06.01: Critical bridges in high‐speed railway lines: Systematic identification for specific trains

Abstract

ABSTRACTFor the design of railway bridges in railway lines with a speed limit above 200 km/h the dynamic effects have to be considered. The present design codes such as Eurocode (EN 1991‐2) achieve this by assuming different high‐speed load models (for example HSLM‐A) for the dynamic calculations of all railway bridges in the network. If train manufacturers design a new high‐speed train which fulfills the limits of the load model HSLM‐A (geometric and weight parameters), then no additional verification of the dynamic effects are required as all the railway bridges already comply with the HSLM‐A. New challenges arise if a train manufacturer decides to differ from these limits, as they may be uneconomic (for example short length of single car). Furthermore, a railway operator may wish to expand the use of high‐speed trains on traditional lines, which were, up to now, not verified for dynamic loads. In both cases, each single railway bridge in the railway network has to be recalculated by considering the geometry and weight parameters of the new developed train, which seems to be a cumbersome task. Therefore this paper deals at first with the different train parameters and their limits, which need to be fulfilled in order to be in line with the load model HSLM‐A and shows which of them are more critical than the others. This is done by assuming 8 different fictitious trains which fulfill or slightly exceed these limits. The different structural hazard is determined by performing systematic dynamic analyses for a large parameter range of single‐span bridges and train speeds. The second part of this paper deals with a methodology, which makes it possible to determine the critical bridges in high‐speed railway lines (critical length and critical first natural frequency) for a given train load model in order to reduce the total number of bridges to be investigated. In addition, the train signature curve is analysed with respect to support the dynamic analysis.