Mechanism behind the Size Effect Phenomenon
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Volume 136, Issue 1
Abstract
Size effect (SE) on quasi-brittle fracture of concrete and concretelike heterogeneous materials has been commonly demonstrated by the influence of specimen size on the transition from strength-dominant fracture to toughness-dominant fracture for geometrically similar specimens with a common initial-crack/specimen-size ratio, i.e., . Under such a condition, size appears to be the single controlling parameter for SE. In this study, we clarify that the primary source of quasi-brittle fracture, the presence of a large fracture process zone (FPZ) in front of a crack-tip, does not follow the condition of geometry similarity even for geometrically similar specimens. This suggests that the role of FPZ is not clearly explained for SE. Therefore, this study emphasizes the interaction between FPZ and the nearest specimen/structure boundary, and the consequent SE phenomenon. The deficiencies associated with the common SE models developed by Bazant and his coworkers are discussed through comparisons with the analysis on the boundary and FPZ interaction, or the boundary effect. It is shown that quasi-brittle fracture and the transition from strength-dominant fracture to toughness-dominant fracture can occur even if specimen/structure size is constant, i.e., size is not the dominant factor for SE.
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Information & Authors
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Published In
Journal of Engineering Mechanics
Volume 136 • Issue 1 • January 2010
Pages: 60 - 68
Copyright
© 2010 ASCE.
History
Received: Apr 6, 2009
Accepted: Jul 1, 2009
Published online: Dec 15, 2009
Published in print: Jan 2010
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