メタボリズム耐震橋脚構造の開発に向けた正負交番載荷及び塑性ヒンジ部取替実験

Abstract

我が国では大地震被害の度に耐震基準が改訂されてきた．その耐震基準は将来また改訂されるかもしれないことを鑑みると，現在の耐震基準を満たすだけでなく将来の耐震基準の変化にも対応できるような構造の開発が求められる．そこで本研究では，耐震性能を新陳代謝できる構造，すなわちメタボリズム耐震橋脚構造の開発を目指す．橋脚基部を軸力・せん断力を支持するコア部とその周りを囲う外殻部の二重構造で考えると，地震時には基部に形成された塑性ヒンジがエネルギーを吸収する．塑性ヒンジ部（外殻部）の取替により耐震性能を新陳代謝できると考え，本研究では軸力支持下での取替実験から取替可能性を検証し，正負交番載荷実験により耐震性能の新陳代謝を確認する．最後には本研究から得られるメタボリズム耐震橋脚構造の要求性能を整理した．

There are a lot of earthquakes in Japan. Seismic design code has been updated after tremendous earthquake so far. Therefore, we need a structure which satisfies not only the current seismic design code but also the design code in the future. This research is to develop a structure of pier which has renewable seismic performance according to changes of the seismic code. We call it metabolic seismic pier structure. Specifically, it consists of two parts. One is a core part which supports axial force and shearing force. The other one is an outer shell part which provides energy absorption performance. Such a double structure allows us to metabolize seismic performance easily by replacing the outer shell. We made replacement experiments of outer shell under gravity load and cyclic loading tests. As a result, it was possible to replace the outer shell even under gravity load and the seismic performance could be metabolized. We also got an acknowledgement that secondary stiffness of metabolized pier was greater than the normal’s one because the axial force supported by core part was gradually introduced outer shell part according to the cyclic loading test. Finally, we organized required performance in metabolic seismic pier structure.