Probabilistic safety assessment of a short span high-speed railway bridge

A probabilistic methodology for the safety assessment of short span railway bridges for high-speed traffic is presented. The purpose is to create a simple, efficient and automatic procedure that allows identifying the critical train speeds over the bridge and assessing the safety of the train–bridge system. The methodology combines simulation techniques with the extreme value theory in order to minimise the required computational time and guarantee accurate results. Stochastic simulation is employed as it allows reflecting the real variability of the parameters that characterise the dynamic response of the train–bridge system. As a case study the safety of a short span filler beam railway bridge crossed by a TGV double train is assessed. The behaviour of short span railway bridges is known to be particularly difficult to predict due to the complexity of the coupled train–track–bridge system, as well as for being particularly sensitive to resonant phenomena. The variability of the bridge, the track and the train was accounted for, as well as the existence of track irregularities. The proposed probabilistic methodology proved to be efficient as it allowed identifying the critical train speeds with a reduced computational cost. Furthermore, for these critical train speeds two different methods were used to estimate the probability of failure. The obtained results showed a good agreement guaranteeing the accuracy of the methodology.