Dynamic effects on a train-bridge system caused by stochastically generated turbulent wind fields

Abstract

The present paper presents a methodology for evaluating the possibility of derailment of trains running over bridges subjected to crosswinds. The dynamic model consists of a train–bridge interaction coupling system that takes into account the contact interface between wheel and rail from which the contact forces arise. These contact forces are the inputs for the safety criteria that are later used to evaluate derailment. The wind fluctuating component is accurately considered through a stochastic process that generates correlated wind velocity fields, which are later converted into wind loads that are applied to both the bridge and the train. Before evaluating the running safety, the dynamic response of the train–bridge system is assessed to understand the influence of the train speed and wind velocity on it. Then, the running safety is analyzed based on three criteria, namely the Nadal, Prud’homme and unloading indexes, being the influence of the bridge lateral flexibility in the derailment risk also discussed. Finally, the results obtained with the stochastic wind model are compared with those obtained with a simplified discrete gust model proposed by the European normative. The maximum wind velocities, obtained through the stochastic and simplified formulations, for which no derailment criteria allowance is exceeded are computed and a comparative critical analysis between the models is presented.