Faculty Profiles - HANJI Takeshi

Papers - HANJI Takeshi

Division display 101 - 120 of about 245 ／ All the affair displays >>

Fatigue strength of cruciform joints and longitudinal joints with laser-arc hybrid welding Reviewed

Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu, Daisuke Uchida, Koichi Asano, Ryosuke Kimura

Welding in the World Vol. 63 ( 5 ) page： 1379-1390 2019.9

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

This study examined the fatigue strength of cruciform joints and longitudinal joints fabricated with laser-arc hybrid welding. Load-carrying and non-load-carrying cruciform welded joints with plate thicknesses of 8, 16, and 25 mm were tested under tensile cyclic loads and out-of-plane bending cyclic loads. In longitudinal joints, four-point bending fatigue tests were performed on plate girders with flanges and a web connected by laser-arc hybrid welding. When assembling the plate girder, tack welds were installed at the flange-to-web connection to clarify their effect on the fatigue strength of the longitudinal joints. Measurements of weld toe profiles and residual stress were also conducted. The residual stress was measured using X-ray diffraction. The test results revealed that the fatigue strengths of hybrid welded joints are equivalent to those of arc welded joints and satisfy the fatigue design curves specified by the Japanese Society of Steel Construction. In addition, the effect of plate thickness on the fatigue strength was observed in hybrid welded joints as well as in arc welded joints.

DOI： 10.1007/s40194-019-00745-w

Slip coefficient and ultimate strength of high-strength bolted friction joints with compact bolt spacing and edge distance Reviewed

Shogo Kiyokawa, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

International Journal of Steel Structures Vol. 19 ( 4 ) page： 1191-1201 2019.8

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

In current design codes, the minimum bolt spacing and edge distance for high-strength bolted friction joints are specified based on the bolt diameter, regardless of the plate thickness or steel strength. However, the mechanical performance of joints with a more compact bolt spacing than that given in the current design specifications has been little examined. In this study, the slip and ultimate strength of high-strength bolted joints with a compact bolt spacing and edge distance were investigated. Tensile tests were conducted on friction-type joints with various bolt arrangements. The use of a compact bolt arrangement was not observed to have a negative influence on the slip strength in these tests. The estimated strengths corresponding to the experimentally observed failure modes were found to agree fairly well with the experimental results within a 10% error. A parametric finite element analysis was also conducted to investigate the influence of the bolt arrangement on the slip coefficient. It was concluded that the bolt spacing and edge distance have little influence on the slip coefficient.

DOI： 10.1007/s13296-018-0199-3

Fatigue strength of laser-arc hybrid welded joints with tack welds Reviewed

Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu, Daisuke Uchida, Ryosuke Kimura, Koichi Asano

Quarterly Journal of the Japan Welding Society Vol. 37 ( 3 ) page： 99-107 2019.7

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

This study examined the fatigue strength of cruciform joints and longitudinal joints fabricated with laser-arc hybrid welding, in which tack welds were installed at the connection. The cruciform joints were tested under tensile cyclic loads and out-of-plane bending cyclic loads. In the longitudinal joints, four-point bending fatigue tests were performed on plate girders fabricated with the hybrid welding. In addition, finite element analysis was performed on the cruciform joint to investigate the effect of tack welds on stress concentration at weld toes. The test results revealed that the fatigue strengths of the hybrid welded joints are equivalent to those of arc welded joints with or without tack welds and satisfy the fatigue design curves specified in JSSC recommendation. Moreover, the analysis results indicated that tack welds have little influence on stress concentration at weld toes in cruciform joints fabricated with laser-arc hybrid welding.

DOI： 10.2207/qjjws.37.99

Fatigue strength of transverse attachment joints with single-sided weld using low transformation temperature welding consumable Reviewed

Takeshi Hanji, Kazuo Tateishi, Suguru Kano, Masaru Shimizu, Tadahisa Tsuyama, Toshio Takebuchi

The 72nd Annual Assembly of International Institute of Welding page： XIII-2809-19 2019.7

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

This study investigated the applicability of low transformation temperature (LTT) consumables to improve fatigue strength against weld root failure. Transverse attachment joints formed by single-sided welding, similar to rib-to-deck connections in orthotropic steel bridge decks, were fabricated using an LTT welding consumable and conventional welding consumable. Fatigue tests were performed with out-of-plane bending loads using a vibration-type fatigue testing machine. The test results indicated that higher fatigue strength can be achieved in the joint with an LTT consumable compared with a conventional one. In addition, residual stresses around the weld bead were clarified by X-ray diffraction measurements and finite element analyses. The results revealed that the LTT consumable can reduce residual stress around the weld and also introduce compressive residual stress to the weld root, which can contribute to improved fatigue strength.

Crack sizing accuracy of a phased array ultrasonic scanner developed for inspection of rib-to-deck welded joints in orthotropic steel decks Reviewed

Masafumi Hattori, Tohru Makita, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu, Naoto Yagi

Journal of Structural Mechanics and Earthquake Engineering, JSCE Vol. 74 ( 3 ) page： 516-530 2018.12

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

Over the last decade, fatigue cracks have been observed at welded joints between trapezoidal ribs and deck plates in many orthotropic steel deck bridges in Japan. Considering a fatigue crack at rib-to-deck welded joints can cause pavement damage and thus compromise transportation safety, it is necessary to detect and repair it at the early stage of its development.
This paper presents the accuracy of crack sizing with an electrically driven phased array ultrasonic scanner (PAUT scanner) developed for inspection of rib-to-deck welded joints in orthotropic steel decks. The PAUT scanner simultaneously examines a deck plate and a weld bead into either of which cracks propagate from a weld root. Moreover, it can detect the cracks as remained in the steel members.
In this research, firstly an internal crack is induced at rib-to-deck welded joints by using a plate bending fatigue testing machine where crack sizes are controlled by monitoring stresses at regions closed to weld beads. Subsequently, the joints are inspected with the PAUT scanner. Appropriate sizing methods are de-termined for the crack going through a deck plate and a weld bead, respectively, and the accuracy of crack sizing is evaluated by comparing with real cracks on the joints. In addition, the influence of paint coatings on the accuracy in crack sizing is examined. As a result of these investigation, it is demonstrated that the PAUT scanner has enough crack sizing performance.

DOI： 10.2208/jscejseee.74.516

Fatigue strength of laser treated weld joints Reviewed

Cut Atika Putri, Kazuo Tateishi, Takeshi Hanji

Steel Construction Engineering, JSSC Vol. 25 ( 100 ) page： 73-76 2018.12

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

Service lives of steel bridges are limited by corrosion. Coating is commonly applied to steel structures in order to prevent corrosion. In recent years, a laser cleaning treatment is introduced as a new technique for surface preparation of steel structures. However, the influence of laser cleaning on fatigue life of welded joint is unknown. In this study, fatigue tests were conducted on as-welded and laser-treated out-of-plane gusset joints. The test results showed that the laser cleaning treatment only had little influence on fatigue strength of out-of-plane gusset welded joints.

DOI： 10.11273/jssc.25.100_73

Fatigue life prediction of corroded reinforcing steel bars Reviewed

Takeshi Hanji, Niamatullah Ahmadzai, Kazuo Tateishi, Masaru Shimizu

Journal of Constructional Steel Vol. 26 page： 804-810 2018.11

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

This study investigated the fatigue strength of corroded reinforcing steel bars. Several types of rebars consisting of different yield stress and rib shapes were used. The rebar was galvanically corroded to three levels, which are considered as a percentage of mass reduction of 5, 10 and 15% respectively. Fatigue test results revealed that the fatigue life of the corroded rebar decreases as the corrosion level increases. Then, the fatigue life of the corroded rebar was predicted by crack propagation calculations based on fracture mechanics. There are relatively good agreements between the prediction and the test results.

Slip strength of doubler plates with high-strength bolts for fatigue cracks Reviewed

Shogo Kiyokawa, Takeshi Hanji, Masaru Shimizu, Kazuo Tateishi

Journal of Constructional Steel Vol. 26 page： 277-283 2018.11

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

As for retrofitting cracked bridge members, it is often used to attach doubler plates by highstrength bolts after drilling holes at crack tips. In many cases, the doubler plate is designed as frictional connections, but the slip action at the doubler plate and its slip strength have not been well known yet. In this study, tensile tests and FE analyses were conducted as a fundamental study to investigate the slip strength at the doubler plate. The result revealed that the load-sharing ratio between a main plate and doubler plates have linear correlation with the ratio of cross sectional areas of both plates. Therefore, the slip strength at the doubler plates can be designed by using the load-sharing ratio estimated by structural dimensions of the main plate and doubler plates.

Fatigue strength of cruciform joints with laser-arc hybrid welding Reviewed

Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu, Daisuke Uchida, Ryosuke Kimura, Koichi Asano

Quarterly Journal of the Japan Welding Society Vol. 36 ( 4 ) page： 219-229 2018.10

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

This study examined fatigue strength of cruciform joints fabricated with laser-arc hybrid welding. Load-carrying and non-load-carrying cruciform welded joints with a plate thickness from 8mm to 25mm were tested under tensile cyclic loads and out-of-plane bending cyclic loads. Measurements of weld toe profile, residual stress and hardness around a welded portion were also conducted. The test results revealed that the fatigue strength of the hybrid welded joints is equivalent to that of arc welded joints and satisfies the fatigue design curves for arc welded joints in JSSC recommendation. Besides, the thickness effect on fatigue strength was observed in the hybrid welded joints as well as in arc welded joints.

DOI： 10.2207/qjjws.36.219

Fatigue cracks in I-beam end in railway steel bridges and its life extension by stop-hole repair Reviewed

Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu, Masaki Iwai, Ken Ikegashira, Yuichiro Niwa

Journal of Structural Mechanics and Earthquake Engineering, JSCE Vol. 74 ( 2 ) page： 290-305 2018.8

Effect of weld penetration on low cycle fatigue strength of load-carrying cruciform joints Reviewed

Takeshi Hanji, Kazuo Tateishi, Yuko Ohashi, Masaru Shimizu

The 71st Annual Assembly of International Institute of Welding page： XIII-2749-18 2018.7

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

This study examined the low cycle fatigue behavior of load-carrying cruciform welded joints containing incomplete penetration. Five types of specimens with different sizes of weld penetrations and weld leg lengths were tested under cyclic plastic strains. During testing, cracking behavior was observed on the side surface of the specimen. The test results revealed that the fatigue strength and cracking patterns depend on the ratio of the weld penetration to the main plate thickness and the ratio of the weld leg length to the main plate thickness, respectively. Elasto-plastic finite element analyses including the effective notch concept were then performed. The results indicate that the fatigue strength and cracking pattern of the specimens can be correlated with the local strain distribution around the effective notch.

A prediction method of local strain range at weld toe of various joints Reviewed

Masaru Shimizu, Kazuo Tateishi, Takeshi Hanji, Naoya Honda

Steel Construction Engineering, JSSC Vol. 25 ( 97 ) page： 61-66 2018.3

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

Welded joints in steel structures are subjected to high strain amplitude during earthquake, which could cause a low cycle fatigue crack. To assess low cycle fatigue strength of welded joints, an estimation method based on local strain range at a crack initiation point has been established. In this method, an FE model with extremely-fine mesh is needed to obtain the local strain range accurately. In this paper, a prediction method of the local strain range from a model with relatively coarse mesh was proposed. Strain ranges obtained from coarse-mesh models were related to the local strain ranges from fine-mesh models. A prediction formula of the local strain range which is applicable to T-shaped joints, cruciform joints and out-of-plane gusset joints was established.

DOI： 10.11273/jssc.25.97_61

Estimation method of strain at drilled hole repaired by adding splice plates Reviewed

Shogo Kiyokawa, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu, Yuya Nakayama

Journal of Structural Engineering, JSCE Vol. 64A page： 445-454 2018.3

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

Adding splice plates is a commonly used technique to repair fatigue cracks. The crack tip is drilled out before the splice plates are add. In some cases, however, a new fatigue crack initiates from the drilled hole. Because the drilled hole is entirely covered by the splice plates, it is impossible to measure its strain that can be used to assess the crack generation from the drilled hole. The purpose of this study is to propose a method to estimate the strain of the drilled hole by using a reference strain on the splice plate. By conducting parametric FE analyses and loading tests, the location for the reference strain which is strongly correlated with the strain in the drilled hole was proposed.

DOI： 10.11532/structcivil.64A.445

Reduction of stress concentration at drilled hole due to adding splice plates Reviewed

Shogo Kiyokawa, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu, Yuya Nakayama

Journal of Structural Engineering, JSCE Vol. 64A page： 435-444 2018.3

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

A typical repair method for fatigue cracks in steel bridge members is the splice plate method. The crack tip is drilled out, and splice plates are added over the crack. For evaluating the remaining fatigue life of the repaired members, it is needed to know the stress of the drilled hole after adding splice plates. In this study, the effect of the splice plates geometric parameters on the stress reduction of a drilled hole was investigated by tensile tests and parametric FE analyses. As a result, a new method to estimate the stress of the drilled hole was proposed, considering stress carrying mechanism of the splice plate. This method could estimate the stress within 10% error.

DOI： 10.11532/structcivil.64A.435

Low-cycle fatigue evaluation for welded joint of shear panel damper in multiple steel columns Reviewed

Masaru Shimizu, Kazuo Tateishi, Takeshi Hanji, Hiroki Sugiyama, Yasumasa Soga, Riku Adachi, Hiroshi Noda

Steel Construction Engineering, JSSC Vol. 24 ( 96 ) page： 17-29 2017.12

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

Multiple Steel Columns is an earthquake-resistance bridge pier which has shear panel dampers between four steel columns. In the previous study, although the shear panel damper absorbs the seismic energy, low-cycle fatigue crack has been observed around welding of shear panel. In this study, evaluation method of low-cycle fatigue based on local strain range at crack initiation point was applied to crack in shear panel. To simplify calculation of local strain range, relationship between mean shear strain range of shear panel and local strain range at crack initiation point was developed. For quasi-static and dynamic loading condition, crack initiation life was evaluated by simplified estimation method.

DOI： 10.11273/jssc.24.96_17

Repair effect for cracked I-beam end in railway steel bridges Reviewed

Ken Ikegashira, Yuichiro Niwa, Kentaro Matsumoto, Takeshi Hanji, Kazuo Tateishi

Journal of Constructional Steel Vol. 25 page： 661-666 2017.11

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

Fatigue cracks have been reported in I-beam ends of railway steel bridges, which occur at a lower end of an I-beam web. Its growth may lead to failure of the I-beam, but effective repair methods for the crack have not been established yet. This research investigated countermeasures against the crack at the I-beam end. From the result of the stress measurement, the differential settlement causes out-of-plane bending deformation of the I-beam web, which leads to a fatigue crack at the lower end of the web. The effect of several countermeasures was confirmed by analytical examinations and field trial experiments.

Slip coefficient and fracture strength of high strength bolted friction joints with compact bolt spacing and edge distance Reviewed

Shogo Kiyokawa, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

Proceedings of the ISSS 2017 page： 223-226 2017.11

Authorship：Lead author Language：English

As for bolt spacing and edge distance of high strength bolted joints, minimum values are specified as a function of bolt diameter D, regardless of plate thickness and steel strength. That is, the minimum value is not clearly defined by mechanical performance of the joint. Moreover, there is little knowledge on the performance of the joint with the bolt spacing more compact than given in the current design specifications. This study investigates slip and fracture strength of high strength bolted joints with compact bolt spacing and edge distance. Tensile coupon tests on frictional joints with various bolt arrangement were conducted. It was not clearly observed the negative influence of compact bolt arrangement on the slip strength. The fracture strengths estimated from the cross
sectional area where the fracture occurred and steel strength of the plate agreed with the experimental results within 10% error in all fracture modes. Parametric analyses were also conducted to investigate the influence of the bolt arrangement to the slip coefficient. It was concluded that the bolt spacing and edge distance have small influence on the slip
coefficient.

Fatigue life prediction of corroded reinforcing steel bars Reviewed

Takeshi Hanji, Niamatullah Ahmadzai, Kazuo Tateishi, Masaru Shimizu

Proceedings of the ISSS 2017 page： 478-481 2017.11

Authorship：Lead author Language：English

In this study, fatigue lives of corroded reinforcing steel bars were investigated. Several kinds of rebars consisting of different yield stress and rib shapes were used. The rebar was galvanically corroded to three levels, which are considered as a percentage of mass reduction of 5%, 10% and 15% respectively. Fatigue tests were carried out under constant stress amplitude. The test results revealed that the fatigue life of the corroded rebar decreases as the corrosion level increases. Then, 3D elasto-plastic finite element analyses were conducted with models reflecting surface profiles of the corroded rebar. The analysis results indicated that a cross section where the maximum local strain occurs corresponds to a cracking site observed in the test. Finally, the fatigue life of the corroded rebar was predicted by crack propagation calculations based on linear fracture mechanics. There are relatively good agreements between the prediction and the test results.

A simple low cycle fatigue assessment method for steel members and its application to bridge piers under earthquake Reviewed

Tomohiro Furusaki, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu, Naoya Honda

Proceedings of the ISSS 2017 page： 269-272 2017.11

Authorship：Lead author Language：English

This study newly proposed a low cycle fatigue assessment method for steel members which can predict their low cycle fatigue life from nominal strain history calculated with a beam analysis. After establishing a fatigue strength curve for base joints in steel bridge piers, seismic response analyses with beam elements were conducted to assess their low cycle fatigue performance against earthquakes. The analysis results revealed that some of the piers, even though they satisfy with the current seismic design code, have possibility to fail due to low cycle fatigue under earthquake.

Evaluation of repair effect for cracked I-beam end in railway steel bridges Reviewed

Haruya Shirai, Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu, Masaki Iwai, Ken Ikegashira, Yuichiro Niwa

Proceedings of the ISSS 2017 page： 404-407 2017.11

Authorship：Lead author Language：English

Fatigue cracks have been reported in I-beam ends of railway steel bridges, which occur at a lower end of an I-beam web. As a temporary measure, the crack is typically repaired with drilling holes at its tips, called a stop-hole method. In the cracked I-beam ends, however, the effect of life extension due to a stop-hole has not been clearly evaluated yet. In this study, fatigue tests of I-beams repaired with a stop-hole were conducted. And also, in order to make sure local stress distribution around the stop-hole in the test, a finite element analysis was performed. As a result, it was proven that the fatigue life of the repaired I-beam can be predicted from the local stress range at the stop-hole edge. Furthermore, several case studies on life extension of an I-beam due to the stop-hole method were performed.

　 PREV - NEXT 　

<HANJI Takeshi>

Papers - HANJI Takeshi