Abstract：The seismic response analysis of concrete dam is a critical step in evaluating safe performance of proposed and existing dams. The seismic response of concrete dam is substantially affected by the dynamic interaction between the dam and the foundation rock. Therefore，it is necessary to develop a numerical method including dam-foundation rock interaction in the procedure. Among various numerical methods，the finite element method is very attractive since it can be applied to any geometry for any set of material properties and loading conditions as long as the appropriate constitutive relationships and equilibrium conditions are met. In this study，a time-domain finite element method (FEM) for analysis of dynamic responses of concrete dam-foundation rock system subjected to earthquake is presented. During such FEM simulation，the disturbances due to the interaction between the dam and the foundation rock will travel outwards. An effective artificial boundary condition will limit the region for which a solution must be computed. Without such an artificial boundary condition，wave energy will reflect off the edge of the computational region and contaminate the solution. In addition，how to treat seismic input on such a artificial boundary is another key issue in the seismic response analysis of concrete dam. Based on the cylindrical wave equation，a method for treatment of earthquake input and modeling radiation damping is established，it is simple and efficient. Several numerical examples are conducted to verify the validity and accuracy of the proposed method. Finally，the proposed FEM is applied to seismic response analysis of concrete gravity dam including dam-foundation rock interaction；and the results show that the seismic response of concrete dam is substantially affected by the radiation damping of unbounded foundation rock.
