Abstract
Improving the seismic resilience of urban underground structures is among the hot topics concerning disaster prevention and the mitigation engineering of underground structures; however, there is still a lack of research on the quantitative methods for the seismic resilience of underground structures. Based on the existing research results of seismic resilience in other fields and combined with the actual situation of subway stations, in this paper, a quantitative framework for the seismic resilience of subway stations was proposed. In this quantitative framework, the seismic resilience of subway stations was described from the functional and economic levels, respectively, with two indices. Also, a recovery model and an indirect economic loss calculation method for subway stations were proposed. Based on the proposed framework, the strategy and mechanism of improving seismic resilience were analyzed. Moreover, a finite element model was established to calculate and analyze the effects of the two strategies on enhancing the seismic resilience of subway stations by adding seismic mitigation measures before earthquakes and accelerating restoration after earthquakes. The results showed that the proposed framework is feasible, as both strategies showed to improve the seismic resilience of a subway station; however, the mechanisms are different. After the installation of seismic mitigation measures before an earthquake, the functional recovery capacity of the station increased by 22–30%, and the economic loss decreased by 43–75%. After the earthquake, by increasing the number of repair workers, the functional recovery capacity increased by 5–25%, and the economic losses decreased by 10–48%.
Highlights
Ensuring that underground structures have enough resistance to earthquakes and that they can be quickly repaired after earthquake damages has become a new research problem, which needs to be solved so as to avoid any excessive indirect economic losses
The results show that the seismic resilience of the subway station can be effectively improved after the use of seismic mitigation measures
It can be seen that the economic loss is inversely proportional to the functional recovery index and that the law is consistent with the actual situation, which proves that the installation of seismic mitigation measures can improve the seismic resilience of subway stations
Summary
With the continuous progress of urbanization, the problem of traffic jams has become increasingly serious, and developing underground transportation methods is one of the effective methods for solving this problem. The current industry standards for seismic resilience evaluation, such as FEMA-P58 (FEMA, 2012), REDi (Almufti and Wilford, 2013), and Standard for the seismic resilience assessment of buildings (GB/T 38591-2020, 2020), all adopt this quantitative method This method is easy to understand and operate, it cannot describe the performance changes of a research object during a repair process, which is very important for some structures. Common index evaluation systems of resilience include DROP (Cutter et al, 2008), BRIC (Cutter et al, 2010), ARUP (Resilience Alliance, 2010), and CDRI (Mayunga, 2009) These methods can analyze the impact of each system’s components on system resilience from multiple angles and levels; they cannot reflect the performance changes of underground structures during a repair process. Where Q(t) is the performance function of a structure, TRE is the time required to repair the structure to its initial state, t0 is the time of the earthquake occurred, frec is the recovery function, and Qresidual is the structural residual performance after the earthquake
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