2001 Volume 50 Pages 115-123
The fundamental equations estimating the compressive load-carrying capacity of RC columns with tie and/or spiral reinforcements are used all over the world, based upon the ultimate limit state design, but the common equations include both the elastic term and the plastic one; so, there is no unification concept of the ultimate limit state. In recent years, the high-strength type reinforcement (SBPD type) has been used frequently in the RC column and beam in Japan. Now, the common equations can not apply to the case of the high-strength primary reinforcement of the RC column. The previous reports have already dealt with the concrete’s sharing capacity, the applicable range of the common equations and the generalized practical equation for the upper-bound load-carrying capacity considering the buckling effect of the primary rebars. Especially, this paper describes that the improvement of load-carrying capacity by virtue of the lateral confinement of tie bars depend on the buckling strength of primary rebars in assuming that those elemental buckling length equals the double pitch spacing.
