Strengthbased criteria

The early investigations on cracking of concrete have mostly applied simple criteria based on the concepts of strength of material (SOM). A crack is assumed to propagate when the predicted stress or strain at the crack-tip exceeds the critical value representative of the strength of the material. The crack propagation criterion, in this approach, is identical to the new crack initiation criterion. A sudden release of stress on the fracture plane is commonly assumed upon reaching the material tensile strength. The gradual release of stress with increasing strain has also been used, mainly for numerical stability reasons, in finite element analyses of cracking problems. The SOM criterion of crack propagation has been used in discrete and smeared crack propagation finite element models. Comparison of computed tensile stress with the strength of the material is not rational for a cracked structure because spurious results may be obtained depending on the size of the finite element ahead of the propagating crack. The lack of finite element mesh objectivity of the SOM criterion was reported.

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