Post-earthquake functionality assessment for urban subway systems: Incorporating the combined effects of seismic performance of structural and non-structural systems and functional interdependencies.

• Post-earthquake functionality assessment framework for subway systems is proposed. • Structural and nonstructural systems and functional interdependencies are incorporated. • Post-earthquake functionality is overestimated by ignoring nonstructural systems. • Ignoring nonstructural systems leads to 73% bias under an earthquake of magnitude 8. • The functionality of subway systems is highly dependent on external systems. This study proposes a framework to evaluate and quantify the post-earthquake functionality of subway systems. The effects of the seismic performance of structural and non-structural systems and the functional interdependencies at different levels are incorporated into the framework. Considering the characteristics of passenger flow and network topology of subway systems, global service efficiency is proposed as the functionality indicator. The computational efficiency of the proposed calculating algorithm of the functionality indicator is improved by 10 times compared to the conventional algorithm. The proposed framework is applied to an actual subway system as a numerical example to verify the effectiveness and operability of the proposed framework. The effects of the non-structural systems on the post-earthquake functionality assessment of the subway system are analyzed, and the result indicates that the post-earthquake functionality of the subway system would be overestimated owing to ignoring the effects of the non-structural systems, and the degree of overestimation is positively correlated with the earthquake intensity. The influence of the municipal power supply system as an essential external system is studied and the results show that the functionality of the subway system is highly dependent on the municipal power supply system. [ABSTRACT FROM AUTHOR]