In seismic prone areas, earthquakes happen more than just main shocks which are happen with sequences of shocks include of different intensity of aftershocks. In technical documents, these kinds of several earthquakes are called mainshock-aftershock ground motions. In this study, seismic behavior of RC frame under mainshock-aftershock with different ratios of maximum acceleration of aftershock to maximum acceleration of mainshock was evaluated. In this paper, nonlinear time-history analysis of frame were performed under mainshock-aftershock sequences and then the residual interstory drift ratio for comparing response of frame under seismic sequences was evaluated. The results show that, residual interstory drift ratio of frame, related to intensity of aftershocks to mainshock and enhance of intensity of aftershock due to increase residual interstory drift ratio of frame. Although, growth of residual interstory drift ratio of top stories more significant than below stories of frame.
