機能分離により地震後の早期復旧を可能とするメタボリズム鋼製柱構造の改良

Abstract

著者らは一連の研究で，軸力支持下での耐震性能の改変や地震後の早期復旧が可能なメタボリズム柱構造の開発を行ってきた．メタボリズム柱構造とは，柱基部を二重構造とし，地震エネルギー吸収能を期待する可換部を外殻に，常時の軸力・せん断力を支持する永続部を柱内部に配置した構造である．本研究では，地震後の橋梁構造の復旧性向上を目的に，橋脚が有する機能を整理しつつ，メタボリズム鋼製柱構造の改良を行った．具体的には，永続部の軸剛性を高めることが柱の耐震性能ならびに地震後の復旧性に与える影響について，正負交番載荷実験により検討した．その結果，永続部の軸剛性の向上により，柱の耐震性能が向上することに加え，支点の位置が保持された状態で地震後の復旧性作業が可能となり，復旧性向上に寄与することが示された．

The authors have developed a ‘metabolism seismic column’ designed to modify seismic performance under axial force and facilitate rapid restoration post-earthquakes. This metabolism seismic column features a double-layered base structure: The outer layer comprises a replaceable plastic zone intended to absorb seismic energy, while the inner part has a permanent hinge designed to support axial and shear forces under regular conditions. In this study, we improved the metabolism seismic steel column by organizing the functions of the bridge piers in order to improve the recoverability of the bridge structure after earthquakes. We specifically examined the impact of augmenting the axial stiffness of the permanent hinge on the column’s seismic performance and its post-earthquake recoverability using cyclic loading tests. The results indicate that enhancing the axial stiffness of the permanent hinge not only improved the seismic performance of the columns but also aided in post-earthquake restoration. This was attributed to the column’s ability to maintain the position of the upper structure due to the permanent hinge.