锈蚀RC梁抗弯承载性能及其增强技术研究

发布时间：2018-09-17 16:16

【摘要】：钢筋混凝土(RC)梁是土木工程领域使用最广泛的基本构件之一,RC梁内钢筋在氯盐环境的长期侵蚀下逐渐锈蚀;锈蚀钢筋有效截面积、屈服强度及弹性模量等参数均发生不同程度劣化,这极大地削弱了 RC梁的抗弯承载性能。碳纤维复合材料(CFRP)增强技术,凭借抗拉强度高、耐腐蚀、质轻等优势,在RC梁构件增强修复中得到广泛应用。因此,有必要进一步定量研究锈蚀RC梁的抗弯承载力劣化规律,建立锈蚀及CFRP增强锈蚀RC梁的抗弯承载力计算方法,探讨CFRP增强锈蚀RC梁抗弯承载力与其可靠度指标间的内在联系。此外,为了论证掺纳米高岭土水泥砂浆对锈蚀RC梁二次锈蚀的阻抑作用,特采用增大截面法对锈蚀RC梁进行增强试验。具体研究内容包括以下几方面。(1)采用人工通电方式得到主筋锈蚀率不同的试验梁,明确了锈蚀梁锈胀裂缝的分布及发展规律;经静力加载试验,得到锈蚀及CFRP增强锈蚀RC梁的抗弯承载力及其他力学指标的变化规律。(2)基于复合材料力学经典层合梁理论,建立了线弹性条件下的锈蚀及CFRP增强锈蚀RC梁抗弯承载力计算公式,得到了对应的荷载-挠度关系,并与试验数据进行对比。(3)在ANSYS通用有限元软件中,建立了对应的锈蚀及CFRP增强锈蚀RC梁静力加载模型;在经试验数据比对证明模型合理的基础上,采用有限元手段,定量分析了锈蚀及CFRP增强锈蚀RC梁锈蚀主筋与混凝土间的粘结-滑移规律。(4)基于一次二阶矩法建立了 CFRP增强锈蚀RC梁抗弯承载力可靠度指标计算公式;分析了可靠度指标与极限荷载间的协同变化规律,为具体增强时机提供了预判和建议;并借助MATLAB GUI工具箱编写了相应的可靠度指标计算界面。(5)采用3种增强方式对试验梁进行"锈蚀-增强-锈蚀"历程试验;分析了各锈蚀RC梁的二次锈蚀通电电流强度值变化情况及其抗弯承载性能劣化规律;论证了掺纳米高岭土水泥砂浆补强方式对锈蚀RC梁二次锈蚀进程的延缓能力。
[Abstract]:Reinforced concrete (RC) beam is one of the most widely used basic members in civil engineering field. The yield strength and elastic modulus of RC beams are degraded to different degrees, which greatly weaken the flexural bearing capacity of RC beams. (CFRP) reinforced carbon fiber composites (CFRP) have been widely used in the reinforcement and repair of RC beams by virtue of its advantages of high tensile strength, corrosion resistance and light weight. Therefore, it is necessary to study quantitatively the deterioration law of flexural bearing capacity of corroded RC beams, and to establish the calculation method of flexural bearing capacity of corroded and CFRP reinforced corroded RC beams. The relationship between flexural bearing capacity and reliability index of corroded RC beams strengthened by CFRP is discussed. In addition, in order to demonstrate the inhibition effect of nano-kaolin cement mortar on the secondary corrosion of RC beams, the reinforcement test of corroded RC beams was carried out by using the method of increasing cross section. The specific research contents include the following aspects: (1) the experimental beams with different corrosion rates of main tendons are obtained by artificial electrification, and the distribution and development law of rust expansion cracks of corroded beams are clarified, and the static loading tests are carried out. The bending bearing capacity and other mechanical indexes of corroded and corroded RC beams strengthened by CFRP are obtained. (2) based on the classical laminated beam theory of composite mechanics, the formulas for calculating the flexural bearing capacity of corroded and CFRP strengthened RC beams under linear elastic conditions are established. The corresponding load-deflection relationship is obtained and compared with the experimental data. (3) in the general finite element software of ANSYS, the corresponding static loading models of corroded and corroded RC beams are established. On the basis of comparing the experimental data to prove that the model is reasonable, the finite element method is adopted. The bond-slip law between rusty and CFRP strengthened RC beams is quantitatively analyzed. (4) based on the first-order second-order moment method, the formula for calculating the reliability of flexural bearing capacity of corroded RC beams strengthened by CFRP is established. The law of synergistic variation between reliability index and ultimate load is analyzed, which provides prejudgment and suggestion for concrete strengthening time. With the help of MATLAB GUI toolbox, the corresponding calculation interface of reliability index is compiled. (5) the "rust-strengthening-corrosion-corrosion" history test of the test beam is carried out with three reinforcement methods; In this paper, the variation of secondary corrosion current intensity and the deterioration of flexural bearing capacity of the corroded RC beams are analyzed, and the ability of reinforcing the reinforced cement mortar with nano-kaolin to delay the secondary corrosion process of the corroded RC beams is demonstrated.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441

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