Time-dependent fatigue reliability analysis of heavy-haul railway steel bridges

• Published in: Engineering structures 2024-04, Vol.305, p.117737, Article 117737
• Main Authors: Lu, Zhao-Hui, Zhang, Sheng-Wang, Zhang, Xuan-Yi, Li, Chun-Qing, Liu, Liang, Zhan, Jia-Wang
• Format: Article
• Language: English
• Subjects: Fatigue; Heavy-haul railway steel bridges; Outcrossing rate method; Stress range model; Time-dependent reliability
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2024.117737

Fatigue of heavy-haul railway bridges has been an ongoing concern due to the excessive stresses and frequent cyclic effects of freight trains. Current fracture-based fatigue research, which promotes fatigue reliability analysis caused by crack propagation, is challenged by the dilemma between the detailed modeling of cyclic stress and the reflection of temporal characteristics of loading conditions. In addition, due to the strong non-Gaussian nature of the fatigue limit state function and the computational inefficiency of integrating finite element analysis, current time-dependent reliability methods need to be further developed. To evaluate the fatigue reliability of heavy-haul railway steel bridges considering the temporal dependence of cyclic train loading, a time-dependent fatigue reliability methodology is developed in this study with two innovations. Firstly, a cyclic stress range model is proposed based on the load analysis at the bridge level, which can capture the time-dependent characteristics of the incurred stress range throughout service life. Then, an improved outcrossing rate method for strong non-Gaussian fatigue limit state functions is developed to reduce the computational costs associated with reliability analysis integrated with the finite element model. The developed time-dependent fatigue reliability methodology is then applied to a heavy-haul railway steel truss bridge located in Shandong, China, which proves its efficiency and accuracy in evaluating the time-dependent fatigue reliability of heavy-haul railway steel bridges. Furthermore, the developed methodology is able to provide insight into the balance between bridge fatigue damage and freight volume, and it is found that the combination of small train axle weight and high operation frequency is the optimal solution to achieve the fatigue reliability of the steel bridge while fulfilling the freight demand. •A time-dependent stress range model based on bridge level load analysis is proposed.•An improved outcrossing rate method for strong non-Gaussian LSF is developed.•The time-dependent reliability for an actual railway steel bridge is evaluated.•The developed fatigue reliability methodology is proved to be accurate and efficient.