Vulnerability assessment of a high-rise building subjected to mainshock-aftershock sequences

Strong aftershocks have the potential to further aggravate the damage state of structures, and much less attention has been given to the seismic vulnerability of high-rise buildings than that of low- to medium-rise buildings. This study assesses the seismic vulnerability of a 32-storey frame-core tube building by performing the incremental dynamic analysis on the material-based three-dimensional numerical model. A storey damage model based on the material damage is developed using the weighted average method. Eighteen recorded mainshock-aftershock sequences, whose mainshock records match the target spectrum, are selected. The results indicate that the developed stroey damage model can effectively reflect the additional damage induced by aftershocks. Strong aftershocks have high potential to change the location of weak storeys. Notably, shifts of weak storeys are observed in more than 30% of aftershocks with relative spectral acceleration of 0.8. As the mainshock-induced damage state becomes more severe, the mainshock-damaged building becomes increasingly fragile to the aftershock excitation and more sensitive to aftershock intensities. The probability of exceeding severe damage state increases from 35.3% to 62.1% due to the effects of strong aftershocks. The results in this study can provide supports to the seismic resilience assessment of this high-rise building.