Experimental and numerical analysis of a composite bridge for high-speed trains

This paper presents the in situ dynamic measurements and the experimental validation of the numerical model for the prediction of high-speed train-induced vibration. The Sesia viaduct is considered, which is a composite railway bridge consisted by seven spans. The responses of the bridge are measured both under ambient vibration and under the excitation of Italian ETR500Y high-speed trains. From the modal analysis of the ambient vibration data, two types of mode shapes are identified by operational modal analysis. Based on the dynamic behavior of the adjacent spans, the modes of the bridge can be distinguished as symmetrical and anti-symmetrical patterns, which indicates that although each span is statically decoupled, the ballast and the rails realize a connection between the adjacent spans of the bridge. To predict the bridge response due to the passage of high-speed trains, two numerical models are considered. First, a train–bridge interaction model for a vehicle system with 15 degrees of freedom is implemented. Second, the train is modeled as a series of moving load. The numerical simulation is validated by comparing the predicted accelerations and strains with measured results, Both models give a good correspondence between the predicted and the measured response. This study provides a better understanding of the structural behavior of a composite railway bridge under the excitation of high-speed trains.