Lateral Load Resisting Behaviour of Existing Railway Bridge Piers

Abstract

Most of the sub-structures of new railway river bridges in the state of Odisha are built with solid mass concrete gravity piers and abutments. These piers do not have steel reinforcement to bear the load as it does not subject to any tensile stress under regular type of loading. Safety of these piers is of major concern during high magnitude earthquake as frequent occurrence of such earthquakes is observed in India in recent times. Failure of pier may result in loss of functionality of Railway Bridge leading to the cut down of rail communication line for an indefinite amount of time and a huge loss to the society. This study aims to assess the vulnerability of the solid gravity bridge piers which forms the important component of railway bridges as the load transfer between substructure and superstructure takes through them. In the present study seven existing piers from the state of Odisha are evaluated using free vibration analysis and nonlinear static (pushover) analysis. Free-vibration analysis of the bridge pier shows that the mass participation of fundamental mode is always below 50%. Also, the cumulative mass participation for first six mode is found to be less than 80% for all the selected bridge pier. This indicates the significant contribution of higher modes. The pushover analysis indicates the brittle mode of failure of all the bridge piers at ultimate load. This is due to poor energy dissipation capacity of the mass concrete used for building these structures.