Three-dimensional dynamic response analyses of Cogswell Dam

The recorded strong motions at the Dam during the 1987 Whittier Narrows and 1991 Sierra Madre earthquakes provide a valuable opportunity to evaluate the applicability of established engineering procedures for evalauting the dynamic response of dams with highly three-dimensional geometries. In addition, these records provide an opportunity to back-calculate the dynamic properties of rockfill materials, which cannot be easily measured in the laboratory or in situ. Dam-canyon interaction and topographic effects appear to have influenced the seismic response of the dam significantly. Estimates of the in situ dynamic rockfill properties, including the modulus degradation relationship, are presented. -from Author