Quantification of Fracture Mechanics Size Effect

In the classical theories based on plasticity or limit analysis, the strength of geometrically similar structures is independent of the structure size. As already pointed out, however, concrete structures and, in general, structures made of brittle or quasibrittlc materials, do not follow this trend. In this section wc first define what is understood by strength and size of a structural element and then examine how the strength depends on the size. We finally give a simple justification of Bazant’s size effect law. The experimental evidence supporting the existence of size effect will be presented in the next section.