碳纤维布约束加固混凝土偏压柱的试验研究与分析

通过5根碳纤维布约束加固混凝土柱的偏心受压试验,研究了加固后混凝土柱在不同偏心距荷载作用下的破坏特征和受力性能,对外包碳纤维布的横向应变、柱截面应变、侧向挠度以及极限承载能力等进行了分析。结果表明,碳纤维布约束加固小偏心受压混凝土柱是有明显效果的,随着偏心距的增大,加固效果逐渐减小;柱截面平均应变符合平截面假定;因偏心受压下混凝土受压膨胀不均匀碳纤维布存在拉应变梯度。根据拉应变梯度简化约束性能,提出修正的受压区等效矩形应力图形以及界限受压区相对高度值,并给出碳纤维布约束加固偏心受压柱的承载能力计算公式。

Behaviors of concrete columns strengthened by CFRP sheets under eccentric compression

An experimental study of eccentrically loaded concrete columns confined by CFRP sheets is presented.The behaviors investigated in the test of five concrete columns reinforced by CFRP sheets include the ultimate strength,the lateral deflection,and the sectional strain distribution of concrete columns and transverse strains in the CFRP sheets.It is found that,via the reinforcement of CFRP sheets,the ultimate strength of concrete columns is enhanced and the ductility of concrete columns improved.The efficiency of reinforcement increases when the eccentricity decreases.It is also shown that the plane strain condition remains valid,i.e.,strain in concrete is linearly proportional to the distance from the natural axis.The strain gradient in CFRP sheet,which is attributed to the non-uniform expansion of concrete,is observed.A formula is proposed for calculating the ultimate strength of eccentrically loaded concrete columns strengthened by CFRP sheets,including the modified equivalent rectangular stress block and the limit value of the relative depth of the compression zone.