Concrete Mesoscopic Model and Numerical Simulation Based on Quadtree Mesh Refinement Technology

In the concrete mesoscopic model established by using the traditional background mesh method, a mesh refinement technology based on balanced quadtree is proposed to refine the elements of interfacial transition zone (ITZ). Considering the control standards of the minimum size requirement and the balancing condition, the implementation program of mesh refinement is studied. The polygonal FEM is applied to ensure the consistency of the mesh after quadtree refinement. Then, the modified concrete mesoscopic model is given, which is more reasonable for reflecting the constitutive behavior of ITZ. In the proposed concrete mesoscopic model, the correlative material parameters can directly assign to the elements of ITZ. The sawtooth defect of meshes around the aggregates in the background mesh method is also enhanced to a certain degree. Accordingly, the geometrical morphology and material property of ITZ are simulated better and more realistic. In the end, the numerical simulation is presented to preliminarily compare the differences between the background mesh method and the proposed method.