研究者詳細 - 判治　剛

論文 - 判治　剛

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Review of recent bridge asset management systems 査読有り

Takeshi Hanji, Kazuo Tateishi

Proceedings of International Symposium on EcoTopia Science 2007 頁： 1322-1326 2007年11月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

A number of transportation agencies throughout the world have adopted and implemented the bridge management system with advanced asset management decision-making capabilities. However, there are still significant room for improvement in the information and data upon which the bridge management systems are based, and on the results and decision-making that occurs based on the output of these systems. In order to address some of gaps in knowledge, the Federal Highway Administration (FHWA) of the U.S. Department of Transportation is initiating a Long-Term Bridge Performance (LTBP) program in 2006. In this paper, we will introduce the recent bridge management systems and the LTBP program in the States.

Extremely low cycle fatigue test on un-stiffened steel pier with thick-walled box section

Takeshi Hanji, Kazuo Tateishi, Tao Chen

Proceedings of the 9th Korea-Japan Joint Seminar on Steel Bridges 頁： 227-233 2007年8月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Several steel piers suffered low cycle fatigue damage in the Great Hanshin Earthquake (1995), which raises concerns about their performance in future earthquakes. However, researches on the low cycle fatigue of civil structures in extremely large strain region, corresponding to a strain magnitude of more than 10% and a fatigue life of less than ten cycles, are limited and design guidelines have not been established. In order to provide the benchmark data for extremely low cycle fatigue assessment, thick-walled steel piers with box section were fabricated and subjected to incremental or constant amplitude cyclic loading. During the test, fatigue cracks were initiated from weld toe at the corner. With the loading repetition, the cracks propagated along the weld toe. Finally, oblique cracks formed both in flange and web plate, and the pier was ruptured without local buckling. Although the cracks occurred at relatively early stage of the test, the loading capacity hardly decreased before failure. In other words, the crack propagation occupied the most part of life of the specimen. After the test, the low cycle fatigue strength of steel pier specimens was assessed based on the strain near the crack initiation point.

Local strain approach to extremely low cycle fatigue assessment for thick-walled steel pier with box section

Tao Chen, Kazuo Tateishi, Takeshi Hanji

Proceedings of the 9th Korea-Japan Joint Seminar on Steel Bridges 頁： 235-246 2007年8月

記述言語：英語掲載種別：研究論文（学術雑誌）

In a seismic event, steel piers may undergo large strain fluctuations of typically one to tens of cycles. That will possibly result in fracture of base end joints or beam-column joints, namely extremely low cycle fatigue. In this paper, thick walled un-stiffened box section steel piers subjected to incremental cyclic loading are analyzed by a three-dimensional elastic-plastic finite element analysis with shell and solid elements to investigate the behavior of local strain at weld toe. Several parameters, such as width thickness ratio, slenderness ratio, weld toe radius and axial loading, are taken into account. From engineering point of view, it is preferable to employ a simple parameter reflecting the local strain behavior. Here, the local strain is correlated to nominal strain, which is average strain along effective failure length by fiber model. Finally, a simple approach to extremely low cycle fatigue assessment is proposed and applied to test results.

Low cycle fatigue assessment for welded joints based on local strain approach 査読有り

Kazuo Tateishi, Takeshi Hanji, Tao Chen

The 60th Annual Assembly of International Institute of Welding 頁： XIII-2160-07 2007年6月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

As a method to predict fatigue strength of welded joints in extremely low cycle fatigue region, local strain based approach was discussed in this paper. Low cycle fatigue tests were conducted on T-shaped welded joints in order to find the crack initiation point and to obtain the fatigue life. On the other hand, local strain field around welded toe, where fatigue cracks were formed in fatigue tests, was analyzed by elasto-plastic finite element analysis, and the local strain amplitude at the cracking point was quantified. Based on the fatigue life obtained by fatigue test and the local strain amplitude by FEA, fatigue test results were compared with the low cycle fatigue strength curve, i.e., strain versus fatigue-life diagram. Test data were consistent with the strength curve. Consequently, it was demonstrated the fatigue assessment method based on local strain approach is available to predict the fatigue strength of welded joints even in extremely large strain region.

A prediction model for extremely low cycle fatigue strength of structural steel 査読有り

Kazuo Tateishi, Takeshi Hanji, Kuniaki Minami

International Journal of Fatigue 29 巻 ( 5 ) 頁： 887-896 2007年5月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Miner's rule has been accepted as a simple and effective method for predicting the low cycle fatigue life under variable strain amplitude. However, in an extremely large strain field, corresponding to the fatigue life of less than 10 cycles, the accuracy of Miner's rule has not been verified. In this study, low cycle fatigue tests under variable strain amplitude in an extremely large strain field were conducted with a newly developed testing system. Miner's rule always predicted a longer fatigue life than the observed life. A simple model introducing the damage mechanics concept was proposed and its validity was examined as another method for predicting low cycle fatigue
life.

DOI： 10.1016/j.ijfatigue.2006.08.001

溶接継手の低サイクル疲労強度評価のための新しい局部ひずみ推定手法査読有り

舘石和雄，陳涛，判治剛

鋼構造論文集 13 巻 ( 52 ) 頁： 73-81 2006年12月

A prediction model for extremely low cycle fatigue strength of structural steel and welded material 査読有り

Kazuo Tateishi, Takeshi Hanji

The 59th Annual Assembly of International Institute of Welding 頁： XIII-2119-06 2006年7月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Miner's rule has been accepted as a simple and effective idea for predicting the low cycle fatigue life under variable strain amplitude. However, in an extremely large strain field, corresponding to the fatigue life of less than ten cycles, the accuracy of Miner's rule has not been verified. In this study, low cycle fatigue tests under variable strain amplitude in an extremely large strain field were conducted with a newly developed testing system. Since test results indicated that Miner's rule always predicted a longer fatigue life than the observed life, we proposed a modified life prediction model introducing the damage mechanics concept and investigated its validity.

TIG処理による溶接継手の極低サイクル疲労強度の向上効果査読有り

判治剛，舘石和雄，鬼頭和也，南邦明

鋼構造論文集 13 巻 ( 50 ) 頁： 27-34 2006年6月

局部的なひずみを基準とした溶接継手の極低サイクル疲労強度評価査読有り

判治剛，舘石和雄，南邦明，鬼頭和也

土木学会論文集 ( 808/I-74 ) 頁： 137-145 2006年1月

担当区分：筆頭著者記述言語：日本語掲載種別：研究論文（学術雑誌）

本研究では，極低サイクル疲労領域における溶接継手の低サイクル疲労強度を推定するための手法として，局部的なひずみを基準とする疲労強度評価手法に着目した．溶接継手の例として，T字溶接継手試験体を対象とした極低サイクル疲労試験を行った．一方，弾塑性有限要素解析により，溶接部周辺のひずみ分布を明らかにし，き裂発生点における局部的なひずみを求めた．局部的なひずみにより疲労試験結果を整理した結果，全ての試験データがき裂発生点である溶接金属部の疲労強度曲線と一致し，極低サイクル疲労領域においてもき裂発生点の局部的なひずみを用いることにより疲労強度を推定することが可能であることが明らかとなった．

DOI： 10.2208/jsceja.62.101

Extremely low cycle fatigue assessment method for welded joint by peak strain approach

Takeshi Hanji, Kazuo Tateishi, Kazuya Kitoh

Proceedings of 6th Japanese-German Bridge Symposium 頁： CD-ROM 2005年8月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

As an estimation method of fatigue strength of welded joint in extremely low cycle fatigue region, peak strain based fatigue assessment method was verified. T-shape welded joints were employed for the verification test. The specimen was analyzed by elasto-plastic finite element method in order to quantify the local strain field around welded portion and the peak strain at the cracked point. On the other hand, fatigue life of the specimen was experimentally obtained by low cycle fatigue tests. The relationship between the peak strain and the fatigue life was consistent with the fatigue strength curve proposed by the authors. Consequently, it was demonstrated that the fatigue assessment method by peak strain approach was available even in extremely low cycle fatigue region.

A prediction model for extremely low cycle fatigue life under variable strain amplitude

Kazuo Tateishi, Takeshi Hanji

Proceedings of the 8th Japan-Korea Joint Seminar on Steel Bridges 頁： 251-257 2005年8月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Extensive experiments on low cycle fatigue for plain steel material have been conducted and obtained some important results. However there are few studies for extremely low cycle fatigue, corresponding to the strain more than 0.10.
In this study, a new low cycle fatigue testing system, in which a steel plate specimen was subjected to bending deformation and the image technique was introduced to measure the strains in the specimen, was developed. The testing system has enabled the low cycle fatigue test with introducing extremely large strains into the specimen. Low cycle fatigue tests on plain steel plates under constant and variable strain amplitude were conducted by using the system. Based on the test results, an estimation method for low cycle fatigue strength in extremely low cycle fatigue region was proposed.

Improvement of extremely low cycle fatigue strength of welded joints by TIG dressing

Kazuo Tateishi, Takeshi Hanji, Kazuya Kitoh

Proceedings of 6th Japanese-German Bridge Symposium 頁： CD-ROM 2005年8月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

The improvement of extremely low cycle fatigue strength of welded joints by TIG dressing was investigated. T-shape welded joint specimens of which weld toes were finished by TIG dressing were tested. The fatigue test results were compared with that of as-weld specimens tested in the same conditions. The test results indicated that TIG dressing could substantially increase the extremely low cycle fatigue strength of welded joints.

Low cycle fatigue testing system by means of image technique and its application to steel welded joints 査読有り

Takeshi Hanji, Kazuo Tateishi

Proceedings of the 1st International Conference on Advances in Experimental Structural Engineering 頁： 603-609 2005年7月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

A new low cycle fatigue testing system has been developed, in which a steel plate specimen is subjected to bending deformation, and strains of the specimen are measured by image technique. In this study, the low cycle fatigue tests of steel welded joints under constant and variable strain amplitude, particularly the fatigue life less than ten cycles in extremely large strain field, was conducted by using the newly developed testing system. On the basis of the test results, the applicability of low cycle fatigue life prediction model was confirmed, which has been developed for plain steel material, to welded portion, such as deposit metal and heat affected zone (HAZ).

デジタルステレオグラフィーによる腐食鋼材表面形状の簡易計測手法査読有り

舘石和雄，柴田憲吾，判治剛

鋼構造論文集 12 巻 ( 46 ) 頁： 27-34 2005年6月

溶接部を対象とした極低サイクル疲労強度予測モデル査読有り

舘石和雄，判治剛，鬼頭和也，南邦明

構造工学論文集 51A 巻頁： 1275-1282 2005年3月

Low cycle fatigue strength of butt-welded steel joint by means of new testing system with image technique 査読有り

Kazuo Tateishi, Takeshi Hanji

International Journal of Fatigue 26 巻 ( 12 ) 頁： 1349-1356 2004年12月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

In this study, we investigated the low cycle fatigue strength of welded joints using a new fatigue testing system in which the image analysis technique was used to measure the strains in specimens. After checking the validity of the testing system, we used this new system to conduct fatigue tests on welded joint specimens. The test results indicate that the fatigue strength of welded material (weld deposit and heat affected zone) is much lower than that of the plain material.

DOI： 10.1016/j.ijfatigue.2004.03.016

Low cycle fatigue strength of welded joints in extreme large strain field 査読有り

Kazuo Tateishi, Takeshi Hanji

Proceedings of the 2nd International Conference on Bridge Maintenance, Safety, Management and Cost 頁： CD-ROM 2004年10月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Authors have developed a new low cycle fatigue testing method, in which a specimen is subjected to bending deformation and strain of the specimen is measured by image analysis. The advantage of this method is to be able to induce extreme large strain in steel plate even if it includes welding. In this study, the fatigue strength of welded joints in extreme large strain field was investigated by a newly developed testing system. The test results indicated that the fatigue strength of welded joints was much lower than that of plain material, and heat affected zone (HAZ) was the weakest spot.

Low cycle fatigue strength of steel in extreme large strain field 査読有り

Kazuo Tateishi, Takeshi Hanji

Proceedings of the 3rd International Conference on Earthquake Engineering 頁： 561-565 2004年10月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Extensive experiments on the low cycle fatigue for plain steel material have been conducted and obtained some important results. There are few studies, however, on the low cycle fatigue in the extreme large strain field, corresponding to the fatigue life less than ten cycles.
In this study, we developed a new low cycle fatigue testing system, in which a specimen was subjected to bending deformation and the strain in the specimen was measured by image analysis technique. Low cycle fatigue tests on plain steel plates under constant and variable strain amplitude were conducted by using the testing system. Based on the test results, an estimation method for low cycle fatigue strength in the extreme large strain field was proposed.

極低サイクル疲労領域における変動振幅ひずみ下の低サイクル疲労寿命予測モデル査読有り

舘石和雄，判治剛，南邦明

土木学会論文集 ( 773/I-69 ) 頁： 149-158 2004年10月

担当区分：筆頭著者記述言語：日本語掲載種別：研究論文（学術雑誌）

変動振幅ひずみ下での鋼材の低サイクル疲労強度については，従来より，Miner則を用いることにより比較的精度よく予測できるといわれている．しかし，これは疲労寿命が数百回以上の領域での検討結果に基づいており，極低サイクル疲労領域における寿命予測手法は確立されていないのが現状である．本研究では新たに開発した低サイクル疲労試験システムを用い，極低サイクル疲労領域における変動振幅ひずみによる低サイクル疲労試験を行った．その結果，極低サイクル疲労領域ではMiner則は危険側の予測結果を与えることが明らかとなった．そこで極低サイクル疲労領域における新たな疲労寿命予測モデルを提案し，試験結果と比較した結果，提案モデルにより精度よく疲労寿命を推定できることが明らかとなった．

DOI： 10.2208/jscej.2004.773_149

画像計測を用いた試験システムによる突合わせ溶接継手の低サイクル疲労強度の検討査読有り

舘石和雄，判治剛

土木学会論文集 ( 752/I-66 ) 頁： 277-287 2004年1月

担当区分：筆頭著者記述言語：日本語掲載種別：研究論文（学術雑誌）

本研究では，従来の砂時計型試験体では困難とされている，溶接部の低サイクル疲労強度を実験的に明らかにすることを目的とし，新たな試験システムとして，画像計測を用いたひずみ制御低サイクル曲げ試験システムを開発した．あらかじめ，画像計測面近傍にひずみゲージを貼付し，それにより測定できた範囲内で画像計測値とゲージ値を比較することで本計測手法の精度を確認した．本手法を用いて素材試験体と突合わせ溶接継手試験体の疲労試験を行った結果，素材試験体に関しては過去の研究におけるデータと同様の傾向を示した．一方，溶接継手試験体では，素材試験体の疲労強度を大幅に下回っており，溶接継手の低サイクル疲労強度は著しく低下することを明らかにした．

DOI： 10.2208/jscej.2004.752_277

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