Numerical Simulation Of Uniaxial Tension Of Concrete Based On Mesoscopic Scale

Concrete is a widely used engineering material.Coarse aggregate mortar and the interface transition zone(ITZ)between them constitute the internal structure of concrete at the meso-scale.The macroscopic mechanical behavior of concrete depends on the distribution characteristics of internal materials and the mechanical properties of internal materials Therefore,it is of great significance to establish the relationship between concrete meso-structure and macroscopic mechanical properties for the design and evaluation of concrete in engineering practice.In this paper,a large commercial software ABAQUS was redeveloped by Python language,and the model of concrete random aggregate was successfully generated.And considering the concrete mortar and interface(ITZ)in the material mechanics performance discreteness is bigger,in order to solve this problem,achieved by secondary development of mortar matrix and the interface mechanics performance obeys Weibull distribution stochastic mechanics model,and through programming,with the method of "interval method" to solve the mechanical properties of discrete too much cause the results difficult to convergence problems.The specific research work is as follows:By Monte Carlo method,the spatial distribution of aggregate in meso-concrete is transformed into a random variable problem in mathematics,and the concrete meso-structure is established in accordance with the actual situation.Based on Fuller gradation curve and Valavin formula,the particle number of each aggregate size was determined.The concrete random aggregate model was established by programming,and the uniaxial tensile simulation was carried out.The simulation results were in good agreement with the test results,which proved the validity of the numerical model.Based on the numerical model of concrete random aggregate,the mechanical response of concrete under uniaxial tensile action is simulated.Through variable parameter analysis,the influences of the shape or maximum particle size of aggregate,the content of coarse aggregate,the thickness of interfacial transition zone and pores on the macroscopic mechanical properties of concrete are studied.The results show that the aggregate shape and maximum particle size have little effect on the mechanical properties,and the aggregate content.The tensile strength first increased or decreased with the increase of aggregate content,and the elastic modulus showed a linear relationship.Pore has a great influence on the development path of cracks in concrete,which weakens the mechanical performance of concrete.Based on the stochastic mechanics model of concrete,the effects of homogeneity,mesh size and specimen size on the macroscopic mechanical behavior of concrete under uniaxial tension were studied.The results show that the effect of homogeneity is mainly reflected in the tensile strength and the dispersion of the stress-strain curve.The mesh size had little effect;The tensile strength of the material decreases with the increase of the specimen.