Numerical Simulation Of Damage Evolution Of Ceramsite Concrete Based On Lattice Model

From the microscopic scale,the concrete material can be regarded as a three-phase heterogeneous composite material consisting of coarse aggregates,cement mortar and the interface transition zone between the two.As the most widely used building material,the mechanical property of concrete can have a direct relation to safety of the building structure.In recent years,with the deepening of the concept of environmental protection,ceramsite concrete as a novel green material has been more and more widely used in engineering construction,therefore it is very essential to carry out researches on the mechanical properties of concrete and ceramsite concrete.This paper takes concrete and ceramsite concrete as the object of study,and it utilizes the MATLAB language to complete the parameterized numerical modeling for the lattice models of the concrete and ceramsite concrete samples.The numerical simulation results for the lattice model of the concrete sample verify the effectiveness of the lattice models in this paper.On this basis,the damage mechanism of the ceramsite concrete sample is studied,and the effect of changes in the microscopic-scale composition of the ceramsite mixed aggregate concrete to the mechanical property of the sample itself is discussed.The following main jobs are done:Based on the lattice model theory,the mechanical equivalence is carried out for the continuous medium by adopting discrete Timoshenko beam elements,the element stiffness matrix of the beam element is deduced,and the parallel assembly of the overall stiffness matrix of the structure is completed.By adopting the Mazars damage constitutive model,the deterioration for the mechanical property of the material is simulated,and the numerical simulation calculation code is written in the MATLAB language to be applied to the numerical calculation of all lattice models in this paper.The MATLAB language is used to perform parametric numerical modeling for the lattice models of heterogeneous materials.The generation of random aggregates and the interface transition zone is completed.The randomness of the lattice model is reflected by the randomness of the geometric grid and the material properties.The geometric model is projected into the lattice model,and the assignment for the material properties of each element is given according to the location of the element.Combining with the modeling method for the lattice model of the heterogeneous materials,a lattice model of the concrete sample is established.The relevant parameters of the model are determined,and the effect to numerical simulation results from the geometric network randomness of the lattice model,the element type and the element length are studied.The precast open concrete three-point bending beam samples are loaded symmetrically and asymmetrically,and the numerical simulation results are compared with the experimental results to verify the validity of the lattice model in this paper.A lattice model of the ceramsite concrete sample is established,and the parameters for each phase of materials in the model are determined and analyzed.Numerical simulation is carried out for the ceramsite concrete three-point bending beam samples,and the damage evolution mechanism of the sample is explored;the lattice model of the ceramsite mixed aggregate concrete sample is established,and the effect to the macro-mechanical property of the ceramsite mixed aggregate concrete material and the microscopic damage evolution process of each component material from the ceramsite mixing amount,the aggregate distribution and the mixed aggregate grading is studied.The study results show that,the lattice model in this paper can reasonably simulate the damage evolution process of the concrete and ceramsite concrete samples,and it can accurately analyze the damage and failure process of the concrete type quasi-brittle materials,which has a high research value for deep exploration on the mechanical properties of the ceramsite concrete in the microscopic scale.