Numerical Investigation of Train-Induced Vibrations on Overpass Bridges at Road-Railway Intersections and Determination of the Optimal Distance Between the Track Centerline and Bridge Piers

The movement of trains induces vibrations in structures adjacent to railway tracks, which can compromise the user comfort and even the safety of these structures. Given this context, road overpass bridges, as one of the most common structures of road-railway grade separations, are particularly vulnerable to the adverse effects of these vibrations due to their closer proximity to railway tracks compared to residential buildings. Additionally, the vibration effects caused by trains passing underneath such bridges are often overlooked in the design process, highlighting a significant gap in current engineering practices. This study investigates the effects of train-induced vibrations on road overpass bridges and determines the optimal distance between the track centerline and bridge piers. To achieve this goal, a single-span concrete bridge, a ballasted railway, and the surrounding soil with infinite element boundaries were simulated in ۳D using ABAQUS software. The effects of train speed, number of tracks, and the distance between the track centerline and bridge piers on the vibrations generated in the overpass bridge were then analyzed. Furthermore, vibration velocity level in decibels was used as the criterion for determining the optimal distance between the track centerline and bridge piers. Based on the results of finite element analysis under various scenarios, it was concluded that train-induced vibrations on the bridge are directly related to the number of tracks and the train speed, while inversely related to the distance between the track centerline and bridge piers. Additionally, the vertical acceleration, velocity, and displacement at various points on the overpass bridge are negligible due to its high rigidity. Consequently, based on these findings, in cases where there is no access road, an optimal distance of ۳ meters between the track centerline and bridge piers is recommended for single-track routes and ۵ meters for double-track routes.

کلیدواژه ها:

Overpass bridges ، road-railway grade separation ، Train-induced vibrations ، Wave propagation in surrounding media ، ۳D finite element modeling