Mainshock-Aftershock Ground Motion Features and Their Influence in Building's Seismic Response

This article presents the results of examining ground motion characteristics in 184 real mainshock-aftershock earthquake ground motions. It is shown that the predominant period (a measure of the frequency content) of the set of mainshocks tends to be longer than that of the corresponding aftershocks. It is highlighted that the response of structures under artificial sequences is very different from that of real sequences, particularly when the approach of repeating the real mainshock with identical ground motion features as an artificial aftershock is employed. It is also demonstrated that the predominant period of the aftershock significantly influences the post-mainshock response.