Anisotropic constitutive model of plasticity capable of accounting for details of meso-structure of two-phase composite material

In this work, we discuss a novel anisotropic constitutive model of plasticity, which can be used to replace the classical phenomenological models for composite materials, like concrete, with marked difference of behavior in tension and compression. The model is constructed from fine scales by making use of the corresponding meso-scale representation of concrete distinguishing aggregate from cement paste. The elastic response and failure mechanisms at this scale are represented by the corresponding unstructured mesh of truss elements, which is shown to be capable of representing a number of fine features of inelastic response, such as the statistical isotropy of elastic response placed in-between the stringent Hashin-Shtrikman bounds, the pronounced difference of behavior in tension and compression, the sensitivity of bi-axial compression strength to the volume fraction of aggregate and the bi-axial fracture energy corresponding to each particular mode of failure. The results of this kind obtained with meso-model are then packed within a new meso-scale model with these enhanced features, which can be used to successfully replace the standard phenomenological models of concrete in ultimate state computations of complex structures providing increased predictive capabilities.