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外贴FRP是重要的混凝土结构加固技术,但目前对外贴FRP加固混凝土结构的疲劳性能研究尚不充分,尤其对FRP-混凝土粘结界面的疲劳退化规律和破坏模式的研究更为缺乏。本文采用双面剪切试件,通过2个静载试件和4个疲劳试件的试验研究,考察了粘结长度和胶层厚度等因素对FRP-混凝土界面粘结疲劳性能的影响。通过分析沿粘结长度的FRP应变分布在疲劳循环过程中和疲劳后静载过程中的变化情况,讨论了不同粘结长度和粘结胶层厚度条件下的粘结界面疲劳退化规律和疲劳后静载性能。试验结果表明:胶层树脂-混凝土粘结界面是发生疲劳剥离破坏的薄弱环节;胶层厚度增大时,由于疲劳引起的界面损伤累积发展显著减小,疲劳后静载中胶层厚度较大试件的粘结承载力也更大;粘结长度增大时,界面粘结呈现更为明显的损伤退化,但由于试验粘结长度小于有效粘结长度,疲劳后的静粘结承载力仍更大。
The application of FRP is an important reinforcement technology for concrete structures. However, the research on the fatigue properties of FRP reinforced concrete structures is still inadequate at present, especially for the fatigue degradation and fracture modes of FRP-concrete bonded interfaces. In this paper, the test of two static specimens and four fatigue specimens were used to study the influence of bond length and thickness on the bond fatigue behavior of FRP-concrete interface. By analyzing the variation of the FRP strain distribution along the bond length during the fatigue cycle and after fatigue, the fatigue degradation of the bonded interface and the fatigue degradation under different bond length and bond coat thickness are discussed. Static load performance. The results show that the interface between the resin layer and the concrete is the weakest link in the process of fatigue failure. When the thickness of the rubber layer is increased, the cumulative damage of the interface due to fatigue is significantly reduced, and the thickness of the layer after fatigue is larger The bond capacity of the specimen is also greater; when the bond length increases, the interface adhesion shows more obvious damage degradation, but the static bond capacity after fatigue is still more because the test bond length is less than the effective bond length Big.