1991 Fiscal Year Final Research Report Summary
Study on Servceability Limit States of Reinforced Concrete Structure
| Project/Area Number |
01460194
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Building structures/materials
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| Research Institution | Osaka University |
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Principal Investigator |
SUZUKI Kazuo Osaka University Faculty of Engineering, Professor, 工学部, 教授 (60028991)
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| Co-Investigator(Kenkyū-buntansha) |
OHNO Yoshiteru Osaka University Faculty of Engineering, Associate Professor, 工学部, 助教授 (30029194)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Sustained loading / Repeated loading / deflection / cracking / creep / Shrinkage / Relaxation of Bond Stress / PRC |
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| Research Abstract |
1. Under Sustained Loading
(1) Relation between bond stress and slip of reinforcement in concrete under sustained loading was understood. (2) Additional deflection due to slip of reinforcement from anchor zone was larger than flexural deflection on cantilever beam. The slip of reinforcement could be predicted by use of proposed bond stress - slip model. (3) Delay of loading time after prestress transfer resulted in increase of long-term crack width and decrease of long-term deflections. (4) Crack width could be predicted by the proposed method. The ACI method for predicting deflections underestimated long-term deflections in beams.
2. Under Repeated Loading
Reinforced concrete beams and partially prestressed concrete beams were repeatedly loaded for 20 or 200000 cycles at two load levels which correspond to 1000 and 2000 kgf/cm^2 of steel stress. The results obtained were as follow : (1) Increase in crack width and deflections under repeated loading after 2 or 3 cycles was extremely little at the lower load level. At the higher load level, however, deformations increase linearly with number of cycle on a semi-loga scale. (2) Increase of deformation due to repeated load was caused by relaxation of bond stress and increase of compression strain of concrete.
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