鉛直地震動が基礎回転系構造の耐震性能に及ぼす影響に関する研究

摘要

本論では、杭頭浮き上がりによる基礎回転系構造の設計法の確立を目的とし、地震動上下成分が基礎回転系構造の鉛直方向の応答に及ぼす影響について、1質点系モデルを用いた地震応答解析により検討した。また、杭頭部に緩衝材を設けることで浮き上がりに伴い生じる、上部構造の鉛直方向加速度応答の低減効果についても地震応答解析を行った。さらに、地震動上下成分が上部構造の水平方向の応答に与える影響についても検討した。以下に得られた知見を記す。%The structural system with the rotational foundation due to uplift at pile heads has an excellent seismic performance. However, in this structure, the weight of the structure has great influence on the restoring force characteristic. So, it is conscious that vertical ground motions may affect on the response of the superstructure. Also, the vertical acceleration due to vertical input motion may be important subject to be considered because the horizontal response of this structure causes the vertical acceleration due to uplift. The purpose of this study is to research the influence of vertical ground motions on the vertical and horizontal response of the superstructure by the dynamic analysis. The effect of the shock absorber at the head of the piles on vertical acceleration is also investigated. The paper concludes that the influence of vertical input motion on horizontal restoring force characteristic is slight and the vertical acceleration of the structure is given by sum of those due to horizontal input motion and vertical input motion, respectively.