SEISMIC RELIABILITY ANALYSIS OF LIFELINE NETWORKS TAKING INTO ACCOUNT FAULT EXTENT AND LOCAL GROUND CONDITIONS

概要

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An efficient procedure for assessing the seismic reliability of lifeline networks has been developed using the concept of the transition distance, the shortest distance to the fault that causes failure of components for a given earthquake magnitude. Lifeline components are assumed to fail because of ground shaking and liquefaction. The seismic environment of a lifeline is defined by the fault rupture model through the relation between the seismic moment and the rupture area. The enumeration of paths or subgraphs of the network was found to be at most 4n^2-4n+8 for a network with n components. The intensity of ground shaking was estimated by the response spectrum method for stationary random vibration analysis. We have proposed a repetition scheme for calculating the modal stiffness and damping in order to use modal analysis for layered ground with nonlinear properties. Characteristic equation for obtaining the modal frequency and free vibration modes are obtained from a newly derived general wave transfer function in multi-layered media with nonhomogeneous and nonlinear soil properties. The results, in conjunction with fatigue theory, can be used to analyze liquefaction phenomena. Computation of the seismic reliability of a simple network shows that this new technique is feasible for use with large networks.
日本自然災害学会の論文