Fracture in concrete specimens of differing scale

A planar lattice network of beam elements is used to study the mechanisms o f fracture in cement-based materials. Beam properties are controlled by a n onlinear elastic fracture law which roughly accounts for three-dimensionali ty of the material and fracture process. Special attention is given to mode ling toughening mechanisms associated with aggregate-matrix interlace failu re. The distributions of damage and fracture energy consumption are resolve d at the material mesoscale and are shown to depend on strain gradient. An adaptive remeshing procedure is used to reduce computational cast and enabl e analyses of specimens of significantly differing scale, while keeping the lattice density constant. Larger process zones, higher specific fracture e nergies, and lower specific peak loads are obtained with increasing specime n size, in agreement with published test results. These computations provid e information useful in developing refined macromodels for engineering anal yses.