On the Dynamic Response of Soil-Structure Coupled Railway Infrastructures: The Case of a Portal Frame Bridge

Predicting the dynamic response of portal frame bridges is challenging because of the strong influence of the soil-structure interaction.This aspect adds complexity to the vibratory phenomenon, and, as a result, accurate numerical analyses are difficult to conduct and time-consuming.For this reason, the soil-structure interaction mechanism is seldom considered in the numerical models.However, as evidence shows, this constitutes an important source of discrepancy between numerical and experimental results.In this investigation, a study on an existing portal frame railway bridge is carried out.First, the identification of its modal parameters from experimental data is addressed.Then, a 3D finite element numerical model considering the track-bridge-soil system is implemented.Perfectly matched layers are considered at the model boundaries.The soil-structure interaction is evaluated and the results are used to implement a simplified model, on which the soil is substituted by a series of spring-dampers.After calibration, an experimental-numerical comparison is performed on the bridge 1