Simplified Earthquake Analysis of Concrete Gravity Dams: Separate Hydrodynamic and Foundation Interaction Effects

Simplified procedures are presented for the analysis of the fundamental vibration mode response of concrete gravity dam systems for two special cases: (a) Dams with reservoirs of impounded water supported on rigid foundation rock; and (b) dams with empty reservoirs supported on flexible foundation rock. In the first case, the effects of dam‐water interaction and reservoir bottom absorption on dam response are included, whereas the effects of dam‐foundation rock interaction are included in the second case. In each case, the response of the fundamental vibration mode of a dam monolith is modeled by an equivalent single degree‐of‐freedom system with frequency‐independent properties chosen to represent the effects of complicated, frequency‐dependent hydrodynamic terms or foundation‐rock flexibility terms, as appropriate. The maximum earthquake‐induced deformations and equivalent lateral forces can be computed using the response spectrum for a specified ground motion. The procedures and results presented in this paper are extended in a companion paper to develop a simplified analytical procedure for concrete gravity dams that includes the simultaneous effects of dam‐water interaction, reservoir bottom absorption, and dam‐foundation rock interaction.