Meso-modeling Analysis Of Damage And Failure Behaivior Of Ceramsite Concrete

As a widely used building material,mechanical properties of concrete are directly related to the safety of the building structure.In recent years,environmental protection has become a popular trend in building engineering,ceramsite concrete can realize the goal of recycling of resources,energy saving and low carbon development.Therefore,ceramsite concrete is drawing attention widely.Ceramsite is a kind of material with low tensile strength,the mechanical properties of which are not similar with stone aggregates,cracks are initiated in ceramsite aggregates.Therefore,it’s of great importance to carry out research on the mechanical properties of concrete and ceramsite concrete.In this paper,concrete and ceramsite concrete are studied.Lattice models of specimens of these two materials are established based on MATLAB,and numerical simulations are carried out on the basis of the models.The numerical simulation results of concrete materials are used to verify the rationality and advantages of the Lattice models.The models are then used to study the effect of microstructural changes on the damage and destruction behavior of ceramsite concrete specimens.The main research contents are as follows:1.Based on the Lattice model theory,the method of establishing Lattice models of heterogeneous materials is introduced using MATLAB.The connection of the elements and the placement of random aggregates are completed.There are two types of random aggregates:round random aggregates and polygonal random aggregates.The disorder in the modeling of heterogeneous materials is considered in this model,including the disorder of the geometric grid and the disorder of the internal materials.2.Numerical simulation calculation codes are written by MATLAB,which are applied to the numerical simulation of all Lattice models in this dissertation.The aggregate gradation in the concrete specimens is calculated,and the interface transition zone(ITZ)of the aggregates are generated.Using the method of establishing Lattice models of heterogeneous materials,the Lattice models of the concrete specimens are established.The numerical simulations of threepoint bending test are carried out on the Lattice models of unnotched and notched concrete specimens.The whole process of deformation and failure of the concrete specimens is simulated,and complete load-displacement curves are obtained.The comparison with the test results verified the rationality of the Lattice model.The finite element model(FEM)of the concrete specimen is established and simulated,and the advantage of the Lattice model in simulating the tensile failure of the material is verified.The effect of the changes of aggregate distribution on the damage and destruction behavior of concrete specimens is studied.3.The mechanical parameters of all kinds of materials in ceramsite concrete are determined.Using the method of establishing Lattice models of heterogeneous materials,the Lattice model of the ceramsite concrete specimen is established.Compared with the crosssection of actual ceramsite concrete specimen,the Lattice model of the ceramsite concrete specimens can reflect the real distribution of ceramsite aggregates in the ceramsite concrete specimens.4.Numerical simulation of three-point bending test of the ceramsite concrete specimen is conducted to simulate the damage evolution process of the ceramsite concrete specimen.The difference between the damage evolution process of the ceramsite concrete specimen and the concrete specimen is analyzed.5.The effects of the randomness of the location of ceramsite aggregates,the size of ceramsite aggregates and the volume fraction of ceramsite aggregates on the damage and destruction behavior of ceramsite concrete specimens are analyzed.The Lattice model of the L-shaped ceramsite concrete specimen is established,and the damage and failure behavior of the specimen of this shape is studied,which verifies the rationality of the Lattice model introduced in this dissertation.