Tensile fracture of concrete at high loading rates taking account of inertia and crack velocity effects

Experiments on concrete have shown a considerable increase of apparent tensile strength with increasing loading rate. This phenomenon can be attributed to various mechanisms such as kinetics of energy barriers and inertia effects in the vicinity of a running crack. After a general introduction into the behaviour of concrete under a uniaxial tensile stress, a model is presented which accounts for flaws in concrete and the inertia effects around a crack at high loading rates. It turns out that the quite crude model predicts rather accurately the relation between apparent strength and loading rate, the influence of concrete quality on this relation, and the relation between crack propagation velocity and loading rate.