Incorporating the dam-reservoir-foundation interaction effects into the seismic analysis of a dam can lead to a more accurate evaluation of its behavior. This study proposes a method for modeling the dam-reservoir-foundation system by considering mass of the foundation. In order to validate the proposed numerical modeling approach, its results are compared with those of previous studies. The Koyna concrete gravity dam is used as the case study and to consider the nonlinear material behavior, the Concrete Damage Plasticity (CDP) model is applied. Four models are established and their results are compared and discussed through displacement, principal stresses, crack propagation, damage dissipation energy curves and damage indices. The results show that considering massed foundation trigger a profound impact on the seismic response of the gravity dams. The results of this study could be used as an approach for conducting nonlinear seismic evaluation of concrete gravity dams by considering mass of the foundation.
