Effects of Aftershocks on the Potential Damage of FRP-Retrofitted Reinforced Concrete Structures

Abstract

This study investigates the effects of aftershocks on the potential damage of reinforced concrete (RC) structures retrofitted by fibre-reinforced polymer (FRP). An eight-storey RC frame that was poorly confined due to deficient transverse reinforcement was selected and then retrofitted by FRP wraps to provide external confinement. Inelastic time history and damage analyses of the frame under single earthquakes and mainshock–aftershock sequences were performed. FRP retrofit did not ensure a damage-free structure, and it minimised the damage though. The results indicated different contributions of aftershocks to the damage of the retrofitted frame, and this finding illustrates the limitations of current seismic codes. The damage caused by single earthquakes is proposed to be used as a criterion for dealing with the effects of aftershocks as follows. If the mainshocks cause minor or light damage, the effect of aftershocks is negligible, whereas the effect of aftershocks needs to be considered if the mainshocks cause moderate or severe damage. The outcomes of this study can be used in making decisions about whether the effects of aftershocks should be considered.