不同受力形式的表面内嵌FRP筋与混凝土界面粘结滑移性能研究

发布时间：2018-03-07 09:18

本文选题：表面内嵌　切入点：FRP筋　出处：《沈阳建筑大学》2015年硕士论文　论文类型：学位论文

【摘要】：当建筑结构在承载能力或者使用功能无法继续满足正常使用的要求时,不可避免地将面对加固问题。FRP筋作为一种新型的复合材料,具有良好的受力性能和耐久性,表面内嵌FRP筋加固技术已逐渐成为混凝土结构加固领域的研究热点。表面内嵌FRP筋与粘结剂之间的粘结性能是FRP筋结构中最基本的力学行为,是设计、应用和推广该种加固方法的关键技术之一。本课题通过研究表面内嵌FRP筋混凝土的粘结滑移性能,期望为表面内嵌FRP筋加固技术的研究与应用提供一定的参考依据。本文通过对一组表面内嵌FRP筋混凝土拉拔试件进行试验分析,研究试件的受力形式和破坏模式,对FRP筋直径d、粘结长度l和FRP筋类型等影响因素进行分析。试验表明,试件的破坏模式表现为FRP筋与结构胶界面破坏、结构胶与混凝土界面剥离、FRP筋被拉断和结构胶劈裂四种。通过分析影响因素发现,在粘结长度不变的情况下,d=8mm的试件的最大粘结应力均大于d=10mm的试件；在直径相同的情况下,BFRP筋试件的最大粘结应力随粘结长度的增加而增大,GFRP筋试件的最大粘结应力随粘结长度的增加而减小；在粘结长度和FRP筋直径均相同的情况下,GFRP筋试件的最大粘结应力大于BFRP筋试件。通过对试验曲线进行分析拟合,建立了一种适用于表面内嵌FRP筋与混凝土粘结性能的粘结-滑移本构关系模型。该模拟能够较为准确地模拟两者之间粘结滑移性能。在此基础上,推导了表面内嵌FRP筋锚固长度限值的计算公式。利用有限元分析软件对表面内嵌FRP筋混凝土拉拔试验进行数值模拟。将有限元分析结果与试验结果进行分析对比,曲线吻合良好,验证了有限元模型的正确性。在此基础上,对粘结区域FRP筋的应变和粘结应力分布曲线进行分析。通过对一组表面内嵌FRP筋加固混凝土梁试件进行梁式试验,研究FRP筋加固混凝土梁的受力形式和破坏模式,对FRP筋直径d、粘结长度l和FRP筋类型等影响因素进行分析。试验表明试件的破坏模式为：结构胶整体破坏、粘结区域结构胶剥离破坏、和FRP筋被拉断三种。通过对影响因素分析发现,在粘结长度不变的情况下,d=8mm的试件的极限荷载均小于d=10mm的试件；在FRP筋直径相同的情况下,当粘结长度不大于400mm时,试件的极限荷载随粘结长度的增加而增大,当粘结长度大于400mmm时,试件的最大粘结应力随粘结长度的增加而减小；在粘结长度和FRP筋直径均相同的情况下,当粘结长度不大于200mm时,GFRP筋试件的极限荷载大于BFRP筋试件,当粘结长度大于200mmm时,GFRP筋试件的极限荷载小于BFRP筋试件。
[Abstract]:When the carrying capacity or function of building structure can not meet the requirements of normal use, it is inevitable to take the reinforcement problem as a new type of composite material, which has good mechanical performance and durability. The surface FRP reinforcement technology has gradually become the research hotspot in the field of concrete structure strengthening. The bond behavior between the surface embedded FRP reinforcement and the binder is the most basic mechanical behavior and the design of the FRP reinforcement structure. One of the key techniques for applying and popularizing this method is to study the bond-slip behavior of FRP reinforced concrete embedded in the surface. It is expected to provide a certain reference for the study and application of the strengthening technology of surface embedded FRP bars. Through the experimental analysis of a group of concrete drawing specimens with FRP tendons embedded in the surface, the force form and failure mode of the specimens are studied. The influence factors such as diameter d of FRP bar, length of bond l and type of FRP bar are analyzed. The test results show that the failure mode of the specimen is the interface failure of FRP bar and structural glue. There are four kinds of FRP bars at the interface between structural adhesive and concrete. Through the analysis of the influencing factors, it is found that the maximum bond stress of the specimen with 8 mm is higher than that of the specimen with 10 mm. Under the same diameter, the maximum bond stress of BFRP bars increases with the increase of bond length, and the maximum bond stress of GFRP bars decreases with the increase of bond length. Under the same bond length and diameter, the maximum bond stress of the specimens with FRP tendons is larger than that of BFRP tendons. A bond-slip constitutive model suitable for the bond behavior of FRP bars and concrete embedded on the surface is established. The simulation can accurately simulate the bond-slip behavior between the two. In this paper, the formula for calculating the limit of anchoring length of FRP reinforcement embedded on the surface is derived. The drawing test of FRP reinforced concrete on the surface is numerically simulated by using the finite element analysis software. The results of finite element analysis are compared with those of the test. The curve agrees well, which verifies the correctness of the finite element model. On this basis, the distribution curves of strain and bond stress of FRP tendons in the bond region are analyzed. The beam tests are carried out on a group of concrete beam specimens strengthened with FRP tendons embedded in the surface. The stress forms and failure modes of concrete beams strengthened with FRP bars are studied. The influence factors such as diameter d of FRP tendons, bond length l and type of FRP bars are analyzed. The test results show that the failure modes of the specimens are as follows: structural adhesive failure. There are three kinds of structural adhesive debonding failure in the bond area and tensile fracture of the FRP tendons. Through the analysis of the influencing factors, it is found that the ultimate load of the specimens with 8 mm of bond length is smaller than that of the specimens with the same diameter of the FRP tendons, and the ultimate load of the specimens with the same diameter of the FRP bars is less than that of the specimens with the same diameter of the FRP bars. When the bond length is less than 400 mm, the ultimate load of the specimen increases with the increase of the bond length, and the maximum bond stress decreases with the increase of the bond length when the bond length is greater than 400 mm. When the bonding length and the diameter of FRP tendons are the same, when the bonding length is not more than 200mm, the ultimate load of GFRP-reinforced specimens is larger than that of BFRP tendons, and the ultimate load of GFRP-reinforced specimens is smaller than that of BFRP tendons when the bonding length is more than 200mmm.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU377

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