FRACTURE OF CONCRETE UNDER MULTIAXIAL STRESS - RECENT DEVELOPMENTS

The paper reviews the influence of structural effects on the softening of concrete in multiaxial compression. The post-peak stress-deformation response of concrete subjected to uni- and multiaxial compression is influenced by geometrical and boundary condition effects. Comparison of results obtained by various investigators indicates that fracture in compression is a localized phenomenon. Conical intact material elements are separated by discrete shear bands. Structural effects determine the movement of the intact blocks with respect to one another. Material aspects of softening include the appearance of intact (grain) bridges in the shear bands, and frictional restraint in the shear band. The similarities with fracture in uniaxial tension are outlined. In the latter case crack interface grain bridging is observed too, which is considered as the salient characteristic of the fracture of brittle disordered materials.