Application of Fracture Mechanics to Concrete Structures

Material properties (heterogeneity and non-linearity) and disturbing phenomena (slow crack growth and microcracking) cause several research workers to be pessimistic about the applicability of Fracture Mechanics to concrete structures. A critical review of the preceding works dealing with concrete fracture is presented. During the 1960's and 1970's it became more and more evident that notch sensitivity is not a material property but only a phenomenon dependent on the specimen and crack sizes, and that the degree of heterogeneity is only a matter of scale. A true fracture collapse can occur only with very large structures. On the other hand a real ultimate strength collapse can occur only with very small fracture specimens. Usually, with the sizes of the structures built by man and the lengths of the natural cracks, the two collapses are interacting.