Meso-structure Numerical Smulation Of Concrete Based On Lattice Model

In this article, concrete is considered as a three-phase composite material consisting of aggregate, mortar matrix and the interfacial transition zone between them, and the macro-level mechanical properties are simulated. The number of aggregate in the numerical specimen is calculated according to the gradation of aggregate and Walraven function. A procedure is used to generate the random position of aggregate based on Monte Carlo method, and then establish the random aggregate model. Furthermore, the regular triangle lattice is projected on the random aggregate model, and the different material property of elements is identified and assigned automatically. Then the numerical model is obtained.Secondly, lattice model based on the previously research is developed. Considering the initial defects of concrete, tensile strength of composite material phases(mortar matrix, aggregates and bond) is assumed to obey Weibull distribution. Consequently, the lattice model generated is more reasonable.Thirdly, some routine tests of full grading concrete including uniaxial compression test and uniaxial tension test are simulated. The results obtain the stress-strain curve, and describe the complete failure process caused by the initiation, propagation and connection of cracks. The influence on simulation results caused by homogeneity index (m) in Weibull distribution, element size, different aggregate distributions with the same gradation, bond strength and matrix strength are discussed. And the size coefficient and wet screening coefficient are obtained by simulating full grading specimen and wet screened specimen. The computational results are in good agreement with the experimental data.Finally, lightweight aggregate concrete is simulated with the same method, stress-strain curves under uniaxial compression and uniaxial tension are obtained. And the full failure progress is demonstrated, proving the phenomenon observed in the library.Seeing from the simulation results, the improvement to lattice model is suitable to simulate the mechanical property of concrete under uniaxial compression and uniaxial tension, and compensate for the disadvantage of using the previous lattice model under uniaxial compression.