehicle weights. The changing regularity of the damage index can reflect the damage cases of tie-down cables. For the actual application of the proposed method, the damage index possessing a minimum initial value, which is obtained when vehicles pass in the outermost lane of a bridge, is optimum.