Two-Parameter–Based Damage Measure for Probabilistic Seismic Analysis of Concrete Structures

Traditional seismic fragility analysis defines the structural damage measure (DM) as a single parameter based on either strength, displacement, damage, or energy to evaluate the postearthquake performance of the structure, thus it is difficult to fully catch the behavior characteristics of the structures, e.g., both the maximum deformation capacity and the repairability of the structure. In this paper, we developed a multiparameter-based DM $(m\mathrm{DM})$ index (here actually two parameters) for the probabilistic seismic analysis of reinforced concrete (RC) structures to capture a more comprehensive view of structural performance. Two parameters (i.e., the maximum interstory drift ratio ${\theta }_{\mathit{max}}$ and the maximum residual interstory drift ratio ${\theta }_{\mathrm{r},\max }$) are combined to represent the overall structural performance, and different combination rules are investigated. To verify the superiority of the proposed $m\mathrm{DM}$, the fragility analysis of three different structures is conducted, i.e., ordinary RC structure, aging RC structure, and new self-centering structure. The fragility curves derived from single DM and $m\mathrm{DM}$ are compared, and it is found that fragility curves with $m\mathrm{DM}$ can reflect both the maximum displacement and residual displacement features of the structure, thus $m\mathrm{DM}$ gives a more comprehensive and synthesis assessment of the postearthquake performance of the structure, which is beneficial for informed decision-making.