Modeling Of Concrete Crack By Kriging Meshless Method

During the construction and use process, varing degree and different forms of crack will be generated in the concrete structure. Scientific research and engineering practice shows that the crack is inevitable, however, the destruction and the collapse of the constructure is always derived from the crack. Therefore, studying the failure process of concrete has engineering significance in improveing the design level,evaluating the performance and maintenance of underground structure.Numerical method provides an important way to study the failure process of concrete. As the relationship between strain and stress based on the experiment can reflect the macro characteristics of concrete, combination the numerical methods with the constitutive relationship can reflect the cracking characteristics of concrete and be applied to the engineering practice. Effort of different concrete crack model which based on finite element method fully vandicates its feasibility. However, as the difficulty of remeshing,grid sensitivity in simulating concrete crack by finite element method, the application of these achievement is limitedAs the difficulty met in simulating crack by traditional numerical method, researchers turn to other new numerical methods for help. Meshless method is exactly such a new numerical analysis method. As it only needs nodal data and boundary conditions, so it is especially suitable for the large deformation and cracking problem. Combination the meshless method with the constitutive relationship and taking full advantage of meshless method's merits will provide a new way to study concrete failure.In this paper, a new meshless method-Kriging interpolation meshless method is first introduced. Then this method is introduced into the concrete failure analysis. A composite crack model is established which is based on the Kriging meshless method, and the model is applied to evaluate the safety of the underground structure with crack. The main job of this paper is listed as follows:(1) The latest trend and hotspot of the research about concrete structure failure are summarized, then the research trend of meshless method is introduced, the latest reliability research of the underground structure with crack is also summarized in detail.(2) The basic theories of the Kriging meshless method is introduced a, then it is compared with finite element method and the traditional Galerkin meshless method, differences of the three methods is given and the merits of Kriging meshless method is pointed out. Then the calculation program of Kriging meshless method is developed based on Shuguang numerical platform and the practicability effectiveness of the method and correctness of the program is verified by examples.(3) The significant influence of the fracture process zone to the concrete failure is pointed out, then the limitation of the finite element method in simulating the concrete crack is pointed out. A composite crack model based on Kriging meshless method is put forward. The treatment of the crack boundary,the fracture criterion,the expand step length of crack,the appearance and expand of the macro crack is given in detail. Then the program of Mazars damage constitutive relationship and the expansion of crack is developed.(4) The evaluating methods of the safety of the underground structure with crack are summarized and their relative merits are put forward. Based on the studying ahead, the rebar element is introduced into the Kriging meshless method, and then the crack model is applied to the structure analysis, then an evaluation approach is put forward and the feasibility is approved by the example.(5) The thesis is summarized and research trend of Kriging meshless method,concrete crack simulation is viewed in the end of the analysis...