Fatigue study on improved composite box girder bridge with corrugated steel webs

The purpose of the study is to estimate the fatigue behavior of an improved composite box girder bridge with corrugated steel webs (ICBGBCSW) based on a three-dimensional vehicle-bridge coupled vibration system (VBCVS). In the VBCVS, the benchmark of the ICBGBCSW widely used in the highway bridges of Gansu Province of China was adopted as the bridge model, and a 6-axle fatigue load model established based on the traffic data of China was adopted as the fatigue vehicle loading. Based on the established VBCVS, the critical fatigue details of the ICBGBCSW were determined and the effects of pavement roughness condition (PRC) and vehicle speed on the stress ranges experienced by critical fatigue details were first investigated. Then, the fatigue live of critical fatigue details were evaluated based on the deterministic analysis method and reliability analysis method. The results show that the fatigue life of the ICBGBCSW can reach more than 375 years from a deterministic perspective under the current traffic conditions of Gansu Province of China and that the fatigue reliability index of the ICBGBCSW sharply decreases to the target fatigue reliability index of 2 if the PRC stays in the "Poor" class and the "Very poor" class for eight years and two years, respectively. The results obtained in the study can provide a technique support for the wide application of the ICBGBCSW and provide a reference for the bridge management agency to make plans for bridge pavement maintenance.