负载下碳纤维布约束混凝土圆柱轴压应力-应变关系试验研究

通过32个碳纤维布约束混凝土圆柱的轴压试验,研究了圆柱在不同的负载水平、混凝土强度和碳纤维包裹层数下的破坏特征和力学性能,并对负载导致约束混凝土峰值点应力和应变下降的原因进行了分析.试验结果表明,负载水平的大小对于碳纤维布的约束效果有明显影响.随着负载水平的提高,第2阶段刚度、峰值点应力和应变均逐渐下降;而碳纤维包裹层数的增加,则放大了这种效应.在已有未负荷状态下碳纤维布约束混凝土的相关研究成果的基础上,根据试验结果,首次提出了考虑负载影响的第2阶段刚度、侧向膨胀系数、峰值点应力和应变的计算公式,并提出了考虑负载影响的碳纤维布约束混凝土圆柱的应力-应变关系计算模型.

Axial stress-strain relation of circular-section concrete Columns confined by CFRP under preload

A total of 32 circular-section concrete columns confined by carbon fiber reinforced plastic(CFRP) sheet were tested in uniaxial compression with different preload ratio,concrete strength and CFRP plies.The failure characteristic and mechanics behavior of confined concrete columns were investigated,and the descending of the peak stress and strain of confined concrete due to preload were analyzed.The experimental results indicate that the confinement effect of CFRP is influenced by preload ratio observably.The second stiffness,the peak stress and strain decline with preload ratio ascending,and the extent develops with the number of CFRP plies.Based on the existing study about unconfined concrete and the test data in this experiment,the formulas of the second stiffness,dilation rate and the peak stress and strain of confined concrete considering preload are determined firstly.Besides,a model for calculating the axial stress-strain curve of circular-section concrete columns confined by CFRP under preload is presented.