Since the damage of structure increases by the effect of the aftershock, it is necessary to clarify the accumulated damage on the performance-based design due to earthquake. Because the damage of the structure may be closely related to the earthquake input energy, it is importanto carry out the accumulated damage assessment by means of the energy evaluation. In this present study, by applying the target performance due to demand strength spectra with the damage index, it is examined with cumulative damages which are given by aftershocks for the earthquake performance evaluation of the structure. It is shown that seismic performance evaluation is closely related to accumulative damage estimation due to aftershocks.
