Asymptotic analysis of boundary effects on concrete fracture

The recently-developed boundary effect concept and associated asymptotic model are used to analyse the various size-dependent fracture behaviours of concrete specimens. It is shown that the dependence of concrete fracture on specimen size, crack and/or ligament length is due to the same mechanism, i.e. the interactions between the crack tip fracture process zone and specimen boundaries. By introducing an equivalent crack AE, all these dimension dependent fracture behaviours become equivalent to a large plate with a small edge crack, and therefore, follow the same relationship of the "net" nominal strength ON versus AE. As a result, the size dependent fracture can be predicted using the data measured on different types of specimens. To demonstrate the flexibility and effectiveness of the asymptotic boundary effect model, three previous experimental results available in the literature are analysed, and excellent agreements are achieved. Furthermore, the implications behind the successful predictions are discussed.