In-situ dynamic load testing and high-speed train safety assessment on a railway long-span deck type arch bridge with ballastless track

This study investigates the dynamic characteristic of the Meixi River Bridge, the longest high-speed railway bridge with ballastless track and deck-type reinforced concrete arch, under a running train at different speeds. The testing train speeds varied from 200 km/h to 385 km/h. The bridge was instrumented with different types of sensors to measure accelerations, strains, and dynamic deflections. The measured data were used to identify mode shapes of the bridge. Based on the measurement results, this study assessed the effects of train speed on the vertical and transverse accelerations, strain impact factors, dynamic deflections, derailment coefficient, and wheel unloading rate, which are critical parameters affecting train safety and riding stability. Based on the in-situ measurement data, a train-track-bridge coupled vibration model was established using the finite element method and multi-body dynamics method to investigated the dynamic behavior of the train under different temperatures. The results revealed that extreme high temperatures have significant impacts on driving safety. This study provides in-situ dynamic test data and a new assessment method for promoting the driving safety and operation efficiency of high-speed railway arch bridges.