Design of a seismically isolated railway viaduct over Axios River in Northern Greece

This paper presents the salient features of the design of a railway viaduct over the Axios River on the new high-speed double railway line, which is the longest (800m) railway bridge in Greece constructed using the travelling gantry method. Located in a high seismic hazard area, the viaduct is provided with an isolation system with the aim of reducing the structural response to seismic loading, a solution that presents several challenges in the case of railway bridges and cannot be implemented solely on the basis of existing codes. Lead-rubber bearings are provided at each pier to deck connection and system damping is further increased through the use of fluid viscous dampers at each abutment. To verify the performance of the isolation system, the analysis for seismic actions is conducted in three discrete stages of increasing complexity. Seismic forces and displacements are found to be within acceptable limits and serviceability requirements are also met. Conclusions are drawn regarding the feasibility of using passive systems in railway bridges in seismic areas.