碳纤维布加固混凝土结构中碳纤维锚固的力学性能与设计原理研究

The ability of quick applying CFRP anchors with virtually no change in the geometry of the element makes this anchorage system a viable and attractive candidate for anchoring CFRP strips. Recent research indicates an adequate CFRP anchor is able to continue transferring the tensile load from a debonded CFRP strip to concrete member until the fracture of the CFRP strip. Without adequate CFRP anchors, however, the premature failure of CFRP strips debonding from concrete substrate limits 50% capacity of CFRP strips at least. Therefore, the usage of CFRP anchors is considered as a promising method to fully develop the strength of CFRP strips. This study is firstly going to explore the impact of anchor locations, space, and arrangement on the performance of CFRP anchors. Based on the experimental observations of this and the previous investigations, the analytical model of CFRP anchors will be proposed to describe the load-slip response between anchored CFRP strips and concrete substrate at the anchored area. Then, parametric studies on this proposed model will be conducted by means of finite element (FE) simulations. The numerical results will be evaluated using available experimental observations to demonstrate the capability and accuracy of this proposed model. Based on the Hook’s law, ultimately, design guidelines with considerations of the parametric contributions on the strength of CFRP anchors will be developed by analysis of experimental and numerical results. The importance of this research is to clarify the CFRP anchor mechanism and provide design guidelines for CFRP anchors.

碳纤维(CFRP)锚固因其安装简便，基本不改变原结构的几何尺寸而被视为一种切实可行的锚固方案。近期的研究结果表明在CFRP布从混凝土表面剥离后，设计合理的CFRP锚固仍可以将CFRP布上的荷载传递给混凝土试件直至CFRP布断裂，而未经CFRP锚固的CFRP布会在达到自身强度50%之前从混凝土表面剥离而丧失加固能力。因此CFRP锚固的研究对于提高CFRP布的加固能力意义重大。本项目首先研究锚固位置、间距和排列方式对CFRP锚固力学性能的影响。根据本次与前期的试验结果，提出CFRP锚固的力学模型即锚固区域里CFRP布与混凝土之间的受力与滑移模型。其次通过有限元模拟、试验研究等方法对该模型进行参数研究和验证。最后根据胡克定律并结合数值模拟与试验结果，综合考虑各参数对于CFRP锚固强度的影响，提出CFRP锚固的设计方法。本项目的意义在于阐明了CFRP锚固的力学机制并提出了CFRP锚固的设计方法。

轻质、高强、不易发生腐蚀的碳纤维强化聚合物CFRP是理想的混凝土结构加固材料。但是由于其自身变形能力差，易发生脆性破坏和剥离破坏等特点，现阶段CFRP还没有在加固工程中得到广泛的应用。针对于CFRP现阶段的特点与局限性，本项目首先提出了“量身定制CFRP筋”的设计理念，该CFRP筋可以做成板型和棒型，其应力应变性能可以通过改变其几何形状并同时运用有限元软件预先设计，以达到理想的非线性力学性能。该CFRP筋的设计理念已经在本项目的支持下得到了实验验证，未来可以用于替代钢筋加固混凝土，大大减少因为钢筋腐蚀给我国每年带来的重大经济损失和安全隐患。同时本项目又在总结现阶段CFRP剥离破坏的力学机理，和防止剥离破坏的锚固方法之上，提出了两种集CFRP筋和锚固于一体的加固方法。与美国德克萨斯交通部所采用的同等方法比较，该方法施工简便且加固效率高，具有良好的工业实用前景。