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Calculation of dynamic impact loads for railway bridges using a direct integration method

Abstract This paper introduces railway bridge assessment in the UK and the concept of dynamic impact loads. The dynamic impact loads demonstrated in the codes of practice in several other countries have been reviewed and have been found to be significantly different in the different codes. A technique for calculating dynamic impact load using a direct integration method has been developed. In many cases, the mass of the train may be similar to the mass of the bridge in heavy railway bridges but the mass of the vehicle is normally neglected in an analysis due to complexities in computation. Time-varying non-linear mass models are employed to reflect the effect of moving vehicle mass. An existing prototype bridge has been selected to compare results from the codes of practice and the technique developed in this study. The correlation between vehicle speed, axle load, and dynamic impact load has been investigated.