PRACTICAL ASPECTS OF ENGINEERING SEISMIC DAM SAFETY -CASE STUDY OF A CONCRETE GRAVITY DAM

摘要

This paper reports on the practical issues encountered in the seismic assessment of a concrete gravity dam.Ruskin Dam is situated on a site for which the maximum design earthquake has a peak groundacceleration of 0.54g, corresponding to an annual probability of exceedance of 10-4. In the Ruskin damdeficiency investigations, a combination of 3-D and 2-D analyses, linear and non-linear, pseudostatic anddynamic, were employed in an attempt to bring together information necessary to form a seismicassessment of the dam and its appurtenant structures. A number of key parameters were investigated.These include: (1) selection of the appropriate damping level for use in assessing the structural response;(2) evaluation of the loads experienced by the upper portions of the dam and their variation along the damdue to the nature of the amplification of the of the seismic motion through the structure; (3) evaluation ofthe ability of the structure to develop 3-D action through the grouted shear keys at contraction jointsbetween monoliths; (4) evaluation of the hydrodynamic loads on the spillway gates considering theinteraction between the dam and the gates. From these experiences, the need for research in critical areasis indicated.