A micromechanics-based approach to damage propagation in fiber-reinforced fractured cementitious materials

Resumo

A model combining micromechanical reasoning with macroscopic thermodynamic concepts is formulated in this paper to evaluate the damage propagation in fiber-reinforced fractured cementitious materials. Unlike cracks, fractures are discontinuities able to transfer stress and can be regarded from a mechanical viewpoint as interfaces endowed with a specific behavior under normal and shear loading. Fibers are increasingly incorporated into cementitious materials to enhance their mechanical performance, durability, and ability to minimize the emergence and propagation of microfractures. Making use of the Mori-Tanaka homogenization scheme, this work employs a micromechanical approach based on Eshelby’s equivalent inclusion theory to formulate the homogenized elastic behavior of fiber-reinforced fractured cementitious materials. In this context, fractures and fibers are modeled as oblate and prolate spheroids endowed with appropriate elastic properties. The proposed macroscopic damage model, reflecting fracture propagation at the microscopic scale, combines the above results with classical thermodynamic principles within the framework of damage mechanics, where the fracture density parameter is treated as a damage parameter at the macroscopic scale. The model’s ability to capture damage-induced anisotropy is demonstrated through a comparison with experimental data on randomly distributed steel fiber-reinforced concrete, showing an accurate prediction of their strain-hardening response under uniaxial loading.