고속철도 PSC 박스 거더 교량의 경간수에 따른 지진취약도 함수 수정계수

초록

Seismic resilience assessment of railway networks requires fragility functions for all bridges in the network. However, developing detailed probabilistic models and conducting nonlinear time-history analyses for each bridge configuration requires substantial computational effort. To overcome this limitation, this study proposes adjustment factors for system-level seismic fragility curves for prestressed concrete box-girder bridges, the most common class of high-speed railway bridges in Korea, with different numbers of spans. A database was constructed from design documents of 69 bridges in the first phase of the Honam High-Speed Railway, and major uncertain model parameters were identified. Three-dimensional probabilistic track-bridge models were generated using Latin hypercube sampling, and nonlinear time-history analyses were performed for 2-, 3-, 4-, 5-, 10-, and 20-span bridge models. Component fragility curves were derived using probabilistic seismic demand and limit-state models, and system fragility curves were obtained under a series-system assumption. Bearing responses dominated the slight-limit-state system fragility, followed by column responses. As the number of spans increased from 2 to 20, the median value of the fragility curve decreased by approximately 67%. Finally, adjustment factors for the median value and dispersion of the fragility curve were proposed to estimate the seismic vulnerability of bridges with different numbers of spans without additional computational effort.

키워드