Fracture parameters of high-strength concrete – mode II testing

Abstract

This paper presents an experimental investigation on fracture parameters (fracture energy and brittleness number) of double-edge-notched, high-strength concrete specimens of different sizes with varying notch depth ratios under mode II testing. Fracture energy and brittleness number are the important parameters for modelling the fracture behaviour of concrete. The fracture parameters are calculated by using size effect law. The size effect indicates that the failure stress of geometrically similar structures decreases with increasing size. From the experimental results it is observed that shear fracture energy (GII) is about 23 times more than that of mode I fracture energy (G1). It is also observed that the cracks do not propagate from the notches in the direction normal to the maximum principal stress but in a direction in which shear stresses dominate as reported by Bazant. The crack propagation direction seems to be governed by maximum energy release rate.