Spatial Variability of the Two‐Phase Lattice Discrete Particle Model for Simulating Mechanical Behavior of Concrete

Concrete, a composite material made of aggregates embedded in a cement matrix, exhibits complex mechanical behavior at the mesoscale, where the distribution and interaction of components significantly influence macroscopic properties, including failure patterns. The traditional Lattice Discrete Particle Model (LDPM) has been effective for simulating concrete at the coarse aggregate level, but it oversimplifies the heterogeneity between aggregates and the cement matrix. In the standard LDPM, tetrahedral subdomains combine aggregates and matrix as uniform material, neglecting essential heterogeneity. This oversimplification fails to accurately capture the variability and scatter observed in experiments. To address this, a two‐phase LDPM is proposed, explicitly considering aggregates and the matrix as separate phases within each subdomain. Hence, the local material property is linked to the heterogenous mesostructure of the material. The random fields of the spatially variable concrete stiffness are characterized by the determination of the correlation model, considering different particle sizes, positions, and specimen dimensions. This new approach improves the realism of LDPM simulations without increasing the computational cost.