Running safety of high-speed railway vehicles on the elastoplastic track-subgrade-bridge system under near-fault pulse-type earthquakes

In this study, the running safety assessment (RSA) of high-speed railways is carried out, with the wheel lift being the derailment criterion. Seventy near-fault pulse-type earthquakes (NFPTEs) are imposed on an elastoplastic vehicle-track-bridge coupled model with elastoplastic supports and shear keys. Since the bridge length in the simulation model is limited by the 14-span high-speed railway simply supported bridge prototype with subgrades and a CRTS II track plate, it is difficult for the vehicles going through the full time-history of ground motions while passing over the bridge. Therefore, the excitation-input-time (EIT) analysis is conducted herein, and it is found that the effects of EIT on RSA under NFPTEs are significant and, as such, cannot be ignored. The EIT analysis also shows that the appearance times and EITs of peak ground acceleration and peak ground velocity of NFPTEs significantly affect the RSA results. In order to reveal and describe the potential relationship between dynamic responses of rail and wheel lift, dynamic contact point responses (DCPRs) are also proposed, and after comparison with the traditional dynamic responses, including rail deformations and displacements, the dynamic contact point velocity in Y-direction (DCPV-Y) are selected for developing of relationship with wheel lift and RSA limitation zone proposal.