研究者詳細 - 判治　剛

論文 - 判治　剛

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鋼床版Uリブ・デッキプレート溶接継手におけるルートの局部応力による疲労強度評価査読有り

清水優，判治剛，内田大介，服部雅史，吉田黎

鋼構造論文集 31 巻 ( 121 ) 頁： 72-87 2024年3月

タップボルト継手の疲労強度および材間相対変位の評価査読有り

丹羽雄一郎，舘石和雄，判治剛，清水優

鋼構造論文集 31 巻 ( 121 ) 頁： 115-126 2024年3月

疲労き裂が発生した鉄塔部材の鋼管割込み継手に対する疲労損傷比の評価査読有り

早田直広，舘石和雄，判治剛，清水優

構造工学論文集 70A 巻頁： 521-534 2024年3月

疲労耐久性に優れた鋼床版垂直補剛材上端部の切欠き形状の検討査読有り

清水優，舘石和雄，判治剛，金子大介，末次宏基

構造工学論文集 70A 巻頁： 458-469 2024年3月

Evaluation of thickness effect on fatigue life variation of longitudinal welded gusset joint 査読有り

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

International Journal of Steel Structures 24 巻 ( 2 ) 頁： 246-255 2024年3月

記述言語：英語掲載種別：研究論文（学術雑誌）

Numerous studies have been conducted regarding the fatigue strength of longitudinal welded gusset joints. Most studies employed relatively small specimens. Thus, this study aims to evaluate the variation of fatigue life of longitudinal welded gusset joints by using the probabilistic fracture mechanics approach, particularly for larger specimens. Although some studies claimed that lower fatigue strength is found in the thicker main plate specimens, however only a limited number of fatigue test was conducted. A probabilistic approach was employed to conquer the shortfall. In this study, fatigue crack propagation analysis was performed on the main plate thicknesses of 12, 40, and 60 mm to evaluate the effect of main plate thickness on the fatigue life of the joints. Then, a probabilistic approach is given to investigate the variation of fatigue life of the joint. In addition, fatigue tests were carried out to investigate the crack propagation behavior on larger specimens. A significant decrease in fatigue life was observed by the increase of the main plate thickness from 12 to 40 mm, however, no further decrease thereafter. The fatigue strength of longitudinal welded gusset joints with the main plate thickness of 12 mm was appertained to category F in the JSSC design curve. Meanwhile, the fatigue strength of longitudinal welded gusset joints with the main plate thickness of 40 and 60 mm falls into category G in JSSC. This condition was also confirmed by the fatigue test results, where both specimens were classified as category G in JSSC.

DOI： 10.1007/s13296-024-00812-z

Structural hot-spot stress approach for toe cracking from plate edge of load-carrying welded attachment 査読有り国際誌

Takeshi Hanji, Kazuo Tateishi, Nima Rabsel, Masaru Shimizu

Welding in the World ?? 巻 ( ?? ) 頁： ??-?? 2024年2月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The structural hot-spot stress approach is an effective method for assessing welding details when nominal stress is hard to determine due to geometric or loading complexities. Hot spots can be classified into two types: type “a,” which refers to a weld toe located on a plate surface, and type “b,” denoting one located on a plate edge. Previous studies on type “b” hot spots have mainly focused on in-plane gusset welded joints, and the applicability of type “b” hot-spot S-N curves proposed for in-plane gusset joints in IIW to the other details is not well understood. In this study, fatigue tests were conducted with a load-carrying attachment welded on a plate surface, where a crack occurred from a weld toe on the plate edge. The tests were also numerically simulated using finite element analysis. Upon evaluating the test results through the nominal stress, structural hot-spot stress (4, 8, and 12 mm method), and notch stress approaches, it was found that all the data lie above FAT71 for nominal stress, FAT100 for hot-spot stress, and FAT225 for effective notch stress.

DOI： 10.1007/s40194-024-01724-6

新しいリベットにより取替え補修した継手の力学的挙動に関する研究査読有り

柴田美希，判治剛，舘石和雄，清水優，長坂康史，竹渕敏郎

鋼構造年次論文報告集 31 巻頁： 409-416 2023年11月

未溶着部を有する鋼製橋脚角溶接部の低サイクル疲労による破壊形態の推定査読有り

清水優，舘石和雄，判治剛，村上智明，萩原直樹，稲熊唯史，真木有岳

鋼構造年次論文報告集 31 巻頁： 160-170 2023年11月

Fatigue damage evaluation for root cracks in U-rib to deck welded joints of orthotropic steel decks based on field measurements 査読有り国際誌

Masafumi Hattori, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

Proceedings of the ISSS 2023 頁： 189-192 2023年11月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Root cracks in U-rib to deck welded joints of orthotropic steel decks (OSDs) have been reported, which are two types of fatigue cracks initiating at the weld root that propagate into either the deck plate or the weld bead. For early detection of these internal cracks which may cause road surface damage, screening methods for priority inspection area in areal extent OSDs is needed. Therefore, the authors proposed a method of fatigue damage evaluation by estimating stresses to evaluate root crack initiation and propagation behavior from measurable stresses near the joints, aiming to establish a screening method. This paper examines application of the developed evaluation method for these root cracks in the actual OSDs. Field measurements were conducted in two sections with different trends of crack initiation, and a procedure was proposed to obtain the cumulative fatigue damage ratio from the measurement results and regularly obtained data. In addition, the validity of the developed evaluation method for the crack initiation and propagation direction was verified by comparing with the actual crack situation, and a screening method to select out the priority inspection area was proposed.

Flexural behavior of rational joints between precast steel-concrete composite slabs 査読有り国際誌

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

Proceedings of the ISSS 2023 頁： 273-276 2023年11月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Steel-concrete composite slab has rational structure consisting of bottom steel plate stiffened with ribs and concrete casted on them. In addition, the composite slab also has advantage in maintenance since there is no concern about concrete spalling. In recent years, replacement of aging slabs has been increasing, and the use of precast composite slabs is being promoted to shorten the construction period on site. When precasting concrete for composite slabs, rational joints thatachieve both strength and workability are required. Conventional bolted joints in bottom steel plate requires scaffolding to access the underside of the slab when fastening bolts and painting after fastening. Construction of scaffolding extends the whole construction period. In this study, two types of the joints that can be constructed from the top of the slab are proposed. Mechanical performance of the joints was investigated through the four-point bending tests. In addition,
evaluation method of yield resistance for each joint was discussed.

Study on mechanical behavior of riveted joints repaired by re-driving new rivets 査読有り国際誌

Miki Shibata, Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu, Yasushi Nagasaka, Toshio Takebuchi

Proceedings of the ISSS 2023 頁： 678-681 2023年11月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

There are three main connection types, such as welding, bolting, and riveting. Among them, riveted joints are hardly used in current bridge assembly. On the other hand, a large number of old bridges with riveted joints still exist and its proper maintenance are required. In this study, the repair method of riveted joints by re-driving new rivets with an Induction Heating (IH) technique was considered. First, fatigue tests for riveted joints using IH technique were performed. As a result, it has similar fatigue strength to those fabricated in the traditional way. In addition, finite element analysis to simulate the replacement of the rivets under statically applying load (dead load) was performed. The analysis clarified the load-displacement relationship and load re-distribution mechanism of the joint when replacing rivets under static load.

Fatigue crack propagation characteristic of out-of-plane gusset welded joints with developed anti-fatigue damage steel 査読有り国際誌

Terazawa Takuya, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu, Thihuyen Doan

Proceedings of the ISSS 2023 頁： 645-648 2023年11月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Anti-fatigue damage steel, in which the hard and soft phases in the microstructure of the steel are appropriately arranged by controlling the composition and manufacturing process to reduce the crack propagation rate, was developed in past studies. In this study, a steel newly developed with the concept of the existing anti-fatigue damage steel was applied to the main plate of out-of-plane gusset welded joints, and its crack propagation characteristics were clarified by plate bending fatigue tests. The results of the fatigue tests and the discussion using finite element analysis showed that the crack propagation rate of the out-of-plane gusset welded joints using the developed steel tended to be smaller than that using a structural steel conventionally used in steel bridges.

Simplified estimation of elasto-plastic strain amplitude at weld toe by elastic analysis 査読有り国際誌

Chie Nishijima, Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu

Proceedings of the ISSS 2023 頁： 564-567 2023年11月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

When large cyclic deformations due to excessive external forces, such as those caused by an earthquake, are induced in steel bridge members, Low-cycle fatigue cracks sometimes occur in welded joints due to high strain concentration around the weld. Such cracks can lead to brittle fracture of the member. The low-cycle fatigue strength of steel members, particularly that of welded joints, should be evaluated as efficiently as possible to prevent low-cycle fatigue failure during earthquakes. In this study, as a first step to establish a simple and versatile low-cycle fatigue verification method, finite element analyses were conducted on cruciform joints of various dimensions to investigate a method to determine the local strain amplitude at the weld toe from the nominal strain amplitude by elastic analysis, and an estimation formula was developed.

Fatigue strength of HFMI-treated welded joints under variable amplitude block loading 査読有り国際誌

Takeshi Hanji, Shunsuke Masui, Taisei Tomita, Kazuo Tateishi, Masaru Shimizu

Proceedings of the ISSS 2023 頁： 556-559 2023年11月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

High-Frequency Mechanical Impact (HFMI) treatment is a technique to improve the fatigue strength of welded joints by inducing compressive residual stress. In this study, fatigue tests under variable amplitude loading were conducted on HFMI-treated welded joints to clarify its fatigue strength improvement effect. As a fundamental investigation, multi-stage amplitude block loading, which is a relatively simple waveform among variable amplitude loading, was employed. In addition, the residual stress state due to the HFMI treatment was reproduced by finite element analysis, and the change in the residual stress state around the treated area was confirmed by applying several loading patterns.

Fatigue strength improvement methods for front fillet welded joint of sole plate in steel bridge bearings 査読有り国際誌

Yuichiro Niwa, Tetsuya Kowaki, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

Proceedings of the ISSS 2023 頁： 552-555 2023年11月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Around the bridge bearing in steel plate girder bridge, various fatigue cracks have been found at the front fillet welded joint between lower flange and sole plate, such as toe cracks on lower flange or sole plate and root cracks. Therefore, various countermeasures are required for each of these cracks. The purpose of this study is to propose simple fatigue strength improvement methods for weld joints of sole plate. In order to verify the effect of the methods on fatigue strength, fatigue tests were conducted on a girder specimen simulating loss of movability in bearing support. As a result, it was clarified that the peening treatment had a significant improvement on the fatigue strength of the toe cracks, and the tap bolting and resin injection had a large effect on the fatigue strength of the root cracks.

Retardation of fatigue crack growth by injection of corrosion accelerator 査読有り国際誌

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

Proceedings of the ISSS 2023 頁： 548-551 2023年11月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In this study, as a simple repair method for fatigue cracks, injecting a corrosion accelerator to retard crack growth was investigated. When the inner surface of a fatigue crack is corroded, corrosion products arrest crack closure. Due to this wedge effect, the crack opening displacement and crack growth rate are reduced. In this study, Nitric acid (HNO3), which has highly corrosive property and low viscosity, was adopted as the corrosion accelerator. Fatigue tests were carried out on compact tension (CT) specimens with various load range, minimum to maximum load ratio, and initial crack length at injection. The corrosion accelerator is injected to the initial crack by the dropper. After the injection, the corrosion reaction inside the crack completed approximately after 24 hours. By producing corrosion products, the strain at crack tip and crack growth rate were significantly reduced. From the test results, the crack growth retardation effect was affected by the crack length at injection and load condition.

Analytical study on local stress evaluation at welded joints of sole plates of steel bridges 査読有り国際誌

Yuichiro Niwa, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

Proceedings of the ISSS 2023 頁： 438-441 2023年11月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

There have been many reports on fatigue cracks at fillet welded joints of sole plates of steel bridges. When preventive maintenance management of these cracks is conducted, the screening process to determine crack-prone fillet welded joints of sole plates and prioritize to apply the countermeasures to prevent the crack is necessary. In this study, in order to propose a screening method, a method for evaluating the local stress near the fillet welded joint of sole plate based on simple calculations was investigated by finite element analysis (FEA). The results revealed that the local stress at the front fillet welded joint of sole plate is well correlated with the local cross-sectional area of the lower flange and web. Moreover, it was revealed that the horizontal reaction force additionally caused by the movability loss of bearing can affect the local stress at the fillet welded joint of sole plate. Based on these results, a simple equation for evaluating the local stress at the fillet welded joint of sole plate using the local cross-sectional area and horizontal reaction force was proposed.

Structural hot-spot stress approach for toe cracking from plate edge of load-carrying welded attachment 査読有り

Takeshi Hanji, Kazuo Tateishi, Nima Rabsel, Masaru Shimizu

The 76th Annual Assembly of International Institute of Welding 頁： XIII-2996-2023 2023年7月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The structural hot-spot stress approach is an effective method for assessing welding details when nominal stress is hard to determine due to geometric or loading complexities. Hot spots can be classified into two types: Type “a”, which refers to a weld toe located on a plate surface, and Type “b”, denoting one located on a plate edge. Previous studies on Type “b” hot-spots have mainly focused on in-plane gusset welded joints, and the applicability of Type “b” hot-spot S-N curves proposed for in-plane gusset joints in IIW to the other details is not well understood. In this study, fatigue tests were conducted with a load-carrying attachment welded on a plate surface, where a crack occurred from a weld toe on the plate edge. The tests were also numerically simulated using finite element analysis. Upon evaluating the test results through the nominal stress, structural hot-spot stress (4, 8, and 12 mm method) and notch stress approaches, it was found that all the data lie above FAT71 for nominal stress, FAT100 for hot-spot stress, and FAT225 for notch stress.

Fatigue strength evaluation by measurable stresses for root cracks in U-rib to deck welded joints of orthotropic steel decks 査読有り

Masafumi Hattori, Kazuo Tateishi, Takeshi Hanji, Masaru Shimizu

Welding in the World 67 巻 ( 7 ) 頁： 2273-2282 2023年7月

記述言語：英語掲載種別：研究論文（学術雑誌）

Root cracks initiating from U-rib to deck welded joints of orthotropic steel deck bridges have become a problem for maintenance. Some fatigue strength evaluation methods for root cracks based on local stress criteria have been proposed, such as the effective notch stress method, but these methods cannot evaluate fatigue strength directly from the measurable response values of the structure. In this study, the evaluation method of crack initiation by measurable stresses was investigated by fatigue tests and FE analysis for both deck and bead propagation-type cracks, which are root cracks in U-rib to deck welded joints of orthotropic steel decks. As a result of the study, the relationship between the stress of weld root and the fatigue life was obtained by using the fillet shaped notch stress as the evaluation stress, and the S-N curve for the evaluation stress was proposed. And a method to estimate the evaluation stress of the root from the measurable stresses at four points was proposed. It was confirmed that the error of the proposed estimation method was generally within 10%. As a validation of the estimation method, it was confirmed that the fatigue test results could be properly evaluated.

DOI： 10.1007/s40194-023-01568-6

Numerical investigation of fatigue crack propagation behavior in trough-girder bridges 査読有り

Habil Putra Teuku, Takeshi Hanji, Kazuo Tateishi, Masaru Shimizu

Journal of Structural Engineering, JSCE 69A 巻頁： 558-567 2023年4月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Fatigue cracks have been observed from welded joints of end diaphragms at steel railway trough-girder bridges due to vertical movement behavior at their supports that is not expected during the design phase. Since this movement behavior is complicated and varies on each bridge depending on the damage around the support, effective retrofitting methods against the crack have not been established yet. In this study, the influence of the vertical movement tendency at the bridge supports on the crack initiation location and crack propagation behavior at the end diaphragm was investigated through numerical simulation. The result indicated that the relative displacement at the bedplate affected the crack initiation location and crack propagation path, and that the stress intensity factor tended to gradually decrease after propagating a certain length.

DOI： 10.11532/structcivil.69A.558

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