Faculty Profiles - HANJI Takeshi

Papers - HANJI Takeshi

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Fatigue evaluation of cut-out at the edge of corner plate and improvement effect by peening Reviewed

Masaru Shimizu, Kazuo Tateishi, Takeshi Hanji, Shinta Ayuningtyas, Misa Fujibayashi

Proceedings of the ISSS 2021 page： 136-139 2021.11

Language：English

Corner plates are often welded to cover web-to-flange joints in box girders which can hold appropriate angle between webs and flanges during construction, and enhance the buckling resistance of the web plate. The corner plates are installed by single-sided welding because circumference of corner plates can only be approached from one side. Since weld root remains in the welded joints of corner plates, many fatigue cracks found out in the weld joints of corner plates. Although the end of corner plates was cut-out and ground smoothly as a countermeasure, fatigue cracks have again occurred from weld root exposed on the cut-out surface. In this study, the fatigue durability of cut-out at corner plate ends was investigated. Fatigue tests on small-scaled specimens were performed. Two types of specimens with different angles at the corner plate ends were tested. As the results, low fatigue durability can be seen regardless of the angle at the corner plate end. In addition, fatigue strength improvement due to peening application at the weld root was investigated. Peening application increased the fatigue strength grade and fatigue limit of the joint.

Low cycle fatigue crack growth rate testing with compliance method and its application to different structural steels Reviewed

Chao Jiang, Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu

Proceedings of the ISSS 2021 page： 128-131 2021.11

Authorship：Corresponding author Language：English

In this study, low cycle fatigue crack growth tests with several structural steels were performed, in which compliance method was newly introduced to determine crack size that is a technique usually used in high cycle fatigue region. The test results indicated that the crack size from the compliance method relatively agrees with that from image measurements, and the proposed relationship between the compliance and the crack size was verified. Moreover, it was revealed that the crack growth rate can correlated with the cyclic J-integral range calculated by finite element analysis regardless of the steel types.

Effect of UHPFRC overlay on fatigue cracks propagating from U-rib welds of orthotropic steel decks Reviewed

Masafumi Hattori, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

Proceedings of the ISSS 2021 page： 24-27 2021.11

Language：English

Over the last decade, fatigue cracks have been observed at welded joints between U-ribs and deck plates in many orthotropic steel deck bridges in Japan. Among the cracks, this paper focuses on fatigue cracks that initiate from a weld root of rib-to-deck welded joints and propagate to a deck plate. This study examines the effect of countermeasure with overlaying Ultra-High Performance Fiber Reinforced cement-based Composites (UHPFRC) on steel decks with cracks from U-rib welds, and confirms the fatigue durability of this countermeasure method. Specifically, the suppressing effect on crack propagation and the fatigue durability of UHPFRC itself and the interface between UHPFRC and the deck plate were confirmed by a wheel running test and finite element analysis. As a result, it was clarified that this countermeasure has a positive effect to retard further crack propagation compared with a countermeasure with overlaying steel fiber reinforced concrete which is generally adopted. In addition, it was revealed that this countermeasure has enough fatigue durability.

Fatigue improvement for weld joint between deck plate and vertical stiffener by slit-shaped notch Reviewed

Daisuke Kaneko, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu, Hiroki Suetsugu

Proceedings of the ISSS 2021 page： 79-82 2021.11

Language：English

Since orthotropic steel deck is lighter than concrete slab, it has been used for long span bridge and bridge in urban areas. Wheel loads induces the local stress reputation at weld joints between deck plate and vertical stiffener, and large number of fatigue cracks have been generated in their weld joints. In order to reduce the stress concentration, construction of semicircular notch at the top of the vertical stiffener has been suggested. In this study, construction of slit-shaped notch is suggested as enhancement of the stress reduction and retaining crack propagation.
The stress reduction at the weld joint by slit-shaped notch was investigated from finite element (FE) analysis. In addition, the crack with various size was introduced to the weld joint, and reduction in stress intensity factor (SIF) by slit-shaped notch was examined. To confirm the fatigue propagation life extension due to slit-shaped notch, fatigue tests were performed for small-scaled specimens. Fatigue life extension can be seen in most specimen while another crack was developed from the notch in a specimen.

Mechanical behavior and limit states of combination joints using rivets and high-strength bolts Reviewed

Shunya Sumi, Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu, Yasushi Nagasaka, Toshio Takebuchi

Proceedings of the ISSS 2021 page： 20-23 2021.11

Authorship：Corresponding author Language：English

In riveted bridges, generally, rivets deteriorated with loosening and corrosion are replaced with high-strength friction-type bolts. In this case, both riveted and bolted connections which have different load transfer mechanism coexist in the same joint, however, the mechanical behavior and limit states of the rivet-and-bolt combination joints have not been well investigated yet. In this study, in order to clarify the mechanical behavior and limit states of the combination joints using rivets and bolts, static tensile tests were performed on specimens with different arrangement of rivets and bolts. Moreover, finite element analysis was performed to investigate load transfer mechanism in the combination joints. Based on the experiment and analysis, the evaluation method for the strength of the combination joints was indicated.

Weld crack and opening and closing behavior of root gap during welding under cyclic loading Reviewed

Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu

Journal of Structural Mechanics and Earthquake Engineering, JSCE Vol. 77 ( 2 ) page： 287-303 2021.8

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

This study investigated opening and closing behavior of root gap and weld crack occurrence in slit-welding under cyclic loading through welding tests and thermal elasto-plastic finite element analysis. Sectional observations after the welding test revealed that the crack occurrence highly depends on the magnitude of root gap opening displacement and loading frequency in welding process, and also restraint intensity of slits. Then, through the simulation of welding under cyclic loading, it was clarified that root gap opening behavior during welding changes due to the restraint intensity of the slit, which correlates the tendency of the crack occurrence under different restraint conditions. Based on the test and analysis results, a conditional expression for the weld crack occurrence consist of the initial root gap opening displacement, loading frequency and restraint intensity of slits was obtained, and its validity was verified by the experiments.

DOI： 10.2208/jscejseee.77.2_287

Fatigue evaluation for root cracks in U-rib to deck welded joints of orthotropic steel decks Reviewed

Masafumi Hattori, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

Journal of Structural Mechanics and Earthquake Engineering, JSCE Vol. 77 ( 2 ) page： 255-270 2021.7

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

This paper examines a fatigue evaluation method for the cracks in the weld joints between a U-rib and a deck plate in orthotropic steel bridge decks. The crack initiates from the weld root and propagates into the deck plate or the weld bead. Fatigue tests and FE analyses were conducted in order to examine the local stresses available for fatigue assessment, and to propose a method to estimate them from some reference stresses around the weld joint. In addition, based on fatigue crack propagation analyses, a method to predict the crack propagation path was proposed.

DOI： 10.2208/jscejseee.77.2_255

Prediction of residual stress induced by high-frequency mechanical impact treatment Reviewed

Takeshi Hanji, Kazuo Tateishi, Suguru Kano, Masaru Shimizu

The 74th Annual Assembly of International Institute of Welding page： XIII-2904-2021 2021.7

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

In this study, a method for predicting residual stress introduced by high-frequency mechanical impact (HFMI) was investigated using energetics. Steel plates of different grades were treated by a high-frequency impact treatment device under different treatment conditions (such as intensity of impact, number of passes, and treatment length). In addition, the motion of the HFMI indenter was recorded using a high-speed camera during the treatment, and a simple calculation method for the energy applied to steel plates was proposed. The results confirmed that the compressive residual stress introduced to the steel plates correlated closely with the calculated energy. In addition, experiments demonstrated that the energy-based residual stress prediction is applicable to a longitudinal attachment welded joint with sufficient accuracy.

Fatigue strength and residual stress of longitudinal attachment joints improved by HFMI treatment under static load Reviewed

Takeshi Hanji, Kazuo Tateishi, Suguru Kano, Masaru Shimizu

The 74th Annual Assembly of International Institute of Welding page： XIII-2903-2021 2021.7

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

In this study, the effect of the stress state of a welded joint during application of high-frequency mechanical impact (HFMI) treatment on the resulting fatigue strength was investigated through fatigue tests and finite element analysis. A high-frequency impact treatment tool was used as the HFMI device. Longitudinal attachment welded joints were treated under a state in which a static load was applied and subsequently tested under a constant stress amplitude with stress ratios of 0 or 0.5. The test results indicate that improved fatigue strength can be achieved even under a high stress ratio when the joint is treated under the minimum stress of fatigue loading. In addition, residual stress measurements and finite element analysis simulating welding and treatment processes indicated that the magnitude of compressive residual stress introduced to a weld toe is almost the same regardless of the stress state in the joint during treatment.

Local stress based fatigue assessment of welded joints in steel-concrete composite slab using angle-shape shear connectors Reviewed

Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu, Koichi Asano, Takaaki Ishii, Kiyoshi Kobayashi, Daisuke Uchida

Proceedings of the 10th International Conference on Bridge Maintenance, Safety and Management (IABMAS 2020) page： 2673-2681 2021.4

Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings)

This study investigated the fatigue strength of welded joints in steel-concrete composite slabs by fatigue testing. In addition, the local stress around the welded joint was evaluated through finite element analysis. In the test, fatigue cracks occurred at the toes of boxing welds of angle-shape shear connectors as a result of stress concentration due to the local out-of-plane bending deformation of the steel plates around the boxing weld. This local deformation can be produced by the steel and concrete behaving independent of one another locally near welds when the bond at their interface is lost. The test results demonstrated that the fatigue assessment of welded joints in a composite slab can be performed using the hot-spot stress approach. Then, actual composite slabs with different structural characteristics were analyzed to investigate the local stress behavior around welded joints, and their fatigue performance was assessed based on the hot-spot stress approach.

DOI： 10.1201/9780429279119-365

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

Shogo Kiyokawa, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

Proceedings of the 10th International Conference on Bridge Maintenance, Safety and Management (IABMAS 2020) page： 3531-3539 2021.4

Language：English Publishing type：Research paper (international conference proceedings)

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, the stress at a drilled crack-arrest hole after the addition of the splice plates with high-strength bolts is required. In this study, the effect of the geometric parameters of the splice plate on stress reduction at a drilled crack-arrest hole is investigated using static loading tests and parametric finite element analyses. Based on the results, a method for predicting the stress at the drilled hole that considers the load-carrying mechanism through the bolted splice plate is proposed. It is demonstrated that the proposed method can predict stress with an error of within 10%.

DOI： 10.1201/9780429279119-478

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

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

Proceedings of the 10th International Conference on Bridge Maintenance, Safety and Management (IABMAS 2020) page： 3946-3954 2021.4

Language：English Publishing type：Research paper (international conference proceedings)

Fatigue cracks have been observed at welded joints between U-ribs and deck plates in many orthotropic steel decks. Considering a fatigue crack at rib-to-deck welded joints can compromise transportation safety, it is necessary to detect and repair the crack at the early development stage.
This paper presents the accuracy of crack sizing with a Phased Array Ultrasonic Testing (PAUT) scanner developed for inspection. Firstly, an internal crack propagating from a weld root was induced at rib-to-deck welded joints by using a plate bending fatigue testing machine. Subsequently, the joints were inspected with the PAUT scanner. Appropriate sizing methods were determined for the deck and weld bead propagation type cracks, respectively, and the accuracy of crack sizing was evaluated. In addition, the influence of coating on the accuracy in crack sizing was examined. As a result, it is demonstrated that the PAUT scanner had enough crack sizing performance.

DOI： 10.1201/9780429279119-540

Fatigue behavior of bearing type bolted joint with pultruded CFRP composites Reviewed

Masaru Shimizu, Kazuo Tateishi, Takeshi Hanji, Yasuo Kitane

Proceedings of the 10th International Conference on Bridge Maintenance, Safety and Management (IABMAS 2020) page： 3657-3663 2021.4

Language：English Publishing type：Research paper (international conference proceedings)

Carbon Fiber Reinforced Polymer (CFRP) composites, consisting of carbon fiber and matrix resin, has high stiffness and tensile strength. Recently, pultrusion method is developed for manufacturing CFRP composites. The bearing type bolted joint is typically adopted for permanent joint of CFRP composites. Due to bearing pressure around bolt hole, fatigue damage can be introduced around bolt hole in a bearing type bolted joint. In this study, fatigue performance of bearing type bolted joint with the pultruded CFRP composite was examined. To observe fatigue crack generation and propagation around bolt hole, tensile fatigue test on pultruded CFRP composites with a circular hole was performed. While fatigue crack was generated from the edge of the hole and propagates in longitudinal direction, the CFRP composites was not ruptured during the test. The fatigue test on a bearing type bolted joint for pultruded CFRP composites was also performed, and its fatigue strength was clarified. Finite element analysis (FEA) simulating multiple layer was constructed. The stress distribution around bolt hole was examined from FEA. The fatigue strength was arranged by maximum principal stress range.

DOI： 10.1201/9780429279119-496

Investigation on low cycle fatigue crack propagation in steel under fully random variable amplitude loading Reviewed

Arief Panjaitan, Kazuo Tateishi, Masaru Shimizu, Takeshi Hanji

Journal of Structural Engineering, JSCE Vol. 67A page： 174-182 2021.4

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

Low cycle fatigue is a failure mode which is possibly caused by random large strains such as seismic motion. To examine the effects, this study elaborated crack propagation behavior in steel under random amplitude loading. Firstly, study on crack growth rate under constant amplitude conditions was conducted to obtain basic characteristics. Next, several patterns of random amplitude loading were applied. It is discovered that crack growth accelerated when amplitude decreased from high to low levels at tensile portions, compared to that in constant amplitude conditions. Prediction model was constructed with establishing relationship between cyclic J-integral range and crack growth rate and confirmed to give good estimation.

DOI： 10.11532/structcivil.67A.174

Charpy impact tests on low-yield point steel subjected to thermal cycle and pre-strain Reviewed

Masaru Shimizu, Kazuo Tateishi, Takeshi Hanji, Yasumoto Aoki

Steel Construction Engineering, JSSC Vol. 28 ( 109 ) page： 183-190 2021.3

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

Low-yield point steel has been used in seismic control dampers due to its high energy absorption ability. Meanwhile, thermal cycle during welding can change mechanical properties and microstructure of low-yield point steel. In addition, large plastic strains caused by seismic motion can induce defects in microstructure. They can cause the reduction in toughness of the low-yield point steel. In this study, Charpy impact tests were performed for low-yield point steel with thermal cycle simulating heat affected zone and preliminary plastic strain. Significant reduction in Charpy absorbed energy was observed when applying simulated thermal cycle, while the preliminary strain gives insignificant reduction.

DOI： 10.11273/jssc.28.109_183

Simplified analysis method for estimation of strain at drilled crack-arrest hole with bolted splices Reviewed

Shogo Kiyokawa, Takeshi Hanji, Ryojiro Kato

Steel Construction Engineering, JSSC Vol. 28 ( 109 ) page： 155-168 2021.3

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

The drilled crack-arrest hole and the attaching splices by high strength bolts are often used in combination as retrofit for fatigue cracks in steel structures. In this case, in order to evaluate the remaining fatigue life, it is important to accurately estimate the strain at the crack-arrest hole. Non-linear FE analysis considered the friction contact was often applied for the strain estimation in previous researches. In this study, a linear analysis model with simplified meshing was newly introduced. Through static loading tests and parametric FE analyses, it was verified that the model can estimate the strain at the hole with practically sufficient accuracy.

DOI： 10.11273/jssc.28.109_155

Study on low cycle fatigue crack propagation behavior under two-steps variable amplitude Reviewed

Arief Panjaitan, Masaru Shimizu, Kazuo Tateishi, Takeshi Hanji

Steel Construction Engineering, JSSC Vol. 27 ( 108 ) page： 93-103 2020.12

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

Low cycle fatigue in steel caused by earthquakes can result in large cyclic strain failures. In the studies conducted to date, low cycle fatigue crack propagation has primarily been investigated under constant amplitude loading. However, actual seismic motions are characterized by amplitude changeability from high to low or from low to high levels, and the effect of these alterations on crack growth in steel has not yet been clarified. Accordingly, this study examines crack propagation patterns under two-steps variable amplitude loading, which has two different uniform amplitude steps. The first part of this paper examines crack growth rates under constant amplitude conditions to obtain basic characteristic. Then, several patterns of two-steps variable amplitude loading are investigated. Research results show that, when compared to constant amplitude conditions, crack growth rates in steel increase when the amplitude decreases from high to low levels. Finally, a formula containing finite element analysis parameters was constructed and verified, thus providing a new method for obtaining good estimations of the crack growth rate.

DOI： 10.11273/jssc.27.108_93

Countermeasure effect of UHPFRC overlay on fatigue cracks propagating from U-rib welds of orthotropic steel decks Reviewed

Masafumi Hattori, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

Journal of Structural Mechanics and Earthquake Engineering, JSCE Vol. 76 ( 3 ) page： 542-559 2020.11

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

Over the last decade, fatigue cracks have been observed at welded joints between U-ribs and deck plates in many orthotropic steel deck bridges in Japan. Among the cracks, this paper focuses on fatigue cracks that initiate from a weld root of rib-to-deck welded joints and propagate to a deck plate. This study examines the effect of countermeasure with overlaying Ultra-High Performance Fibre Reinforced cement-based Composites (UHPFRC) on steel decks with cracks from U-rib welds, and confirms the fatigue durability of this countermeasure method. Specifically, the suppressing effect on crack propagation and the fatigue durability of UHPFRC itself and the interface between UHPFRC and the deck plate were confirmed by a wheel running test and finite element analysis. As a result, it was clarified that this countermeasure has a positive effect to retard further crack propagation compared with a countermeasure with overlaying steel fiber reinforced concrete which is generally adopted. In addition, it was revealed that this countermeasure has enough fatigue durability.

DOI： 10.2208/jscejseee.76.3_542

Local strain-based low-cycle fatigue assessment of joint structure in steel truss bridges during earthquakes Reviewed

Chao Jiang, Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu

International Journal of Steel Structures Vol. 20 ( 5 ) page： 1651-1662 2020.8

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

During the 2011 Tohoku Earthquake, a truss bridge joint structure was cracked due to large cyclic deformation, making us recognize the importance of assessing the seismic performance of joint structures in truss bridges from the viewpoint of low-cycle fatigue. In this study, seismic response analysis of an actual deck truss bridge was performed under different seismic waves, and local strain behavior generated at welded joints around a joint structure was clarified using a zooming analysis technique. The results revealed the possibility that welded joints for a lateral gusset-plate in a joint structure can be cracking sites during earthquakes. In addition, it was indicated that seismic isolation bearings can significantly reduce the local strain at the joint structure and improve its low-cycle fatigue performance. Moreover, as a simple countermeasure, weld toe treatment by grinding is also effective to decrease the possibility of low-cycle fatigue cracking at the joint structure.

DOI： 10.1007/s13296-020-00399-1

Low cycle fatigue crack propagation of steel under constant amplitude displacement histories Reviewed

Arief Panjaitan, Kazuo Tateishi, Masaru Shimizu, Takeshi Hanji

Steel Construction Engineering, JSSC Vol. 27 ( 106 ) page： 75-80 2020.7

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

Low cycle fatigue is a failure mode exhibiting a small number of loading repetitions to failure. Former work conducting research on constant displacement amplitude presented crack growth rate was related to cyclic J-integral range, but the data were limited. This research aimed to provide additional information to cover study done at the past so that a formula for obtaining crack growth rate can be precisely proposed. Research work was conducted with applying two different cyclic displacement means of loading histories to CT specimen. Cumulative plots in crack growth rate addressed to past and current research work were found enforcing formula used for obtaining crack growth rate under larger cyclic strains proposed at the past.

DOI： 10.11273/jssc.27.106_75

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Papers - HANJI Takeshi