Concrete Micromechanics Analysis And Experimental Simulation,

Concrete is a composite material with a three-phase of inhomogeneities in mesoscopic level. It is consisting of coarse aggregate mortar matrix and interfacial zones between the coarse aggregate and the mortar matrix. In this paper, a procedure that adopts the take-and-place method is used to generate random aggregate structures based on the Monte Carlo random sampling principle. The random aggregate structure in which the shape size and distribution of the aggregate particles resemble real concrete. Then meshing the aggregate domain and the mortar matrix domain separately using finite element analysis software-ANSYS and generating triangle and three-node element with controllable thickness in the interface domain by procedure. So the three-phase mesh can sew up. The mesh is a mesoscopic calculation model of nonlinear finite element analysis of concrete.Secondly, in order to study the formation and growth of cracks in concrete materials, pursue all processes from damage to fracture, predict load-bearing capacity of concrete, find the relationships between meso-structure and macro-property of concrete materials, a suitable for mesoscopic study of concrete nonlinear finite element method that bases on the previously research results is developed. A failure criterion combining tensile strength and fracture toughness is adopted. Stress relief as cracks propagate is also allowed. An incremental displacement controlled iterative scheme that can deal with post-peak behavior is employed.A program with various functions is made out. It could be used to simulate all processes from damage to failure by video-graph and putout the graphs of distortion and crack at random time.Finally the method is applied to simulate the process of concrete trial under axial tension, axial compression and various double axis tension-compression and analyze the concrete macroscopic mechanics property effect that is caused by the aggregate particles random distribution. Some results are obtained from the relationships between meso-structures and macro-properties and the dependence of macro-properties on the mechanism of mesolevel failure. Mesoscopic elements tension damage is the main reason of shaping macro-cracks. "Aggregate drawing phenomenon" and "crack surface bridge phenomenon" is observed. Concrete elasticity module and concrete strength under uniaxial tension and compression are gained. Computer strength method was developed.