Determination of Elastic Engineering Constants in an Orthotropic Constitutive Model for Hardened 3D-Printed Concrete

A methodology for determining elastic engineering constants in an orthotropic constitutive model of hardened three-dimensional (3D)-printed concrete (3DPC) is introduced in this paper. The 3DPC material’s unique configuration of filaments and layers weakens the mechanical interfaces between them, resulting in clear anisotropy along the three principal directions. To address this, a numerical model of a composite representative volume element (RVE) is created that combines a continuum concrete damaged plasticity model for the filaments with an interfacial cohesive zone model for the interfaces. The model’s parameter values are determined through uniaxial compression, splitting tension, cross-bonded tension, and inclined shear tests. By exploring the model’s design space using the design of experiments (DOE) technique, quantitative relationships between the orthotropic elastic engineering constants and the material properties of the filaments and interfaces are obtained, leading to explicit and simple formulas. Comparisons between numerical and experimental results for two hollow beams validate the effectiveness of the developed formulas.