Study on Cross Girder to Rail Bearer Connections of Plate Girder Bridges in Sri Lanka Railways

The connection between the cross girder and the rail bearer stands as one of the most critical structural details of plate girder bridges in Sri Lanka railways. Despite numerous modifications and advancements implemented by Sri Lankan railway engineers over time, this connection remains a repeated point of failure. This paper examines the underlying causes of these failures, in a plate girder railway bridge which is located in the coastal railway line of Sri Lanka, through numerical modelling and experimental validation. A global finite element model of the bridge was developed using SAP2000 V.23 to analyse the overall structural behaviour, while a detailed local finite element model of the cross girder-rail bearer connection was developed in Abaqus V.6.14 to capture localized stress distributions and the failure mechanisms. To validate the numerical findings, vibration analysis was performed using smartphone-based measurements, where natural frequencies extracted from experimental data were compared with numerical predictions. The results of the numerical simulation indicate that the connecting plate in the cross girder–rail bearer connection is the most critical component in the selected bridge. Stress Triaxiality Factor (STF) analysis revealed that the plate undergoes high triaxial tensile stress states, particularly at its central region, indicating a high vulnerability to brittle failure with void growth. These results highlight the necessity of strengthening the connecting plate of the cross girder to rail bearer connection to enhance the structural integrity and the overall durability of the plate girder bridges.