考虑疲劳累积损伤的FRP-混凝土界面剥离模拟

鉴于疲劳累积损伤对FRP-混凝土界面黏结性能有重要影响, 通过统计分析既有FRP-混凝土界面疲劳剪切试验数据, 基于界面黏结疲劳退化双线性模型获得界面残余滑移量、峰值剪应力和初始刚度的疲劳退化规律, 发现随着荷载循环次数的增加, 界面残余滑移量增加, 而峰值剪应力与初始刚度均减小. 并采用基于内聚力模型的有限元法对典型界面疲劳剪切试验进行模拟, 得到了不同荷载循环次数下的界面黏结滑移关系. 模拟所得峰值剪应力、界面断裂能和界面剪切刚度与理论模型接近, 但极限滑移量大于理论模型, 黏结滑移曲线符合典型试验曲线特征. 从有限元模拟结果可知, 疲劳荷载作用会显著降低界面承载力, 但界面破坏特征并未发生显著变化.

Numerical modeling of interfacial debonding between FRP and concrete considering cumulative fatigue damage

Cumulative fatigue damage has significant effects on the interfacial bonding performance between FRP and concrete. Based on the statistical analysis of the existing FRP-concrete interfacial shear fatigue test data and the bilinear model of interfacial bond fatigue degradation, the fatigue degradation law of interfacial residual slip, peak shear stress and initial stiffness are obtained, respectively. It is revealed that, as the number of load cycles increases, the interfacial residual slip increases, while the peak shear stress and the initial stiffness decrease. The finite element method based on the Cohesive Zone Model is used to model the typical interfacial fatigue shear test, and the interfacial bond-slip relationships under different load cycles are obtained. The simulated peak shear stress, interfacial fracture energy and shear stiffness are closely consistent with the theoretical values. However, it is found that the ultimate slip is greater than the theoretical value, and the bond-slip curve conforms to the characteristics of the typical experimental curve. The results of finite element simulation indicate that the fatigue loading will significantly reduce the interfacial bearing capacity, but the failure characteristics of the interface have no noticeable change.