通过对16根转换柱试件的低周反复荷载试验,分析了剪力在转换柱中钢与混凝土之间的分配规律,以及型钢剪力作用点至柱根部的距离,并研究了混凝土在反复荷载作用下的抗剪损伤.结果表明:配钢率、型钢延伸高度及轴压比是影响剪力分配与型钢剪力作用点至柱根部距离的主要因素;型钢剪力随型钢配钢率的增大而增大;随着型钢延伸高度的增加,型钢剪力的分配比例呈现先降后升的规律;型钢剪力的分配系数随着轴压比的增大略有减小;型钢剪力的作用点至柱根部的距离随轴压比的增大而减小,随型钢延伸高度的增加表现出先升后降的变化规律,型钢配钢率对该距离影响相对较小;型钢剪力反作用于混凝土截面中部,导致拉应力的出现,加速了混凝土的损伤,混凝土损伤又反过来降低了型钢的抗剪能力,导致型钢剪力进一步增大,如此交错影响导致混凝土损伤不断积累,直至试件破坏.
Sixteen specimens were tested under low cyclic loading to analyze the shear distribution between the shape steel and the concrete in transfer columns as well as the distance from the shear action spot of shape steel to the column bottom.Then,the shear damage of concrete under low cyclic loading was investigated.The results show that(1) the distance from the shear action spot of shape steel to the column bottom is mainly affected by the shape steel ratio,the extension height of shape steel and the axial compression ratio;(2) the shear force resisted by shape steel increases with the shape steel ratio;(3) with the increase of extension height of shape steel,the shear force ratio decreases first and then increases;(4) the distribution coefficient of shear force slightly decreases with the increase of axial compression ratio;(5) the distance from the shear action spot of shape steel to the column bottom,which is slightly affected by the shape steel ratio,increases with the decrease of axial compression ratio,and increases first and then decreases with the increase in the extension height of shape steel;and(6) the shear force of shape steel reacts upon the central area of concrete section and leads to tension stress,which accelerates the damage of concrete.At the same time,the damage of concrete results in the degradation of shear capacity and the shear enlargement of shape steel.This interplay between concrete damage and shear force of shape steel ultimately leads to the accumulation of concrete damage and the failure of transfer columns.