Tension-compression anisotropic cohesion model for the interlayer interface of 3D-printed concrete compression specimens

Several issues exist with the cohesive model used to simulate the interlayer characteristics of 3D-printed concrete compression specimens: the accuracy of anisotropic simulation is low, cohesion model parameters are difficult to obtain, and the study of these parameters on anisotropic effects is insufficient. This study proposes a tension-compression anisotropic cohesive model to address the limitation of the traditional isotropic model, which lacks dedicated compressive stiffness when applied to printed concrete compression specimens. To obtain suitable model parameters, a parameter inversion framework is proposed, utilizing compression test data from printed specimens. To evaluate the impact of the cohesive model parameters, the SHapley Additive exPlanations method is employed to explore their effects on anisotropy. Results demonstrate that the framework accurately captures the anisotropy of 3D-printed concrete, achieving a relative error below 0.5 %. Parametric analysis reveals that when loaded in the horizontal printing direction, the key parameter of the cohesive model is the compressive stiffness, whereas when loaded in the vertical direction, the key parameters are the compressive stiffness and shear stiffness. The cohesion model, inversion framework, and findings provide valuable research approaches and a more comprehensive understanding of the compression performance of 3D-printed concrete.