Faculty Profiles - HANJI Takeshi

Papers - HANJI Takeshi

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Fatigue crack growth characteristics of several kinds of structural steels under low-cycle fatigue loading Reviewed

Chao Jiang, Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu

International Journal of Steel Structures Vol. 23 ( 1 ) page： 37-49 2023.2

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

Because low-cycle fatigue is one of the failure modes in steel structures during earthquakes, crack growth prediction in the low-cycle fatigue region has become an important factor in the evaluation of the seismic performance of steel structures. This study conducted fatigue crack growth tests with several kinds of structural steels to clarify their crack growth behaviour in the low-cycle fatigue region. These tests employed an elastic compliance technique usually used in the high-cycle fatigue region to determine crack size. Before applying the elastic compliance method to a low-cycle fatigue crack growth test, a correlation between specimen load-line crack-opening elastic compliance and crack size was analytically derived. The test results indicated that crack sizes obtained by the elastic compliance method agree relatively well with those actually measured from images. Moreover, it was revealed that the crack growth rate can be correlated with the cyclic J-integral range calculated by finite element analysis, and that the relationships between the crack growth rate and the cyclic J-integral range are similar regardless of the steel type.

DOI： 10.1007/s13296-022-00677-0

Fatigue countermeasures for U-rib to deck welded joints from underside of existing orthotropic steel decks Reviewed

Masafumi Hattori, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

Japanese Journal of JSCE Vol. 79 ( 1 ) page： 22-00231 2023.1

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

This paper proposes a countermeasure for fatigue cracks that propagate from the weld root of U-rib to deck welded joints to the deck plate or weld bead of orthotropic steel deck. Specifically, the lower flange of the U-rib is removed and the U-rib and deck plate welds are welded from the inside of the U-rib as a countermeasure method. First, to confirm the feasibility of this countermeasure with structural changes, the load-bearing capacity, workability of welding, and effects on asphalt pavement were verified. Next, changes in the local stress properties of the focused welds and other areas due to the countermeasures were confirmed by finite element analysis. Finally, the fatigue durability of the countermeasure was determined by fatigue tests.

DOI： 10.2208/jscejj.22-00231

Fatigue strength of the drilled crack-arrest hole after adding splice plates with high strength bolts Reviewed

Shogo Kiyokawa, Kazuo Tateishi, Takeshi Hanji, Ryojiro Kato

Journal of Structural Mechanics and Earthquake Engineering, JSCE Vol. 78 ( 3 ) page： 417-431 2022.11

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

The adding splice plate with high strength bolts are often used in combination with the drilled crack-arrest hole as a permanent countermeasure against fatigue cracks. On the other hand, the fatigue design method for such splice plate has not been established, and the fatigue durability of the crack-arrest hole after adding splices has not been clarified.
In this study, we conducted several fatigue tests focusing on the geometric parameters of the splice plate to investigate the fatigue fracture mode and fatigue life of the crack-arrest hole after adding splices. Two types of cracks were observed in the fatigue tests. One was a crack re-occurring from the crack-arrest hole and the other was a fretting fatigue crack at the contact surface between the main plate and splices. It was found that by obtaining the local stress at the crack-arrest hole after adding splices, the fatigue life can be estimated using the fatigue design curve proposed for the hole without splices. The fretting fatigue life of splices against the crack was as same as the fatigue life of the high strength bolted frictional joints. From these results, the method of rationally designing the splice plates was proposed by evaluating the durability for the two fatigue fracture modes.

DOI： 10.2208/jscejseee.78.3_417

Fatigue strength of deck-to-rib welded joint and correlation to full-scale orthotropic steel deck system Reviewed

Masaru Shimizu, Takayuki Uchida, Kazuo Tateishi, Takeshi Hanji, Masafumi Hattori

Journal of Constructional Steel Vol. 30 page： 297-305 2022.11

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

Many fatigue cracks occur in the welded joint between deck plate and U-rib. So far, fatigue tests on small-scaled welded joints simulating deck-to-U-rib joint have been conducted. However, the relationship between the stress caused in the actual orthotropic steel deck system and small-scaled specimen have not been cleared. In this study, stress at the root of a small-scaled welded joint specimen and a full-scale steel deck system was investigated. In addition, estimation method for fatigue life of deck-to-U-rib welded joint in a full-scale steel deck system from small-scaled specimen was proposed.

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

International Journal of Steel Structures Vol. 22 ( 6 ) page： 1808-1816 2022.9

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. 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 a countermeasure that uses overlaying Ultra-High Performance Fiber Reinforced cement-based Composites (UHPFRCs) on steel decks with cracks from U-rib welds, and confirms the fatigue durability of this method. Specifically, the retardation of crack propagation and the fatigue durability of the UHPFRC itself as well as the interface between the UHPFRC and the deck plate were confirmed by a wheel running test and finite element analysis. Based on the results, it was clarified that this countermeasure has a positive effect on retarding further crack propagation compared with the method of overlaying steel fiber reinforced concrete, which is generally adopted. In addition, it was revealed that the studied countermeasure has sufficient fatigue durability.

DOI： 10.1007/s13296-022-00660-9

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

Masafumi Hattori, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

Journal of Structural Mechanics and Earthquake Engineering, JSCE Vol. 78 ( 2 ) page： 287-300 2022.8

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

This paper examines application of a fatigue evaluation method for the cracks in the weld joints between a U-rib and a deck plate in orthotropic steel bridge decks. Field measurements were conducted in two sections with different crack initiation trends, and a method was proposed to obtain the cumulative fatigue damage ratio from the measurement results and routinely obtained data such as temperature and traffic volume. In addition, the validity of the evaluation of crack initiation and propagation direction by the developed evaluation method is verified by comparing with the actual crack situation, and a method to screen out the priority inspection and investigation area is proposed.

DOI： 10.2208/jscejseee.78.2_287

Quantifying the intensity of high frequency mechanical impact treatment Reviewed International coauthorship

Jan Schubnell, Takeshi Hanji, Kazuo Tateishi, Stefanos Gkatzogiannis, Thomas Ummenhofer, Majid Farajian

The 75th Annual Assembly of International Institute of Welding page： XIII-2930-2022 2022.7

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

High-Frequency Mechanical Impact (HFMI) is an user-friendly and efficient mechanical post-weld treatment method and the achieved fatigue life improvement is statistically proved. The achieved fatigue life improvement is attributed to HFMI-induced compressive residual stresses amongst other effects. Several studies have shown in the past that the process parameters (treatment intensity and working speed) have an influence on the stress state introduced by the HFMI treatment. Thus far however, only device-specific quantitative recommendation for the HFMI-treatment exists based on the instructions of each HFMI device’s manufacturer. It is not clear, if a certain treatment time for a given intensity leads to optimum results regarding the enhanced fatigue life. Moreover, the treatment parameters of the several HFMI devices cannot be directly compared with each other. For these reasons, a universal and simple definition of the HFMI-treatment’s intensity based on the kinetic energy of the HFMI pin was used to quantitatively correlate the HFMI-induced compressive residual stress with the HFMI-process parameters for two different HFMI devices: Pneumatical Impact Treatment (PIT) and High Frequency Impact Treatment (HiFIT). To this purpose, data from former studies of HFMI-treated base material and welded specimens are revaluated. It is shown, that the compressive residual stresses after reaching a threshold value of the applied kinetic energy show only slight changes. This energy-based approach for the quantification of the treatment intensity was also used for a case study with PIT and HiFIT treated transverse stiffeners with different treatment intensities. A high influence of the treatment intensity on the residual stress state was determined. However, only a slight influence on hardness increase and fatigue strength was shown.

Fatigue strength enhancement of welded joints in existing steel bridges using high-frequency mechanical impact treatment Reviewed

Takeshi Hanji, Kazuo Tateishi, Shunya Sumi, Masaru Shimizu

Proceedings of the 11th International Conference on Bridge Maintenance, Safety and Management (IABMAS 2022) page： 2114-2122 2022.7

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

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. In addition, residual stress measurements and finite element analysis simulating welding and treatment processes were performed. The results indicate that the HFMI treatment is beneficial even when applied under a static tensile load, as the resulting compressive residual stresses are similar regardless of the stress state in the joint during treatment, meaning that the HFMI is applicable to existing structures.

DOI： 10.1201/9781003322641-262

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

Proceedings of the 11th International Conference on Bridge Maintenance, Safety and Management (IABMAS 2022) page： 2123-2130 2022.7

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

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： 10.1201/9781003322641-263

Simple estimation of local strain amplitude at weld toe for low cycle fatigue assessment Reviewed

Takeshi Hanji, Kazuo Tateishi, Shunya Sumi, Masaru Shimizu

The 75th Annual Assembly of International Institute of Welding page： XIII-2951-2022 2022.7

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

There are usually two methods to evaluate the low cycle fatigue strength of a welded joint, namely the local approach and the nominal approach. Previous research has revealed the applicability of the local approach for low cycle fatigue assessment of welded joints, where fatigue cracks were initiated from a weld toe. When calculating the local strain at the weld toe, elasto-plastic finite element analysis using a fine mesh with a resolution of about 0.01 mm is usually employed, but this is not practical because of the tremendous calculation and working costs involved. In this study, finite element analyses were performed for three types of welded joints (cruciform joint, T-joint, and longitudinal attachment joint) with different dimensions, and a simple estimation method for the local elasto-plastic strain amplitude at the weld toe was developed. A feature of this method is that it correlates the local strain amplitude at the weld toe with the elastic strain distribution around the toe obtained by a simple analysis using a relatively coarse mesh. Moreover, the proposed method was verified by low cycle fatigue tests of welded joins.

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

Masafumi Hattori, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

The 75th Annual Assembly of International Institute of Welding page： XIII-2950-2022 2022.7

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

Root cracks initiating from U-rib to deck welded joints of orthotropic steel deck bridge have become a road surface travel safety problem. Some fatigue strength evaluation methods for root cracks have been proposed based on local stress criteria, such as effective notch stress method, but these methods cannot be evaluated directly from the measurable response values of the structure. In order to improve the efficiency of maintenance and to predict crack initiation, it is desirable to be able to accurately evaluate fatigue strength based on information obtained from the structure for root crack initiation. This study examines a fatigue strength 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 strength assessment, and to propose a method to estimate them from some reference stresses around the weld joint.

Fatigue durability of cut-out in corner plate and fatigue life extension by ICR treatment Reviewed

Masaru Shimizu, Kazuo Tateishi, Shinta Ayuningtyas, Takeshi Hanji, Yoshihiko Takada, Misa Kumazawa, Itsuki Yamaguchi, Ryoji Okamoto, Takamitsu Nishishiba

Journal of Structural Engineering, JSCE Vol. 68A page： 580-590 2022.4

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

Corner plates are often welded at the intersection between web and flange in steel box girders. As a measure against fatigue in the weld joint between corner plate and lateral rib, the end of corner plate was cut-out in U-shape. Nevertheless, fatigue cracks have been generated from exposed root on the cut-out surface. In this study, fatigue strength and fatigue life improvement by ICR treatment were investigated. The fatigue strength of the weld joint was JSSC-G class. Application of ICR treatment improves the fatigue strength by 1 grade or more, and the fatigue limit was improved as 59 N/mm2 or more. Furthermore, stress concentration factor around exposed root was investigated by finite element analysis.

DOI： 10.11532/structcivil.68A.580

Residual stress and fatigue strength of longitudinal attachment joints improved by HFMI treatment under static load Reviewed

Takeshi Hanji, Suguru Kano, Kazuo Tateishi, Masaru Shimizu

Journal of Structural Engineering, JSCE Vol. 68A page： 591-602 2022.4

Authorship：Lead author,　Corresponding author Language：Japanese 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. Longitudinal attachment 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 indicated that enhanced 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 a treatment process indicated that the magnitude of compressive residual stress introduced to a weld toe is similar regardless of the stress state in the joint during treatment.

DOI： 10.11532/structcivil.68A.591

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

Takeshi Hanji, Kazuo Tateishi, Suguru Kano, Masaru Shimizu

Welding in the World Vol. 66 ( 3 ) page： 709-720 2022.1

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 kinetic energy of an accelerated indenter. 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 kinetic 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 kinetic energy. In addition, experiments demonstrated that the energy-based residual stress prediction is applicable to a longitudinal attachment welded joint with sufficient accuracy.

DOI： 10.1007/s40194-021-01230-z

Retardation of fatigue crack growth by corrosion accelerator injection Reviewed

Cut Atika Putri, Kazuo Tateishi, Masaru Shimizu, Takeshi Hanji

Steel Construction Engineering, JSSC Vol. 28 ( 112 ) page： 111-116 2021.12

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

In this study, fatigue crack growth was retarded by injecting corrosion accelerator, Nitric acid (HNO3), into the crack to induce corrosion. The presence of the corrosion products is expected to reduce the crack opening width and act as a wedge to control the crack closure. Fatigue tests were carried out on the compact tension (CT) specimens. The test revealed that the corrosion process due to HNO3 injection ends after 24 hours. Then, the reduction in crack opening displacement range can be observed. Retardation in the crack growth was observed regardless of the load range and the effective stress intensity factor range (delta_Keff) at injection. Meanwhile, the retardation level tends to be affected by the ΔKeff and crack length at injection.

DOI： 10.11273/jssc.28.112_111

Failure probability for fatigue crack in web plate of bridge girder Reviewed

Cut Atika Putri, Kazuo Tateishi, Masaru Shimizu, Takeshi Hanji

International Journal of Steel Structures Vol. 22 ( 1 ) page： 42-55 2021.11

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

Out-of-plane gusset joints are commonly used in welded assembly structures such as bridges. The studies regarding out-of-plane gusset joint often define fatigue life of this joint as the condition when the crack has fully penetrated through the web plate. However, the time frame from crack initiation until reaching complete structural failure is unclear. In this study, extended fatigue crack propagation analysis of out-of-plane gusset joint is performed. The variation of influential parameters such as flank angle, weld toe radius, material constant, and the threshold value of stress intensity factor range was considered. The crack propagation analysis was done until the crack reaches 80% of the lower flange plate of the bridge girder. Since the crack propagation life is highly influenced by traffic conditions, the probability distribution of the number of cycles and the crack width (2b) is presented in regards to the fatigue life ratio. In estimating the failure probability of the joint, the influence of human error to detect cracks during the inspection is considered. Five cases of the probability of crack detection are assumed to represent the capability of the inspector. It was found that bridge inspection and reparation of cracks are important in controlling the failure probability.

DOI： 10.1007/s13296-021-00559-x

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

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

Journal of Structural Mechanics and Earthquake Engineering, JSCE Vol. 77 ( 3 ) page： 489-508 2021.11

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

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 investigate 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.

DOI： 10.2208/jscejseee.77.3_489

Effect of static load during HFMI treatment on fatigue strength and residual stress field of longitudinal attachment welded joints Reviewed International journal

Takeshi Hanji, Kazuo Tateishi, Suguru Kano, Masaru Shimizu

Welding in the World Vol. 66 ( 3 ) page： 685-697 2021.11

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

DOI： 10.1007/s40194-021-01208-x

Fatigue strength evaluation method for welded joints in steel-concrete composite slab using L-shaped shear connectors Reviewed

Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu, Takaaki Ishii, Koichi Asano

Journal of Constructional Steel Vol. 29 page： 413-419 2021.11

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

In this study, the fatigue strength of welded joints in steel-concrete composite slabs was investigated by fatigue testing. In the test, fatigue cracks occurred at the toes of boxing welds of L-shaped 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. The test results demonstrated that the fatigue assessment of welded joints in a composite slab can be performed using the hot-spot stress approach.

Influence of weld toe radius on low cycle fatigue life of weld joint in shear panel damper Reviewed

Kai Hiroyama, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu, Yasumoto Aoki

Proceedings of the ISSS 2021 page： 140-143 2021.11

Language：English

Damping devices such as shear panel damper (SPD) are used to ensure the soundness of the principal elements of a bridge in an earthquake. The SPD is made of low yield point steel, which absorbs seismic energy by its plastic shear deformation. Since SPD is assembled by welding, low cycle fatigue is a concern due to strain concentration at the shear panel-to-flange connection. In this study, the relationship between the weld toe radius of SPD and the low-cycle fatigue life was investigated. To examine the low cycle fatigue life and strain distribution, cyclic loading test was performed. In addition, finite element analysis was performed to investigate the influence of weld toe radius on the local strain range at the weld toe. Low cycle fatigue life was estimated from the local strain range for each weld toe radius. From the results, the effect of toe radius on the low-cycle fatigue life of SPD welded joints was quantified.

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Papers - HANJI Takeshi