Effects of frequency content of ground motions on seismic response of concrete gravity dams with varying reservoir levels

Abstract

Ground motion parameters describing the characteristics of strong ground motions are known to have engineering implications on the seismic design of structures. Past studies indicate that the frequency and phase content of strong ground motion alters the seismic performance of concrete gravity dams. The seismic response of the dam-foundation-reservoir systems involves complex dynamics of interacting systems and varying reservoir water levels are known to influence the extent of damage sustained by the dam body during an earthquake. In this preliminary study, we investigate the effects of the frequency content of ground motion on the seismic behaviour of concrete gravity dams with varying reservoir levels. A typical two-dimensional finite element model of the tallest non-overflow monolith of the Pine Flat dam is prepared considering water compressibility, foundation inertia, material non-linearity of concrete using concrete damage plasticity (CDP) and viscous-spring based seismic input mechanism considering radiation damping. Crest displacements, maximum tensile stresses, damage area and energy dissipated are employed to establish the ultimate damage state of the dam. The results demonstrate the significant effects of the frequency content of ground motion and reservoir water levels on accumulated damage and damage distribution in the dam body with implications on the seismic design criteria.