2001 Fiscal Year Final Research Report Summary
Localization and Size Effect of Failure of Concrete Structures Subjected to Compression
| Project/Area Number |
12450176
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
土木材料・力学一般
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
NIWA Junichiro Tokyo Institute of Technology, Graduate School of Science and Engineering, Professor, 大学院・理工学研究科, 教授 (60164638)
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| Co-Investigator(Kenkyū-buntansha) |
OTSUKI Nobuaki Tokyo Institute of Technology, Graduate School of Science and Engineering, Professor, 大学院・理工学研究科, 教授 (40211106)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Concrete / Localization of Failure / Size Effect / Compressive Fracture Energy / Length of Failure Zone / Volume of Failure Zone / Deep Beam / Shear Failure |
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| Research Abstract |
When concrete is failed by compression, the failure does not happen throughout the whole body but it concentrates only in some portion of concrete in the post-peak region. By the localization of the failure in compression, the existence of the size effect in structural concrete subjected to compression can be explained.
In this study, the uniaxial compression test of concrete in which the cross-sectional shape, the ratio of height and cross section width are parametrically changed has been carried out in order to quantitatively clarify the localization effect. Based on the measured results of local strain, the local energy absorption has been quantitatively evaluated. According to this measurement, it has been clarified that the localization happens for the compression failure of the concrete when the ratio of the height and the cross section width increases to some extent. And, it is found that the localization length (the length of the failure region) can be evaluated using the side l
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ength of the square having the same cross sectional area as the original cross section. In addition, it is found that the absorbed energy per unit volume of failure region (the compression fracture energy) can be evaluated as the function of the compressive strength of concrete. In other words, the compression fracture energy can be considered as the material property. These concepts have been applied to RC deep beams which fail in shear compression failure mode, and it has been confirmed that the concept of the localization can be applied for RC deep beams.
The compressive stress-strain relationship which is modified according to the element length to make the energy absorption constant, has been applied for the analysis of RC deep beams in the post-peak region. Then, it has been confirmed that the load-deformation behavior and the size effect of shear strength of RC deep beams can be predicted accurately. The validity has also been confirmed by the comparison with the experimental result.
The above results have been summarized and published in Journal of JSCE, Transactions of JCI and also international conference, such as FRAMCOS-4. Less
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