ヒンジ部コンクリートがメナーゼヒンジの力学特性に与える影響

Abstract

我が国のメナーゼヒンジの耐震設計では，ヒンジ部コンクリートの影響が考慮されていない．そこで本研究では，筆者らが行った先行研究での実験結果を参考に，ヒンジ部コンクリートがメナーゼヒンジの力学特性に与える影響を検討した．その結果，ヒンジ部コンクリートによりメナーゼヒンジの抵抗モーメントが増加することや交差鉄筋に引張ひずみが発生することを確認した．そしてその結果を踏まえ，ヒンジ部コンクリートの影響を考慮できるメナーゼヒンジの設計法として，ファイバー要素を用いた解析による手法と断面解析による手法を提案した．そして，提案手法を用いることで，実験供試体のメナーゼヒンジで確認された最大抵抗モーメントおよび回転剛性の算定が可能であることを示した．

Mesnager hinge is a concrete hinge composed of crossing reinforcing bar and hinge concrete. In Japanese seismic code, the compressive yield point of crossing reinforcing bars is defined as the ultimate state of Mesnager hinges and bending moment of Mesnager hinge is assumed to be small, because influence of hinge concrete in Mesnager hinge is not considered. However, Mesnager hinges commonly used in Japan have thick hinge concrete compared with conventional Mesnager hinges. Thus, this study investigated the results of cyclic loading tests for Mesnager hinges with thick hinge concrete carried out by our previous researches to evaluate the influence of hinge concrete in Mesnager hinge on its mechanical property. As a result, hinge concrete was found to enhanced the bending moment of Mesnager hinge. Additionally, crossing reinforcing bars were subject to tensile deformation due to hinge concrete. The observations contradict the assumption in Japanese seismic code. Therefore, two methods were proposed to calculate bending moment of Mesnager hinge and tensile yield point of crossing reinforcing bars. From results of numerical analysis with there methods, it is suggested that the proposed methods can evaluate the influence of hinge concrete in Mesnager hinge on its mechanical property.