In long welded rails (LWR) considerable longitudinal forces may develop due to temperature variation, train loadings like braking and traction, deck end rotation due to vertical bending. Rail structure interaction (RSI) analysis is an important part of bridge design to evaluate the longitudinal stresses in LWR, longitudinal forces on the substructure and deflection/displacement of the structure. This paper presents the case study of an ongoing bridge project over Balram River, Gujrat India for Dedicated Freight Corridor Corporation (DFCC). Total length of the bridge is 195m. The analysis is carried out by a finite element based software package and as per the endorsements given in the UIC 774-3 code. Stress developed in LWR largely depends on the stiffness of the girder and the substructure (pier and foundation). In general practice, the boundary condition is maintained as fixed on one abutment and free on the other with all the spans being simply supported having one end free and other end fixed. The large span of bridge and height of support increases the flexibility of structure and poses difficulty to satisfy the stress and displacement criteria mentioned in UIC & Indian Railway Standards (IRS) Codal provisions with these boundary conditions. Excessive displacement of deck can result in deconsolidation of ballast and track stability cannot be ensured. Use of expansion device in rail may require proper monitoring and demand for intensive maintenance. In present study different bearing articulations are tried and a parametric revision is done to arrive at the optimum/economical substructure and foundation stiffness which satisfy the stresses and displacement limits prescribed in UIC 774-3. It is found that the changed bearing arrangement with both the abutments fixed and center pier rendered to be free, keeping the structural dimensions unaltered, which yield the analysis results which satisfy the stress and displacement criteria as per relevent codal provisions and also arrive at an economical substructure design.

rail structure interaction, long welded rail, track bridge interaction, simply-supported bridge