Concrete structures have a highly complex internal structure at the mesoscale, consisting of mortar, coarse aggregate, and reinforcing bars. To accurately reproduce the nonlinear mechanical behaviour of concrete, it is essential to construct sophisticated three-dimensional (3D) mesoscale models and develop corresponding 3D fracture simulations. In this study, a method was developed to construct a 3D mesoscale model of reinforced concrete [1]. This method reproduces the 3D geometry of deformed bars, including the shape of ribs, as well as the irregular 3D shapes and spatial distribution of coarse aggregates. Furthermore, this study presents the numerical results of 3D mesoscale fracture simulations using a damage model [2] applied to the developed 3D mesoscale model. The damage model [3] employed in this study can evaluate damage by accounting for material heterogeneity within the finite element analysis. 3D mesoscale fracture simulations were performed for reinforced concrete beams both with and without stirrups (shear reinforcements). The results demonstrate that the proposed approach can capture different failure modes and quantitatively reproduce experimental data.