Study On Simulation System For Crack Propagation Of Concrete

Concrete structures have been widely used in industrial and civil buildings, bridges, tunnels, harbor engineering and other more projects. However, the concrete has the disadvantage of cracking, and although rigorous crack control steps are adopted, the concrete structures still work with cracks especially for the mass concrete such as concrete dam, concrete pool and underground concrete structures. The mechanism of crack propagation and what impact on concrete structures the cracks will carry have been a hot research point in recent years.To solve the above issues, the theory of concrete fracture mechanics combined with computer simulation technology is applied to analyze the problem of crack propagation. A crack propagation simulation system is established by using Visual C++6.0to research on the property of complete process of cracking in the crack carrying concrete, which is designed to provide a new method for monitoring the cracks propagation of concrete in the actual project.The main works of this paper are as follows:(1) The difficulty in numerical simulation of cracking lies in mesh rezoning and material nonlinear problems in the failure process of concrete. In the paper, the finite element software ANSYS is used with its powerful meshing technology, fracture solving module and optimized solver. With the Fictitious Crack Model and model I crack propagation criterion of concrete, the program on simulating model I crack propagation is compiled by the secondary development language APDL of ANSYS.(2) The APDL command stream is encapsulated using VC++by its powerful packaging features. A crack propagation simulation system including parameterized modeling, numerical calculation and result visualization is established. A series of parameters-input interfaces are developed by using Visual C++, and parameterized modeling is accomplished by the transmission of APDL macro document. Based on the interface between VC and ANSYS, ANSYS can be invoked by VC automatically, meanwhile, the APDL command stream is read by ANSYS and the crack propagation is calculated in the background. Therefore, the proposed system is easy to use and high-efficient.(3) The numerical analysis on whole process of crack propagation is carried out by the simulation system established in the paper to verify its reliability and practicality, and the calculated results are in good agreement with the experimental results. Therefore, the reliability of the system is proved.(4) The proposed system is used to analysize the size effect of concrete fracture toughness. The calculated results show that, there is no obvious size effect in fracture toughness to specimens with different depths, it can be regarded as a sort of material parameter.