Cable Reliability Assessments for Cable-Stayed Bridges using Identified Tension Forces and Monitored Loads

Abstract

The reliability of stay cables is critical to the safety of cable-stayed bridges. This paper investigates and compares reliability assessments of stay cables by using identified cable tension forces and monitored bridge loads. One-year monitoring data from a cable-stayed bridge was used to characterize the probability distributions of cable forces and pertinent bridges loads including temperature of the cable, wind load, and vehicle load. The results show that, for the bridge under study, the cable temperature, the wind load, and the vehicle weight obey the Beta distribution, whereas the axle weight obeys the lognormal distribution, indicating deviations from the design codes. Subsequently, two performance functions are proposed to compute the cable reliability index, where one directly uses the monitored cable forces and the other is based on the monitored loads and the finite element method simulation of the bridge. The computed index based on the monitored cable forces and the performance function I is larger than that based on the monitored loads and the performance function II. The reasonings attributed to the differences and the implication of the present findings in structural design and optimization are discussed.