鉄筋コンクリート柱部材の曲げじん性と横拘束(コンファインド)補強筋量

概要

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Application of confined concrete to the compression zone of reinforced concrete columns is very useful to improve flexural ductility of the columns. However, equations to estimate confining reinforcement necessary for flexural ductility required are not established sufficiently. In this paper, the amount of confining reinforcement to give flexural ductility requirement to the columns are investigated. The main results obtained are as follows. 1) The equation (4) to calculate the required confining reinforcement ratio (p_tr) was derived from the analytical investigation and examination to the previous experimental data as for the effects of various factors on p_tr. The factors employed in the investiation were the rotation angle required in plastic hinges, the axial force ratio, the material properties such as concrete strength and the ratio of core area to the whole area of column sections. 2) Examination of eq. (4) indicates that (a) the ultimate rotation in plastic hinges (θ_u) calculated by eq. (4) is more conservative than the ultimate rotation angle of members (R_u) obtained by test columns. (b) R_u of columns failed in shear is smaller than θ_u estimated by eq.(4), and (c) NZS code tends to recommend rather large confining reinforcement under low axial force ratio and rather small one under high axial force ratios.
社団法人日本材料学会の論文
1991-09-15