A Finite Element Methodology to Study Soil–Structure Interaction in High-Speed Railway Bridges

This paper analyzes the dynamic soil–structure interaction (SSI) of a railway bridge under the load transmitted by high-speed trains using the finite element method (FEM). In this type of bridges, the correct analysis of SSI requires proper modeling of the soil; however, this task is one of the most difficult to achieve with the FEM method. In this study, we explored the influence of SSI on the dynamic properties of the structure and the structure's response to high-speed train traffic using commercial finite element software with direct integration and modal superposition methods. High-speed trains are characterized by the high-speed load model (HSLM) in the Eurocode. We performed sensitivity analyses of the influence of several parameters on the model, such as the size and stiffness of the discretized soil, mesh size, and the influence of the dynamic behavior of the excitation. Based on the results, we make some important and reliable recommendations for building an efficient and simple model that includes SSI. We conducted a dynamic analysis of a full model of a general multispan bridge including the piers, abutments, and soil and identified the impact factors that affected the design of the bridge. The analysis revealed that the methodology we propose allows for a more accurate determination of the dynamic effects of the passage of a train over the bridge, compared to the simpler and more widely used analysis of a directly supported isolated deck, which tends to overestimate the impact factors.