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 ground acceleration of 0.54g, corresponding to an annual probability of exceedance of 10-4. In the Ruskin dam deficiency investigations, a combination of 3-D and 2-D analyses, linear and non-linear, pseudostatic and dynamic, were employed in an attempt to bring together information necessary to form a seismic assessment 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 dam due to the nature of the amplification of the of the seismic motion through the structure; (3) evaluation of the ability of the structure to develop 3-D action through the grouted shear keys at contraction joints between monoliths; (4) evaluation of the hydrodynamic loads on the spillway gates considering the interaction between the dam and the gates. From these experiences, the need for research in critical areas is indicated.
展开▼
