钢筋和混凝土粘结界面滑移性能分析

发布时间：2019-01-11 12:33

【摘要】：钢筋混凝土材料由混凝土、钢筋和两者之间的粘结界面组成,钢筋混凝土的细观结构特征及材料性能决定了其宏观表现。分析钢筋和混凝土之间粘结界面的材料特性和结构特征,对了解钢筋混凝土结构服役过程中的粘结失效原理具有重要的指导意义。此外,作为混凝土的重要组成成分,由细骨料、水泥净浆构成的水泥砂浆中含有大量的初始缺陷。分析细观结构对水泥砂浆宏观性能的影响,有利于水泥砂浆性能的改进及新型混凝土材料的研发。文中分别建立了水泥砂浆多相模型和钢筋混凝土三相模型,分析讨论了细观结构特征对水泥砂浆和钢筋混凝土宏观行为的影响,为钢筋混凝土耐久性分析奠定了基础。本文的主要工作及成果有：建立了水泥砂浆多相模型,相对于传统模型,该模型能够将水泥砂浆在拌制过程中引入的气泡以初始缺陷的形式体现在该模型当中,并控制孔洞的含量及其分布,可以有效的分析水泥净浆强度和初始缺陷在水泥砂浆轴向拉伸过程中对水泥砂浆宏观性能的影响。编写了以面积为控制条件的圆形骨料及圆形孔洞随机投放程序。该程序可以准确的控制孔隙率和细骨料含量,避免手动投放骨料和缺陷孔洞的繁琐过程,大幅提高模型的建立效率。结合商用有限元软件,编写了一套水泥砂浆多相模型分析一体化的程序,有效的降低了模型建立和数据结果提取分析的时间,为数值模拟的大批量计算奠定了基础。建立了钢筋混凝土三相模型。该模型根据实际观测结果,将钢筋与混凝土之间的粘结界面定义为一层具有一定几何尺寸和实际材料特性的第三相材料。在分析钢筋混凝土粘结失效原理过程中,相比将滑移本构关系赋值于无几何尺寸的有限元单元,该模型更加合理,符合实际。利用钢筋混凝土三相模型,进行了钢筋混凝土拉拔试验过程的数值模拟并分析钢筋混凝土拉拔失效的全过程,可以有效的分析钢筋和混凝土之间粘结界面的细观材料特性的改变对钢筋混凝土宏观拉拔特性的影响。
[Abstract]:The reinforced concrete material is composed of concrete, steel bar and the bond interface between them. The macro performance of reinforced concrete is determined by its meso-structure characteristics and material properties. The analysis of the material characteristics and structural characteristics of the bond interface between steel bar and concrete is of great significance in understanding the mechanism of bond failure during the service of reinforced concrete structures. In addition, as an important component of concrete, cement mortar composed of fine aggregate and cement paste contains a large number of initial defects. It is beneficial to improve the performance of cement mortar and to develop new concrete material by analyzing the influence of meso structure on the macroscopic properties of cement mortar. In this paper, the multi-phase model of cement mortar and the three-phase model of reinforced concrete are established, and the influence of mesoscopic structure characteristics on the macroscopic behavior of cement mortar and reinforced concrete is analyzed and discussed, which lays a foundation for the durability analysis of reinforced concrete. The main work and achievements of this paper are as follows: the multi-phase model of cement mortar is established. Compared with the traditional model, the model can reflect the bubble introduced in the mixing process of cement mortar in the form of initial defects. The influence of strength and initial defect of cement paste on the macroscopic properties of cement mortar during axial tensile process can be analyzed by controlling the content and distribution of the holes. A program for random placement of circular aggregates and circular voids with area as control condition was written. The program can accurately control the porosity and fine aggregate content, avoid the tedious process of manual loading of aggregate and defective pores, and greatly improve the efficiency of modeling. Combined with the commercial finite element software, a program for the integration of multi-phase model analysis of cement mortar is developed, which effectively reduces the time of model establishment and data extraction and analysis, and lays the foundation for mass calculation of numerical simulation. A three-phase model of reinforced concrete is established. According to the actual observation results, the bond interface between steel bar and concrete is defined as the third phase material with certain geometric size and practical material characteristics. In the process of analyzing the failure principle of reinforced concrete bond, the model is more reasonable than the sliding constitutive relation to the finite element without geometric size. Based on the three-phase model of reinforced concrete, the numerical simulation of the process of reinforced concrete pull-out test is carried out and the whole process of the failure of reinforced concrete pull-out is analyzed. It can be used to analyze the effect of the change of mesomaterial characteristics of the bond interface between steel bar and concrete on the macroscopic drawing behavior of reinforced concrete.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU375

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