DYNAMIC ANALYSIS - OF A CONCRETE GRAVITY DAM

Abstract

Analysis of the dam-reservoir system subjected to earthquake type of excitation has been carried out here. The .interaction between the dam and the reservoir as well as the compressibility of water has been taken into account. The complete system has been considered to be composed of two substructures, namely the dam and the reservoir. To take into account the large extent of reservoir, the reservoir has been idealised using finite elements coupled with infinite elements, while the dam is idealized using finite elements alone. Structural damping of the dam and radiation damping in the fluid phase have been accounted for in the analysis. Complex frequency amplitudes of responses of the system have been obtained for harmonic ground motion. Earthquake ground motion has been represented in terms of harmonic components using Discrete Fourier Transform. These harmonic components are then combined with the complex frequency amplitudes of responses to obtain the total responses of the system due to earthquake ground motion. It is noted that the radiation damping plays an important part in limiting the structural and hydrodyna-mic responses of the system. The effect of the flexibility of the dam and compressibility of water vii vii i shows that the responses of the system are highly r;sonant at the fundamental natural frequency but are significantly less at higher natural frequencies. The method is quite general, computationally quite economical and is recommened for practical applica-tions.