Sensitivity analysis of weakly coupled multi-span bridges subjected to high-speed trains

Passing a bridge at high speeds can cause a train to induce large vibrations in the structure. The acceleration of the bridge deck is a critical design parameter, as exceeding its limit value can cause ballast instability, resulting in track misalignment. High-speed railway bridges often span large valleys and consist of several single-span beams of the same length that are weakly coupled by the superstructure of ballast and rail. Bridge structures can be modeled with varying degrees of sophistication, ranging from simply supported Euler-Bernoulli beams weakly coupled with rotational springs, to coupled two-beam systems that represent the bridge and track separately and are coupled by vertical and horizontal spring-damper elements. These models typically feature many uncertain parameters that affect the dynamic response to varying degrees. The train modeling strategy further increases the complexity, ranging from single loads to detailed train models with multiple degrees of freedom (DOF) afflicted by additional uncertainties. This study aims to quantify the impact of various parameters on the numerical prediction of the dynamic response of weakly coupled ballasted bridge structures. A sensitivity analysis reveals the most influential parameters, contributing to more reliable design strategies. This is achieved by applying probabilistic methods to the optimized C++ model of the structure. To conduct the parallelized stochastic evaluation, this study uses the software openCOSSAN and the high-performance computing infrastructure of the University of Innsbruck.