CURRENT STATES OF THE ARTS ON LIFELINE EARTHQUAKE ENGINEERING IN JAPAN

Lifeline earthquake engineering, as a branch of earthquake engineering, is being concerned by the more persons both from academic and engineering fields. The lifeline engineering differs from common engineering projects in that usually it has large system, and provides an important service for modern cities. Once the damage takes place on one part of the lifeline system, it may lead to the loss of functions on the whole urban areas. Seismic behavior of lifelines has been investigated in Japan for recent two decades. Because today's modern cities depend heavily on lifelines for their daily operation, earthquake treats to lifelines becomes increasingly influential in proportion with the level of urbanization. Furthermore, as a result of population growth and environmental considerations, much more lifelines for utilities and transportation systems are now placed in underground. Since most lifelines, particularly buried pipelines, are in networks having sources, transmission lines, storage facilities and distribution systems within themselves, damage to a single location in a lifeline network often affects significant portions of the entire system. Many earthquake disasters have shown that the well function of lifelines will play an important role in preventing secondary disasters