2003 Fiscal Year Final Research Report Summary
Strain Rate Effect on Reinforced Concrete Members under Cyclic and Dynamic Loading
| Project/Area Number |
14350296
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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 |
Building structures/materials
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| Research Institution | Chiba University (2003)
The University of Tokyo (2002) |
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Principal Investigator |
OTANI Shunsuke Chiba University, Faculty of Engineering, Professor, 工学部, 教授 (30133101)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Toru Chiba University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (10226855)
SHIOHARA Hitoshi University of Tokyo, School of Engineering, Associate Professor, 大学院・工学系研究科, 助教授 (50272365)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Strain Rate / Loading Rate / Reinforced Concrete Members / Strength / Failure Mode / Ductility / Test / Loading History |
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| Research Abstract |
To simulate accurately the behavior of building structural systems under earthquake loading, the model for the structural members should be accurate enough in particular under dynamic and cyclic loading condition. Hence, one-third scale nine-teen reinforced concrete cantilever beam specimens were tested to failure to compare their behavior under dynamic and quasi-static loading condition. The parameters for the test include loading speed as well as amount of longitudinal reinforcement, shear reinforcement, shear-span to depth ratio, shear stress level, strength of transverse reinforcement and loading history. The list of conclusions are as follow,
1.The specimens under dynamic loading showed always larger flexural yielding strength than its pair with same parameter tested under quasi-static loading. It is possible to estimate the strength increase quantitatively with affordable presision, by considering the increase in yield point strength of the longitudinal steel and flexural theory.
2.As far as the tests in this research concerns, loading speed has little effect on the ductility capacity in terms of the largest deflection at which significant strength decay initiates after cyclic loading. One of the most influential parameter on the ductility is not loading speed, but loading history, i.e. strength decay was delayed significantly in the specimen tested under one directional cyclic loading history.
3.A special technique was invented to measure stress in longitudinal bar after tensile yielding and applied to the tests. The observed tensile stress in longitudinal bar were well estimated by flexural theory before flexural yielding, whereas, larger tensile stress is obtained than the theory for tensile reinforcing bars in hinge zone and larger compressive stress in compressive reinforcing bars which gradually increased due to cyclic loading.
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