Numerical Study on the Influence of Coupling Beam Modeling on Structural Accelerations during High-Speed Train Crossings

The applied mechanical modeling of train and bridge structures is essential in accurately predicting structural vibrations caused by high-speed trains, particularly for the often design-relevant structural accelerations. Considering the interaction effects between the train, the superstructure, and the supporting structure yields more realistic and lower acceleration results compared to simplistic reference models disregarding interaction dynamics. The research presented in this article focuses on modeling single-span girder bridges with a ballasted superstructure as coupling beams. In this approach, the bridge is represented as two vertically coupled beams, with one representing the track (rails and sleepers) and the other representing the supporting structure. Their connection incorporates the stiffness and damping properties of the ballasted superstructure, reproducing its load distribution capacity. A numerical study encompassing a wide range of bridge parameters is conducted, focusing on the calculation of maximum structural accelerations. The results from modeling the bridge as a coupling beam model are compared to those from a simply supported Bernoulli–Euler beam. The excitation is applied as either a moving load or a multi-body model of an Austrian Railjet to evaluate the interdependencies of interaction effects between the vehicle and track and between the track and bridge structure. The comprehensive analysis considers varying bridge span, fundamental bending frequency, mass distribution, structural damping, and coupling stiffness and damping properties to identify correlations with the achievable acceleration reduction using the coupling beam model. Compared to the reference model, the coupling beam model can significantly reduce structural acceleration by up to 80%. Reduction levels primarily depend on the coupling stiffness and critical train speed relative to the bridge’s fundamental frequency, with higher fundamental frequency bridges benefiting the most. These findings provide valuable insights for future structure-specific recommendations for adopting the coupling beam and multi-body train models.