Reza Tarinejad - Assistant professor of civil engineering faculty of university of Tabriz, Tabriz, Iran
Arman Roshanravan - M.Sc. student of Civil engineering faculty of University of Tabriz, Tabriz, Iran
Hesaneh Ghanbari - M.Sc. student of Civil engineering faculty of university of Tabriz, Tabriz, Iran
Hamed Mahjoob - M.Sc. student of Civil engineering faculty of University of Tabriz, Tabriz, Iran

Dam-reservoir interaction affects modal characteristics of dam but its effect’s amount depends on amplitude of excitations and water level of reservoir. In this paper, effect of dam-reservoir interaction on modal characteristics of arch dams due to weak and strong ground motions investigated. Finite element models of dam-reservoir-foundation and dam-foundation systems excited due to weak and strong ground motions andmodal parameters of the system extracted by Frequency Domain Decomposition (FDD) and Continues Wavelet Transform (CWT) method based on dam responses to investigate the relation between amplitude of excitation and effect’s amount of dam-reservoir interaction on natural frequencies of the system. Effect of reservoir water level on natural frequencies of the system is also investigated

Modal identification, dam-reservoir interaction, FDD, ground motion