Evaluation of base isolation systems based on recorded and predicted responses of actual buildings under recent earthquakes

摘要

This paper presents the following three items. First, actual behavior of base isolated buildings during minor to moderate earthquake in Japan have been discussed based on recorded ground motions. The effectiveness of base isolation has been found to be remarkable along with level of ground motions and to be consistent with the trend of calculation. The responses under vertical ground motions was also discussed. Second, prediction of the behavior of base isolated buildings under recently recorded strong ground motions with maximum velocities as high as over 100 cm/sec have been conducted. The acceleration response level of 200 gal, usually used as design level, has been obtained only by setting the natural period of system for greater than 5 sec, for this high level of ground motions. Finally the predictions of earthquake damages conducted over nearly all prefectures in Japan has been reviewed.