Lifeline systems

including transportation systems

water and gas transmission networks

energy supply systems etc.

are indispensable to our daily life.They are also essential for sustaining the life of city after a catastrophic event such as a strong earthquake.Up to now

evolutionary methods such as genetic algorithms and simulated annealing algorithms have been developed for the seismic topological optimal design of lifeline systems.More recently

ant colony optimization algorithms

which are the newly heuristic algorithms inspired by the foraging behavior of ants

have been successfully applied to a number of mixed optimization problems.In this paper

a seismic topological optimization model of lifeline network systems is presented firstly.Then

the minimal path-based recursive decomposition algorithm

an efficient and precise algorithm to calculate the seismic connectivity reliability of network

is introduced.According to the analysis of network optimization problem

a binary coding-based ant colony algorithm is suggested.Finally

a simple network with 17 nodes and 27 pipelines is investigated in detail.Also the results calculated using genetic algorithms and simulated annealing algorithms are compared with the results using ant colony algorithm.The results show that ant colony algorithm is encouraging and feasible to be a novel tool for topology optimization problem of lifeline systems.