2021 Fiscal Year Final Research Report
Introduction of vibro-Doppler technique to wideband ultrasonic echo method for health assessment of PC structures
| Project/Area Number |
19K22025
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 25:Social systems engineering, safety engineering, disaster prevention engineering, and related fields
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| Research Institution | Gunma University |
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Principal Investigator |
Takashi Miwa 群馬大学, 大学院理工学府, 教授 (30313414)
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| Project Period (FY) |
2019-06-28 – 2022-03-31
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| Keywords | 非破壊検査 / 超音波エコー法 / 加振 / PC構造物 / 健全性評価 |
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| Outline of Final Research Achievements |
A broadband ultrasonic echo method is used to detect insufficient grout filling in the sheaths of PC concrete structures for the protection of steel rods. However, it is sometimes difficult to identify the reflected wave from the PC steel bar due to unwanted scattered waves caused by aggregates in the concrete.
In this study, a broadband ultrasonic Doppler measurement system was developed to selectively receive the response of vibrating steel bars from the Doppler echoes of the vibrating steel bars by electromagnetic excitation of the steel bars. However, the contrast of the echo signal corresponding to the vibrating object was 5.5 times higher than that of the normal echo signal.
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| Free Research Field |
計測工学
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| Academic Significance and Societal Importance of the Research Achievements |
鉄筋コンクリート(RC)構造物は引張応力に弱いコンクリートを鉄筋で補強した複合材料であるが、よりひび割れに強い材料として、あらかじめ鋼材によりコンクリート軸方向に圧縮応力を加え、たわみによるひび割れ発生の影響を低減するプレストレストコンクリート(PC)構造物が開発され、これまで6万橋ものPC橋が建設されてきた。しかし、それらの平均経過年数は30年を超えており、今後、更なる老朽化によるPC橋の安全性が危惧されている．本研究により，グラウト充填不足の評価法として，従来法よりもより4倍程度高いコントラストが期待できる評価パラメータを抽出でき，今後の非破壊検査への応用に期待できる．
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