減衰定数一定の弾塑性応答スぺクトルによる1995年兵庫県南部地震での建物被害の再検証

摘要

Three noticeable cases of damage during the 1995 Hyogoken-Nanbu earthquake are reviewed; the damage rate of reinforced concrete buildings in Kobe city, the behavior of the Shin-Nagata high-rise residential building, the fractures of columns of high-rise buildings in Ashiyahama Seaside town. In these cases, the predominant periods of ground motions are considerably longer than the natural periods of buildings and resonance is not expected. These phenomena are examined by a proposed response spectrum of elasto-plastic system with constant damping factor and explained as transitions of natural periods of buildings. This method gives appropriate estimates of an increase in period with an increase in amplitude.%建築物本体の減衰のメカニズムは摩擦に起因する履歴減衰であることを与件とすると，粘性減衰と同様に一定の減衰定数をもつ弹塑性1自由度質点系では，観測される固有周期は振幅によって変動することになる。振幅の増大によって建物の周期が伸びる現象は，実験や観測でも構造体が塑性化するよりはるかに小さな振幅レベルから確認されている。