海洋环境下FRP外贴加固混凝土结构粘结界面的疲劳性能及提升方法

The interfacial fatigue behavior between fiber reinforced polymer (FRP) and concrete substrate is one of the bottleneck problems in the externally bonded FRP concrete bridge structures subjected to marine corrosive environment. To clarify this issue, a series of in-depth studies will be carried out in this project by using indoor/outdoor exposure tests and toughening modification of bonding adhesives. Firstly, accelerated corrosion tests will be conducted to investigate the interfacial fatigue behavior of FRP to concrete interface. Interfacial bond stress-slip models will be proposed based on the above experimental results. Secondly, long-term exposure tests will be carried out in natural marine environment to reveal the equivalent relationship between the accelerated durability tests and the long-term exposure natural marine environments. This will lay the foundation for the long-term durability evaluation and service-life prediction based on the accelerated durability test results. Thirdly, toughening modification will be applied to the adhesive epoxies to enhance the long-term durability behavior of the FRP to concrete interface under marine environments, which is one of the unsolved issues existed in the previous studies. Finally, numerical finite element models will be established to study the interfacial fatigue behavior of FRP strengthened concrete members under marine environments. The investigation will be very conducive to the development of fatigue life design and performance enhancement for FRP strengthened concrete members subjected to marine corrosive environment.

针对海洋腐蚀环境下纤维增强复合材料（FRP）外贴加固混凝土桥梁结构中存在的瓶颈问题——疲劳荷载下FRP与混凝土的界面剥离问题，项目通过室内外海洋腐蚀试验和树脂改性，对海洋腐蚀环境下FRP-混凝土界面的疲劳性能及提升方法进行深入研究。首先，通过室内加速试验测试加速腐蚀下FRP-混凝土界面的疲劳性能，建立界面粘结滑移退化模型；其次，基于海洋暴露试验站开展长期暴露试验，研究室内加速试验与自然海洋腐蚀之间的等效关系，为使用加速试验结果分析实际加固结构的长期耐久性能奠定基础；进一步，针对既有研究暴露出的FRP-混凝土界面长期耐久性能不足的问题，对粘结树脂进行增韧改性，以期提升海洋腐蚀环境下界面的疲劳性能；最后，基于既有研究及上述成果，建立有限元模型，分析海洋腐蚀与疲劳荷载共同作用下FRP加固混凝土构件的界面剥离问题，为海洋腐蚀环境下FRP-混凝土界面疲劳性能设计及控制提升方法的建立提供依据。

针对纤维增强复合材料（FRP）外贴加固混凝土桥梁结构中存在的瓶颈问题——车辆疲劳荷载下FRP与混凝土的界面剥离问题，本项目对常规及海洋环境下FRP-混凝土界面的疲劳受力行为及界面性能提升方法进行了系列试验、理论和数值模拟研究。首先，试验研究了粘结树脂性能对FRP-混凝土界面受力行为的影响，建立了能考虑粘结树脂性能的精细化有限元模型，揭示了粘结树脂性能对FRP-混凝土界面受力行为的影响机理，建立了考虑粘结树脂性能的界面粘结滑移模型；其次，进行了常规环境下FRP-混凝土界面疲劳性能试验，探讨了不同种粘结树脂对界面疲劳受力性能的影响，提出了基于碳纳米管树脂改性的界面疲劳性能提升方法；在此基础上，进行了海水腐蚀环境下FRP-混凝土界面的疲劳性能试验，建立了考虑海水腐蚀影响的界面粘结滑移疲劳损伤退化模型。最后，建立了疲劳荷载下FRP-混凝土面内剪切有限元分析模型，基于前述研究建立的界面粘结滑移关系疲劳损伤退化模型，分析了海洋腐蚀环境下FRP-混凝土界面疲劳损伤发展的全过程及主要影响参数，探讨了实现海洋环境下FRP-混凝土界面疲劳性能提升的优化方法。