Seismic running safety assessment for stochastic vibration of train-bridge coupled system

With the rapid development of high-speed railway, the seismic running safety problem of high-speed train passing on bridge is becoming increasingly prominent. Since different wheel-rail contact states including uplifting, climbing up, detachment, recontact and derailment have been introduced into the simulation of train-bridge coupled (TBC) system, there are many problems arising for the mainstream derailment index in evaluating seismic running safety and stochastic analysis of train. To this end, a seismic running safety assessment for stochastic response of TBC system was first proposed in this paper. In this system, a detailed wheel-rail contact model was built to calculate the time-varying contact point and the contact force, which can be applied to simulate the detachment and recontact between the wheel flange and rail. Meanwhile, a stochastic analysis framework for derailment of the TBC system is developed. The stochastic vibration of a high-speed train traversing a multi-span prestressed simply supported box-girder bridge under earthquake with random magnitude was studied. In addition, an improved train running safety index, lateral wheel-rail relative displacement, was proposed and compared with the derailment factor and the offload factor to verify its feasibility. It shows an intuitive result as a derailment index in a stochastic train running safety analysis under earthquake. Furthermore, the lateral wheel-rail relative displacement and pertinent derailment probability were significantly affected by the intensity of the earthquake. The methodology herein can be helpful in seismic running safety assessment of high-speed train.