ABSTRACT
Important for making predictions is that the model parameters can be determined independently of specimen geometry and boundary conditions. What follows in this chapter is mainly an exposure of models that are used for modelling localised cracks in concrete. In a continuum model, the material structure effects are not included directly, but rather the effect is hidden in the constitutive law. However, if a relation should be made between material structure and fracture response, it would be more appropriate to map the structure of the material under consideration directly into the model. This chapter discusses possible fracture laws for lattice type models. It describes in Ingraffea and Saouma's model, Linear Elastic Fracture Mechanics is used, and the crack tip singularity must be computed and compared to a critical stress intensity factor. The lattice models described above do not have very much in common with concrete or other disordered materials.
