Affiliation |
Faculty of Urban Innovation, Division of Urban Innovation |
Job Title |
Assistant Professor |
Research Fields, Keywords |
Structural engineering, Non Destructive Inspection, Machine learning, Signal processing, High-strength bolted friction joints |
Web Site |
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Related SDGs |
HIRAO Kensho
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Education 【 display / non-display 】
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-2022.9
Tokyo Institute of Technology Doctor Course Completed
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2017.4-2019.3
Tokyo Institute of Technology Master Course Completed
Degree 【 display / non-display 】
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Doctor of Engineering - Tokyo Institute of Technology
Campus Career 【 display / non-display 】
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2022.10
Duty Yokohama National UniversityFaculty of Urban Innovation Division of Urban Innovation Assistant Professor
Academic Society Affiliations 【 display / non-display 】
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2017
Japan Society of Civil Engineers
Research Areas 【 display / non-display 】
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Social Infrastructure (Civil Engineering, Architecture, Disaster Prevention) / Structure engineering and earthquake engineering
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Others / Others / Steel structure
Qualification acquired 【 display / non-display 】
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First Kind of High School Teacher License
Thesis for a degree 【 display / non-display 】
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Quantification of Uncertain Influential Parameters Affecting the Structural Performance Evaluation of High Strength Bolted Friction Joints
Kensho HIRAO
2022.9
Doctoral Thesis Single Work [Reviewed]
Papers 【 display / non-display 】
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Kensho HIRAO, Quang Vy TRAN, Hiroshi TAMURA
Journal of Structural Engineering 70A ( 0 ) 61 - 74 2024.3 [Reviewed]
Authorship:Lead author Language:Japanese Publishing type:Research paper (scientific journal) Publisher:Japan Society of Civil Engineers Joint Work
There is concern that the slip coefficient of high-strength bolted joints with different faying surfaces may be lower than that of conventional joints, and it has been reported that the slip coefficient is improved by inserting friction shims. In this study, shims were modified to be disk-shaped, which can be inserted into each bolt hole, for application to arbitrary bolted joints, and their slip resistance was evaluated by slip resistance tests. As a result, it was confirmed that a slip coefficient of 0.6 or higher could be expected with the insertion of shims. Failure modes of the contact surfaces were also investigated by dismantling the specimens after the test and observing the contact surfaces.
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A study on stabilizing mechanism of flap countermeasures mitigating VIV of a box girder bridge section
Phan Duc Tam, Hiroshi Katsuchi, Wang Jiaqi, Hiroshi Tamura, Kensho Hirao
IOP Conference Series: Materials Science and Engineering 1289 ( 1 ) 1 - 15 2023.8 [Reviewed]
Language:English Publishing type:Research paper (scientific journal) Joint Work
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ULTRASONIC HIGH-STRENGTH BOLT AXIAL FORCE EVALUATION BY MACHINE LEARNING-BASED TO WAVEFORM ANALYSIS
Kensho HIRAO, Keigo SUZUKI, Kastumi MORITA, Yuichi ITO, Kouichi TAKEYA and Eiichi SASAKI
Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)) 78 ( 1 ) 108 - 120 2022 [Reviewed]
Authorship:Lead author Language:Japanese Publishing type:Research paper (scientific journal) Publisher:Japan Society of Civil Engineers Joint Work
Bolt axial force of high-strength bolted joints decreases due to deterioration. One of the conventional methods to evaluate the bolt axial force is ultrasonic testing. However, quantitative evaluation of the bolt axial force is controversial in terms of accuracy, and some problems remain for practical use. This study attempts the accurate evaluation of the bolt axial force by ultrasonic testing. The time zone analysis of the ultrasonic waves indicated that the waveform in the initial time zone includes bolt axial force information. The parasitic discrete wavelet transform (P-DWT) was applied to improve the evaluation accuracy. As a result of targeting bolts manufactured in the same lot, machine learning using linear regression evaluated the unknown bolt axial force within an error of 6% or less. Therefore, it was shown that the proposed method of this study corresponds to the existing bolt and can evaluate the bolt axial force with high accuracy.
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Kensho HIRAO, Eiichi SASAKI, Yuichi ITO, Kouichi TAKEYA, Ayako AKUTSU
Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)) 78 ( 3 ) 508 - 519 2022 [Reviewed]
Authorship:Lead author Language:Japanese Publishing type:Research paper (scientific journal) Publisher:Japan Society of Civil Engineers Joint Work
<p> 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.</p>
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APPLICABILITY OF PRETENSIONED BOLTED JOINTS INCLUDING DIFFERENT CONTACT FACES
TAMURA Hiroshi, MINAMI Kuniaki, YOSHIOKA Natsuki, UCHIDA Daisuke, MORO Mitsuru, HAMA Tatsuya, HIRAO … Show more authors
TAMURA Hiroshi, MINAMI Kuniaki, YOSHIOKA Natsuki, UCHIDA Daisuke, MORO Mitsuru, HAMA Tatsuya, HIRAO Kensho Hide authors
Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)) 76 ( 2 ) 255 - 274 2020
Language:Japanese Publishing type:Research paper (scientific journal) Publisher:Japan Society of Civil Engineers Joint Work
<p> In frictional type pretensioned bolted joints, one specification is employed for contact faces in each joint in principle. Meanwhile, in some cases such as protection works of existing bridges and fabrication of box girders made of weathering steel without coating, introduction of usage of different contact faces in one joint might often allow labor-saving and accelerated works.</p><p> In present study, bolted joints including different contact faces are defined as a hybrid faying surfaces joint, and 33 bolted joint specimens were used in bolt pretension relaxation test and slip test. This paper reports these results and compares degree of pretension loss and slip resistance in hybrid faying surface joints with homogeneous (i.e. normal) joints. Finally, also on the basis of previous research, the applicability and slip coefficient for designing of hybrid faying surfaces joints are discussed regarding.</p>
Review Papers 【 display / non-display 】
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BIMによるデジタルツイン技術を用いた鉄道橋のメンテナンスの最適化 -オーストラリアのミナムラ鉄道橋を対象とした実証実験結果の報告-
平尾 賢生,黒田璃紗,駒場 駿介,鹿野 光一,島田 剛気,島野 孝則,末松 慎介,土田 僚,平井 貴大,舟橋 景介,柳 博文
橋梁と基礎 57 ( 12 ) 63 - 65 2023.12 [Reviewed] [Invited]
Authorship:Lead author Language:Japanese Publishing type:Book review, literature introduction, etc. Joint Work
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Asia Steel Bridge Competition 2023
Bridge and Foundation Engineering 58 ( 3 ) 53 - 55 2024.3 [Reviewed] [Invited]
Language:Japanese Publishing type:Book review, literature introduction, etc. Joint Work
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GISとリモートセンシングデータを使用した橋梁の洪水リスク評価 -2020年 メディケーン「イアノス」による被害/ギリシャ-
平井 貴大,平尾 賢生,倉橋 和希,黒田璃紗,駒場 駿介,鹿野 光一,島野 孝則,末松 慎介,土田 僚,舟橋 景介,柳 博文
橋梁と基礎 58 ( 1 ) 57 - 59 2024.1 [Reviewed] [Invited]
Language:Japanese Publishing type:Book review, literature introduction, etc. Joint Work
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Asia Steel Bridge Competition 2023
Kouichi TAKEYA, Yuichi ITO, Koji KINOSHITA, Keigo SUZUKI, Hiroshi TAMURA, Ayako AKUTSU, Kensho HIRAO
Bridge and Foundation Engineering 57 ( 10 ) 53 - 53 2023.10
Language:Japanese Publishing type:Article, review, commentary, editorial, etc. (other) Joint Work
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多径間鉄筋コンクリートアーチ橋崩落要因の検討 -イタリア カプリリオラ橋-
島野 孝則,平尾 賢生,黒田璃紗,駒場 駿介,鹿野 光一,島田 剛気,末松 慎介,土田 僚,平井 貴大,舟橋 景介,柳 博文
橋梁と基礎 57 ( 9 ) 39 - 41 2023.9
Language:Japanese Publishing type:Book review, literature introduction, etc. Joint Work
Other external funds procured 【 display / non-display 】
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Loose bolt detection by nut rotation history using AI image processing
2023.7 - 2024.6
Investigator(s):Kensho HIRAO
Authorship:Principal investigator
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Evaluation of the existing performance of high-strength bolted friction joints considering the effect of uncertainty
2022.6 - 2023.5
Investigator(s):Kensho HIRAO
Authorship:Principal investigator
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Evaluation of the existing performance of high-strength bolted friction joints considering the effect of uncertainty
2021.6 - 2022.5
Investigator(s):Kensho HIRAO
Authorship:Principal investigator
Presentations 【 display / non-display 】
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Proposal of ultrasonic bolt axial force evaluation method using machine learning and signal processing
Kensho HIRAO
IABSE 2022.5
Event date: 2022.5
Language:English Presentation type:Oral presentation (general)
Venue:Prague, Czech Republic Country:Czech Republic
It has been confirmed that bolt axial force of high-strength bolted joints decreases due to various effects. Generally, evaluating the bolt axial force of existing bolts has been an important issue. In a conventional ultrasonic bolt axial force evaluation method, bolt length change due to the change of bolt axial force is evaluated. However, bolt length can include uncertainty due to manufacturing errors. Hence, in this study, attention was paid to the deformed shape of the bolt head, which has a little dependency on the bolt length, and application of signal processing and machine learning was attempted. It was shown that the waveform data obtained from the bolt head by ultrasonic testing included characteristic signals indicating the bolt axial force. The target characteristic signal was detected by the parasitic discrete wavelet transform (P-DWT). A highly accurate bolt axial force evaluation method was proposed by applying machine learning to characteristic signals.
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Applicability of disk-type friction shim in high-strength bolted joints including different faying surface
Kensho Hirao, Yuki Goka, Hiroshi Tamura, Jiaqi Wang, Hiroshi Katsuchi
JSCE 2023 Annual Meeting 2023.9 JSCE
Event date: 2023.9
Language:Japanese Presentation type:Oral presentation (general)
Venue:Hiroshima Country:Japan
There is concern that the slip coefficient of high-strength bolted joints with different faying surfaces may be lower than that of conventional joints, and it has been reported that the slip coefficient is improved by inserting friction shims with electroless nickel and diamond treatment into the faying surfaces. In this study, shims were modified to be disk-shaped so that they can be inserted into each bolted joint hole, and their applicability to arbitrary bolted joints was evaluated by slip tests. The results of slip resistance tests confirmed that a slip coefficient of 0.65 or higher can be expected with the insertion of shims, indicating the applicability of the shims to arbitrary bolted joints.
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Effect of steel strength on load carrying capacity of high-strength bolted joints under compression
Kensho HIRAO
12th Pacific Structural Steel Conference 2019.11
Event date: 2019.11
Language:English Presentation type:Oral presentation (general)
Venue:Tokyo, Japan Country:Japan
In this research, the steel strength of the high-strength bolted frictional joint, i.e., the strength and thickness configuration of the base plate and the splice plate were investigated. In order to clarify the effect on the load carrying capacity of high-strength bolted frictional joints under compressive load, compressive loading experiment and numerical analysis were conducted. In the experiment, the mechanism up to the post-slip behavior was confirmed for joints of yield precedence type, and it was shown that hybrid joints of slip precedence type can secure the design slip resistance calculated by the general slip coefficient and the design bolt axial force. In the analysis, it was confirmed that the stress distribution of the homogeneous joint and some hybrid joints in pre-slip was almost the same.
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Influence of Steel Strength on Load Carrying Capacity of High-Strength Bolted Frictional Joints Under Compression
Kensho HIRAO
2019.9
Event date: 2019.9
Language:Japanese Presentation type:Oral presentation (general)
Country:Japan
Charge of on-campus class subject 【 display / non-display 】
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2024 Experiment in Civil Engineering B
College of Urban Sciences
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2024 Exercises on Structural Mechanics
College of Urban Sciences
Charge of off-campus class subject 【 display / non-display 】
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物理1及演習
2024.4 Institution:法政大学
Level:Undergraduate (specialized)
Committee Memberships 【 display / non-display 】
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Japan Steel Bridge Engineering Association "Working Group on Joints of Steel Bridges"
2022.11 Academic Member
Committee type:Academic society
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Bridge and Foundation Engineering
2022.10
Committee type:Other