高延性混凝土加固框架柱抗震性能试验研究及其#br# 轴压比限值分析

混凝土框架柱的轴压比较高时，在水平地震荷载作用下通常发生小偏心受压破坏。为改变高轴压比下混凝土柱的破坏形态并提高其抗震性能，提出采用高延性混凝土（HDC）围套加固混凝土柱。设计6个RC柱，其中4个采用HDC或钢筋网高性能复合砂浆加固。通过低周期反复荷载试验，研究加固层形式和轴压比对试件破坏形态、滞回性能、承载力、变形能力、耗能能力和刚度退化的影响。试验结果表明：采用HDC围套加固可使试件的破坏形态由小偏心受压破坏转变为大偏心受压破坏，试件达到极限位移时仍维持稳定的竖向承载力；通过HDC围套加固后，试件的承载力，延性和耗能能力均得到明显提高，刚度退化速率减缓。采用HDC围套加固，可增加柱截面受压区面积，提高柱截面的相对受压区高度，使加固柱的轴压比限值明显提高，同时柱截面仍具有良好的变形能力。

Experimental research of the seismic performance of frame columns strengthened with high ductile concrete jacket and analysis of the limitation of axial load ratio

 The reinforced concrete (RC) columns are vulnerable to small eccentric compression failures in severe earthquake when the axial load ratio is at a high level. In order to change the failure modes and improve the seismic performance of the RC columns under high axial load ratio，the high ductile concrete (HDC) jacket was proposed to strengthen the RC columns. Six RC columns were designed and four of them were strengthened with HDC jacket or ferrocement jacket. The influence of strengthening schemes and axial load ratios on the failure modes, hysteresis performance, shear capacity, deformation capacity, energy dissipation capacity and stiffness degradation of the specimens were studied by the low cyclic loading test. The experimental results show that the failure mode of the RC columns was changed from small eccentric compression failure to large eccentric compression failure and the vertical load-carrying capacity were stably maintained when the ultimate displacements were reached. The bearing capacity，ductility and energy dissipation capacity of the RC columns were significantly improved and the stiffness degradation rate was slowed down after strengthening with HDC jackets. The area of the compression zone, the relative compression height and the limitation of the axial load ratio of the columns were obviously increased after strengthening. Besides, the column still exhibited good section deformation capacity.