Concrete, as a heterogeneous composite material, consists of several phases, including cement paste, aggregates, and interfacial zones, and its mechanical properties depend on the shape, size, volume fraction, and spatial distribution of aggregates. In this study, a three-dimensional representative volume element (RVE) model of concrete was generated using real aggregate shapes and analyzed under periodic boundary conditions in Abaqus. The main objective was to extract the effective mechanical properties of concrete in an orthotropic form, including elastic moduli, shear moduli, and Poisson’s ratios.

To determine the appropriate RVE size, specimens with dimensions of 40, 50, 60, and 70 mm were investigated. Based on the convergence of the results, the 60 mm specimen was selected as the representative volume element. Subsequently, models with aggregate volume fractions of 10%, 20%, 30%, and 40% were analyzed. The results indicated that, with increasing aggregate volume fraction, the effective elastic moduli increased from approximately 21.5 GPa at 10% aggregate volume fraction to approximately 31.8 GPa at 40%. Furthermore, the shear moduli increased from about 8.96 GPa to about 13.27 GPa. The Poisson’s ratios varied within the approximate range of 0.196 to 0.200. The results demonstrate that the use of real aggregate geometry combined with periodic boundary conditions can provide a more accurate prediction of the effective mechanical properties of concrete.