圆角半径对碳纤维增强聚合物复合材料布约束型钢混凝土矩形短柱轴压性能的影响

为研究圆角半径对碳纤维增强聚合物 （Carbon fiber reinforced polymer，CFRP）复合材料约束型钢混凝土矩形短柱轴压性能的影响，对1个对比构件和5个不同圆角半径的约束构件进行静力轴压试验。试验结果表明:随圆角半径增大，柱外围的CFRP复合材料布环向应变更高且分布趋于均匀；约束柱的峰值荷载和延性也随之增大，荷载-变形曲线在峰值荷载后由平缓的下降段逐渐向上升段转化。通过建立三维有限元模型进行数值分析，可见随圆角半径增大，构件横截面上混凝土有效约束区面积增大，混凝土压应力分布趋于均匀；型钢包围的核心区混凝土应力则显著增大。随后对截面的混凝土约束区域进行了划分，设定型钢包围部分为高强约束区，最后基于叠加法建立了约束组合短柱的轴压承载力计算公式。计算显示增大圆角半径降低了组合柱的横截面积，但却显著提高了约束后柱的轴压承载力。 

Effect of corner radius on axial compressive performance of steel reinforced concrete rectangular short columns confined by carbon fiber reinforced polymer composite

In order to study the effect of corner radius on axial compressive performance of large scale steel reinforced concrete rectangular short columns confined by carbon fiber reinforced polymer(CFRP) composite, the static axial compression experiment were conducted on one contrast specimen and five strengthened specimens. The results indicate that with the increasing corner radius, both the strength and ductility of the confined columns increase, the descending portion of the load-displacement curve after the peak load point gradually turns to ascending portion; the circumferential strain of CFRP composite sheets also gets higher working value and more uniform distribution. Through numerical analysis, it was seen that with the corner radius increasing, the area of the effectively confined concrete zone on the cross-section increases, the axial compressive stress distribution of concrete tends to be uniform, and the stress in the core area surrounded by steel increases significantly. Then the different confined concrete areas in cross-section were divided, and the core area surrounded by steel was set as the high-strength confined concrete zone. The superposition formulation of the axial bearing capacity of steel reinforced concrete rectangular short columns confined by CFRP composite was proposed. The calculation results show that increasing the corner radius significantly reduces the cross-sectional area of the large-size steel reinforced concrete rectangular columns, but improves the axial compression bearing capacity.