Hydrodynamic Effects in Earthquake Response of Gravity Dams

The frequency response functions with or without hydrodynamic interaction, including or neglecting compressibility of water, and numerical results for the increase in periods of vibration of the dam due to water in the reservoir are presented. Also presented are responses of a typical concrete gravity dam, Pine Flat Dam, to Koyna 1967 and Taft 1952 ground motions. Hydrodynamic interaction as well as compressibility of water have very significant effects on the periods of vibration as well as frequency response functions of concrete gravity dams. A full reservoir causes a significant increase in the lateral displacements of the dam due to earthquake ground motion. Whether this increase in displacements is accompanied by an increase in the stresses or not depends on the frequency characteristics of the ground motion. Because of the hydrodynamic effects, the vertical component of ground motion is more important in the response of gravity dams in comparison with other classes of structures.