Cohesive crack, size effect, crack band and work-of-fracture models compared to comprehensive concrete fracture tests

Christian Hoover, Zdeněk P. Bažant

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

The simplest form of a sufficiently realistic description of the fracture of concrete as well as some other quasibrittle materials is a bilinear softening stress-separation law (or an analogous bilinear law for a crack band). This law is characterized by four independent material parameters: the tensile strength, f'-t f t, the stress \sigma -k σ k at the change of slope, and two independent fracture energies - the initial one, G-f G f and the total one, G-F G F. Recently it was shown that all of these four parameters can be unambiguously identified neither from the standard size effects tests, nor from the tests of complete load-deflection curve of specimens of one size. A combination of both types of test is required, and is here shown to be sufficient to identify all the four parameters. This is made possible by the recent data from a comprehensive test program including tests of both types made with one and the same concrete. These data include Types 1 and 2 size effects of a rather broad size range (1:12.5), with notch depths varying from 0 to 30 % of cross section depth. Thanks to using identically cured specimens cast from one batch of one concrete, these tests have minimum scatter. While the size effect and notch length effect were examined in a separate study, this paper deals with inverse finite element analysis of these comprehensive test data. Using the crack band approach, it is demonstrated: (1) that the bilinear cohesive crack model can provide an excellent fit of these comprehensive data through their entire range, (2) that the G-f G f value obtained agrees with that obtained by fitting the size effect law to the data for any relative notch depth deeper than 15 % of the cross section (as required by RILEM 1990 Recommendation), (3) that the G-F G F value agrees with that obtained by the work-of-fracture method (based on RILEM 1985 Recommendation), and (4) that the data through their entire range cannot be fitted with linear or exponential softening laws.

Original languageEnglish (US)
Pages (from-to)133-143
Number of pages11
JournalInternational Journal of Fracture
Volume187
Issue number1
DOIs
StatePublished - 2014
Externally publishedYes

Fingerprint

Cohesive Crack
Size Effect
Crack
Concretes
Cracks
Notch
Forms (concrete)
Fracture energy
Softening
Tensile strength
Recommendations
Model
Cross section
Finite element method
Entire
Range of data
Tensile Strength
Scatter
Deflection
Batch

Keywords

  • Fracture energy
  • Nonlinear fracture mechanics
  • Quasibrittle fracture
  • Scaling
  • Strength

ASJC Scopus subject areas

  • Mechanics of Materials
  • Computational Mechanics
  • Modeling and Simulation

Cite this

Cohesive crack, size effect, crack band and work-of-fracture models compared to comprehensive concrete fracture tests. / Hoover, Christian; Bažant, Zdeněk P.

In: International Journal of Fracture, Vol. 187, No. 1, 2014, p. 133-143.

Research output: Contribution to journalArticle

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