Investigation of Vehicle-Bridge Interaction in Railway Bridges under the Effect of Earthquake Excitation: An Analytical and Numerical Approach

Abstract

Vehicle-bridge interaction (VBI) is critical in the design, assessment, and monitoring of bridge structures, especially for high-speed railway (HSR) systems. Given the expansion of HSR networks into seismic-prone regions, the likelihood of earthquake excitation during train passage has increased, giving rise to seismic vehicle-bridge interaction (SVBI) as a vital research focus. Unlike traditional earthquake engineering, which evaluates bridge performance in isolation, SVBI considers the dynamic coupling between vehicle and bridge systems under seismic loads.

Accurate SVBI analysis requires high-fidelity models; however, the complexity of coupled systems poses significant challenges. Decoupling methods offer a practical alternative by enabling independent analysis of vehicle and bridge subsystems. This study first derives the analytical formulation of Extended Modified Bridge System (EMBS) approach for decoupling SVBI, considering a three-dimensional VBI model. The proposed approach accommodates multi-degree-of-freedom (MDOF) models, encompassing detailed formulations for the vehicle subsystem as well as the bridge structure, thereby allowing for realistic simulations. It then demonstrates the application of the method through a set of representative case studies. Results show excellent agreement between decoupled and coupled models across various excitation scenarios and different bridge configurations.

Additionally, the study examines the common assumption that vehicles act as tuned mass dampers (TMDs), reducing bridge seismic response. Through comparative simulations, it investigates the influence of moving versus stationary vehicles, revealing key differences in dynamic behavior. The analysis identifies dominant physical mechanisms in both VBI and TMD systems and highlights their similarities and distinctions. It also investigates the influence of vehicle motion parameters—such as speed and entry timing relative to seismic excitation—on the bridge’s subsystem dynamics response.

Key words: decoupled approach, seismic analysis, Extended Modified Bridge System (EMBS) approach, dynamic analysis.

Date of Award	2026
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Ilias DIMITRAKOPOULOS (Supervisor)