基于锈蚀特征的纤维布加固钢筋混凝土梁抗剪承载力分析

发布时间：2018-05-14 07:12

  本文选题：玄武岩纤维布 + 抗剪加固　； 参考：《浙江大学》2013年硕士论文

【摘要】：混凝土构件内钢筋锈蚀是其性能退化的主要原因,但当前研究针对钢筋锈蚀的机理和发展规律尚不明确,虽然大量工程检测报告显示,钢筋锈蚀形态可大致区分为均匀锈蚀和局部坑蚀,局部坑蚀导致应力集中明显影响构件受力性能,但这方面的系统试验和理论分析尚亟待开展。工程中的锈蚀的钢筋混凝土构件必须及时采用加固措施,纤维布作为一种新型的加固材料,以其轻质、高强、耐高温、耐腐蚀等优点在服役结构工程加固领域具有可观的应用前景。在过去十年里,国内外学者对FRP布的材料性能及其加固混凝土梁的力学性能进行了大量的试验研究,并基于此建立计算方法和设计规程。由于剪切失效存在更多的不确定性和离散性,钢筋锈蚀形态研究的不足加之纤维增强作用长期耐久性研究的空白,导致采用纤维布加固存在锈蚀损伤的钢筋混凝土构件的抗剪承载力分析模型具有较大的误差。针对以上问题,本文具体开展的研究工作如下： (1)采用试验室加速锈蚀法制备侵蚀环境下的混凝土构件中锈蚀钢筋样本,针对局部锈蚀特征开展统计分析,结合锈蚀钢筋力学性能测试,研究了钢筋锈蚀程度与蚀坑形态特征之间的关系,建立了更为合理的钢筋锈蚀程度分类方法和更为准确的钢筋性能评估指标；通过锈蚀钢筋拉伸试验,研究锈蚀钢筋退化规律以及蚀坑参数对锈蚀钢筋力学性能的影响；建立了钢筋力学性能退化模型。 (2)针对锈蚀钢筋建立3D有限元模型,与试验结果进行对比,验证了有限元模型的有效性,研究了通用Ⅱ级钢筋的蚀坑形状参数,包括蚀坑深度、蚀坑长度、蚀坑宽度,以及相邻蚀坑之间的相互作用对钢筋力学性能的影响,并提出蚀坑应力放大系数和蚀坑不均匀系数与蚀坑参数之间的关系,从而为钢筋坑蚀的应力集中现象提出定量分析方法。 (3)开展了10根不同锈蚀程度和后续退化程度的纤维布抗剪抗弯加固梁静载试验,分析了不同初始退化程度以及不同加固材料对抗剪加固效果的影响；基于现有FRP抗剪加固混凝土梁计算模型和试验研究成果,分析了钢筋锈蚀和长期侵蚀作用对抗剪加固后构件性能及破坏形态的影响,为FRP抗剪加固后承载力预测提供更为精确的预测模型。
[Abstract]:The corrosion of steel bars in concrete members is the main cause of its performance degradation. However, the mechanism and development law of reinforcement corrosion are not clear at present, although a large number of engineering inspection reports show that, The corrosion morphology of steel bars can be roughly divided into uniform corrosion and local pit corrosion. The stress concentration caused by local pit corrosion obviously affects the mechanical performance of the members, but the systematic tests and theoretical analysis in this respect need to be carried out urgently. Reinforcement measures must be adopted in time for corroded reinforced concrete members in engineering. As a new type of reinforcement material, fiber cloth is light, high strength and high temperature resistant. Corrosion resistance and other advantages in the field of structural engineering reinforcement has a considerable application prospects. In the past ten years, scholars at home and abroad have carried out a lot of experimental studies on the material properties of FRP cloth and the mechanical properties of reinforced concrete beams. Based on this, the calculation method and design rules have been established. Due to the more uncertainty and dispersion of shear failure, the lack of research on the corrosion morphology of steel bar and the lack of long-term durability study of fiber reinforcement. As a result, the shear capacity analysis model of reinforced concrete members strengthened with fiber sheets with corrosion damage has a large error. In view of the above problems, the specific research work carried out in this paper is as follows: 1) using laboratory accelerated corrosion method to prepare specimens of corroded steel bars in corroded concrete structures, and carrying out statistical analysis on local corrosion characteristics and testing the mechanical properties of corroded steel bars. The relationship between the corrosion degree of steel bar and the morphological characteristics of corrosion pit is studied. A more reasonable classification method of corrosion degree of steel bar and a more accurate evaluation index of steel bar performance are established, and the tensile test of corroded steel bar is carried out. The degradation law of corroded steel bar and the influence of corrosion pit parameters on the mechanical properties of corroded steel bar are studied, and the degradation model of mechanical properties of corroded steel bar is established. The 3D finite element model for corroded steel bar is established and compared with the experimental results. The validity of the finite element model is verified. The shape parameters of the corrosion pit of the universal grade 鈪，

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