A Semi-Empirical Framework for Modeling Anisotropy, Spatial Variation and Failure Mechanisms in 3D Printed Concrete (2025-07)¶

This study introduces a modeling approach to simulate the anisotropic mechanical behavior of 3D-printed concrete (3DPC), considering the influence of porosity inherent to the printing process. Computed tomography (CT) scans of cylindrical cores extracted from a 2.35 m 3DPC wall revealed two key porosity types: large and elongated voids at interlayer-interstrip intersections and finer pores within and between layers. Building on these observations, a novel Equivalent Porosity Geometry (EPG) representation was developed to idealize interface porosity through mechanically representative shapes, while the porosity effects in the intralayer matrix was incorporated using spatially calibrated parameters within an isotropic Concrete Damage Plasticity (CDP) framework. The proposed approach predicted anisotropic mechanical properties (compressive strength, elastic modulus, and Poisson’s ratio) with strong agreement to experimental data, capturing spatial property variations along the wall height and reliably reproduced the direction-dependent ascending portion of the compressive stress–strain response. Furthermore, the numerically observed fracture patterns aligned with experimental results, capturing fracture initiation at the tips of interfacial voids and revealing the progressive failure mechanisms responsible for anisotropic behavior in 3DPC. A comparative analysis with existing models highlights the superior predictive performance and practical scalability of the semi-empirical framework. Drawing from both continuum and interface-based modeling strategies, proposed hybrid modeling strategy offers a physically grounded and computationally efficient tool for linking CT-derived porosity to anisotropic mechanical behavior, supporting future optimization of printing parameters and structural design in 3DPC.