THREE-DIMENSIONAL DYNAMIC ANALYSIS OF GRAVITY DAM AND RESERVOIR SYSTEMS (BOUNDARY-ELEMENT, SEISMIC)

An economical procedure for the frequency domain analysis of gravity dam and reservoir systems is developed and the three dimensional effects on their earthquake response are investigated.; The dam is modeled as a thick plate which includes shear, bending and rotatory inertia effects. The reservoir is assumed to be of constant cross-section with its far end extending to a large distance upstream. Water compressibility and a wave absorbing reservoir bed are incorporated. The system is completely linear. The substructure approach is found to be suitable.; The dam is analyzed by a Rayleigh-Ritz technique for the free vibration and by an extension of the technique for the forced vibration case that includes hydrodynamic effects. The differential equation describing the mechanics of the water is treated with a separation-of-variables approach that leads to a continuum solution in the upstream direction and necessitates a numerical solution in the cross-stream plane. A boundary element method is employed and the results compared with a finite element solution.; The free vibration study presents the natural frequencies and mode shapes. Frequency response functions for the crest acceleration and displacements are generated for all three components of ground motion. These functions are later used to determine the time-domain responses of the system to typical strong motion earthquakes. Pine Flat Dam is modeled as described above and some of the results from a full scale vibration test were compared. The agreement was found to be reasonably good.