Elastoplastic damage model and numerical implementation of nano-silica incorporated concrete

An energy-based isotropic elastoplastic damage model is developed for investigating the elastoplastic damage responses and stress-strain relationships of nano-silica incorporated concrete. The formulation employs a multiscale micromechanical framework to determine the effective elastic properties of composites at different scales. The stress-strain constitutive relation is derived by splitting the strain tensor into "elastic-damage" and "plastic-damage" parts while introducing the homogenized free potential energy function and the undamaged potential energy function. The elastoplastic damage response of the material is further characterized by elastic-plastic-damage coupling. To construct realistic 3D three-phase concrete mesostructures in numerical simulations, this paper introduces an encapsulation placement method that avoids particle overlap checking when placing aggregates. This methodology allows adjustments for the aggregate compactness as needed and enhances computational efficiency in concrete mesostructure construction. The numerical results of the modeling show good agreement with the experimental values in the open literature. Further, the influence of nano-silica addition contents and ITZ (interfacial transition zone) thicknesses on the elastoplastic damage response of nano-silica incorporated concrete are quantitatively and qualitatively investigated for the optimization of nano-silica incorporated cementitious composites. The proposed model facilitates simulating and optimizing the mechanical characteristics of nano-silica incorporated concrete and enhances the computational efficiency of 3D concrete modeling with the introduced encapsulation placement method.