A rigorous and relatively efficient algorithm based on the non-orthogonal smeared crack approach is coded in a special finite element program to study the seismic response of arch dams. The formulation is briefly presented. The 130 m high Shahid Rajaee arch dam in Iran subjected to the Friuli-Tolmezzo earthquake is selected to present a practical application of the technique. Under the same geometry and loading conditions, six nonlinear analyses with different parameters are performed, and the results are compared with each other and a linear case. The varied parameters include secant and elastic unloadingreloading options, threshold angle, and tensile strength of the material. It is concluded that the non-orthogonal smeared crack approach can redistribute the state of stresses and produces a more realistic profile of stresses in the dam. A drift in the crest displacements forms the prominent characteristics of the cracking behavior. The results also suggest that the dam can suffer significant cracking during a strong earthquake and still remain stable. Moreover, the influences of the mentioned parameters in the seismic response of the dam are comprehensively discussed.Key words: nonlinear dynamic analysis, concrete arch dam, smeared crack approach.