The present paper deals with dynamic dam-foundation interaction analysis using direct coupling method considering unified viscous boundary condition. A time domain analysis has been performed to obtain the transient response of the concrete gravity dam-foundation coupled system using finite element method. The entire dam-foundation system has been modeled as plain strain problem to obtain the displacement and stress responses at the salient positions of the system. In order to assess the importance of the soil structure interaction effects on a massive structure like concrete gravity dam a comparison has been done for the proposed dam-foundation model with and without considering the soil structure interaction effects against the earthquake loading. In order to absorb the reflected waves from the soil truncated boundary, unified viscous boundary condition has been implemented to the vertical sides of the foundation domain. The proposed methodology can be easily implemented to a computer code due to its simple nature.

Keywords: Dynamic dam-foundation interaction, Transient analysis, Direct coupling, Unified viscous boundary condition.