Explanation of size effect in concrete fracture using non-uniform energy distribution

A local fracture energy model explain the influence of fracture process zone (FPZ) oil fracture energy of cementitious materials is further developed in this study. By assuming a bilinear distribution for the fracture energy distribution, the ligament-dependent fracture energy G(f) is obtained. The analytical expression of G(f) contains two important parameters: the intrinsic size-independent fracture energy G(F) and a reference ligament size a(l)(*) which determines the intersection of the two linear energy functions. It is shown that the ligament-dependent G(f) approaches the size-independent G(F) asymptotically. As a result, G(F) can be determined from the ligament-dependent G(F) results. It is also found that while the reference ligament size a(l)* is influenced by the specimen geometry, size and loading conditions, the derived fracture energy G(F) is virtually constant. The present local fracture energy distribution model is also discussed and compared with the original local fracture energy model.