Elasto-Plastic Microplane Model for Fiber Reinforced Cementitious Composites

Quasi-brittle materials like concrete or rocks, typically present localized failure modes due to cracking processes which start from internal material defects, e.g. micro-cracks or non-homogeneous weak zones, and develop in brittle mode throughout the material. In this work both plain concrete and Fiber Reinforced Cementitious Composite (FRCC) are analyzed and modeled by means a novel microplane plasticity formulation. The continuum (smeared-crack) formulation, based on non-linear microplane theory combined with the well-known “Mixture Theory” is considered for describing the fiber effects on the failure behavior of FRCC. The interaction between cementitious matrix and steel fibers is simulated in terms of crack-bridging effect and dowel action, as similarly treated in a discontinuous model previously formulated by the authors. After describing the constitutive model, this work focuses on the numerical analysis on plain concrete and FRCC failure behavior, with particular emphasis on the fracture resistance, post-peak strength and the mechanical response related to the microplane formulation. The capabilities of the proposed model to capture the significant enhancement in the post-cracking behavior of FRCC with different fiber contents and types is finally evaluated by considering some experimental data available in scientific literature.