Simulation study on the effect of the initial defect of recycled aggregate concrete based on BFEM.

• The aggregate compression method for modeling the elliptical geometry of recycled aggregate was established. • The BFEM on complementary energy principle was applied to analyze the damage problem of non-homogeneity materials. • The effects of initial internal defects characteristics on the properties of RAC were explored and analyzed. • The projection length of the initial defect in the loading direction has a significant effect on the properties of RAC. To study the effect of the initial defect on the mechanical properties and failure pattern of recycled aggregate concrete (RAC), several numerical models containing the initial defects were established and simulated under uniaxial compression. The recycled aggregate was simulated as an ellipse geometry, which can be constructed by compressing the circular geometry. The base force element method on the complementary energy principle was applied for the loading condition analysis. In addition, the stress–strain curves, deformation, and crack extension patterns of RAC were explored. Moreover, the maximum principal stress distribution and stress concentration were also investigated. The results demonstrate that the angle and length of the initial defect have a significant effect on the mechanical properties of the RAC. The initial defect interrupts the loading transfer path, forcing it into other continuous regions and forming a new transfer path. In addition, the longer the projection length of the initial defect in the loading direction, the most substantial influence on the mechanical properties, stress transfer, and damage mode. [ABSTRACT FROM AUTHOR]