Incremental Dynamic Analysis Considering Main Aftershock of Structures Based on the Correlation of Maximum and Residual Inter-Story Drift Ratios

Aftershocks often occur after strong earthquakes and aggravate structural damage. Commonly, the incremental dynamic analysis (IDA) considering the main aftershocks only used a single index such as the maximum or the residual inter-story drift ratio. However, results of IDA using different indices may suggest that a structure has collapsed but is still repairable, which is not realistic. Given these shortcomings, this paper proposes selecting two indices in the IDA method based on the correlation between the maximum and the residual inter-story drift ratio, considering the main aftershocks. The influence of the double-indices model on the structural vulnerability analysis was discussed by establishing a commercial building in SAP2000 software, and single-index and double-index IDA were carried out, respectively. The joint distribution probability of the two indices under fixed seismic intensity was also calculated. The difference between the single-index and double-index IDA results was compared considering both the main shock and the main aftershock. The results showed that the effect of aftershocks would improve the correlation coefficient between the maximum and the residual inter-story drift ratio, and the building model has a higher probability of overrun after considering the correlation of the two indices. This paper provides a new method for IDA and vulnerability analysis using multiple indices.