Investigation of damage caused by recent large earthquakes and earthquake-proofing in Japan and the USA

Japan and the U.S.A. have suffered large earthquakes from 1989 to 1995. It is very important to carefully investigate the damage they caused and look into the effectiveness of our earthquake-proofing methods. The purpose of this study is to use site research and interviews with specialists to investigate and compare the earthquake damage， restoration efforts，progress with earthquake-proofing，and new techniques requiring development. Research shows that further studies are needed on the following : 1)a reasonable level of seismic design criteria to prevent collapse of strucures，2) innovative，lightweight，and cost effective methods of retrofitting existing structures，3) of supports and restrainers，seismic isolation and active controlling to prevent falling of girders， and 4) the flow taking into account the degree of deterioration， deterioration prediction， the life cycle cost，and so on