軸圧をうける鉄筋コンクリート部材の弾塑性曲げ変形性状に関する研究 (III) : 交番繰返し曲げ : 曲げモーメント-曲率関係

Abstract

In the previous papers, Part I and II, there were analyzed on the transverse moment-curvature and load-deflection relationships of reinforced concrete members subjected to constant axial load and compared with test results in the elasto-plastic range. Here, in this paper, the moment-curvature relationships and axially accumulated strains of reinforced concrete members subjected to transverse cyclic bending moment under constant axial load are presented. They are shown in Figs. 6 : (a-1) under the variation of several constant curvature amplitudes and several constant axial load ratios. It is discussed the influences of reinforceing indices β_s・p=σ_y/F_c・p of 0.10, 0.20 and 0.30 constant axial load ratios of 2/3 N_0, 1/3 N_0, 1/6 N_0 and 0 N_0, and constant curvature amplitudes upon the behaviours mentioned above. The hysteresis loops, m-ψ, show perfect elastic perfect plastic process under the axial load ratios of 2/3 N_0 and 0 N_0, S-figure process with smaller and slipped process with larger curvature amplitude under the axial load ratios of 1/3 N_0, and binary step slipped perfect elastic-perfect plastic process under the axial load ratios of 1/6 N_0. Axially accumulated strains are most remarkable under the higher axial load ratios but not so remarkable under lower axial load ratios and smaller curvature amplitudes. In the foregoing analysis, to simplyfy the calculation, it is assumed that, the concrete area of a cross section of a reinforced concrete member is divided into three parts, each of which is considered to be concentrated on the positions of the reinforcing steels in top and bottom and of the centroid cross section.