DYNAMIC ANALYSIS OF SIMPLY SUPPORTED BRIDGE

Abstract

The major causes of failure of bridges in past are the failures of substructure and the complexities associated with the bearings, expansion joints and support. So, the necessity of analysing the structural response considering the dynamic charac-teristics of structure and those of bearings Is very important for safe design in highly seismic areas. In the present work an Integrated plane frame analysis of all the structural components of a bridge from foundation to girder has been done. A lumped mass model is made for dynamic analysis in longitudinal direction. A comprehensive study of dynamic response of pier has been conducted between the individual pier model and complete bridge model. In the former case consi- dering the girder as rigid its whole weight is lumped on the top of the pier. A comparison is also made between conventional simply supported bridge and elastomeric bearing supported bridge. The influence of different foundation soil spring on dynamic response of bridge supported on different types of bearings has been studied. The modelling of rocker bearing is done by replacing it by beam element with hinge at one end. The frictionless roller is modelled by replacing it by axial force element, while the fric-tional roller is modelled by beam element with hinge at one end and then selecting the member property to delimit the shear force in the member equal to frictional force transferred. The elasto-meric bearing has been designed considering the property of elas- tomer and the geometry of the bearing.