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外贴碳纤维增强复合材料(CFRP)-混凝土的界面抗疲劳性能是影响重复荷载作用下外贴CFRP加固混凝土梁加固效果的关键因素之一。基于梁铰式疲劳试验,对CFRP布-混凝土界面抗疲劳性能进行研究。试验结果表明:在黏结长度大于有效黏结长度时,重复荷载作用下CFRP布-混凝土界面的破坏过程可以分为初始剥离形成、剥离缓慢发展、剥离快速发展3个阶段,分别约占疲劳寿命的0~10%、10%~90%和90%~100%;在其他条件相同的情况下,提高混凝土强度或增加黏结长度可提高疲劳寿命,而随着CFRP布与混凝土宽度比的增大,疲劳寿命降低。基于试验结果,提出了考虑应力比(循环荷载作用下CFRP布的谷值应力与峰值应力之比)、混凝土强度、CFRP布与混凝土宽度比、黏结长度4个影响因素的CFRP布-混凝土界面的疲劳寿命曲线,并在传统疲劳寿命预测方法基础上,提出了考虑多因素的CFRP-混凝土界面疲劳寿命预测方法。
The anti-fatigue performance of externally bonded CFRP-concrete interface is one of the key factors that affect the reinforcement effect of CFRP-reinforced concrete beams under repeated load. Based on the beam hinge fatigue test, the anti-fatigue properties of CFRP cloth-concrete interface were studied. The test results show that the failure process of CFRP cloth-concrete interface under repeated loading can be divided into initial peel formation, stripping slowly development and rapid development of peel, which account for about 0% of fatigue life ~ 10%, 10% ~ 90% and 90% ~ 100% respectively. When other conditions are the same, increasing the strength of concrete or increasing the bonding length can improve the fatigue life, and as the ratio of CFRP cloth to concrete width increases, fatigue Life expectancy decreased. Based on the experimental results, the CFRP cloth-concrete interface considering the influence of stress ratio (ratio of valley stress to peak stress on CFRP cloth under cyclic loading), concrete strength, CFRP cloth to concrete width ratio, and bond length Fatigue life curve. Based on the traditional fatigue life prediction method, a multi-factorial CFRP-concrete interface fatigue life prediction method is proposed.