Numerical Simulation Of Crack Propagation In Concrete Beams Based On Statistical Damage Model

Under the prosperous and developed application prospect of concrete,people have been exploring the application mechanism of concrete,which can initially meet the basic engineering development needs.Therefore,on the premise of statistical damage practice,this paper establishes a meso-mechanism constitutive model of concrete based on macroscopic phenomena,so as to show the failure mechanism and crack propagation mechanism of concrete internal structure.In this paper,the crack propagation mechanism of concrete deformation and failure is numerically simulated based on the multi-scale damage fracture mechanism of statistical damage theory.A statistical damage constitutive model of concrete under confining pressure effect was established.The damage in the principal pressure direction was firstly controlled by lateral tensile damage.Considering the two meso damage modes of fracture and yield,the meso heterogeneity of materials was introduced by assuming that the evolution process of the two types of damage followed the triangular probability distribution.The distribution morphology was characterized by four characteristic parameters.Based on the shape,environment and size effect of specimens,the influence of confining pressure on the damage accumulation and evolution process of concrete under confining pressure environment was observed,and the transformation mechanism of macroscopic nonlinear stress-strain behavior of concrete from "brittleness" to "plasticity" was discussed.The secondary damage constitutive was developed in the large finite element calculation software ANSYS based on the established statistical damage model of orthogonality anisotropy of concrete.Uniaxial tension and compression were regarded as the basic macroscopic failure modes,and two mesoscopic damage mechanisms such as fracture and yield were considered.The whole destruction process of concrete was studied by numerical simulation.Uniaxial and biaxial tensile and compressive tests of a single unit of concrete were simulated to study the optimal numerical simulation loading mode and method for secondary development.The three-point bending beam and four-point bending beam are numerically analyzed by ANSYS finite element software,and the dead weight,size effect,loading mode and energy absorption capacity of concrete beam under compression are considered.To simulate the whole process of concrete beams with different joint height ratio and shear span ratio from the beginning of load application to the final instable failure,obtain the whole process form of crack initiation,propagation and penetrating fracture,analyze the development process and mechanism of crack during the loading process,and verify the validity and applicability of the model.