考虑剪力滞效应的嵌贴CFRP布加固RC箱梁的抗弯极限承载力

发布时间：2018-03-02 09:42

本文关键词： 碳纤维嵌入式加固抗弯极限承载力剪力滞效应　出处：《兰州交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：工程中常用的混凝土桥梁加固方法有增大截面加固法、粘贴钢板加固法、体外预应力加固法，，此外，碳纤维凭借其高强、轻质、耐腐蚀和施工便利的优点，越来越广泛地应用于混凝土桥梁结构的补强中。近十几年来，科研人员对碳纤维加固钢筋混凝土结构进行了大量的试验研究和理论分析，但是现有的研究大部分局限于矩形梁、T形梁抗弯加固和抗剪加固的研究，而箱梁凭借其结构轻、抗扭刚度大的优点在工程实践中有广泛的应用，因此研究碳纤维片材加固混凝土箱梁具有重要的现实意义。另外表层嵌贴加固技术除了与表层粘贴加固技术一样可以提高被加固构件的强度和刚度，还可以相对减少构件受恶劣环境(高温、高湿和冻融等)的影响，并且能搞提高碳纤维片材的利用率，基于此本文对嵌贴CFRP加固RC箱梁进行了研究，主要研究工作有： (1)以三片钢筋混凝土箱梁为试验对象，未加固的箱梁做为对比梁，外贴碳纤维布加固的箱梁和嵌贴碳纤维布加固的箱梁与之对比，分别测量特征截面的挠度、混凝土及碳纤维布的应变。通过试验研究获得必要的试验数据，分析研究嵌贴CFRP布加固RC箱梁的力学性能。 (2)在现行成熟的钢筋混凝土梁受弯正截面极限承载力计算理论基础上，推导出了嵌贴CFRP布加固RC箱梁的抗弯极限承载力。然而当箱型梁在腹板内存在压应力时，其翼板内将会出现剪力滞后效应，因此，在传统的极限承载力理论基础上，考虑剪力滞的影响，对嵌贴CFRP布加固RC箱梁的计算理论进行了分析，同时提出正截面抗弯极限承载力的计算方法。 (3)以换算截面法为基础，应用变分原理分析了碳纤维布加固钢筋混凝土简支箱梁的剪力滞效应，推导出了简支箱梁在集中荷载作用下的应力计算公式，并且与前文中的试验值进行了对比，发现结果吻合较好。 (4)基于试验和理论分析的结果，利用大型通用有限元软件ANSYS建立嵌入式粘贴CFRP布加固RC简支箱梁的有限元模型，并将计算结果同理论计算结果和试验结果进行对比分析，结果表明计算结果比较接近。
[Abstract]:The common reinforcement methods of concrete bridges in engineering include reinforcement with enlarged section, strengthening with steel plate and external prestressing. In addition, carbon fiber has the advantages of high strength, light weight, corrosion resistance and convenient construction. More and more widely used in the reinforcement of concrete bridge structures. In the past ten years, researchers have carried out a large number of experimental research and theoretical analysis on reinforced concrete structures strengthened with carbon fiber. However, most of the existing studies are limited to the study of bending and shear strengthening of rectangular beams with T-shaped beams. Box girders are widely used in engineering practice because of their advantages of light structure and large torsional stiffness. Therefore, it is of great practical significance to study the reinforcement of concrete box girder with carbon fiber sheet. In addition, the surface embedded reinforcement technology can improve the strength and stiffness of the strengthened members as well as the surface bonding and strengthening technology. It can also reduce the impact of severe environment (high temperature, high humidity, freezing and thawing etc.), and can improve the utilization ratio of carbon fiber sheet. Based on this, the RC box girder strengthened by embedded CFRP is studied, the main research work is as follows:. 1) taking three reinforced concrete box girders as experimental objects, the unreinforced box girders are used as contrast beams, and the box girders strengthened with CFRP and those strengthened with CFRP are compared to each other, and the deflection of characteristic sections is measured respectively. The strain of concrete and carbon fiber sheet. The necessary experimental data were obtained and the mechanical properties of RC box girder strengthened with CFRP cloth were analyzed. 2) based on the mature theory of ultimate bearing capacity of reinforced concrete beams under bending normal section, the ultimate flexural bearing capacity of RC box girder strengthened by encased CFRP cloth is deduced. However, when the box girder has compressive stress in the web, the ultimate bearing capacity of RC box girder is derived. The shear lag effect will occur in the flange. Therefore, based on the traditional ultimate bearing capacity theory and considering the influence of shear lag, the calculation theory of RC box girder strengthened with CFRP cloth is analyzed. At the same time, the calculation method of flexural ultimate bearing capacity of normal section is put forward. Based on the conversion section method, the shear lag effect of reinforced concrete simply supported box girder strengthened with carbon fiber sheet is analyzed by using variational principle, and the stress calculation formula of simply supported box girder under concentrated load is deduced. The results are in good agreement with the experimental data in the previous paper. Based on the results of experiment and theoretical analysis, the finite element model of RC simply supported box girder strengthened with embedded CFRP sheet is established by using the large scale universal finite element software ANSYS, and the calculated results are compared with the theoretical calculation results and the experimental results. The results show that the calculated results are close to each other.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U445.72

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