Faculty Profiles - HANJI Takeshi

Papers - HANJI Takeshi

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Development of new database of fatigue damage and repairing cases by using editor-friendly platform Reviewed

Chitoshi Miki, Keigo Suzuki, Kiyoshi Ono, Takeshi Hanji

The 63rd Annual Assembly of International Institute of Welding page： XIII-2332-10 2010.7

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

This study presents a newly developed web database for fatigue damage and repairing cases. Authors use a new platform “PukiWiki" for the web data base instead of html documents. The new platform includes two advantages. One is the editing language, the simple structure of which enhances easy updating; hence, it is possible for the researchers and engineers who are unfamiliar with editing a web page to use it. Another advantage is multi-editor system. Authorized researchers and engineers can edit and update the web at any time from anywhere; that is, we can skip the process of collecting, editing and updating information by a web administrator. It means the platform enables to less laborious editing and quick updating. We expect to enlarge new information on the web; also, expand professional judgment and outlooks to the world from the new database.

Weld repair for fatigue cracked joints in steel bridges by applying low temperature transformation welding wire Reviewed

Chitoshi Miki, Takeshi Hanji, Kohei Tokunaga

The 63rd Annual Assembly of International Institute of Welding page： XIII-2331-10 2010.7

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

The weld repair requires no additional member such as splice plates, therefore it will be more cost efficient and shorten the work period comparing with the conventional bolted splice method. However, the weld repair has possibility to induce weld defects or residual deformation which may reduce the fatigue strength of the repaired joints. Besides, even though fatigue cracked joints are restored to the initial condition with sound weld repairs, cracks will reoccur in the repaired part, because the fatigue strength of cracked joints is originally low in most of the cases. In this study, a new welding wire named low temperature transformation (LTT) welding wire, which enables to introduce compressive residual stress in the vicinity of the weld bead and reduce weld deformation, was applied to the weld repair. The applicability of LTT welding wire to the weld repair was investigated by the fatigue tests with compact tension specimens and a plate girder specimen.

Radiation characteristics of ultrasonic tip echo and its application to detect fatigue crack closure in welding residual stress fields Reviewed

Chitoshi Miki, Ryohei Onishi, Takumi Kubota, Takeshi Hanji

Doboku Gakkai Ronbunshuu A Vol. 66 ( 2 ) page： 219-228 2010.4

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Ultrasonic tip echo is scattered wave which radiates all direction from the sharp tip of reflection source such as fatigue cracks. Tip echo has been utilized for sizing defects as so-called “tip echo method" and also may apply to identify fatigue cracks from other defects. In this study, radiation characteristics of the tip echo were experimentally examined. A linear phased array ultrasonic testing system was applied to send and receive ultrasonic waves in various directions. The experimental results demonstrated the relationship between incident wave directions and directivity of the tip echo. Besides, the tip echo method was applied to a fatigue crack in a welded steel plate, and damping of echoes due to fatigue crack closure was indicated.

DOI： 10.2208/jsceja.66.219

Cause identification of fatigue damage in steel bridge by applying Wireless Sensor Network Reviewed

Chitoshi Miki, Hiroshi Yamaguchi, Takeshi Hanji, Atsushi Tanabe

Journal of Structural Engineering, JSCE Vol. 56A page： 671-679 2010.3

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)

In order to guess the behavior of member causing fatigue damage at joint part in a railway truss bridge, experimental measurements in actual bridge was conducted by using wireless acceleration sensor devices and strain gauge. The grobal behavior of member, causing the fatigue damage when train passed through the target panel point, was verified based on the local strain data from strain gauges and acceleration data from wireless sensors. Finally, from the measurements, a countermeasure for the prospective fatigue crack was suggested.

DOI： 10.11532/structcivil.56A.671

Fatigue behavior of load carrying cruciform joints with weld defect under cyclic plastic strain Reviewed

Takeshi Hanji, Kawin Saiprasertkit, Chitoshi Miki

Proceedings of the 7th International Conference on Urban Earthquake Engineering page： 1997-2004 2010.3

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

In this study, fatigue behavior of load-carrying cruciform joints with incomplete penetrations under cyclic plastic strains, corresponding to the fatigue life is less than hundreds cycles, was experimentally investigated. In all specimens, fatigue cracks initiated from the weld root and propagated into the weld deposit. Crack initiation life was rather small compared with crack propagation life. This means that the propagation life is dominant in the fatigue life of the joints. Fracture surfaces under cyclic plastic strains contained dimples, which can produce an evidence of ductile crack propagation.

A proposal on low cycle fatigue strength curve for base joints of steel bridge pier Reviewed

Takeshi Hanji, Kazuo Tateishi

Steel Construction Engineering, JSSC Vol. 16 ( 64 ) page： 21-30 2009.12

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)

Steel bridge piers are often used for elevated highway bridges. The Hanshin-Awaji earthquake in 1995 revealed two types of failure mode in the pier, which are local buckling and low cycle fatigue. However, researches on low cycle fatigue of civil structures are limited, and design methods have not been established yet.
In this study, low cycle fatigue strength curves for base joints of the steel pier based on nominal strain, which can be calculated by finite element analysis with a beam element, were proposed. Fatigue tests with steel pier specimens demonstrated that the proposed fatigue strength curves could provide fatigue life estimation with enough accuracy.

DOI： 10.11273/jssc.16.64_21

Improvement of extremely low cycle fatigue strength of welded joints by toe finishing Reviewed

Kazuo Tateishi, Takeshi Hanji, Shuji Hanibuchi

Welding in the World, IIW Vol. 53 page： 238-245 2009.10

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

The improvement of extremely low cycle fatigue strength of welded joints by TIG dressing and burr grinding was investigated. The weld toes of T-shape welded joints were improved by TIG dressing or burr grinding and tested under displacement control conditions. The crack initiation life of finished specimens was at least threefold longer than that of as-welded specimens. There was no clear difference in improvement between TIG dressing and burr grinding. We also analysed the local strain around the cracking point by finite element analysis, and performed local strain-based fatigue assessment. The results indicated that extremely low cycle fatigue strength of the joints improved by TIG dressing and burr grinding can be assessed by evaluating the local strain and referring to the extremely low cycle fatigue strength curve.

DOI： 10.1007/BF03321135

A simulation on fatigue crack propagation in welded joints Reviewed

Takeshi Hanji, Kazuo Tateishi, Keisuke Tsuchiya

Proceedings of the 10th International Conference on Structural Safety and Reliability page： 3377-3381 2009.9

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Fatigue crack propagation simulations on T-shape welded joints were carried out. Main plate of the joint was supported at ends and tensile and bending loads were applied to an attached rib. An initial crack of 0.5 mm in length was given at weld toe on the main plate. Five kinds of stresses, i.e. nominal bending stress, membrane stress and average shear stress in the main plate, nominal bending stress and membrane stress in the attached rib, were picked up as parameters. With changing these parameters, the crack propagation simulation was performed. Simulation results demonstrated that the crack direction at the beginning was influenced by the parameters, particularly the average shear stress in the main plate. These results were supported by fatigue test results conducted under the same conditions as the simulation. Finally, the relationship of the average shear stress and the crack direction at the beginning were presented.

Fatigue strength of load carrying cruciform joints in beam to column connection of steel bridge piers Reviewed

Kawin Saiprasertkit , Chitoshi Miki, Takeshi Hanji

Proceedings of the 11th International Summer Symposium, JSCE page： 5-8 2009.9

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

The purpose of this study is to evaluate the fatigue strength of load carrying cruciform welded joints which contain incomplete penetration in both high and low cycle fatigue regions. Cyclic loading experiment was carried out in this study, and failure surfaces were investigated in order to verify the crack propagation and initiation point.

Fatigue strength of load-carrying cruciform joints with incomplete penetration in low- and high-cycle fatigue regions

Takeshi Hanji, Chitoshi Miki, Kawin Saiprasertkit

Proceedings of the 10th Japan-Korea Joint Symposium on Steel Bridges page： CD-ROM 2009.8

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

In this paper, fatigue strength of welded joints with incomplete penetrations was experimentally investigated overall from low-cycle to high-cycle fatigue regions, corresponding to the fatigue life is from tens cycles to millions cycles. Fatigue tests on load-carrying cruciform joints containing root discontinuities were carried out. In all specimens, fatigue cracks initiated from the weld root and propagated into the weld metal. Fracture surfaces of the specimen were observed in order to verify the crack initiation point and propagation behavior.

Study on structural behavior causing fatigue damage in steel bridge by applying wireless sensor network

Hiroshi Yamaguchi, Chitoshi Miki, Atsushi Tanabe, Takeshi Hanji

Proceedings of the 10th Japan-Korea Joint Symposium on Steel Bridges page： CD-ROM 2009.8

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

The purpose of this research is to guess the behavior of member causing fatigue damage at joint part in Railway Truss Bridge using wireless acceleration sensor devices and local strain measurement, and to suggest the countermeasure for the prospective fatigue crack. In this paper, the experimental measurement in actual bridge was conducted, then the behavior of member causing the fatigue damage when train passed through the target panel point was verified by the local strain data from strain gauge and acceleration data from wireless sensor. Finally, from the measurement results, the countermeasure is suggested.

Extremely low cycle fatigue strength of finished welded joint

Kazuo Tateishi, Takeshi Hanji, Shuji Hanibuchi

Proceedings of the 10th Japan-Korea Joint Symposium on Steel Bridges page： CD-ROM 2009.8

Fatigue crack propagation path in T-shape welded joints subjected to plate bending

Kazuo Tateishi, Keisuke Tsuchiya, Takeshi Hanji

Proceedings of the 10th Japan-Korea Joint Symposium on Steel Bridges page： CD-ROM 2009.8

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

In this paper, fatigue crack propagation analysis on T-shape welded joints under out-of-plane plate bending was carried out. Main plate of the joint was supported at the ends, and tensile and bending loads were applied to an attached rib. We picked up five kinds of stresses as parameters, i.e. nominal bending stress, membrane stress and average shear stress in the main plate and nominal bending stress and membrane stress in the attached rib. We performed the analysis with changing these parameters and investigated the crack propagation path. The analysis results indicated that the crack angle at the beginning was influenced by these parameters, particularly the average shear stress in the main plate. These results were verified by fatigue tests conducted in the same conditions as the analysis. Finally, we presented the correlation between the average shear stress in the main plate and the crack angle at the beginning.

Radiation characteristics of ultrasonic tip echo from fatigue cracks Reviewed

Chitoshi Miki, Ryohei Onishi, Takumi Kubota, Takeshi Hanji

The 62nd Annual Assembly of International Institute of Welding page： XIII-2285-09 2009.7

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Tip echo is scattered wave which radiates all direction from the sharp tip of reflection source such as fatigue cracks. Tip echo has been utilized for sizing defects as tip echo method and also may apply to identify fatigue cracks from other defects. The radiation characteristics of tip echo were examined experimentally and the relationship between incident wave directions and directivity of echo and dumping of echo due to fatigue crack closure were shown. The steering and focusing functions of linear phased array ultrasonic testing system was applied to send waves to the tip of crack with various angles and to receive echo waves from various directions. Then, the tip echo method was applied to a crack to grasp crack tip opening and closing behaviour in the residual stress field.

A case study of performance based design on low cycle fatigue improvement

Kazuo Tateishi, Takeshi Hanji, Shuji Hanibuchi

Proceedings of the 5th International Symposium on Steel Structures page： 201-205 2009.3

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

In this study, we analyzed the local strain around the cracking point of the finished joint and the as-welded joint by FEA, and demonstrated that the local strain could be affected by the toe geometry parameters, such as radius, depth of the groove, and the main plate thickness. Then, we presented an example way to determine the desirable shape of the finished zone for satisfying the fatigue performance requirement of the welded joint.

A simulation of fatigue crack propagation in steel girder bridges Reviewed

Kazuo Tateishi, Akira Tanikaga, Takeshi Hanji

Journal of Constructional Steel Vol. 16 page： 453-458 2008.11

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)

In this study, fatigue crack propagation simulations in steel girder bridges were conducted by ZENCRACK, which is a commercial software for three dimensional crack propagation analysis based on fracture mechanics. A steel bridge with three I-girders was employed and modeled in detail. It was confirmed that the crack propagation simulation can be a beneficial method to investigate the changes on structural behavior of the bridge due to crack propagation and identify the serious cracks for the bridge.

Extremely low cycle fatigue assessment method for un-stiffened steel pier with box section

Kazuo Tateishi, Tao Chen, Takeshi Hanji

Proceedings of the 11th East Asia-Pacific Conference on Structural Engineering and Construction page： CD-ROM 2008.11

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

In the Great Hanshin Awaji Earthquake (1995), steel bridge piers were damaged by extremely low cycle fatigue, which has raised concerns about the seismic performance of the piers. However, researches on extremely low cycle fatigue strength of structural steel members have been limited and no design guidelines have been established for bridge structures. The authors have already conducted a series of researches on extremely low cycle fatigue strength of structural steel members and proposed a simple assessment method for extremely low cycle fatigue strength of the steel bridge piers. In this study, steel pier specimens were fabricated and tested under large cyclic deformation, and the proposed assessment method was verified by the test results.

Improvement of extremely low cycle fatigue strength of welded joints

Shuji Hanibuchi, Kazuo Tateishi, Takeshi Hanji

Proceedings of the 11th East Asia-Pacific Conference on Structural Engineering and Construction page： CD-ROM 2008.11

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

In this study, the improvement of extremely low cycle fatigue strength by toe finishing was investigated. T-shape welded joints, which are in as-welded, TIG dressed or burr ground condition, were tested under displacement control conditions. The test results indicated that crack initiation lives of finished specimens were much longer than those of as-welded specimens. Between TIG dressing and burr grinding, no clear difference on improvement was observed. We also performed elasto-plastic finite element analyses to calculate local strain around the cracking point, and assessed the fatigue strength of the finished specimen based on the local strain. The results demonstrated that the fatigue strength of TIG dressed and burr ground joints can be reasonably assessed using the local strain at the cracking point and the extremely low cycle fatigue strength curves.

A study on fatigue crack propagation path in T shape welded joint

Keisuke Tsuchiya, Kazuo Tateishi, Takeshi Hanji

Proceedings of the 11th East Asia-Pacific Conference on Structural Engineering and Construction page： CD-ROM 2008.11

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

In this study, fatigue crack propagation analyses on T-shape welded joints subjected to plate bending were carried out. We picked up five kinds of stresses as parameters, i.e. nominal bending stress, membrane stress and average shear stress in the main plate, nominal bending stress and membrane stress in the attached rib. We analyzed the crack propagation path with changing these parameters. Analysis results indicated that the crack angle at the beginning was influenced by these parameters, especially the average shear stress in the main plate. These results were supported by fatigue test results conducted on T-shape welded joints with the same conditions used in the analysis. Finally, we presented the relationship of the average shear stress and the crack angle at the beginning.

Improvement of extremely low cycle fatigue strength of welded joints by toe finishing Reviewed

Kazuo Tateishi, Shuji Hanibuchi, Takeshi Hanji

The 61st Annual Assembly of International Institute of Welding page： XIII-2232-08 2008.7

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

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Papers - HANJI Takeshi