Seismic Reliability Analysis Of The Lifeline System Networks

Lifelines, which include power transmission, transportation, and urban water, heat, gas supply pipeline systems, are the fundamental infrastructure systems to support modern cities' functions and maintain regional economical development. The rapid development of modern cities increases their dependences on lifelines. The post-earthquake properties of lifeline engineering systems would directly determine the recovery of daily life and production as well as the efficiency of fighting the secondary disasters. Thus, to ensure the safety of lifelines, it is of great necessity to analyze their seismic reliabilities.Lifelines extend spatially over large geographical regions to make up a network. Therefore, the reliability analysis of lifeline engineering systems can be transformed to the corresponding analysis of network systems. As well known, seismic reliability analysis of large scale lifeline networks is a typical 'NP-Hard' problem and it has been an important subject of considerable researches.This paper systematically investigates the advantages and disadvantages of some popular network algorithms with their abilities of reducing computation complex as the criterion. Research results show that the minimal path based recursive decomposition algorithm can efficiently decrease the computation complex and is senior to other algorithms in finding reliability solutions of large scale networks. However, detailed investigations have shown that it may be inapplicable to networks whose components have very low reliability.In this paper, a new kind of algorithm based on recursive decomposition algorithm is studied. Firstly, the hard disk storage technology is employed to solve the problem of the space complexity caused by decomposition in this algorithm. Secondly, to realize the analysis of systems when the components in the low reliability region, the recursive decomposition and minimal cut searching method is to propose a recursive decomposition algorithm based on minimal cut and this algorithm is successfully put into the reliability analysis of lifeline engineering systems under destructive earthquake. It is concluded that the seismic reliability of lifelines suffering different seismic intensities can be accurately predicted if the recursive decomposition algorithm based on minimal cut/minimal path being reasonably used. At the same time, the convergence of Recursive Decomposition Algorithm is analyzed and the advices to further improve the performance of the algorithm are also given.Finally, the seismic reliability analysis of Shenyang main gas supply network is performed using the minimal cut based recursive decomposition algorithm.