Rail-Structure Interaction in Railway Bridge Design: Challenges and Modeling Approaches

Rail-Structure Interaction (RSI) refers to the complex mechanical and structural interplay between railway track systems and supporting bridge structures. This interaction arises from a combination of temperature-induced expansion and contraction, longitudinal forces generated by train braking and acceleration, and vertical deformations resulting from live loads and differential settlement. With the increasing prevalence of high-speed rail networks, heavier axle loads, and longer-span bridges, RSI has become a critical consideration in railway bridge design and safety assessment. Inadequately addressed RSI effects can lead to excessive stresses in the rails, rail misalignment, premature wear of structural components, and, in severe cases, track buckling or bridge damage. This paper investigates the mechanisms of RSI, reviews international design guidelines—particularly EN 1991-2 and AREMA—and presents a numerical modeling framework to analyze RSI behavior under various conditions. A two-dimensional finite element model (FEM) was developed using ANSYS to simulate ballasted track systems over simply supported steel bridge spans. The model incorporates nonlinear boundary conditions, frictional interfaces, and ballast stiffness variations to closely replicate field conditions. A parametric study was conducted by varying bridge span lengths (30–90 meters), bearing types (fixed, guided sliding, free), ballast stiffness (20–100 MN/m), and thermal and braking loads. The results highlight the sensitivity of rail stresses and bridge displacements to both structural and track-related parameters. Specifically, the study finds that guided sliding bearings and optimal ballast stiffness significantly reduce RSI-induced stresses. Expansion joints, while effective in stress relief, may pose long-term maintenance concerns. The findings underscore the necessity of an integrated design approach that considers bridge, track, and environmental factors concurrently. The paper concludes with practical recommendations for improving RSI modeling and suggests that future research should focus on field validation and real-time monitoring to enhance the reliability of design practices.