Dynamic Behavior of Railway Bridges Under High-Speed Traffic Loads

The interest on the dynamic behavior of railway bridges has grown in recent years due to the emergence of high-speed trains that induce a significant dynamic effect. A correct understanding of the dynamic behavior of a railway bridge is essential, as an accurate prediction of the structure's response contributes to cost-effective design for new bridges and rational operation of existing ones.The objective of this study was to investigate the dynamic behavior of an existing single-track railway bridge under dynamic traffic loads. For this study, it was assumed that the bridge is traversed by a high-speed train traffic with different speeds, ranging from a minimum speed of 100 km/h to a maximum of 300 km/h.Moving vehicles, represented by Eurocode LM 71 and HSLM-A1 models, are simulated using constant intensity forces at the wheel locations, moving across the bridge at a constant speed. Dynamic interactions between the vehicle and the bridge, as well as track irregularities, are not considered.To illustrate the variation of the dynamic amplification factor during the passage of the convoy at different speeds, a 3D dynamic model of the bridge structure was created, and dynamic analysis was performed using the modal superposition method.The paper presents variations in displacements, accelerations, and the dynamic amplification factor determined through dynamic analysis for different elements of the bridge structure, depending on the speed of the moving forces. The numerical resonance speed, significantly amplifying the bridge structure's response, was identified.