Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

Structures receive thermal energy from solar radiation, and temperature differences occur between structural members due to differences in solar exposure and heat capacity. This study attempted to generate electricity from this structural thermal energy, particularly targeting the temperature difference between the pavement and decks of steel deck bridges. The thermal environment of a full-scale steel deck bridge specimen was measured, and a thermal conduction analysis using a finite element model was conducted to explore the structural design for efficiently transferring heat to thermoelectric modules. The installation position that is advantageous for power generation in steel deck bridges was investigated through experiments and heat conduction analysis, followed by power generation simulations. Finally, prototype thermoelectric energy harvesters were installed on the target steel deck bridge and verification experiments demonstrated the potential for utilizing thermal energy in structures.

DOI： 10.2208/jscejj.23-00293

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Other Link： https://www.jstage.jst.go.jp/article/jscejj/80/10/80_23-00293/_pdf

Authorship：Lead author   Language：English  

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Language：English  

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Language：English   Publisher：International Association for Bridge and Structural Engineering (IABSE)  

<jats:p>Orthotropic steel decks in long-span steel bridges are susceptible to fatigue cracking, especially subsurface root-deck cracks. These cracks, hard to detect visually, can cause significant damage if unnoticed. Therefore, the early detection of these subsurface cracks is crucial in preventing further deterioration and ensuring the long-term sustainability of the bridge. In this study, a novel approach for the detection of subsurface cracks in orthotropic steel decks, utilizing new signal processing techniques based on eddy current technology (ECT), as well as optimizing the configuration of the ECT probes, is proposed. Through numerical analysis, response signals obtained from subsurface crack detection using ECT in frequency domains are extracted and analyzed with the proposed method to develop advanced feature extraction techniques that enhance sensitivity and improve the depth of subsurface crack detection. Additionally, various coil-based eddy current probes are examined to identify the most suitable probe configuration that offers robust performance in detecting subsurface cracks. The findings from this study contribute to the advancement of more effective strategies for subsurface crack detection in orthotropic steel decks by integrating advanced eddy current techniques, feature extraction methods, and optimized hardware configurations.

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DOI： 10.2749/manchester.2024.0822

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Recently, inorganic zinc-rich paints have been increasingly applied to the faying surfaces of high-strength bolted friction joints. The coating thickness of the faying surface is said to affect the slip coefficient of the bolted joint. If the coating thickness on faying surfaces of bolts in existing joints can be measured without disassembly the joints, it is possible to evaluate the structural performance of bolted joints on the basis of the current coating thickness on the faying surfaces and the slip coefficient. Furthermore, if it becomes possible to measure areas of high contact pressure, where the coating thickness changes after joining, this information could be useful for discussing the mechanism of structural performance of bolted joints. In this study, the construction of an ultrasonic measurement method with machine learning showed the feasibility of evaluating the coating thickness on the backside of a single steel plate. Subsequently, an attempt was made to evaluate the coating thickness on faying surfaces of bolts in existing joints without disassembly.

DOI： 10.2208/jscejseee.78.3_508

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

High-strength bolted joints are widely used in steel bridges since they have advantages to construction, maintenance, and replacement. On the other hand, bolt axial force may decrease after tightening due to tightening method, tightening order, relaxation, traffic load, or earthquake. The remaining axial force of high-strength bolts is a factor that includes uncertainty therefore, it is important to evaluate the remaining bolt axial force. In this study, in order to evaluate the remaining axial force of high-strength bolts non-destructively and simply, a new remaining axial force evaluation method based on eddy current measurement was constructed. In the eddy current measurement, the stress change can be obtained by using the relationship between the magnetic permeability and the stress. Therefore, authors proposed the method considering the stress state of the bolt head and simply install the eddy current probe on the bolt head. In addition, considering that the bolt head is deformed by the axial force, the relationship between the output signal and the gap between the probe and the measurement target, which is an important evaluation index in eddy current measurement, has clarified, and the influence of the axial force evaluation has also investigated.

DOI： 10.2208/jscejseee.78.2_231

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Language：English   Publisher：International Association for Bridge and Structural Engineering (IABSE)  

<jats:p>High-strength bolted joints are widely used in steel bridges. However, bolt axial force may decrease during the service life of a bridge for many reasons including relaxation, traffic load, and earthquake. Consequently, the remaining bolt axial force is considered a factor with uncertainty that is important to evaluate. In a previous study, the authors proposed an axial force evaluation method using eddy current. In this study, to apply the proposed axial force evaluation method to the actual measurements, new evaluation indices with the possibility of reducing measurement errors and simplifying measurement have been considered. The applicability of the improved method for high- strength bolts using weathering steel has also been examined. An experiment using both high- strength bolts and weathering steel high-strength bolts was conducted to investigate the possibility of evaluating the stress change due to the axial force with the new indices.

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DOI： 10.2749/prague.2022.1148

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Language：English   Publisher：International Association for Bridge and Structural Engineering (IABSE)  

<jats:p>Many bridges have been in service for over 40 years and face to the repapering or reinforcing period due to deterioration. Particularly, in a high-strength bolts used for joints may be loosened due to co-rotation, corrosion, or vibration caused by the vehicles. Thus, it is important to evaluate an axial force of the high-strength bolts. In this research, an axial force evaluation of high-strength bolt using eddy current that does not require measurement preparation has been investigated. The eddy current method is capable of capturing the change in permeability of steel members due to the stress change. Further, the stress distribution of the bolt head is assumed uniform without directionality. Therefore, a numerical simulation and an experiment that measures the output signal of the eddy current probe while introducing axial force to the high-strength bolt has conducted.

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DOI： 10.2749/christchurch.2021.0045

DOI： 10.2208/jscejseee.78.1_108_references_DOI_KdqNvwTxWX9VgSfhIHPHYlZz5ts

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Language：English   Publishing type：Doctoral thesis  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

&nbsp;The authors have proposed a corrosion damage evaluation method for corroded steel members to estimate rust layer and residual thickness. In this method, detected voltage signal obtained by a low frequency eddy current of 500 Hz or less was used as an index. In this research, in order to further advance the method and to simplify the measurement system, a more sophisticated method utilizing a phase characteristic which is considered to be able to simultaneously estimation of thickness information together with the detected voltage has been investigated. Firstly, to clarify the low frequency eddy current characteristics assuming the difference in damaged condition by numerical simulation was performed. Then evaluation method focusing on the phase between the detected voltage and the input current and the detected voltage as an index to capture the differences has investigated. Based on results of all process, a corrosion damage evaluation method focused on phase characteristics which can obtain information of rust layer and residual thickness simultaneously was proposed. Finally, the applicability of proposed method was clarified by experiment.

DOI： 10.2208/jscejseee.74.145

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Language：English  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

&nbsp;In this research, a method which is able to analyze corrosion damage condition such as local thickness reduction or formation of rust layer of steel members of steel members at same time has been investigated. Considering eddy current testing which uses especially low frequency eddy current such as 1~1000Hz, corrosion damage condition analysis method which performs inspection from only one side of steel members has investigated to become easy non-destructive testing method. Firstly, differences of dynamic magnetic field characteristics due to damage form was clarified using numerical simulation, and further data analyzing method to obtain the differences was investigated. Then sweep wave and frequency step wave were designed as induced wave and analysis using both detected voltage and wavelet coefficient was performed. Based on results of all process, a corrosion damage condition analysis method was proposed. Finally, in the applicability of proposed method was clarified by experiment.

DOI： 10.2208/jscejseee.73.387

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Language：English  

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1080/15732479.2016.1236132

Web of Science

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Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)  

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Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)  

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Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)  

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Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)  

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Language：Japanese   Publishing type：Research paper, summary (national, other academic conference)  

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J-GLOBAL

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