EFFECT OF GEOMETRY ON SEISMIC RESPONSE OF GRAVITY DAMS

Abstract

The object of this study is to examine the effect of geometry on the response of concrete gravity dams. Limited parametric variations have been examined and dams analysed with different slopes The height of dam and its base width have been kept constant and both the upstream and downstream slopes are varied keeping the volume constant.Finite Element Method has been used to calculate the static and the dynamic response.The dynamic response consisting of both free vibration characteristics and forced response to seismic input has been studied The free vibration characteristics consist of the time periods of vibration and corresponding mode shapes The dynamic forces due to earthquake ground motion have been computed using the average acceleration spectr in accordance with Indian Standards recommendations IS:1893-1984. The total response in individual modes has been evaluated The seismic response parameters evaluated are the base shears and element stresses.Static response due to gravity and hydrostatic forces and pseudostatic response due to hydrodynamic forces have also been considered. The results of the conducted static and dynamic analysis indicate that the geometrical configuration does play a significant role in the response of dams.Furthermore a symmetrical profile about the dam axis presents a better configuration for utilization of material strength/stiffness under the action of both static and dynamic loads.