多層多スパン鉄筋コンクリート平面骨組模型の実験 : 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平面骨組の弾塑性性状に関する研究(第1報)

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 spreading out of the columns, the elongation in the horizontal direction is restrained to some extent. Taking into account this phenomenon, the beam tending to yields is considered to be subject to compressive forces from the surrounding beams and columns. We have previously described an analysis of three-story single-span reinforced concrete frame. We have showed that rate of shear force of the first story columns changes because of the additional force from the beam of the second floor, and that second floor beam is subject to a compressive force from the first story columns. In this study, monotonic loading experiments of three types of multi-story multi-span reinforced concrete frame (FR1, FR3, FR7) are performed to consider the effect of axial restriction of beam deformation. All of the specimens are four stories high. Specimen FR1, FR3 and FR7 has single span, three spans and seven spans respectively. Main conclusions are : 1. Horizontal load-horizontal displacement relationships of each column differ, due to axial elongation of the beam tending to yield. 2. Horizontal loads of all reinforced concrete frames increase because of axial restriction imposed by the horizontal stiffness of columns.