POST-EARTHQUAKE FUNCTIONAL ASSESSMENT OF THE MULTI-FUNCTIONAL STATE OF SUBWAY STATION SYSTEMS

Subway station is an important part of urban rail transit system. Varying degrees of seismic damage to structural components, non-structural components, and equipment facilities within the stations can lead to a decline or loss of various functions of the subway stations. Existing research lacks a comprehensive model for evaluating the post-earthquake functional state of subway station systems. This study, based on real seismic damage and recovery records of subway stations, clearly defines the post-earthquake functional requirements of subway station systems and categorizes the post-earthquake functional state of subway station systems into five types. The subway station system is represented as a system composed of seven sub-systems, i.e., main structure, staircases/escalators facilities for passengers, power supply, signal, et al. The fault tree model are used to represent the component units required for sub-systems functions, the interdependency between different sub-systems, and the impact of sub-systems on the post-earthquake functionality of the subway station systems. The Monte Carlo simulation method is used to randomly sample component units and obtain their post-earthquake states, and the fault tree is used to analyze the post-earthquake functional state of sub-systems and subway station systems. The results demonstrate that with the decrease of the post-earthquake functional requirements of subway station systems, the median failure probability curve of the system function increases, and the median failure probability curve of the highest required functional state I is 20% of the lowest required functional state V. The importance of the same component unit in different functional states of the system can be up to 17 times different.