Earthquake Response of Concrete Gravity Dams

The problem is simplified to a linear analysis of the two-dimensional vibration of coupled reservoir-dam systems, with the response of the dam being approximated by its deformations in the fundamental mode. Four cases are considered: dam alone (without reservoir); reservoir-dam system-interaction neglected; reservoir-dam system-interaction included; and reservoir-dam system-interaction included but water compressibility neglected. Expressions for the complex frequency response functions for the dam displacement and lateral hydrodynamic force in each of these four cases are presented. These results along with the Fast Fourier Transform algorithm are utilized to compute the time-history of responses of 28 reservoir-dam systems to Taft, CA, earthquake. It is concluded that: (1) the presence of the reservoir may increase the dam response significantly, and (2) the commonly used simpler analyses which neglect reservoir interaction or compressibility of water may result in significant error.