| Project/Area Number |
09650506
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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 |
土木材料・力学一般
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| Research Institution | Gifu University |
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Principal Investigator |
MORIMOTO Hiroaki Gifu University, Engineering, Professor, 工学部, 教授 (30021629)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1999: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1997: ¥700,000 (Direct Cost: ¥700,000)
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| Keywords | High strength concrete / Autogenous shrinkage / Young age / Compressive creep / Tensile creep / Variable stress / Method of superposition / Effective Young's modulus / 自己収縮 |
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| Research Abstract |
The following concepts were clarified on the compressive and tensile creep, the evaluation method of creep under changing stress and the calculation method of autogenous shrinkage stress of high strength concrete in early ages.
1. Creep is proportion to a stress to the extent of 40 % of stress-strength ratio, at least.
2. A significant difference is not recognized with compressive and tensile creep.
3. Creep characterisitic changes greatly near by the age of 1 or 2 days, and the change is small after the age of 3 days.
4. Basic creep function for high strength concrete in early age can be given by the product of final creep value and creep progress function.
5. Creep value right after the stress reversal estimated by the method of superposition is grater than the measured a little, yet the estimated value generally agree well with the measured value.
6. There are no remarkable differences between the estimated values by the time hardning rule and the strain hardning rule, and the estimated vales are fairly small compared with the measured value, especially right after the stress reversal.
7. The time hardining rule and the time hardning rule require some appropriate correction considering the softning due to the stress reversal.
8. The autogenous shrinkage stress of 1.5N/mmィイD12ィエD1 at the age of 7 days and 2.2N/mmィイD12ィエD1 at the age of 60 days were measured by using JCI method in high strength concrete having water-cement ratio of 30%.
9. The autogenous shrinkage stress can be estimated by the increment method using the effective Young's modulus calculated from measured creep coefficient of high strength concrete having water-cement ratio of 30%.
10. The Young's modulus reduction coefficient for calculation of autogenous shirinkage stress is a little smaller than that for thermal stress calculation
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