Validation of a scaled dynamic test system for simulating a high-speed train passing bridges under seismic excitation

This study presents the validation of a dynamic test system to simulate a high-speed train passing bridges under seismic excitation. The system comprises scaled models of a CRH380A high-speed train and an 11-span simply supported bridge on a shake table array. This innovative apparatus combines seismic loading with the moving train load to replicate train-track-bridge interaction (TTBI) during earthquakes. It allows investigation of various train speeds and seismic excitations, providing invaluable insights into TTBI. First, the detailed similarity design principle based on the equations of motion was discussed, and its applicability to the wheel-rail contact relationship was verified. Then, the dynamic characteristics of the scaled model were identified, and the impact of the error between the scaled model and the theoretical model on the TTBI response was assessed. Furthermore, the comparison of the dynamic test model and the numerical simulation in acceleration responses validated the accuracy of the rigid-flexible coupling model method for the actual TTBI system. Test cases without external excitation, with simple harmonic excitation and with seismic excitation were conducted on the dynamic test system. Results showed that the influence of track irregularity and running speed on train response aligns with the classical train-bridge interaction theory. The successful implementation of this test system marks a significant advance in understanding TTBI mechanics and has significant implications for seismic safety enhancement of railway infrastructure.