論文 - 森田 千尋
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SfMを用いた構造物の３次元モデル化について
小川裕棋、森田千尋、松川尚史、塩竃柚貴、白井敬大
「歴史的構造物の非破壊検査」ミニシンポジウム論文集 3 41 - 46 2020年3月
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等）
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Zhao C., Niu J., Zhang Q., Yu S., Morita C.
Journal of Materials in Civil Engineering 31 ( 12 ) 2019年12月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Materials in Civil Engineering
© 2019 American Society of Civil Engineers. The expanded distinct element method based on a strain strength criterion was applied herein with the aim of analyzing and comparing the cracking behaviors of rock-like specimens with single flaws under uniaxial and biaxial compressions. The cracking characteristics in uniaxial and biaxial compressions were compared and the effects of confining pressure on the tensile/shear behaviors were analyzed. The confining pressure obviously changed the boundary condition and the cracking behaviors in biaxial compression. The initiation stress, the peak strength, and the number of shear cracks in biaxial compression were obviously larger than in uniaxial compression. The confining pressure affected the initiation and propagation of the secondary cracks, the failure mechanisms, and the distribution of horizontal displacement fields in a large extent. The initiation and propagation of the tensile cracks were inhibited by the confining pressure. An increase in confining pressure had no obvious effects on the initiation time and the propagation rates of the shear cracks but mainly affected the numbers of shear cracks.
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人工海水腐食環境下におけるZn-Al溶射皮膜の腐食性評価 査読あり
森田千尋，中野敦，白井敬大，押川渡，米沢昇
鋼構造年次論文報告集 27 374 - 383 2019年11月
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等）
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A HBM approach for temperature and heat flux convection–diffusion equations and nonlinear problems 査読あり
Zhao Y., Huang M., Tang J., Ouyang X., Morita C.
Nuclear Engineering and Design 342 115 - 127 2019年2月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Nuclear Engineering and Design
© 2018 Elsevier B.V. Solving convection diffusion equation is widely required in many fields of science, technology and engineering. The calculation is usually difficult and time-consuming. In this paper, a highly efficient method, the half boundary method (HBM), is proposed to solve the convection diffusion equation. The main idea of HBM is to reduce the order of the convection–diffusion equations by introducing a new variable and constructing the relations of the variables between the nodes inside the area and the nodes on half of the boundaries. Using the relations, the temperature and heat flux at any point can be calculated simultaneously, after obtaining the variables on the half of the boundaries. Because the unknown variables exist on only half of the boundaries, the computing matrix is reduced to only second order regardless of the number of nodes, the internal storage in the HBM is even less than that required in the finite volume method, making the HBM extremely fast and efficient. The validity and accuracy of the proposed method are investigated. Numerical studies for steady and unsteady, as well as nonlinear convection–diffusion equations, were carried out. The results show that HBM is more accurate than the finite volume method under identical grids conditions.
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中島和俊, 加納勇, 安波博道, 森田千尋
鋼構造論文集 25 ( 98 ) 35 - 43 2018年6月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：社団法人 日本鋼構造協会
The soundness evaluation of weathering steel bridges is generally based on external visual inspection and is not quantitative, it is known that it greatly influences the experience and subjectivity of the evaluator. In this study, patch type exposure tests were conducted on 7 bridges of weathering steel bridges managed by Nagasaki prefecture, and the soundness was evaluated based on corrosion prediction. Also, the corrosion behaviors of each part such as flange and web were analyzed and evaluated.
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シザーズ構造の力学特性に関する研究
池畑雄太，森田千尋，有尾一郎，濱優太，近広雄希
九州橋梁・構造工学研究会シンポジウム論文集 5 53 - 57 2017年12月
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等）
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インフラ再生技術者育成のための道守養成講座の構築と認定者の活用の取組み 査読あり
松田浩, 中村聖三, 森田千尋, 奥松俊博, 高橋和雄
土木学会論文集F4（建設マネジメント） 73 ( 4 ) I_21 - I_32 2017年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：公益社団法人 土木学会
インフラ再生を担う技術者育成の重要性に着目した長崎大学インフラ長寿命化センターは自治体，地域の建設業等からなるコンソーシアム"道守"養成ユニットを全国に先駆けて2008年度に設立した．社会人技術者を対象としたインフラの維持管理のキャリアを形成する学習ユニット積み上げ方式の道守養成講座のカリキュラムを開発し，人材育成を継続してきた．道守認定者の活動はこれまで主としてボランティアであったが，国土交通省による民間資格への登録を契機に維持管理に関する技術者としての活動が開始された．本論文は，道守養成講座の実施体制，養成講座のカリキュラム，達成評価基準，養成者数等の実績をこれまで蓄積された資料に基づいてまとめる．さらに，道守認定者の資格更新，認定後の自主的な活動，技術者としての活動等についてまとめる．
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アンケート調査に基づく道守認定者の活動・意向と道守養成ユニットへの反映 査読あり
高橋和雄, 松田浩, 中村聖三, 森田千尋
土木学会論文集F4（建設マネジメント） 73 ( 4 ) I_10 - I_20 2017年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：公益社団法人 土木学会
長崎大学は2008年度に全国に先駆けて自治体及び建設業界からなる産学官連携コンソーシアムにより，道路の維持管理を担う社会人技術者を育成する道守養成講座を開催してきた．道守養成講座の開始から7年が経過した2015年4月の時点で道守認定者は約200人に達し，公共工事等に活用できる程度の認定者数が確保された．道守認定者の活動，活用及び意向等はこれまで具体的に把握されていない．そこで，本アンケート調査により，道守認定者としての活動内容，技術者としての活動，道守に関する情報入手，組織化，道守認定者としての自己評価，今後の道守養成講座の実施等についての現状と課題を明らかにした．さらに，アンケート調査の結果に基づいた道守養成講座の見直し，道守認定者への情報提供方法，認定後の活動内容等についてまとめる．
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宮崎県における耐候性鋼橋梁の現状について 査読あり
森田千尋，野中拓海，大木翔太
鋼構造年次論文報告集 25 559 - 565 2017年11月
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等）
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塗膜除去不要な鋼部材疲労亀裂の熱的負荷による光学的全視野探傷法 査読あり
松田浩, 小金丸暁, 草野壱俊, 伊藤幸広, 森田千尋
土木学会論文集A2（応用力学） 72 ( 2 ) I_643 - I_652 2017年1月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：公益社団法人 土木学会
近年，道路橋の鋼製橋脚や鋼床版等の部材に疲労き裂の発生する事例が増加している．疲労き裂の発生部位によっては，進展すると脆性破壊を引き起こし，橋梁の安全性に重大な影響を及ばす恐れがある．したがって，それらを早い時期で発見し，適切な補修を行うことが重要である．本論文は熱源を用いてき裂を開閉させ，それを光学的全視野計測法の一つであるデジタル画像相関法（以下，DICMと表記）で計測することにより，塗膜除去を必要としないき裂発生を可視化させる新しい鋼部材のき裂欠陥検知法の開発を目的としたものである．
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Meso-experimental study of failure mechanism of rock based on uniaxial compression test 査読あり
Zhao C., Yu Z., Wang W., Matsuda H., Morita C.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering 35 ( 12 ) 2490 - 2498 2016年12月
記述言語：中国語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering
© 2016, Science Press. All right reserved. The evolution of microscopic fabric of rock has an important effect on its mechanical property and failure shape and it is therefore essential to study the microscopic fabric on rock. In this study, the scanning electron microscope(SEM) was used to scan the micro structure of the failure section of samples after compression shear test and Brazil split test. The morphological characteristics of the fracture surface of specimen were highlighted and the criteria of microscopic morphology matching macroscopic mechanical properties of crack surface were established. Meanwhile, the whole failure section of manufactured pre-crack was scanned with different angles of inclination. The criteria was applied to distinguish their microscopic morphology. As a result, the ratio of tensile-shear stresses on the fracture surface was obtained. The variation of the ratio in the cracking propagation process was studied. The results show that the ratio of tensile-shear stresses is closely related to the dip angle of the pre-existing crack. When the inclination angle is less than 45°, the tensile stress on the fracture surface is high, and the ratio decreases with the crack angle increasing. When the inclination angle is more than 45°, the results are opposite to the former. When the inclination angle is 45°, there are two macroscopic cracks owing to the combined effect of tensile and shear stresses. The proportion of wing cracks tensile stress changes from high to low during crack propagation process, and the results of secondary crack are converse to the former.
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Zhao C., Liu F., Tian J., Matsuda H., Morita C.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering 35 3626 - 3632 2016年10月
記述言語：中国語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering
© 2016, Science Press. All right reserved. Through laboratory test by employing the digital image correlation method(DICM), the laws of crack propagation and mechanism of plastic deformation of rock-like material with single crack pre-existing with various inclined angles when subjected to static loading are studied. The results show that when the inclined angle α = 15° and α = 30°, the position of the maximum strain is near the inner crack tip point, the new crack propagation begins at the initial crack wing, and the tension stress is the main reason of the new crack generation and propagation. With the increasing of α, when α = 60° and α = 75°, the strain concentration is detected at the crack tip. The main propagation mode of new cracks is secondary cracks, and the shear stress play a dominant role. There are both wing cracks and secondary cracks when α = 45°. The crack initiation stress increases as α increasing. The sample shows there are the minimum compression strength and the fastest crack propagation speed when α = 30°. The uniaxial compressive strength of the sample with secondary cracks is significantly higher than that sample with wing cracks.
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遠隔非接触振動計測装置を用いた橋梁の振動計測に関する研究—実橋梁計測のためのレーザ照射ターゲットの検討— 査読あり
森田千尋, 出水享, 松田浩, 岩吹啓史, 木本啓介
実験力学 16 ( 3 ) 243 - 249 2016年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：日本実験力学会
The technological development which efficiently checks the huge infrastructure structure is urgent need. From several years ago, we have studied using a laser Doppler velocimeter capable of remote non-contact measurement in vibration measurement. However, a seal for retro-reflection is employed as a laser illumination target by LDV measurement, but installation is sometimes difficult. Furthermore, it is difficult to multi-directional vibration measurement at a single target for normal measurement. Therefore, in order to solve the problems described above in the present study, we examined the new vibration measurement using heterologous laser irradiation targets.
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Zhao C., Bao C., Tian J., Matsuda H., Morita C.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering 34 ( 11 ) 2309 - 2318 2015年11月
記述言語：中国語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering
© 2015, Science Press. All right reserved. Cracks in rock will initiate, propagate and coalesce under loading, which remarkably influences the strength and damage property of rock. Based on a DIC system which was proved reliable, uniaxial compression experiments were carried out on the specimens with two precast flaws. The strain field and strain localization of the whole specimen were obtained. It was found that the strain localization and the progressive damage were very distinctive in the test. The strain localization zone appeared in the initial phase governed the range and trend of the whole process of the strain field development. There were four failure modes found in the test, that is the non-coalescence mode, the coalescence mode at inner tip of flaws, the coalescence mode at outer tip of fracture and the inner-outer tip coalescence mode. The bridge angle and the arrangements of flaws had the effect on the formation of strain localization zone in mesoscopic level and determined the cracking path and the failure mode in macroscopic level. The coalescence of strain localization zone in the bridge area resulted in a fluctuation of stress-strain curve before the peak and reduced the peak strength. The slower the coalescence of the strain localization zones, the higher the peak strength.
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Free vibration analysis of stepped rectangular plates resting on non-homogeneous elastic foundations 査読あり
Huang M., Sakiyama T., Matsuda H., Morita C.
Engineering Analysis with Boundary Elements 50 180 - 187 2015年1月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Engineering Analysis with Boundary Elements
© 2014 Elsevier Ltd. A Half Boundary Method (HBM) is proposed for analyzing the free vibration problem of rectangular plates with stepped thickness resting on non-homogeneous elastic foundations. The unknown quantities of the method exist only on half of the boundary. The non-homogeneous elastic foundation discussed here consists of two-segment elastic Winkler foundation. The fundamental differential equations are established for the bending problem of the plate on elastic foundations. The Green function, which is obtained by transforming these differential equations into integral equations and using numerical integration, is used to establish the characteristic equation of the free vibration. The effects of the modulus of the foundation, the stepped thickness and aspect ratio on the frequency parameters are considered. By comparing the present numerical results with those previously published, the efficiency and accuracy of the present method are investigated.
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Existing bridge structural identification by vibration measurements using Laser Doppler Velocimeter 査読あり
Makino K., Morita C., Matsuda H., Sumitro P., Yanai S.
Bridge Maintenance, Safety, Management, Resilience and Sustainability - Proceedings of the Sixth International Conference on Bridge Maintenance, Safety and Management 2190 - 2196 2012年7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） 出版者・発行元：Bridge Maintenance, Safety, Management, Resilience and Sustainability - Proceedings of the Sixth International Conference on Bridge Maintenance, Safety and Management
Nowadays in Japan, there is an increasing demand to investigate those suspicious structural-degraded-bridges which were constructed in 1970s. In common, those bridges are investigated by simple inspections such as visual inspections and hammer tests. Cons of the above mentioned method are less-objective, accuracy insufficiency and lack of promptness. Moreover, there are some difficulties to evaluate current load carrying capacity and earthquake resistance of aging-bridges due to unavailability of design drawings. Thus, the vibration measurement method is utilized simply to evaluate bridge's structural performance. Structural properties are mainly influenced by fatigue, material deterioration and earthquakes. These factors cause the changes of characteristic frequency due increasing of lateral displacement and decreasing of stiffness. Therefore, damage identification of a structure can be assessed by grasping its vibrational property. Conventional vibration measurement was generally conducted by using accelerometers. This consumed a lot time for cabling, installation and dismantling sensors and cable, and rather than that, efficiency and safety issues remained, especially, in case of installation at dangerous spots during a post-disaster or emergency events. In view of above mentioned problems related to conventional measurement, a long distance, non-contact, and easily-assembled LDV (Laser Doppler Velocimeter) has been developed in recent years. Without requiring on-structure sensor installation and having huge flexibility under variety of measurement environments made LDV measurement technique attractive and to be considered as better than other non-destructive investigation methods. This study targeted in-service bridges by measuring their natural frequencies and displacements using two LDV devices. Measuring numerous spots with two LDV devises enables to achieve high accuracy and reliability to verify the most-scrutinized structural vibration mode shape. Furthermore, the field-measured-based analyzed results were compared with three-dimensional FEM model analyses to evaluate the validity of the analytical model and to grasp the structural vibration characteristics of measured-bridges. © 2012 Taylor & Francis Group.
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Study on failure characteristic of rock-like materials with an open-hole under uniaxial compression 査読あり
Zhao C., Matsuda H., Morita C., Shen M.
Strain 47 ( 5 ) 405 - 413 2011年10月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Strain
The failure strength model of brittle materials with a pre-existing open-hole defect is proposed in this paper. A modified Sammis-Ashby model is deduced, in which it can be used to calculate the peak strength of brittle materials. It shows the law between peak strength Ïpand independent variable Î, which is the ratio of open-hole radius (a) to half-width of the specimen (t). Moreover, numerical and experimental investigations on failure process of rock-like materials with an open-hole imperfection were carried out. In the experiments, 3D-digital image correlation method, an optical technique which utilises the full-field and non-contact measurement, was employed. A progressive elastic damage method realistic failure process analysis (RFPA) was used in the numerical investigation to inspect and verify the modified model and simulate the failure process. The investigation finds that there are good correlations between the experimental, numerical and theoretical results. Moreover, because of the influences of boundary conditions, shear failure type was obtained both experimentally and numerically. © 2010 Blackwell Publishing Ltd.
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Morita C., Zhao C., Demizu A., Makino K., Matsuda H., Ichimiya K.
Bridge Maintenance, Safety, Management and Life-Cycle Optimization - Proceedings of the 5th International Conference on Bridge Maintenance, Safety and Management 2550 - 2556 2010年12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） 出版者・発行元：Bridge Maintenance, Safety, Management and Life-Cycle Optimization - Proceedings of the 5th International Conference on Bridge Maintenance, Safety and Management
Cylindrical shells are widely used in the most diverse branches of civil engineering technologies because of they combine light weight with high strength. However the buckling strength and postbuckling behavior prediction are extremely complex especially for thin-walled ones. Initial geometric imperfections are normally known to have a strong detrimental on the buckling strength and to be the reason of large discrepancy between experimental buckling loads and theoretical predictions. Moreover random imperfections in real shells are not known at the stage of design and may take a complex form. In order to investigate the effects of geometric imperfections on the buckling strength and post-buckling phenomena of thinwalled cylinders, these investigations were carried out both experimentally and numerically. In present paper, a general and simple approach is proposed for modeling the geometric imperfection of thin-walled shell specimens by utilizing 3-D digital image correlation method (DICM), an optical non-contact and full-field measurement. Realistic geometric imperfection of thin-walled shell specimens were obtained and applied in numerical simulation, the thickness of specimens used in this experiment is 0.131mm and the ratio of external diameter (R) to thickness (H) R/H is 250. Procedures of scanning on the geometric imperfection of thin-walled shell specimen and its application in numerical simulation are described detailed in this paper. The experimental investigation agrees well with the numerical simulation on both the strength and buckling behaviours. Therefore by using this effective approach the potential of strength capacity can be tapped in real thin-walled shell structures and it is demonstrated the visualization of buckling behaviors with initial random geometric imperfections by using this digital image correlation technique. © 2010 Taylor & Francis Group, London.
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Free vibration analysis of continuous rectangular plates 査読あり
Huang M., Ma X., Sakiyama T., Matsuda H., Morita C.
Journal of Sound and Vibration 329 ( 4 ) 485 - 496 2010年2月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Sound and Vibration
Vibration characteristics of rectangular plates continuous over full range line supports or partial line supports have been studied by using a discrete method. Concentrated loads with Heaviside unit functions and Dirac delta functions are used to simulate the line supports. The fundamental differential equations are established for the bending problem of the continuous plate. By transforming these differential equations into integral equations and using the trapezoidal rule of the approximate numerical integration, the solution of these equations is obtained. Green function which is the solution of deflection of the bending problem of plate is used to obtain the characteristic equation of the free vibration. The effects of the line support, the variable thickness and aspect ratio on the frequencies and mode shapes are considered. By comparing the numerical results obtained by the present method with those previously published, the efficiency and accuracy of the present method are investigated. © 2009.
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Natural vibration study on rectangular plates with a line hinge and various boundary conditions 査読あり
Huang M., Ma X., Sakiyama T., Matsuda H., Morita C.
Journal of Sound and Vibration 322 ( 1-2 ) 227 - 240 2009年4月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Sound and Vibration
A discrete method is proposed for analyzing the natural vibration problem of rectangular plates with a line hinge. The fundamental differential equations and the solutions of these equations are derived for two parts of the plate, which are obtained by dividing the plate along the line hinge. By transforming these equations into integral equations, and using numerical integration and the continuous conditions along the line hinge, the solutions of the whole plate can be expressed by the unknown quantities on the boundary and the quantities of the rotation along the hinge. The Green function of the deflection problem is used to obtain the characteristic equation of the free vibration. The effects of the position of the line hinge, the aspect ratio, the thickness ratio and the boundary condition on the natural frequency parameters are considered. By comparing the numerical results obtained by the present method with those previously published, the efficiency and accuracy of the present method are investigated. © 2008 Elsevier Ltd. All rights reserved.