ABSTRACT
Until comparatively recently concrete was either assumed to have negligible tensile strength or to fail in a brittle manner at a low stress. As long as the stresses in a structure are small this assumption is reasonable. However, the trend is to use concrete more efficiently and to subject it to higher stresses. Also in many cases, such as un-reinforced beams, mass structures like dams, punching shear in concrete decks, reinforcement bonds and anchorages, and pipes, tensile failure can govern the strength. It has been shown in the preceding chapters that there is a size effect in strength that cannot be explained in terms of either strength of materials or classic LEFM. The application of fracture mechanics to concrete structures has therefore received considerable attention in the last few years, particularly by RILEM (Elfgren, 1989).
