2001 Fiscal Year Final Research Report Summary
Study on Practical Development of Monitoring Techniques of Damage Degree and Improvement of Structural Performance of Piles
| Project/Area Number |
12650559
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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 |
SUGIYAMA Yoshiro Tohoku University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (90206425)
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| Co-Investigator(Kenkyū-buntansha) |
ISHII Kiyoshi Shimizu Corporation, Research Institute of Technology, Chief Researcher, 技術研究所, 主席研究員
MITSUJI Kazuya Tohoku University, Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (90292250)
KARKEE Madan Akita Prefectural University, Dept. of Architecture and Environment System, Professor, システム科学技術学部, 教授 (90315630)
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| Project Period (FY) |
2000 – 2001
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| Keywords | helth monitoring / sensor / pile / crack / damage degree / carbon fiber |
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| Research Abstract |
Many examples of damage to pile foundations supporting buildings are reported in Hyogoken-Nambu earthquake in 1995. Because these were underground occurrence, it becomes clear to raise some problems such as, 1) It took a lot of labors, time and money in excavation work, 2) Integrity tests and bore-hole cameras used as survey apparatuses were not sufficient to confirm damage occurred in deep place, and 3) It does not exist and looks forward to a health monitoring system and an appropriate judgement standard of damage of piles.
This research work trys to prepare a convenient monitering techniques possible to judge immediately damage of piles without excavation after earthquakes. Carbon fiber was selected as a sensor for economic reason. Through several structural experiments of PHC piles, it is found out that the built-in carbon sensors are possible to detect bending cracks if those are arranged in axis direction of pile, and shear cracks are also able to be detected if sensors are arranged in circular direction of pile. In the case of the final failure state, electric resistance reaches infinity because sensors are broken. And, even in the condition of deformation of pile goes back to some extent of beginning state by unloading, memory effect can be expected to show residual electric resistance.
Based on these results, two examples of carbon sensors were buried in a cast-in-place concrete pile and another case in a PHC pile at construction work of real buildings as a foothole of practical application.
An analysis introducing effect of rotational performace at pile head was also carried out. It can be found out as a result, that nonlinear behavior at pile head shows the effect of absorbing energy and attenuates input motion to superstructure changing into long period components.
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