DYNAMIC ANALYSIS OF . BRIDGES WITH NONLINEAR MODELLING OF BEARINGS

Abstract

It has been observed from failures of bridges in the past under earthquake conditions that the bridge bearings play an inportant role in the behaviour of the bridge. Nowadays elastomeric bearings are being used as bridge bearings. Stoppers are also provided so that the movement which is permitted by the elastomeric bearings, does not exceed the prescribed limit. The behaviour of the bridge, provided with such an elastomeric bearing with stopper arrangement, under dynamic loading becomes essential not only for the design of the bearing but also the stopper and the piers.ith an, object to study the behaviour of the bridge under earthquake loading, two consecutive bridge piers have been modelled as a spring mass connected together by means of another spring which represents the characteristics of the elastomeric bearing element with stopper. The load displacement curve of the elastomeric bearing with stopper has been considered as piecewise linear. Provision for the yielding of the stopper has also been made. When the distance between the piers is large, there is a possibility of multiple excitations at the piers. This has also been considered. The method of arriving at the spring mass model for the pier is also given. Parametric study has been carried out using the model mentioned above, The main conclusion that has been arrived at from the study is that the stiffness of the elastomeric bearing element with stopper has a great influence on the forces that develop in the piers as well as in the relativ:k, displacements at the ends of the bearing element.