The Latest Achievements in Seismic Evaluation Methods and Upgrading Techniques for Gas and Water Lifelines

Seismic upgrading of lifelines, including gas and water systems, is a very vital issue for seismic risk mitigation program in all seismic countries. The common features of gas and water systems make it possible to have similar approaches for their seismic upgrading. For seismic upgrading of these systems at first it is necessary to evaluate their existing capacity for sustaining the seismic effects, or on the contrary, their seismic vulnerability. During recent decades, particularly 1990s, several researches have been performed on these issues. This paper presents the state- f-the-art and the current practice on evaluation methods as well as upgrading techniques of these two systems subjected to earthquakes, and proposes some new ideas in this regard.