Site-Specific Fatigue Load Spectrum for Urban Bridges

Significant changes in vehicle loads - particularly the rapid increase in traffic flow and the large-scale emergence of heavy trucks - have occurred in China due to the development of the automobile industry and transportation within the past two decades. However, the codes used in China are relatively old and there are no explicit formulations for calculating the fatigue of components with specific loading patterns, loading values, and fatigue stress amplitudes. In this study, ten representative vehicle types were obtained from traffic flow data collected on an urban expressway in a logistics zone using weight-in-motion system, and the fatigue load spectrum was studied. Based on the axle weight and axle space of ten representative vehicle types, six equivalent vehicle models were established using the equivalent fatigue damage theory and a simplified fatigue vehicle load spectrum was developed for urban expressway bridges.