Field measurement and dynamic analysis of a steel truss railway bridge

Abstract

In this study a dynamic analysis of a 77-year-old single-span steel truss railway bridge was carried out. The study was approached by three different methods – field measurement, modal analysis using a three-dimensional finite element model of the bridge, and a simple generalised single degree of freedom (SDOF) analysis. Field measurement was conducted using accelerometers and displacement transducers, which were mounted on special sections fixed to an adjacent bridge. The finite element models of the bridge were prepared using beam and shell elements. The dynamic responses studied include the displacement, acceleration and natural frequency of the bridge. The results showed that the generalised SDOF model, with simple addition of the effects of each axle, provided reasonably accurate displacements compared to the measured values. The generalised SDOF model, finite element model with beam elements and finite element model with shell elements also gave reasonably accurate estimates for the natural frequency of the bridge.