曲面构件CFRP-混凝土复合界面分析方法及模型试验研究

发布时间：2018-01-08 00:06

本文关键词：曲面构件CFRP-混凝土复合界面分析方法及模型试验研究　出处：《长安大学》2017年博士论文　论文类型：学位论文

【摘要】：碳纤维材料(CFRP)加固技术,以其优良的材料性能和简易的施工方法,被广泛应用于混凝土桥梁结构的加固工程中,碳纤维材料与混凝土的界面粘结性能研究迅速成为桥梁加固领域的热点和难点。通过对大量相关文献的查阅发现,已有的研究成果大多是基于等截面构件的模型试验,且试验结果离散性较大,缺乏理论依据。因此,本文以碳纤维布(CFRP)加固曲面构件为研究对象,对26个不同曲率的混凝土曲面构件进行剪切试验,研究了曲面构件CFRP-混凝土界面的粘结破坏特征、极限承载力影响因素以及应力(应变)分布规律等问题。同时,对3个钢筋混凝土(RC)拱肋(RCA-1为对比拱、RCA-2和RCA-3为加固拱)进行抗弯试验,研究了在不同的加固方式下,结构的破坏形态、裂缝分布规律、极限承载能力提升效果等问题。在界面粘结试验中,分别以混凝土强度等级、粘结层数、粘结长度和曲率为参数,对曲面构件的极限承载能力提升效果进行分析发现,CFRP粘结层数和曲率对构件极限承载力的影响较大,而混凝土强度等级和粘结长度的影响则较小,曲面构件加固效果随着曲率的减小而增大,即结构越平坦承载力提升越明显。曲面构件的界面破坏形态主要包括沿裂缝向两侧的剥离破坏、拉断破坏和沿裂缝向单侧的剥离破坏。在实际加固工程中,应严格按照CFRP的粘结工艺,并采用合理的锚固措施,避免沿裂缝向单侧的剥离破坏现象产生。在CFRP加固混凝土拱模型试验中,采用不同的加固方式,即拱顶下表面和拱肩上表面同时加固方式以及仅加固拱顶下表面的方式发现,考虑整体效果的加固较局部加固方式,其结构极限承载能力明显提高。采用CFRP加固能够有效减小拱顶下挠,抑制裂缝的开展和扩张,提高结构整体刚度。由于曲面构件的界面粘结力是粘结剪应力和剥离正应力耦合作用,等截面构件的粘结滑移本构模型和粘结强度模型已不再适用。通过对已有粘结滑移本构模型和粘结强度模型的对比,分别对陆新征提出的粘结滑移本构模型和粘结强度模型进行了修正,提出了考虑曲率影响的CFRP-混凝土界面粘结滑移本构模型和粘结强度模型,并根据弹性力学和结构力学相关理论,推导出了曲面构件CFRP-混凝土复合界面应力解析式。采用非线性有限元软件Midas FEA,对CFRP加固RC拱肋进行了全过程仿真模拟,通过对有限元结果(包括荷载-挠度曲线、钢筋应变、CFRP应变)与试验结果进行对比分析,验证了有限元模型合理性,并为以后相关的数值分析提供借鉴与指导。
[Abstract]:Carbon fiber (CFRP) reinforcement technology, with the construction of its excellent material properties and simple, is widely used in the reinforcement engineering of concrete bridge structure, the interface bonding performance of carbon fiber concrete material and quickly become a hot and difficult point in the field of bridge reinforcement. Through access to a large number of relevant documents, research results most of the existing model test section members based on the discrete and the test results is large, the lack of theoretical basis. Therefore, in this paper, carbon fiber cloth (CFRP) reinforced surface structure as the research object, the shear tests are performed on 26 different curvature of the concrete surface bonding component, study the surface component of CFRP- concrete interface failure characteristics and the factors affecting the ultimate bearing capacity and stress (strain) distribution problems. At the same time, the 3 reinforced concrete (RC) arch rib (RCA-1 for RCA-2 and RCA-3 than the arch, and Solid arch) bending test, were studied in different strengthening modes, the failure pattern of structure, fracture distribution, ultimate bearing capacity problem. To enhance the effect of interfacial bonding in the experiment, with the grade of concrete strength, bonding layer, bond length and curvature parameter, ultimate bearing capacity of surface lifting structure the effect analysis shows that the effect of CFRP bonding layer and curvature on the ultimate capacity of the larger, and the influence of the strength of concrete and the bond length is smaller, the surface structure of the reinforcement effect increases with the decrease of the curvature, the structure is more flat and carrying capacity is more obvious. The surface structure of the interface failure mode mainly includes damage to both sides stripping along the crack, tensile failure and crack along to unilateral debonding. Reinforcement in the actual project, should be strictly in accordance with the bonding process of CFRP, and the reasonable anchorage measures Application, avoid cracks along to unilateral debonding phenomenon. In CFRP reinforced concrete arch model test, using different strengthening modes, namely the vault and spandrel on the surface and surface and surface reinforcement reinforcement only under the arches, considering the overall effect of a local reinforcement reinforcement, improve bearing capacity the structure of the limit. The CFRP reinforcement can effectively reduce the vault deflection, restraining the crack development and expansion, improve the overall stiffness of the structure. Because the bonding force between the surface structure is the bonding shear stress and the peeling stress coupling, the bond slip constitutive model of steel structure and bond strength of the model is no longer applicable through. Comparing the existing bond slip constitutive model and bond strength of the bond slip model, respectively to Lu Xinzheng's theory of constitutive model and bond strength model, is proposed The constitutive model and the bond strength of CFRP- concrete interfacial bond slip model considering the effect of curvature, and according to the elastic mechanics and structure mechanics theory, deduced the surface structure of CFRP- concrete composite interface stress formula. Using nonlinear finite element software Midas FEA, RC of CFRP reinforced arch ribs were simulated through the whole process of simulation. The results of finite element method (including the load deflection curve, steel strain, CFRP strain) were compared with the experimental results, verify the rationality of the finite element model, and for the future of the numerical analysis and provide reference and guidance.

【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：U445.72

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