曲げ降伏するはりの軸方向伸びを考慮した鉄筋コンクリート骨組の弾塑性挙動に関する解析研究

抄録

It is well known that a reinforced concrete beam will elongate in the axial direction when the beam begins to yield in bending. If this phenomenon occurs throughout all the spans, the horizontal length of the building will incease as a whole. Due to expansion of the slabs and spreading out of the columns, the elongation in the horizontal direction is restrained to some extent. Taking into account this condition, the beam tending to yield is considered to be subject to compressive forces from the surrounding structural members. We have previously described a cyclic load experiment for reinforced concrete frames which was performed to examine the effect of axial restriction of beam deformation. The experiment showed that the story shear strength of reinforced concrete frames increased 50 % to 170 % because of axial restriction imposed by the horizontal stiffness of columns. In this study, analyses of the above experiment and 3-story single-span reinforced concrete frame are performed. The results of the analyses show that this analytical method is applicable to the study of elastic and plastic behaviors of reinforced concrete structures which yield due to bending, and that rate of shear force of the first floor columns changes because of the additional force from the beam of the second floor, and that the second floor beam is subject to a compressive force from the first floor columns.