||Urban and civil engineering
||Main research topic is structural engineering. In particular, research interests are focused on steel structure, bridge engineering and maintenance engineering. Steel is one of the most fundamental materials of infrastructure. The causes of failure of steel bridges include earthquake and aging deterioration such as fatigue and corrosion. Recently in Japan, the maintenance works are getting important because deterioration of infrastructure constructed several decades ago has become a great concern. The maintenance work is done by visual inspection usually. However, sometimes, detailed inspection is necessary. Nondestructive technique plays an important role. The laboratory aims at accurate nondestructive technique such as ultrasonic test, eddy current test and thermography. Ultrasonic test has some advantages; it is noninvasive and harmless to the environment. It is possible to detect an internal defect. The laboratory also investigates the applicability of phased array ultrasonic test. Thermography is also a relatively emerging technique, because of the development of inexpensive sensor such as microbolometer. One of the advantages of thermography is no-contact. Detection of water leakage of structures is investigated by thermography in the laboratory. The thermography is related to image that is a good match with artificial intelligent. Some AI algorithms of random forest or convolutional neural network are investigated. Since a steel is a ferromagnetic material, eddy current test can be applied. Detection of fatigue crack under paint coating and/or stainless-steel lining by the eddy current test.
|Research Field(Keyword & Summary)
- (1) Detection of fatigue crack of rib-to-deck weld of orthotropic steel deck
Fatigue cracking of orthotropic steel deck system is one of the most serious problems. In the study, rib-to-deck welded joint is focused on, because it is the longest weld line in the system. The objective of the study is to investigate the applicability of phased array ultrasonic test. There are two types of fatigue cracks. One is deck crack, and the other is bead crack. Using not only one-dimensional array transducer, but two-dimensional array transducer both types of cracks could be detected.
- (2) Detection of water leakage of drainpipe of bridge
It is possible that corrosion occurs at bridge bearings, because of the inappropriate dimension around the abut and the malfunction of drainage of rainwater. Detection of water leakage is very important. Thermography is applied to detect the leakage. As the recent tendency, drainpipes are connected more complicatedly than ever for sufficient drain. The number of check points of drainpipes is increasing. For the automated detection, artificial intelligent was applied. Experiments by the connection of pipes were carried out. The precision of 90 % could be achieved by random forest algorithm.
- (3) Detection of fatigue crack under paint coating
Generally, steel bridge is painted for the protection of corrosion. A fatigue crack can be detected as a paint crack. When a paint crack is detected, however, there is not always a fatigue crack under the paint coating. Usually, when a paint crack is detected, the paint coating is removed by grinding. After grinding, magnetic particle test is applied to confirm the fatigue crack. This process is time consuming. The objective of the study is to detect fatigue crack without removing paint. By applying the ultrasonic test of creeping wave, fatigue crack can be detected.
- (1) Detection of crack in painted flange gusset welded joint by ultrasonic test, Welding in the World, 2021
- (2) Applicability of 2D ultrasonic phased array nondestructive test for fatigue crack of orthotropic steel deck system, Bridge Maintnance, Safety, Management, Life-Cycle Sustainability and Innovations 2021
- (3) Development of phased array ultrasonic test system for detection of fatigue carck of rib-to-deck weld of orthotropic steel deck system, Maintenance, Safety, Risk, Managament and Life-Cycle Performance of Bridges 2018
- (4) Fatigue crack detection by the use of ultrasonic echo height change with crack tip opening, Welding in the World, Vol.58, No.3, 2014
- (5) Fitness for Purpose Design on Fatigue of Butt Welded Joints, IIW International Conference on Advances in Welding and Allied Technologies, 2009
- (6) Performance Evaluation Test of the Time-of-Flight Diffraction Technique for Welded Joints of Steel Bridges, Journal of Testing and Evaluation, Vol.36, No.3, 2008
- (7) Performance evaluation test of automatic ultrasonic testing systems for welded joints of steel bridges, Journal of Testing and Evauation, Vol.33, No.4, 2005
- (8) Acoustical anisotropy and non-homogeneity of rolled steel plates, Structural Eng./Earthquake Eng, JSCE, Vol.21, No.1, 2004
- (9) A fundamental study on detection of defects in the web gap region of steel plate girder bridges by the plate wave ultrasonic technique, Quantitative Nondestructive Evaluation, Vol.23, 2004
|Grant-in-Aid for Scientific Research Support: Japan Society for Promotion of Science (JSPS)
|Recruitment of research assistant(s)
|Affiliated academic society (Membership type)
||Japan Society of Civil Engineeres (member)
|Education Field (Undergraduate level)
||steel structures, structural mechanics, maintenance engineering
|Education Field (Graduate level)
||steel structures, structural mechanics,