不同剪切破坏模式下考虑箍筋锈蚀的CFRP加固梁的抗剪性能研究

发布时间：2019-04-17 13:40

【摘要】：FRP抗剪加固钢筋混凝土梁是当前加固技术领域的一个研究热点。然而,大多试验研究均基于新拌混凝土梁,缺乏考虑实际加固构件中的钢筋往往已处于锈蚀状态对加固性能的影响。在处于滨海环境的混凝土结构,构件可能因为氯离子的渗透和混凝土的碳化导致钢筋钝化膜消失,进而诱发钢筋锈蚀。一旦发生锈蚀,将会导致其力学性能的下降、与混凝土的界面粘结性能退化以及造成混凝土表面开裂甚至剥落。另外,剪跨比是试验梁剪切破坏模式的主导因素,对FRP的加固效果影响显著。因此本文利用三点受弯梁试验,研究剪跨比和箍筋锈蚀两者的耦合作用对外贴FRP抗剪加固钢筋混凝土梁的影响机理和规律。首先,所有试验梁通过静力加载试验,得到的裂缝发展过程、最终破坏形态、荷载-挠度曲线、箍筋应变、FRP条带应变及其应变不均匀分布等试验结果,分析剪跨比和箍筋锈蚀的相互作用对FRP抗剪贡献的影响,整体把握试验的宏观现象和规律,为探索FRP-混凝土-箍筋在抗剪加固中的互动关系建立理论基础。其次,利用主剪斜裂缝经过的FRP条带和箍筋的计算公式,得到两者的理论抗剪贡献。通过分析FRP实际抗剪贡献与理论抗剪贡献之间的差别,以及加固后箍筋理论抗剪贡献的变化规律,进一步明晰加固梁中FRP-混凝土-箍筋三者之间的互动关系,为建立考虑剪跨比和箍筋锈蚀耦合作用下FRP抗剪贡献计算公式提供坚实的理论依据。最后,在比较了现有设计规范预测值与实际试验值之间的差别之后,总结分析规范因未考虑剪跨比和箍筋锈蚀两者的影响导致的适用性不佳,为此,根据剪跨比和箍筋锈蚀引起的FRP抗剪加固效果的规律性变化,引入考虑剪跨比的影响因子f(λ)和考虑箍筋锈蚀的影响因子f(C),探索性建立适用于不同剪切破坏模式下考虑箍筋锈蚀的FRP抗剪计算公式。
[Abstract]:FRP shear reinforcement of reinforced concrete beams is a hot spot in the field of reinforcement technology. However, most of the experimental studies are based on fresh concrete beams, the lack of consideration of the actual reinforced members of the reinforcement is often in the rusting state of the impact on the reinforcement performance. In the concrete structure in coastal environment, the penetration of chloride ions and the carbonation of concrete may lead to the disappearance of passivation film of steel bar and the corrosion of steel bar. Once the corrosion occurs, it will lead to the decline of its mechanical properties, the degradation of the interfacial bond between the concrete and the concrete, and the cracking and even spalling of the concrete surface. In addition, the shear-span ratio is the main factor of shear failure mode of the experimental beam, and has a significant effect on the strengthening effect of FRP. Therefore, the coupling of shear-span ratio and corrosion of stirrups is studied in this paper by using three-point bending beam test. The mechanism and rule of shear-reinforced concrete beams strengthened with FRP are studied in this paper. First of all, the experimental results of crack development process, final failure pattern, load-deflection curve, stirrups strain, FRP strip strain and its uneven distribution were obtained by static loading test of all test beams. The influence of the interaction of shear span ratio and corrosion of stirrups on the shear strength of FRP is analyzed, and the macroscopic phenomena and rules of the test are grasped as a whole. The theoretical basis for exploring the interaction between FRP- concrete and stirrups in shear reinforcement is established. Secondly, the theoretical contribution of the FRP strip and stirrups passing through the main shear inclined crack is obtained. By analyzing the difference between the actual and theoretical shear contribution of FRP and the variation rule of theoretical shear contribution of reinforced stirrups, the interaction between FRP- concrete and stirrups in reinforced beams is further clarified. It provides a solid theoretical basis for calculating the shear contribution of FRP considering the coupling of shear span ratio and corrosion of stirrups. Finally, after comparing the difference between the predicted value of the existing design code and the actual test value, the applicability of the code due to the failure to consider the influence of shear-span ratio and stirrups corrosion is summarized. According to the regular change of FRP shear reinforcement effect caused by shear span ratio and stirrups corrosion, the influence factors f (位) and f (C), considering shear span ratio and stirrups rust are introduced. The FRP formula for calculating shear strength of stirrups considering corrosion of stirrups under different shear failure modes is established.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.1

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