Quantification of Resiliency in Infrastructures and Its Application in the Selection of Seismic Retrofitting Strategies (Case Study: 15-Khordad Subway Station in Shiraz)

Resilience assessment can be assumed as an important tool for decision making for disaster managers. Considering the recovery time in the resiliency approach causes this approach to be different from other frameworks of decision-making process in the preparation phase in estimation of losses and time-dependent consequences. The recovery process after distaster occurrence may be modeled by simple recovery functions or complex organizational and social models. The obvious point in using resiliency approach is that it could give the disaster managers a recovery trend of infrastructures after disasters, with respect to important factor of time, to allocate the available resources on the basis of resiliency criterion. Currently, the selection of retrofitting strategies of infrastructures, especially subway stations, is performed by economic and technical approaches according to the state of the art standards. In these analyses, recovery trend of the performance after disasters is usually ignored. In this study, on one hand, the concept of resiliency of infrastructures after disasters, its dimensions and analysis methods are investigated, and on the other hand, some retrofitting methods are proposed for stations and subway tunnels. In the next step, considering the proposed algorithm for attaining the quantitative resiliency, first, the 15-Khordad subway station in Shiraz was modeled and displacements due to 11 earthquakes with different PGAs were analyzed in 10 control points. Then, the discrete and cumulative damage-probabilities were calculated by comparing the calculated displacements with damage-level threshold. The resiliency of the substation under different retrofitting strategies is quantified in the next stage considering calculated damage probabilities and different recovery functions. Finally, the ranking of retrofitting strategies for infrastructures was done based on the resiliency concept. The proposed method can be generalized to other infrastructures.