Hydrodynamic and Foundation Flexibility Effects in Earthquake Response of Arch Dams

The dynamic responses of Morrow Point Dam to Taft ground motion are presented under various assumptions for the impounded water and foundation rock for a range of properties of the alluvium and sediments at the reservoir boundary. Study of these response results demonstrates that the earthquake response of arch dams is increased by dam‐water interaction and decreased by reservoir boundary absorption, with these effects being more significant in the response of arch dams compared to gravity dams. It is also shown that the magnitudes of these effects depend significantly on the component of ground motion, and that the assumption of a rigid, nonabsorptive reservoir boundary leads to unrealistically large response for dams with impounded water, particularly due to vertical ground motion.