Bridge length limits due to track-structure interaction in continuous girder prestressed concrete bridges

Abstract The combined structural response of the ballasted track and the deck of railway bridges causes longitudinal forces and displacements that can affect the ultimate resistance of the rail or the serviceability of the bridge. Therefore, the resulting rail stresses and relative rail-deck displacements are limited according to the European design codes. The main parameters to be assessed are the total bridge length and the existence and number of rail and deck expansion joints. In a parameter study of continuous girder pre-stressed concrete bridges, the bridge length limits for 9 different expansion joint combinations are determined by means of non-linear finite element analyses. The temperature changes have a fundamental effect and require that in bridges without rail expansion joints the maximum total bridge length is 144 m with one and 290 m with two deck expansion joints. For bridge lengths close to these values, an individual analysis should prove that rail stress from vertical deflection does not exceed the limit stress. In bridges with at least one rail expansion joint there is usually no length limit. The relative displacement limit between track and structure of 4 mm due to braking and traction force may only be exceeded if the load classification factor α is 1.33 or 1.46.