Discrete elements and size effects

The discrete element method (DEM) in use today generally considers the bonds that bind discrete elements into a continuum to be elasto-perfectly-brittle. Such brittle bonds only give accurate failure loads for large size structures where LEFM applies. But for small to medium size structures of quasi-brittle materials such as rocks and concretes, the presence of the fracture process zone (FPZ) has significant impacts and needs to be considered....