Abstract
In the past few decades, it is observed that the occurrence of earthquakes is in the form of sequences where the mainshock is followed by one or more aftershocks. The earthquakes excite the foundation of a structure in sequence over some hours/days, out of which few seismic sequences may last for years. The aftershocks that accompany the mainshock take a toll on the seismic demands of the buildings which go on increasing in each successive event as the building may not be retrofitted or strengthened after the mainshock due to time constraints or some other reasons. The seismic design codes consider only a single seismic event of earthquake i.e., mainshock and neglect possibility of the aftershocks. Under a strong mainshock event, even a regular structure may be severely damaged and is highly vulnerable under subsequent events may get the severity of its damage worsened and even collapse. In the present study, an 11-storey RC 2-D frame has been analyzed under10 different episodes of sequential earthquakes with each with the same mainshock followed by six aftershocks of increasing PGA from 0.1 g to 0.6 g of near field and far field following nonlinear time history analyses using SAP2000 software. Inelastic response of the structure is studied with respect to the location of plastic hinges, maximum top displacement, residual displacement, and storey drift. Fragility curves for damaged states are plotted for the far-field and near field sequential earthquakes and discussed.
Published Version
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