RC部材中の軸方向鉄筋の座屈に関する実験的検討

抄録

In order to improve the ductility of reinforced concrete (RC) members, it is very effective to confine the concrete laterally in the compression zone of section by spirals or hoops. As for the mechanical properties of confined concrete, many researchers have conducted experimental and theoretical studies, and proposed different stress-strain relationships for confined concrete. In the large deformation zone after the maximum load, however, buckling of longitudinal reinforcement may occur in RC members even if they have an adequate amount of lateral confinement, and this leads to a significant reduction in the load carrying capacity. Therefore, it is important to investigate the effects of various factors on the buckling of longitudinal reinforcement in order to make clear the load carrying behaviors of RC members after the maximum load.
In this study, the effects of (i) spacing of lateral confinement (s), (ii) diameter of longitudinal bar (d), (iii) cover for lateral confinement (c) and (iv) the number of intervals having the length of s (n) on the longitudinal strain at buckling of reinforcing bars were investigated by carrying out the uni-axial loading test on RC square column specimens.
Test results showed that the strain at buckling of longitudinal reinforcement became larger with a decrease in s, c or n and with an increase in d. The effect of s became more significant when the d-value became larger within the s-values selected in this study. On the other hand, the effect of d was more remarkable when the s-value became smaller.