Applications of boundary effect model to quasi-brittle fracture of concrete and rock

A recently-developed asymptotic boundary effect model for the quasi-brittle fracture of finite-sized fracture mechanics specimens is used to analyse the experimental results available in the literature. Three different experimental results are chosen in this study to cover various experiment designs, including geometrically similar specimens, specimens of identical size with different crack lengths and specimens of different configurations and geometries. It is shown that the size effect associated with quasi-brittle fracture, as reported in the literature, is in fact, due to the influence of specimen boundaries, The observed dependence of fracture behaviour on specimen size and crack length can be described by the same boundary effect model. The new asymptotic model is also compared with other size effect models dealing exclusively with geometrically similar specimens, and its distinct advantages over other models are discussed.