| Project/Area Number |
13650613
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Building structures/materials
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| Research Institution | Tohoku University |
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Principal Investigator |
MIHASHI Hirozo Tohoku Univ., Graduate School of Eng., Prof., 大学院・工学研究科, 教授 (90091751)
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| Co-Investigator(Kenkyū-buntansha) |
ARIKAWA Satoshi National Institute for Land and Infrastructure Management, Ministry of Land Infrastructure and Transport, Senior Researcher, 建築研究所・第二研究部, 主任研究員
KIRIKOSI Kazuki Tohoku Univ., School of Eng., Research Eng., 工学部, 教務職員 (60240660)
KANEKO Yoshio Tohoku Univ., Graduate School of Eng., Assoc. Prof., 大学院・工学研究科, 助教授 (60312617)
SAICHI Masayoshi Tohoku Institute of Technology, School of Eng., Lecturer, 工学部, 講師 (90104132)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥4,300,000 (Direct Cost: ¥4,300,000)
Fiscal Year 2002: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2001: ¥3,200,000 (Direct Cost: ¥3,200,000)
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| Keywords | Concrete / Crack / Damage level / Fractal analysis / Microscope observation / Multifractal |
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| Research Abstract |
While geometrical randomness of cracks in concrete structures on micro, meso and macro levels were taken into consideration, methodologies for evaluating the damage level developed and fundamental studies to apply these methodologies for existing damaged concrete structures were carried out. Obtained results are summarized as follows:
1) As a fundamental study to link crack information and damage level of concrete structures, microcracks on the surface of concrete cylinders were observed by means of microscope. Then relationships between the crack information and the stiffness reduction, and/or the velocity of ultrasonic wave were studied experimentally.
2) Microcracks in concrete specimens damaged by freezing and thawing action or cyclic loading were statistically analyzed. Since the microcracks due to freeze and thawing action were so thin and densely distributed that ordinary counting methods don't work sufficiently, a new method was developed on the basis of a stochastic geometry concept. These microcracks due to freezing and thawing actions were remarkably accumulated in an early stage of the cycles and then gradually increased.
3) Strain-rate calculated by the differential of the stress-strain curve showed a possibility to be treated as an index to quantify the damage level.
4) Fractal analyses were carried out to analyze crack patterns observed in existing structures so as the fractal dimension to be a meso level parameter. Damage levels of existing concrete structures were qualitatively evaluated from the typical crack patterns.
5) Multifractarity was examined in cracks on concrete walls. Macroscopic changing patterns of the fractality in each sub-area were also investigated by analyzing the subdivided concrete walls.
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