Application Of Cohesive Zone Model In The Crack Propagation And The Bond-slip Relationship Between Corroded Steel And Concrete

The reinforced concrete structure is currently the most widely used structural forms. It has been successfully applied to industrial and civil buildings, bridges, tunnels, mines, water conservancy and harbour engineering and so on. Because of characteristics of the materials used in the concrete structures and complexity of the environment, concrete structure will inevitably be cracking and performance deteriorated, which will result in durability problems. The corrosion of steel will lead to changes in the physical and chemical properties of steel and concrete, and this will eventually affect the mechanical behavior of reinforced concrete members. The degradation of mechanical properties of reinforced concrete members caused by steel corrosion is a very complicated process. It is of great significance to evaluate bearing capacity and ductility of concrete members which is corroded in different degrees. But, at present, researches on the quantitative relationship between steel corrosion and mechanical performance degradation are still not enough. Therefore, study on the failure of concrete structure caused by the environment, especially the cracking problems and the durability problem is very meaningful. Focusing on this, mainly studied the shear failure procedure of concrete beams, and the bearing capacity of corroded reinforced concrete beam based on the eXtended Finite Element Method and cohesive zone model. The main works are as follows:(1) The shear compression failure for reinforced concrete beams were analyzed based on the eXtended Finite Element Method. The eXtended Finite Element Method is applied to the shear failure analysis for reinforced concrete beam for the first time, and cohesive traction-crack opening exponential decline model was derived based on bilinear model, which is more suitable for the description of concrete cracking; And we get a good agreement with the experimental results, providing reference to further applying of the eXtended Finite Element Method to engineering practice;(2) According to Faraday’s law, the specimens of three different corrosion rates were designed. The shear failure test was conducted for the corroded reinforced concrete beams. The cracking pattern of concrete cover caused by steel corrosion and the crack width were observed. Effects of steel corrosion on propagation of diagonal crack and changes of bearing capacity for reinforced concrete beams were studied, and the bearing capacity formula for corroded reinforced concrete beams was archived through regression fitting;(3) Based on the Cohesive Zone Model(CZM for short), the constitutive model for bond-slip between steel and concrete was given, the bearing capacity for different corrosion rates was calculated, and the results were compared with the experimental, which shows good consistency, indicating that this model can be used to describe the bond-slip relationship between the reinforcement and concrete. Otherwise, the detailed parametric study was performed to show the influence of parameters of the CZM on the bearing capacity, explaining the reason why changes in member capacity from the interface level. Finally, effect of non-uniformly distributed bond strength along the steel on the bearing capacity was also analyzed, proved that the model has a good expansibility.