Assessment of condition of railway track is crucial for track design, repair and effective maintenance operations. In-field dynamic testing in combination with track modelling represents an efficient strategy for identification of the current condition of railway track structure and its components. This paper presents an integrated approach combining field measurements, experimental modal analysis and finite element modelling to evaluate the dynamic parameters of the in-situ railway track components. Based on the discrete support model, a two-degree-of-freedom (2DOF) dynamic model of railway track is analysed in order to extract the modal properties of the track components from the field dynamic testing results obtained using an instrumented hammer impact technique. A railway track site in Central Queensland managed by Queensland Rail (QR) was selected to perform the field tests. Five sleeper-fastening-rail assemblies were selected for dynamic testing. The frequency response functions (FRFs) were recorded by using Bruel & Kjaer PULSE vibration analyser in a frequency domain between 0 and 1,600 Hz. The data obtained have been best fitted using the least-square technique to determine the dynamic stiffness and damping constants of the tested track components. These results can supply a track maintenance engineer with very important information on the current state of the railway track. In addition, the experimentally determined resonance frequencies along with the dynamic properties of the track components can provide an important input for determining the maximum speed and axle load for the future track upgrades.
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