Cohesive crack, size effect, crack band and work-of-fracture models compared to comprehensive concrete fracture tests
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 ten...
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| Format: | Article |
| Language: | English |
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Springer Netherlands
2017
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| Online Access: | http://hdl.handle.net/1721.1/107967 https://orcid.org/0000-0003-4814-1665 |
| _version_ | 1826189779020021760 |
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| author | Bažant, Zdeněk P. Hoover, Christian G |
| author2 | Massachusetts Institute of Technology. Department of Civil and Environmental Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Civil and Environmental Engineering Bažant, Zdeněk P. Hoover, Christian G |
| author_sort | Bažant, Zdeněk P. |
| collection | MIT |
| description | 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′[subscript t], the stress σ[subscript k] at the change of slope, and two independent fracture energies—the initial one, G[subscript f] and the total one, G[subscript 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[subscript 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[subscript 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. |
| first_indexed | 2024-09-23T08:21:31Z |
| format | Article |
| id | mit-1721.1/107967 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T08:21:31Z |
| publishDate | 2017 |
| publisher | Springer Netherlands |
| record_format | dspace |
| spelling | mit-1721.1/1079672022-09-23T12:30:51Z Cohesive crack, size effect, crack band and work-of-fracture models compared to comprehensive concrete fracture tests Bažant, Zdeněk P. Hoover, Christian G Massachusetts Institute of Technology. Department of Civil and Environmental Engineering Hoover, Christian G 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′[subscript t], the stress σ[subscript k] at the change of slope, and two independent fracture energies—the initial one, G[subscript f] and the total one, G[subscript 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[subscript 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[subscript 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. United States. Dept. of Transportation (through Grant 20778 from the Infrastructure Technology Institute of Northwestern University) National Science Foundation (U.S.) (Grant CMMI-1129449) Northwestern University (W.P. Murphy Fellowship) 2017-04-07T19:12:07Z 2017-04-07T19:12:07Z 2014-01 2013-04 2016-08-18T15:19:05Z Article http://purl.org/eprint/type/JournalArticle 0376-9429 1573-2673 http://hdl.handle.net/1721.1/107967 Hoover, Christian G., and Zdeněk P. Bažant. “Cohesive Crack, Size Effect, Crack Band and Work-of-Fracture Models Compared to Comprehensive Concrete Fracture Tests.” International Journal of Fracture 187, no. 1 (January 29, 2014): 133–143. https://orcid.org/0000-0003-4814-1665 en http://dx.doi.org/10.1007/s10704-013-9926-0 International Journal of Fracture Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. Springer Science+Business Media Dordrecht application/pdf Springer Netherlands Springer Netherlands |
| spellingShingle | Bažant, Zdeněk P. Hoover, Christian G Cohesive crack, size effect, crack band and work-of-fracture models compared to comprehensive concrete fracture tests |
| title | Cohesive crack, size effect, crack band and work-of-fracture models compared to comprehensive concrete fracture tests |
| title_full | Cohesive crack, size effect, crack band and work-of-fracture models compared to comprehensive concrete fracture tests |
| title_fullStr | Cohesive crack, size effect, crack band and work-of-fracture models compared to comprehensive concrete fracture tests |
| title_full_unstemmed | Cohesive crack, size effect, crack band and work-of-fracture models compared to comprehensive concrete fracture tests |
| title_short | Cohesive crack, size effect, crack band and work-of-fracture models compared to comprehensive concrete fracture tests |
| title_sort | cohesive crack size effect crack band and work of fracture models compared to comprehensive concrete fracture tests |
| url | http://hdl.handle.net/1721.1/107967 https://orcid.org/0000-0003-4814-1665 |
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