Cellular Automata-finite Element Analysis Of Durability Of Concrete Structures In Erosive Environment

With the development of China’s modernization,the construction of infrastructure has become the focus of today’s social development.As is known to all,the current construction projects mainly use reinforced concrete structure,its design method in addition to the traditional strength,stiffness and other mechanical performance indicators design,but also consider the durability design,life economy.Generally speaking,the durability of concrete has a direct relationship with the internal and external functions,which is caused by various internal and external factors.Therefore,it is of great academic value and practical significance to study the influence of chloride ion on the durability of reinforced concrete structures.This paper presents a Cellular Automata model(CA model)to simulate the diffusion mechanism of chloride and sulfate ions in concrete.The three-dimensional chloride ion diffusion test was carried out,and the damage of concrete structure under the action of load and sulfate ion coupling was also studied.The contents are as follows:1.In this paper,a two-dimensional chloride diffusion CA model based on Cellular Automat(CA)is established.In order to verify the effectiveness of the CA model in this paper,it is assumed that the diffusion of chloride ions in concrete is isotropic.Secondly,a CA model program of chloride ion diffusion was developed by matlab to simulate the process of chloride ion diffusion in concrete.Finally,based on two different foreign experimental backgrounds,the simulation results of CA model are given respectively.The comparison between the results of chloride ion concentration simulation and the experimental data of offshore concrete structures and laboratory concrete specimens shows that the model presented in this paper has high accuracy,is effective and feasible.The model is simple in mathematical derivation,convenient in use and easy to be popularized.It provides a new way to analyze the durability of reinforced concrete structures in complex corrosive environment.2.The three-dimensional experiment of chloride ion in the natural soaking environment of concrete was carried out,and it was found that the concentration of chloride ion diffusion distribution in concrete at the same depth in the same medium solution increased with the increase of soaking time.During the same soaking time,the concentration of Cl-in concrete increases with the increase of the concentration of the soaking medium,and the concentration of Cl-in concrete at the same depth of each medium solution decreases with the extension of the distance from the concrete surface.3.In this paper,based on the CA principle,the three-dimensional chloride ion transport CA model of concrete was established under the influence of factors such as spatial and temporal variability,boundary conditions and water-cement ratio,etc.,and under the condition of natural immersion,the standard prism block(size 300mm×150mm×150mm)was immersed in the Marine environment for 8.2 years with complete chloride ion diffusion.This model can effectively simulate the chloride ion in concrete in three-dimensional direction spread,solves the problem inside the concrete nonlinear diffusion fitting,and the method is simple,easy to operate,can adapt to the actual engineering,the application of the steel bar corrosion in the early time of the decision more accurate,3 d CA model is accurate and feasible,is advantageous to the durability performance degradation in the actual engineering application process of the realization of computer simulation.4.based on the principle of the CA and finite element division,respectively,set up circular cross section and rectangle section of corroded concrete damage calculation model,the application of the model under the action of the load and the coupling of corrosion damage after performance of reinforced concrete structures are studied,and combined with the test data further calculation show that the model is reasonable and feasible,in the actual project by many factors such as ion etching and the continuous stress and structure provide effective research method for structure damage,and helpful to the life prediction of structure.