复合受力模式下CFRP混凝土界面剥离分析方法

为研究复合受力模式下碳纤维增强复合材料(CFRP)混凝土界面的剥离行为,提出在界面受压时采用摩尔-库仑强度理论以及在界面受拉时采用抛物线强度理论的损伤判定法则,建立复合受力状态下的界面本构模型。基于本构模型,推导界面的法向和切向应力对相对位移的偏导数,得到界面数值分析时所需要的雅可比矩阵。通过对比文献中4个试件的试验结果,验证了复合受力状态下界面本构模型的适用性。采用所提出的界面本构模型对CFRP增强混凝土进行参数分析,研究剥离角、界面相对位移的权重系数、法向与切向强度比以及CFRP板厚对界面破坏模式的影响。结果表明,提出的复合受力模式下的界面本构模型能够准确地反映界面剥离破坏的过程以及CFRP板的应变分布情况;剥离角度的增加会大大降低荷载峰值及峰值过后的稳定值,稳定剥离阶段的荷载极值不受界面相对位移的权重系数、法向与切向黏结强度比和CFRP板厚因素的影响;在法向出现剥离的临界位置,CFRP板上表面应变呈现出明显的波动现象;根据应变波动的部位,可以推测出CFRP板法向剥离破坏的位置。

Analysis method for debonding of CFRP-to-concrete interface under mixed-mode loading

To investigate the debonding behavior of carbon fiber reinforced polymer (CFRP)-concrete interface under mixed-mode loading conditions, a damage initiation law based on Mohr-Coulomb strength criterion in tension side and parabola strength criterion in compression side was proposed, and the mixed-mode coupled constitutive law of the interface was established. The partial derivatives of the interfacial stresses on the relative separations were derived, thus the required Jacobian matrix was obtained for the numerical analysis. The proposed model was validated by the comparison with experimental results of 4 specimens in the literature. The parametric study was conducted on the CFRP-concrete interfacial behavior, the influences of the peel angle, the weight ratio of the normal and tangential separations, the normal and tangential strength ratio, and the CFRP plate thickness on the interfacial failure mode were analyzed. The results show that the mixed-mode constitutive model can accurately predict the interfacial debonding failure and the strain distribution of the CFRP plate. The increase of the peel angle can significantly reduce the ultimate strength and steady-state strength, while the steady-state strength is not affected by the weight ratio, the strength ratio or the CFRP plate thickness. Strain variations can be observed on the top surface of the CFRP plate where the critical failure occurs in the normal direction. The interfacial fracture position can be predicted by the location of fluctuating strains.