外包钢加固钢筋混凝土柱的非线性分析

发布时间：2019-04-15 20:37

【摘要】：外包钢加固法因其具有现场工作量小、对建筑空间影响小、施工周期短等优点而在加固行业得到广泛推广,被人们用来加固钢筋混凝土等结构。特别是用于钢筋混凝土构件的加固,能明显改善构件的承载力、刚度等。因此,研究外包钢加固钢筋混凝土柱的非线性是一项实用价值很高的学术课题。对于外包钢加固的钢筋混凝土柱,国内外学者进行了大量的试验研究,并得出了一些重要结论。本文鉴于前人的研究,对于有应力历史的钢筋混凝土柱加固前进行卸载,研究卸载量的多少对钢筋混凝土柱二次受力后受力性能的影响。利用有限元软件ABAQUS,根据《混凝土结构设计规范》和《混凝土结构加固设计规范》相关规定,采用混凝土塑性损伤本构模型及钢筋和外包钢的线性强化弹塑性本构模型,建立六个不同卸载量的外包钢钢筋混凝土柱模型,在轴心加载和偏心加载的情况下对其分别进行非线性分析,研究卸载量的多少对构件的承载力、延性以及外包钢利用率的影响。同时,建立五个有限元模型分析外包钢厚度及强度、缀板间距、角钢及缀板截面尺寸、应力历史等对钢筋混凝土柱加固性能的影响。通过有限元分析得出以下结论:对于轴心受压的钢筋混凝土柱,加固时卸载60%左右承载力提高幅度最大,加固柱延性最好;对于偏心受压的加固柱,卸载40%左右时其加固效果最好;在不同的应力水平指标下,随着外包钢厚度的增加,应力水平指标越小加固柱承载力及外包钢利用率越高;改变缀板间距,发现缀板间距越小加固柱承载力越高,但承载力提高幅度不是线性增加,经有限元分析发现,缀板间距在250mm~300mm之间时,承载力提高幅度最大,加固效果最好;改变角钢截面尺寸和缀板截面尺寸进行研究,发现增大角钢边长比增大缀板宽度加固效果更明显,其加固柱承载力最大能提高34.11%。采用《混凝土结构加固设计规范》中外包钢加固混凝土柱极限承载力公式及外包钢利用系数公式对所建模型进行了有关理论计算,将数值模拟值和理论计算值进行对比分析,发现模拟值在规范规定的范围内,说明模型符合要求,得出本文研究内容可以为工程实例提供理论依据和参考价值。
[Abstract]:Because of its advantages such as small on-site workload, small influence on building space and short construction cycle, the steel-coated steel reinforcement method has been widely used in the reinforcement industry, and has been used to strengthen reinforced concrete structures and so on. Especially for the reinforcement of reinforced concrete members, the bearing capacity and stiffness of the members can be obviously improved. Therefore, it is a practical and valuable academic subject to study the nonlinearity of reinforced concrete columns strengthened with steel. A large number of experimental studies have been carried out on reinforced concrete columns strengthened with steel, and some important conclusions have been drawn. In view of the previous research, the unloading of reinforced concrete columns with stress history before reinforcement is carried out, and the influence of the amount of unloading on the performance of reinforced concrete columns after secondary loading is studied in this paper. By using the finite element software ABAQUS, the plastic damage constitutive model of concrete and the linear reinforced elastoplastic constitutive model of steel bar and coated steel are adopted according to the relevant regulations of Code for Design of concrete structures and Code for Design of reinforced concrete structures. Six models of steel-clad reinforced concrete columns with different unloading capacity were established, and the nonlinear analysis was carried out under axial loading and eccentric loading respectively, and the bearing capacity of the components was studied by studying how much the unloading capacity was to the members, and then analyzed the load-bearing capacity of the concrete columns under axial loading and eccentric loading respectively. The effect of ductility and utilization ratio of coated steel. At the same time, five finite element models are set up to analyze the influence of the thickness and strength of coated steel, the spacing of affixed plates, the cross-section size of angle steel and affixed plates, and the stress history on the strengthening performance of reinforced concrete columns. Through the finite element analysis, the following conclusions are drawn: for reinforced concrete columns subjected to axial compression, the maximum increase in bearing capacity is about 60% or so when strengthened, and the ductility of reinforced columns is the best. Under different stress level indexes, the smaller the stress level index, the higher the bearing capacity of reinforced columns and the higher the utilization ratio of outer steel, with the increase of the thickness of coated steel, and for the columns strengthened by eccentric compression, the loading capacity is the best when the load is unloaded about 40%. It is found that the smaller the spaced plate spacing is, the higher the bearing capacity is, but the increase in bearing capacity is not linear. Through finite element analysis, it is found that when the spacing is between 250mm~300mm, the bearing capacity increase is the largest and the strengthening effect is the best. It is found that the reinforcement effect is more obvious when the length of the angle steel is increased than the width of the plywood, and the bearing capacity of the reinforced column can be increased by 34.11% at the maximum, by changing the cross-section size of the angle steel and the section size of the patch plate. The formula of ultimate bearing capacity of reinforced concrete columns and the formula of outer steel utilization coefficient are used to calculate the model, and the numerical simulation value and theoretical calculation value are compared and analyzed by using the Code of Design for reinforcement of concrete structures and the formula of ultimate bearing capacity of concrete columns strengthened by external steel and the formula of outer steel utilization coefficient. It is found that the simulation value is within the scope of the code, indicating that the model meets the requirements, and that the research content of this paper can provide theoretical basis and reference value for engineering examples.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU375.3

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