Longitudinal forces in continuously welded rails on bridgedecks due to nonlinear track–bridge interaction

In this contribution longitudinal forces in continuously welded rails on railway bridges are addressed. Here, the interaction between track and structure cannot be neglected. European codes recommend an independent treatment of different longitudinal loading cases taking a nonlinear stiffness law into account. The final rail stresses are obtained by a summation of the results of the above independent calculations. The influence of the load history is completely neglected in this conventional approach. Based on an explanation of the track–bridge interaction problem a truly nonlinear description is proposed in this paper. Here, the deformation history is of essential importance. Exact stiffness formulations are derived for the loading cases ‘temperature change’, ‘sudden change of ballast stiffness when the train reaches the bridge’, ‘bending of the supporting structure’ and ‘braking’. Numerical results are presented for a typical track–bridge system and different combinations of the above loading cases. Extensive parameter studies enable a general comparison of the rail stresses obtained using the conventional approach to the results of the proposed truly nonlinear analysis based on a correct combination of loading cases.