Evaluating System Reliability of Cable-Stayed Bridges Considering Cable Corrosion

Abstract

The cables in a cable-stayed bridge are prone to fatigue damage and atmospheric corrosion, which directly affect the bridge safety. This study presents a framework for system reliability evaluation of in-service cable-stayed bridges subjected to cable degradation. The effect of cable strength degradation on the bridge reliability is demonstrated through simulation on a parallel-series system representation. Machine learning techniques are utilized to approximate the nonlinear and dynamic response surfaces of critical components due to cable rupture, and the system reliability is finally evaluated from the event tree established by the βunzipping method. Both short-span and long-span cable-stayed bridges are selected as prototypes to investigate the influence of cable degradation on the structural system reliability. System reliability of the bridge under ultimate limit state was analyzed. Numerical results show that: the intelligent algorithm is applicable in system reliability assessment of cablestayed bridges; the main failure sequence of the cable-stayed bridges is strength failure of cables in side-span followed by bending failure of towers in the cross section of tower and girder, and the second failure sequences is strength failure of cables in mid-span followed by bending failure of girders in root section; Degradation of cables is the main factor to influence on system reliability of cable-stayed bridges. Compared with fatigue damage of cables, the corrosion of cables leads to a larger decline of system reliability indices. It is important for managers to provide maintenance and prompt replacement measures in order to insure the system reliability of cable-stayed bridges in operational period.