Fatigue reliability-based replacement strategy for bridge stay cables: A case study in China

Abstract

Due to repetitive external loads and aggressive environments, performance deterioration of stay cables is a major concern for cable-stayed bridges. To balance failure risk and maintenance cost, this paper presents a case study of using a practical fatigue reliability-based method to form an optimal replacement schedule for stay cables. First, based on long-term recorded vehicle information, the statistical analytic was performed to classify vehicles and establish probabilistic models of vehicle parameters (e.g., gross vehicle weight). Then, with the assistance of finite element model, structural responses in stay cables were generated under the simulated random traffic loads. Meanwhile, the time-variant reliability index was introduced to quantitatively characterize the performance deterioration, where the time-dependent corrosion inside the cables was considered. Based on the time-variant reliability index, the cost analytic was conducted to obtain an optimal replacement schedule for stay cables by minimizing the expected annual average cost. The developed method was applied to stay cables of the Dashengguan Yangtze River Bridge, and the most critical cable No. A5 and the longest cable No. J21 were emphasized. As a result, different stay cables have different optimal replacement timings, where the cable No. A5 has the shortest service life - replaced at the 17th service year with the minimum expected annual average cost of ¥ 44,551. Based on the optimal cable replacement timing for each stay cable, replacement schedule for stay cables in practise could be determined accordingly.