Recently, a wide range of studies and extensive tests have been carried out in order to determine the mechanical properties of dam concrete in fracture for the purpose of non-linear analysis. Conventional concrete gravity dams have been replaced by roller compacted concrete dams (RCCD) during recent years. In this study, statistical methods are used to improve the obtained results of compressive and direct tension tests on 15 x 30cm cylindrical samples from the Jahgin RCC dam site (the first major RCC dam in Iran), in order to evaluate compressive strength, tensile strength, modulus of elasticity and fracture energy, with different confidence degrees and test ages of specimens. The obtained results are used for the purpose of non-linear dynamic analysis. The non-linear seismic analysis of the Jahgin RCC gravity dam, including dam-reservoir interaction, is performed using the 1995 Fin (Iran) earthquake records. The results show high tensile stresses occur near the dam’s heel, and slope discontinuity of the upstream face and upper part of the dam in the vicinity of the downstream slope changes. The development of cracks inside the dam body is considered.