Development of seismic resilience index and assessing framework of underground frame structures based on economic loss

The seismic resilience of underground structures is one of the critical issues for the development of resilient cities. However, existing assessing methods for assessing the seismic resilience of underground structures do not comprehensively address their seismic capacity and post-earthquake recoverability. This paper developed a seismic resilience index and framework for assessing the seismic resilience of underground frame structures by considering both the damage and functionality of underground structures caused by earthquakes, as well as the processes involved in repairs. The seismic resilience index was developed by quantifying the resist resilience and recovery resilience, which can be used to describe the robustness, redundancy, and resourcefulness of the seismic resilience. Then the assessing procedure for this method is presented step by step. Additionally, a case study was conducted to assess the seismic resilience of a frame subway station, focusing on the economic losses associated with earthquakes. The study also discusses the improvements in seismic resilience achieved through the use of reinforced concrete truncated (RCT) columns. Results indicate that RCT columns can significantly enhance the seismic resilience of underground structures. The reasonability and quantifiability of the developed method were compared with existing methods, demonstrating its effectiveness. Furthermore, the developed assessing method can be extended to assess the seismic resilience of underground structures after quantifying their operational functionality.