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Earthquakes and Structures Volume 24, Number 4, April 2023 , pages 303-316 DOI: https://doi.org/10.12989/eas.2023.24.4.303 |
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Markov-based time-varying risk assessment of the subway station considering mainshock and aftershock hazards |
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Wei Che, Pengfei Chang and Mingyi Sun
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| Abstract | ||
| Rapid post-earthquake damage estimation of subway stations is particularly necessary to improve short-term crisis management and safety measures of urban subway systems after a destructive earthquake. The conventional Performance-Based Earthquake Engineering (PBEE) framework with constant earthquake occurrence rate is invalid to estimate the aftershock risk because of the time-varying rate of aftershocks and the uncertainty of mainshock-damaged state before the occurrence of aftershocks. This study presents a time-varying probabilistic seismic risk assessment framework for underground structures considering mainshock and aftershock hazards. A discrete non-homogeneous Markov process is adopted to quantify the timevarying nature of aftershock hazard and the uncertainties of structural damage states following mainshock. The time-varying seismic risk of a typical rectangular frame subway station is assessed under mainshock-only (MS) hazard and mainshockaftershock (MSAS) hazard. The results show that the probabilities of exceeding same limit states over the service life under MSAS hazard are larger than the values under MS hazard. For the same probability of exceedance, the higher response demands are found when aftershocks are considered. As the severity of damage state for the station structure increases, the difference of the probability of exceedance increases when aftershocks are considered. PSDR=1.0% is used as the collapse prevention performance criteria for the subway station is reasonable for both the MS hazard and MSAS hazard. However, if the effect of aftershock hazard is neglected, it can significantly underestimate the response demands and the uncertainties of potential damage states for the subway station over the service life. | ||
| Key Words | ||
| aftershock hazard; Markov chain; subway station; time-varying risk; uncertainty of damage state | ||
| Address | ||
| School of Engineering and Technology, China University of Geosciences, Beijing, No.29, Xueyuan Road, Haidian District, Beijing, P.R. China | ||