Influence of size on fracture energy of concrete

Concrete structures frequently exhibit cracks. In order to investigate the influence of cracks on durability and the remaining load bearing capacity o f buildings, fracture mechanics models can be used. For materials like conc rete non-linear models for example the fictitious crack model introduced by Hillerborg, Modeer and Petersson [1] or the crack band model proposed by B azant and Oh [2] are able to describe crack formation and propagation in a realistic way. But it has been observed, that the parameters of these model s depend both, on structural size and geometry. In this paper a simple mode l to explain the nature of size and geometry dependence of the specific fra cture energy is presented. The model is evaluated with experimental data fr om Trunk and Wittmann [2, 4, 5].