柱の変動軸力を考慮したRC造骨組の弾塑性解析 : その1 解析法と芯筋柱の構造実験解析

Abstract

This paper presents the elastic-plastic analytical method of the reinforced concrete plane frame considering the fluctuation of axial forces on columns and results of application of this method to the lateral loading tests of columns with core rebars in their centers against large axial forces during earthquake. In this analytical method, two surfaces of crack and yield are introduced on the force plane of bending moment and axial force (M-N force plane) at the ends of column as the yield criteria. The yield surface is assumed as the parabolic curves approximated from M-N values at the ultimate strengths which are obtained by summation of M-N strength curves of concrete and reinforcing bars. The crack surface is assumed as the similar parabolic curves to the yield surface. Three states of elastic, crack and yield are assumed at column ends. Introducing the yield criteria, the nomality flow rule regarding to the incremental plastic strain, and the hardening rule, the elastic-plastic equilibrium equations regarding to the incremental stress-strain relationship of column are derived. From the result of application of this method to the analysis of columns with core rebars in their centers, good agreements are shown between the two load-deflection skeleton curves which are obtained from the test and the analysis. From this results it is clarified that this analytical method is adequate and effective in order to investigate the elastic-plastic behavior of the reinforced concrete plane frame under the fluctuating axial forces of columns.