A study on the development for measuring system of bolt axial force using image measurement

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K06532
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Structural engineering/Earthquake engineering/Maintenance management engineering
• Research Institution: University of Toyama (2018-2019); Kyoto University (2017)
• Principal Investigator: Suzuki Yasuo 富山大学, 学術研究部都市デザイン学系, 准教授 (50431698)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 高力ボルト / 残存軸力 / 画像計測 / 非破壊検査

Outline of Final Research Achievements

In this study, loading tests and 3D-FEM analysis were conducted to discuss the effects of shape of bolt head and the position of the bolt on the relationship between bolt axial force and strain.
In addition, the bolts were inspected from the bridges in service for several decades. It was also confirmed that some bolts with a residual axial force of less than 30% of the design axial force exist.
Furthermore, the accuracy of strain measurement using images are examined and it is showed that in an ideal environment with sufficient light intensity, it is possible to measure with an error of about 10% for an actual strain of about 500μ. On the other hand, it was clarified that the variation of the measurement result becomes large due to the influence of light quantity and vibration.

Free Research Field

構造工学・地震工学・維持管理工学

Academic Significance and Societal Importance of the Research Achievements

本研究では，ボルト頭部に貼り付けたひずみゲージによるボルト軸力計測に関して，ボルトの個体差，ボルト孔とボルトとの位置関係が測定精度に与える影響について明らかにした点，また，画像による軸力評価について，現時点での画像計測技術による測定精度および今後解決すべき課題について明らかにした点で意義がある．