Chapter 5 - Crack Interaction and Localization

Abstract

This chapter examines the application of the computational theory for analyzing multiple discrete cracks of the mode-I type (EFCM) to study crack interaction and localization in concrete. Crack interaction is an important issue in the crack analysis of concrete. Because the local stress field and the crack driving force for a given flaw can be significantly affected by the presence of one or more neighboring cracks, clarifying the effect of crack interaction is the key to a clear understanding of various cracking behaviors, including crack localization. In linear elastic fracture mechanics (LEFM), it is known that depending on the relative orientation of the neighboring cracks, the crack interaction can either magnify or diminish the stress intensity factor. Many studies have examined the interaction effects of multiple cracks in the fracturing process of concrete. In the discrete approach that allows the interaction of multiple cracks to be studied most straightforwardly, an explicit mathematical formulation of the crack interaction is possible. Such an approach enables crack interaction to be quantified and various cracking behaviors (such as why some cracks are active, while others are not and why crack localization begins early in some cases and is delayed in others) to be studied based on the nature and the intensity of the crack interactions involved. In order to derive the coefficient of interaction, a numerical formulation of three discrete cracks can be carried out based on the extended fictitious crack model (EFCM).