鉄筋コンクリート柱のせん断降伏による横はらみ性状に関する実験的研究

Abstract

In the last report, the mechanism of lateral expansion of reinforced concrete columns after yielding by shear was theoretically studied. And it was proposed that the method to guess experienced maximum shear displacements of R/C columns yielding by shear from their irrecoverable lateral expansion. In the experiments the lateral expansions and shear strains of R/C columns were measured at several sections along their axes. The correspondence between them was investigated. The experimental results may be summarized as follows. (1) The phenomena of lateral expansion can be theoretically explained by using an analytical model as shown in Fig.-1, in which core concrete of R/C columns are idealized into two dimensional, non-linear and nonhomogeneous elements. (2) The leteral expansion and the plastic shear deformation are due to the plastic tensile deformation of diagonal members in the model. (3) The plastic shear strain can be connected with the lateral expansion ego by Eq. (1). And the relationship was investigated in the experiments. γ_<max>= (0.5/β) tanθ ε_<x0>…(1) where γ_<max> : experienced maximum plastic shear strain β:ratio of the irrecoverable lateral expansion to the maximum one (0<β<1) θ:angle between cracks and a axis of a R/C column (4) In the experiments, it was observed that R/C columns startd compressing along their axes due to axial compressive load when maximum lateral expansions strains were about 1.7〜3.4 %. (5) In the experiments, the ratios of irrecoverable lateral expansions to maximum ones were 0.8〜1.0. (6) Experienced maximum shear displacements of RIG columns can be guessed from laterally expanded widths. In the experiment the measured maximum shear displacements were 1〜2 times the calculated ones.