阪神・淡路大震災-防災研究への取り組み-地震動の強さと建物の耐震力

Abstract

Not only wooden houses but modern building structures in and around Kobe were suffered severe damages done by the 1995 Hyogoken-Nanbu earthquake. We surveyed damage of wooden houses, reinforced concrete structures, steel structure and space structures as well as aseismic safety of urban facilities and indoor furnitures, and investigated dynamic properties of wooden houses by measure of micro-tremor and/or failure tests ofexisting houses.The belt of local intensity 7 zones were mostly distributed about 1 km far from the Rokko fault, where maximum velocity of ground surface were estimated more than 150 cm/s. A lot of existing buildings constructed before 1971, were severely damaged, but few of buildings constructed after 1981 were lightly damaged in that zone.In this paper, one example of observation system in Osaka prefecture were introduced, in which the maximum acceleration on the basement of a building were less than the acceleration in the ground. Other data recorded in Osaka also shows the similar tendency, which may appear the soil-structure interaction effect. We also showed the statistics of the relationships between the ultimate capacity of existing reinforced concrete buildings and the damage done by this earthquake. It is pointed out from those results that input motion into structures may be smaller than the surface motion of ground and that average of simple estimation of ultimate base shear coefficient become larger corresponding to the code revision and buildings having less than 1.0 of shear coefficient may be suffered subjected to the severe ground motion.