Methods for Closing the Discrepancy Between Calculated and Measured Dynamic Behavior of Railway Bridges – Research and Application

Abstract

High-speed traffic imposes dynamic loads on railway bridges that require both structural safety and serviceability considerations. A bridge’s permissible vibration response defined by standards, expressed through acceleration limit values, serves not only to evaluate load-bearing capacity but also to assess the operational suitability of trains on existing railway lines. Comparisons of computational simulations and measurements often reveal significant discrepancies, which can be traced back to simplified or insufficiently accurate modeling approaches and associated conservative assumptions. These frequently lead to overly conservative results. A key input parameter for computational simulations is the assumed damping behavior of the structure, described by Lehr’s damping ratio. If this parameter is not specifically determined for a given railway bridge with in-situ tests, the current Eurocode specifies a lower-bound value to be applied. These values are, however, considered overly conservative compared to measurement data. Furthermore, discrepancies between calculations and measurements are exacerbated by neglecting significant vibration-reducing mechanisms in favor of simpler calculation methods. These mechanisms include vehicle–bridge interaction and track–structure interaction.

The stated objective of the author’s research is to isolate and elucidate these mechanisms as well as their interactions through dedicated research, and to develop novel methods that enable the most accurate vibration predictions possible, with simplified modeling at the same time. The aim is to exploit unused potential wherever possible while avoiding uncertain results.