Seismic resilience assessment of buildings considering the effects of mainshock and multiple aftershocks

Seismic resilience assessment is a hot topic for highlighting the functional recovery of structures in post-earthquake environments. The current resilience assessment method generally ignores the effects of aftershocks, even though more than 85% of mainshocks are followed by multiple aftershocks that further increase functionality loss and recovery time. This study proposes a method to quantify the resilience of structures under mainshocks and multiple aftershocks. The concept of aftershock affecting time window is proposed to assess the effects of aftershocks on the recovery time of structures. Additionally, the effects of infill walls on the state-dependent fragility results and resilience of the structure are considered in this method. The proposed method is applied to two reinforced concrete (RC) frame structures, and the effects of multiple aftershocks and infill walls on the resilience are quantitatively studied. The results indicate that multiple aftershocks increase the economic loss by 20%-30% on average, and the aftershock affecting time can account for more than 20% of the total recovery time. The exclusion of infill walls in the finite element model of the structure induces a significant bias in the resilience assessment results at a minimum level of 25%.

Automated summary

Seismic resilience assessment is important for evaluating the recovery of structures after earthquakes. However, the current assessment methods often overlook the impact of aftershocks, which can significantly increase functionality loss and recovery time. This study proposes a method to quantify the resilience of structures under mainshocks and multiple aftershocks, taking into account the effects of aftershocks and infill walls. The results show that multiple aftershocks increase economic loss and the exclusion of infill walls leads to biased resilience assessment results.