Numerical Analysis Of Damage Evolution Of Concrete With Defects

In recent years,my country has developed rapidly,and the quality of people’s housing has also been improved.The demand for commercial housing is in short supply.Commercial concrete structures have been extremely widely used in engineering construction.However,there are still many unsolved problems in the physical and mechanical properties of concrete materials.This paper conducts a numerical analysis on the damage evolution of concrete with defects.The study of concrete structure needs to grasp the macro-physical and mechanical properties of concrete materials from a micro/micro perspective.Therefore,this paper looks at the dynamic mechanical properties of concrete from a micro perspective based on statics.,The work content has the following aspects.(1)Theoretical analysis of the constitutive relationship between the mortar,aggregate and the transition interface in concrete is carried out,and an appropriate constitutive model is selected.Use Monte Carlo random numbers to determine the location of the aggregates,and establish a randomly distributed concrete aggregate model according to the grade and shape of the aggregate.Based on the random aggregate generation and placement program developed by MATLAB,the aggregate model is imported into the finite element software to generate numerical concrete specimens.At the same time,the steps of randomly generating two-dimensional polygonal aggregates and three-dimensional polygonal aggregates are specifically introduced.The damage evolution process of the two-dimensional polygonal aggregate model and the circular aggregate model is studied with the help of calculation examples,and it is concluded that the polygonal aggregate model can better reflect the law of concrete damage evolution than the circular aggregate model.(2)Characterize defects through circular pores and coin-shaped cracks,analyze the effects of defects and aggregate shapes on the elastic modulus of concrete;study the effects of circular pores and coin-shaped cracks and their content on the failure process and ultimate load of concrete.Compared with circular holes,coin-shaped cracks have a greater destructive effect on concrete,and defects will weaken the macro-mechanical properties of concrete.The ultimate load of the circular random aggregate model is higher than that of the arbitrary polygonal random aggregate model.(3)By improving the traditional modeling method and adopting the double-broken line damage relationship,the internal defects of concrete materials were transformed,and a three-dimensional random aggregate model of concrete with meso-defects was established.Under different impact loads,the section of the analysis area is divided and the influence of internal defects on the microscopic damage of concrete materials and the distribution of stress and strain is analyzed.Finally,the number of load steps and the number of variable defect elements are quantitatively analyzed,and the development of microscopic damage is summarized.The influence law of crack evolution.