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Mechanism behind the size effect phenomenon

journal contribution
posted on 06.12.2017, 00:00 by X Hu, Kai DuanKai Duan
Size effect SE on quasi-brittle fracture of concrete and concretelike heterogeneous materials has been commonly demonstrated by the influence of specimen size D 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., a0 /D=constant. Under such a condition, size Dappears 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 D is constant, i.e., size D is not the dominant factor for SE.

Funding

Category 1 - Australian Competitive Grants (this includes ARC, NHMRC)

History

Volume

136

Issue

1

Start Page

60

End Page

68

Number of Pages

9

ISSN

0733-9399

Location

USA

Publisher

American Society of Civil Engineers

Language

en-aus

Peer Reviewed

Yes

Open Access

No

Era Eligible

Yes

Journal

Journal of engineering mechanics.

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