粘聚力模型在裂缝扩展及锈蚀钢筋混凝土粘结滑移中的应用
发布时间：2018-07-24 10:33
【摘要】：钢筋混凝土结构是世界上使用最为广泛的结构形式之一,目前已成功应用于工业与民用建筑、桥梁、隧道、矿井、水利及海港等工程中。由于混凝土结构所用材料及所处环境的特点,使得混凝土结构不可避免地会出现开裂、性能劣化,最终产生耐久性问题。钢筋锈蚀会导致钢筋混凝土材料物理和化学性质的变化,并将最终影响钢筋混凝土构件的力学行为,钢筋锈蚀导致的混凝土构件力学性能退化是一个极其复杂的过程,如何评定不同锈蚀程度下混凝土构件的承载能力和延性等力学性能的改变具有重要的意义,但是目前关于导致钢筋锈蚀的劣化因素与混凝土构件力学性能改变之间的定量关系研究仍不足。故研究混凝土结构的破坏问题,特别是混凝土结构中的裂缝问题以及环境引起的混凝土结构耐久性问题十分有意义。以此为主线,基于扩展有限元与粘聚力模型研究了混凝土梁的受剪破坏过程,以及锈蚀混凝土梁受剪承载能力的变化情况。主要研究工作如下： (1)基于扩展有限元法对混凝土梁剪压破坏进行了分析研究。尝试将扩展有限元法应用到钢筋混凝土梁的受剪破坏分析中,分析结果与已有研究吻合较好；基于混凝土受拉开裂的双折线模型推导出了粘聚力随裂缝张开位移的指数下降模型,更加符合混凝土开裂的实际情况；证明了扩展有限元法的适用性,可在分析混凝土构件的开裂问题中进一步推广应用； (2)根据法拉第定律设计了三种不同锈蚀率的试件,对锈蚀钢筋混凝土梁进行了受剪破坏试验。观测了钢筋锈蚀引起混凝土保护层开裂的形式及裂缝宽度,研究了钢筋锈蚀对混凝土梁斜裂缝的形成、开展及构件承载性能等方面的影响,并通过回归拟合得到了锈蚀混凝土梁受剪承载力的计算公式； (3)基于粘聚力模型,给出了锈蚀钢筋与混凝土间粘结-滑移的本构模型,计算得出了不同锈蚀率下混凝土梁的承载能力变化,并与试验结果进行了对比分析,表现出了良好的一致性,证明本模型能够很好地描述钢筋-混凝土界面的粘结-滑移关系。另外,还进行了参数分析,得到了模型参数对混凝土粱承载能力的影响规律,从界面层面上解释了钢筋锈蚀引起构件性能变化的原因。最后分析了钢筋纵向粘结强度非均匀分布的影响,证明了本模型的可扩展性。
[Abstract]:Reinforced concrete structure is one of the most widely used structures in the world. It has been successfully used in industrial and civil construction, bridges, tunnels, mines, water conservancy and seaports. Due to the characteristics of the material and environment used in concrete structure, it is inevitable that the concrete structure will crack, the performance will deteriorate, and finally the durability problem will occur. The corrosion of steel bars will lead to the change of physical and chemical properties of reinforced concrete materials, and will ultimately affect the mechanical behavior of reinforced concrete members. The degradation of mechanical properties of reinforced concrete members caused by steel corrosion is an extremely complex process. How to evaluate the change of mechanical properties such as bearing capacity and ductility of concrete members with different corrosion degree is of great significance. However, the quantitative study on the relationship between the deterioration factors and the mechanical properties of concrete members is still insufficient. Therefore, it is of great significance to study the damage of concrete structures, especially the cracks in concrete structures and the durability of concrete structures caused by environment. Based on the extended finite element method and cohesive force model, the shear failure process of concrete beams and the variation of shear bearing capacity of corroded concrete beams are studied. The main research work is as follows: (1) the shear-compression failure of concrete beams is studied based on the extended finite element method. The extended finite element method is applied to the shear failure analysis of reinforced concrete beams, and the results are in good agreement with the previous studies. Based on the double broken line model of concrete tensile cracking, the exponential decreasing model of cohesion force with crack opening displacement is derived, which is more in line with the actual situation of concrete cracking, and proves the applicability of the extended finite element method. It can be further applied in the analysis of cracking of concrete members. (2) three specimens with different corrosion rates are designed according to Faraday's law, and the shear failure tests of corroded reinforced concrete beams are carried out. The form and width of cracking in concrete cover caused by steel corrosion are observed, and the influence of steel corrosion on the formation, development and bearing capacity of concrete beams is studied. The formula of shear capacity of corroded concrete beams is obtained by regression fitting. (3) based on the cohesive force model, a constitutive model of bond slip between corroded steel bar and concrete is given. The load-bearing capacity of concrete beams with different corrosion rates is calculated and compared with the experimental results. The results show good agreement. It is proved that the model can describe the bond-slip relationship between reinforcement and concrete interface well. In addition, the influence of the model parameters on the bearing capacity of concrete beam is obtained by parameter analysis, and the reason of the behavior change caused by the corrosion of steel bar is explained from the interface level. Finally, the influence of non-uniform distribution of longitudinal bond strength is analyzed, and the extensibility of the model is proved.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU375
本文编号：2141097
[Abstract]:Reinforced concrete structure is one of the most widely used structures in the world. It has been successfully used in industrial and civil construction, bridges, tunnels, mines, water conservancy and seaports. Due to the characteristics of the material and environment used in concrete structure, it is inevitable that the concrete structure will crack, the performance will deteriorate, and finally the durability problem will occur. The corrosion of steel bars will lead to the change of physical and chemical properties of reinforced concrete materials, and will ultimately affect the mechanical behavior of reinforced concrete members. The degradation of mechanical properties of reinforced concrete members caused by steel corrosion is an extremely complex process. How to evaluate the change of mechanical properties such as bearing capacity and ductility of concrete members with different corrosion degree is of great significance. However, the quantitative study on the relationship between the deterioration factors and the mechanical properties of concrete members is still insufficient. Therefore, it is of great significance to study the damage of concrete structures, especially the cracks in concrete structures and the durability of concrete structures caused by environment. Based on the extended finite element method and cohesive force model, the shear failure process of concrete beams and the variation of shear bearing capacity of corroded concrete beams are studied. The main research work is as follows: (1) the shear-compression failure of concrete beams is studied based on the extended finite element method. The extended finite element method is applied to the shear failure analysis of reinforced concrete beams, and the results are in good agreement with the previous studies. Based on the double broken line model of concrete tensile cracking, the exponential decreasing model of cohesion force with crack opening displacement is derived, which is more in line with the actual situation of concrete cracking, and proves the applicability of the extended finite element method. It can be further applied in the analysis of cracking of concrete members. (2) three specimens with different corrosion rates are designed according to Faraday's law, and the shear failure tests of corroded reinforced concrete beams are carried out. The form and width of cracking in concrete cover caused by steel corrosion are observed, and the influence of steel corrosion on the formation, development and bearing capacity of concrete beams is studied. The formula of shear capacity of corroded concrete beams is obtained by regression fitting. (3) based on the cohesive force model, a constitutive model of bond slip between corroded steel bar and concrete is given. The load-bearing capacity of concrete beams with different corrosion rates is calculated and compared with the experimental results. The results show good agreement. It is proved that the model can describe the bond-slip relationship between reinforcement and concrete interface well. In addition, the influence of the model parameters on the bearing capacity of concrete beam is obtained by parameter analysis, and the reason of the behavior change caused by the corrosion of steel bar is explained from the interface level. Finally, the influence of non-uniform distribution of longitudinal bond strength is analyzed, and the extensibility of the model is proved.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU375
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