Keywords: railway bridges, dynamics, ballasted track, experiments, damping characteristics, energy dissipation.

The calculated dynamic behaviour of railway bridges under high-speed traffic often differs from the actual behaviour of its bearing structure. Dynamic calculations, especially of bridges with small and middle spans, generally overestimate the actual vibration responses and lead to conservative and therefore uneconomical results. The ballasted track significantly influences this complex gap between measurement and calculation. However, the consideration of its damping and stiffness properties still entails uncertainties. For accurate consideration of ballasted track in a dynamic calculation, there is a wide range of different models of a track-structure model. Still, these models and related characteristic values vary very widely. In their effort to develop track-structure models that take into account the dynamic properties of the ballasted track in a realistic as possible yet easy to handle way and to close the gap between measurement and calculation, researchers at TU Wien have developed a unique, large-scale test facility to investigate the dynamic behaviour of the ballasted track. The test facility allows for specific research of the ballasted track independent of the bridge structure. This contribution describes the operating principle of the test facility and the dynamic effects observed in it. The focus is on determining the damping properties and their dependencies (frequency, acceleration) and clearly identifying different energy dissipation mechanisms in the ballasted track. Furthermore, the test facility allows for determination of the longitudinal displacement resistance of the track, whereat deviations from the normative specifications appear.

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