纤维掺量及粘结长度对混凝土单筋拨出力学性能的物理试验和数值模拟研究

发布时间：2018-02-22 12:25

本文关键词： 纤维混凝土界面拔出过程纤维掺量　出处：《广州大学》2015年硕士论文　论文类型：学位论文

【摘要】：纤维增强混凝土材料目前已经迅速发展成为广泛应用在各工程领域的新型复合建筑材料,其中以钢纤维与碳纤维混凝土材料发展最快。钢纤维和碳纤维混凝土材料具有阻裂、增强和增韧的作用。钢筋与混凝土可以共同工作的主要原因之一是两种材料之间有效的粘结力。本文利用物理试验和数值模拟方法,结合声发射技术手段,研究考虑界面控制的钢筋从纤维混凝土基体中拔出的粘结滑移特性。利用RFPA2D和RFPA3D软件,建立基于Weibull随机分布的细观非均匀损伤模型,将钢筋与纤维混凝土之间的界面单独作为一相,分析单根钢筋从纤维混凝土基体中拔出的损伤破坏过程,重点研究了钢筋的粘结长度、钢纤维和碳纤维的掺量变化对钢筋与纤维混凝土之间粘结滑移特性的影响。本文主要研究内容如下:(1)研究纤维掺量的变化对纤维混凝土基体基本力学性能的影响。分别改变钢纤维混凝土基体和碳纤维混凝土基体中的纤维掺量,运用物理试验和数值模拟两种方法进行研究。物理试验中钢纤维掺量为1.0%、1.2%和1.5%,碳纤维掺量为0.15%、0.20%、0.25%,制作6组不同的纤维混凝土立方体试块并与普通混凝土立方体试块进行对比。在RFPA2D软件中,建立纤维混凝土试块单轴压缩的数值模型,将数值模拟得到的声发射与应力应变曲线的结果与物理试验得到的结果进行对比,以验证数值模型中各相力学参数设置的合理性。(2)研究考虑界面的不同粘结长度对钢筋从普通混凝土基体中拔出的粘结滑移特性的影响。首先,利用中心拔出物理试验模型,得到拔出力-拔出位移曲线;并运用声发射技术对整个拔出过程进行监测,得到不同粘结长度的钢筋从混凝土基体中拔出的声发射信号特征,与拔出力-拔出位移曲线进行对比。其次运用RFPA2D软件建立水泥砂浆、粗骨料、钢筋与混凝土基体之间的界面、钢筋共四相的中心拔出数值模型,得到不同粘结长度的钢筋从混凝土基体中拔出破坏的全过程,分析钢筋与混凝土基体之间的界面单元信息,得到二维数值模拟情况下的界面剪应力等性质;最后建立RFPA3D中心拔出数值模型,探讨三维数值模型中不同粘结长度下的钢筋从混凝土基体中拔出的粘结滑移特性。(3)研究纤维掺量对钢筋从纤维混凝土基体中拔出的粘结滑移特性的影响,考虑钢筋与纤维混凝土基体中的界面性质,分别改变钢纤维与碳纤维的掺量,进行物理试验和数值模拟研究,并利用声发射手段对整个拔出过程进行监测。钢筋粘结长度为5d(d为钢筋直径),最后得到钢筋从纤维混凝土基体中拔出的力-位移曲线及声发射信号特征。
[Abstract]:Fiber reinforced concrete materials have been rapidly developed into new types of composite building materials widely used in various engineering fields, among which steel fiber and carbon fiber reinforced concrete materials have the fastest development. Strengthening and toughening. One of the main reasons why the reinforcement and concrete can work together is the effective bonding force between the two materials. In this paper, we use physical test and numerical simulation method, combined with acoustic emission technology, The bond-slip behavior of steel bar pull-out from fiber reinforced concrete matrix considering interface control is studied. Using RFPA2D and RFPA3D software, a mesoscale nonuniform damage model based on Weibull random distribution is established. Taking the interface between steel bar and fiber concrete as a single phase, the damage and failure process of a single steel bar extracted from the fiber reinforced concrete matrix is analyzed, and the bond length of the steel bar is studied emphatically. The influence of the content of steel fiber and carbon fiber on the bond-slip behavior of steel fiber and fiber reinforced concrete. The main contents of this paper are as follows: 1) the influence of fiber content on the basic mechanical properties of fiber reinforced concrete matrix is studied. To change the fiber content in steel fiber reinforced concrete matrix and carbon fiber concrete matrix, In the physical test, the steel fiber content is 1.0% and 1.5%, and the carbon fiber content is 0.15% and 0.20%, 0.25% respectively. Six different groups of fiber concrete cube test blocks are made and compared with the ordinary concrete cube test blocks. In RFPA2D software, A numerical model for uniaxial compression of fiber reinforced concrete specimens is established. The results of acoustic emission and stress-strain curves obtained by numerical simulation are compared with those obtained from physical tests. In order to verify the reasonableness of setting mechanical parameters of each phase in the numerical model, the effect of different bond lengths of interface on the bond-slip behavior of steel bar pulled out from ordinary concrete matrix is studied. Firstly, the physical test model is drawn out by central pull-out. The drawing force-drawing displacement curve was obtained, and the acoustic emission technique was used to monitor the whole pull-out process, and the acoustic emission signal characteristics of the steel bars with different bonding lengths were obtained. Secondly, the interface between cement mortar, coarse aggregate, steel bar and concrete matrix and the central pull-out numerical model of four phases of steel bar are established by using RFPA2D software. The whole process of tensile failure of steel bar with different bonding length from concrete matrix is obtained. The information of interface element between steel bar and concrete matrix is analyzed and the properties of interface shear stress under two-dimensional numerical simulation are obtained. Finally, a numerical model of RFPA3D center pull-out is established. The effect of fiber content on the bond slip behavior of steel bar pull-out from concrete matrix is studied in the three-dimensional numerical model. Considering the interfacial properties of steel and fiber reinforced concrete matrix and changing the content of steel fiber and carbon fiber, the physical test and numerical simulation are carried out. The whole pull-out process is monitored by acoustic emission method. The bonding length of steel bar is 5 d and the diameter of steel bar is 5 d. Finally, the force-displacement curve and acoustic emission signal characteristics of steel bar drawn from fiber reinforced concrete matrix are obtained.
【学位授予单位】：广州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528.57

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