Concrete fracture is governed by randomly distributed aggregate particles, which make cracks fundamentally not planar. This phenomenon can be captured only by 3D models. Within the 3D framework, material heterogeneity and displacement discontinuity must be incorporated. Lattice models allow to consider all these aspects adequately.
In this thesis a lattice model is used to analyze the influence of the material structure on the global structural response and to compare results from 2D and 3D modelling. Concrete is schematized as a network of beams with different mechanical properties corresponding to three phases: aggregate, matrix, and interfacial transition zone. Fracture is mimicked by sequential removal of elements where the stress exceeds the tensile strength. Though a purely brittle linear elastic behaviour is assumed for each element, structural softening is modelled successfully.