碳纤维布加固低强度混凝土梁的抗剪性能

Shearing behavior of low strength reinforced concrete beams strengthened with carbon fiber composite sheets

采用外贴U形碳纤维布条的方法对12根低强度(fcu≤15MPa)混凝土梁进行了抗剪加固试验。结果表明,外贴碳纤维布能够明显改善低强度混凝土梁的抗剪性能,梁破坏主要源于纤维布剥离,如果布条端部设置压条,加固梁破坏前有明显先兆。基于断裂力学模型,由拉剪粘结试验确定碳纤维布剥离时所能承受的有效拉力;利用平面桁架模型,提出加固梁外贴U形碳纤维布条剥离时抗剪承载力的计算方法。计算和试验结果的比较分析表明,所提方法可用于低强度混凝土梁的抗剪加固设计。

Low strength reinforced concrete beams （the cubic strength of concrete fcu≤15MPa） were strengthened by gluing carbon fiber composite U type strips across the beam section to enhance the shearing behavior of beams, and corresponding tests for 12 strengthened beams were done in the lab. Test results show that the method can be applied to improve the shear behavior of low strength reinforced concrete beams. Using the additional anchoring sheets at the end of U type strips, shearing capacity and deformation ability of reinforced concrete beams can be improved obviously. With the help of fracture mechanics and bond strength test, the effective pulling force between carbon fiber composite sheets and concrete was calculated. Based on the plane truss model, the calculation method to determine the shearing bearing capacity of low strength reinforced concrete beams was proposed when sheets debonded. Verified by the test results, it can be concluded that the proposed method can be used in the shearing strengthening design of low strength reinforced concrete beams.