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事務局
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OBATA Makoto
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Degree
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Ph.D. ( 1985.08 Northwestern University )
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Master of Science ( 1984.07 Northwestern University )
Research Areas
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Social Infrastructure (Civil Engineering, Architecture, Disaster Prevention) / Structure engineering and earthquake engineering
From School
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The University of Tokyo Faculty of Engineering Department of Civil Engineering Graduated
1978.04 - 1982.03
Country：Japan
From Graduate School
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Northwestern University Doctor's Course Completed
- 1985.03
Country：United States
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Northwestern University Master's Course Completed
- 1984.03
Country：United States
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The University of Tokyo Graduate School, Division of Engineering Master's Course Unfinished Course
- 1982
Country：Japan
External Career
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San Diego, California University Researcher
1985.04 - 1987.03
Country：United States
Research Career
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Simulation of corrosive environment of steel bridges
(not selected)
Project Year： 2008.04
Papers
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IMPROVEMENT OF STRESS-STRAIN RELATION UNDER MULTIAXIAL LOADING OF RUBBER FOR BEARINGS Reviewed
Makoto Obata, Takemasa Ebisawa, Yoshiaki Goto
Journal of Japan Society of Civil Engineers Ser A1 (Structural Engineering & Earthquake Engineering (SE/EE)) 76 ( 2 ) 320 - 330 2020.08
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society of Civil Engineers
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Makoto Obata, Taro Murakami
Kozo Kogaku Ronbunshu. A (Journal of Structural Engineering. A) 60 ( A ) 596 - 604 2014.04
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society of Civil Engineers
It is important to estimate corrosion environment of steel bridges for an appropriate corrosion prevention and maintenance program. Estimation of environment has heavily depended on insitu observation and many data have been collected. However, versatile numerical approaches to this problem has not fully pursued yet. To this end, observation of airborne sea salt particles was performed with a standard low volume sampler (JIS Z 8814) beginning from April, 2013 to August, 2013 in the city of Nagoya and compared analytical estimation. A meso scale meteorological analysis employed here is WRF-Chem Ver. 3.4. Although WRF uses land use and terrain data based on USGS by default, the data is sometimes incorrect in Japan and yields inaccurate results especially for wind. Introduction of more accurate land use and geographic data supplied by the Geospatial Information Authority of Japan improves accuracy of basic meteorological data and therefore concentration of airborne sea salt particles. Other factors affecting accuracy of airborne sea salt concentration will also be discussed.
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Global-local approach to numerical simulation of adhesion of seasalt particles on bridge girders Reviewed
Makoto Obata,Li Guotai, Yasunari Watanabe, Yoshiaki Goto
Journal of Structural Engineering A 58 668 - 678 2012.03
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society of Civil Engineers
It is important to estimate corrosion environment of steel bridges for a proper corrosion prevention and maintenance program. Adhered sea-salt particulate matter (SSPM) is an influential factor especially in coastal areas. To this end, it is better to know the adhesion behavior of SSPM to bridge girders. The objective of this manuscript is to pursue numerical method to simulate the adhesion behavior of salt particles oriented from sea surface. Specifically, two scale approach is proposed. Mesoscale Meteorological Analysis and Lagrangian type two phase flow analysis are used in global and local analyses respectively. The comparisons between the numerical and observed results showed that the numerical analysis can reproduce essential behaviors of airborne SSPM.
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Numerical analysis of fracture phenomena observed in a locally buckled circular steel column Reviewed
Hideyuki Fujiwara, Makoto Obata, Yoshiaki Goto
Journal of Structural Engineering A 58 310 - 318 2012.03
Language：Japanese Publishing type：Research paper (scientific journal)
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Construction of a practical finite element model from point cloud data for an existing steel truss bridge Reviewed
Nao Hidaka, Naofumi Hashimoto, Kazuya Magoshi, Tetsuya Nonaka, Makoto Obata, Ei Watanabe
Proceedings of 23° International Conference on Construction Applications of Virtual Reality 1155 - 1166 2023.11
Language：English Publishing type：Research paper (international conference proceedings)
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Construction analysis model of steel bridge by using point cloud data and accuracy verification Reviewed
Hidaka Nao, Hashimoto Yoshifumi, Nakamura Masaki, Magoshi Kazuya, Nonaka Tetsuya, Obata Makoto
Journal of structural engineering 69A 637 - 647 2023.04
Language：Japanese Publishing type：Research paper (scientific journal)
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YIELDING STEEL DAMPERS TO REPLACE CONCRETE SHEAR KEYS FOR SEISMIC RETROFIT OF BRIDGES WITH UNEQUAL HEIGHT PIERS Reviewed International coauthorship International journal
Nailiang Xiang, Y Goto, Makoto Obata, M. Shahria Alam, Jianzhong Li
Proc. 17th World Conference on Earthquake Engineering 2020.09
Language：English Publishing type：Research paper (international conference proceedings)
Irregular multi-span continuous bridges with unequal height piers are commonly adopted in mountainous areas when crossing steep-sided valleys. As common practice, economical unbonded laminated rubber bearings and concrete shear keys are usually installed in such bridges as superstructure-to-substructure connections. In strong earthquakes, the sliding of rubber bearings and the shear key failure are mostly expected, which may weaken the seismic resistance of the irregular bridges. The current study is mainly divided into three parts: the first one investigates the effect of concrete shear keys on the transverse seismic performance of the irregular bridges by incorporating the potential sliding of laminated rubber bearings; the second part proposes the concept of using yielding steel dampers to replace shear keys for mitigating the irregular seismic responses of the unequal height bridges with the practical design method being developed; the third part demonstrates the retrofit effectiveness by conducting nonlinear time-history analyses. The results indicate that the existence of concrete shear keys increases the bridge irregularity by inducing a significant in-plane superstructure rotation response around the vertical axis, posing nonuniform displacement demands at the substructures. The shear keys also contribute to the unbalanced ductility demands on the unequal height substructures, rendering the taller piers more vulnerable to the seismic damages. This differs from the case with fixed bearings, where the shorter piers are more subjected to damages. Using yielding steel dampers that are appropriately designed as per the proposed method, the seismic rotations of the bridge superstructure can be considerably mitigated with a relatively uniform superstructure movement maintained. The steel dampers are also effective in distributing the inertia forces among the unequal height piers. The effectiveness of yielding steel dampers replacing concrete shear keys in unequal height irregular bridges is successfully verified by the results from the numerical simulation.
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Shake-table tests of an innovative structural fusing system for small to medium-span highway bridges
Nailiang Xiang, Y Goto, Makoto Obata, M. Shahria Alam, Jianzhong Li
Proc. 17th World Conference on Earthquake Engineering 2020.09
Language：English
Irregular multi-span continuous bridges with unequal height piers are commonly adopted in mountainous areas when crossing steep-sided valleys. As common practice, economical unbonded laminated rubber bearings and concrete shear keys are usually installed in such bridges as superstructure-to-substructure connections. In strong earthquakes, the sliding of rubber bearings and the shear key failure are mostly expected, which may weaken the seismic resistance of the irregular bridges. The current study is mainly divided into three parts: the first one investigates the effect of concrete shear keys on the transverse seismic performance of the irregular bridges by incorporating the potential sliding of laminated rubber bearings; the second part proposes the concept of using yielding steel dampers to replace shear keys for mitigating the irregular seismic responses of the unequal height bridges with the practical design method being developed; the third part demonstrates the retrofit effectiveness by conducting nonlinear time-history analyses. The results indicate that the existence of concrete shear keys increases the bridge irregularity by inducing a significant in-plane superstructure rotation response around the vertical axis, posing nonuniform displacement demands at the substructures. The shear keys also contribute to the unbalanced ductility demands on the unequal height substructures, rendering the taller piers more vulnerable to the seismic damages. This differs from the case with fixed bearings, where the shorter piers are more subjected to damages. Using yielding steel dampers that are appropriately designed as per the proposed method, the seismic rotations of the bridge superstructure can be considerably mitigated with a relatively uniform superstructure movement maintained. The steel dampers are also effective in distributing the inertia forces among the unequal height piers. The effectiveness of yielding steel dampers replacing concrete shear keys in unequal height irregular bridges is successfully verified by the results from the numerical simulation.
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Passive seismic unseating prevention strategies implemented in highway bridges: A state-of-the-art review Reviewed International coauthorship International journal
Nailiang Xiang , Yoshiaki Goto, Makoto Obata, M. Shahria Alam
Engineering Strucures 194 77 - 93 2019.09
Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier
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Analysis of rubber bearing behavior with material deterioration Reviewed International journal
Makoto Obata, Yoshiaki Goto
Proceedings of ICASS2018 2018.12
Language：English Publishing type：Research paper (international conference proceedings)
Misc
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Closure to "Stability and ductility of thin-walled circular steel columns under cyclic bidirectional loading" by Yoshiaki Goto, Kunsheng Jiang, and Makoto Obata
Yoshiaki Goto, Kunsheng Jiang, Makoto Obata
JOURNAL OF STRUCTURAL ENGINEERING-ASCE 134 ( 5 ) 867 - 869 2008.05
Language：English Publisher：ASCE-AMER SOC CIVIL ENGINEERS
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Large-deformation analysis of flexible beams - Discussion
Y Goto, T Kasugai, M Obata
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 33 ( 9 ) 1369 - 1370 1996.04
Language：English Publishing type：Rapid communication, short report, research note, etc. (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD
Presentations
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Effects of Land Use Data on Numerical Simulation of Corrosive caused by airborne seasalt particles International conference
Masato Fukushima, Seiya Suzuki
ISSS2013 KAIST
Event date： 2013.11
Language：English Presentation type：Oral presentation (general)
Venue：Jeju, Korea
Corrosion of steel bridges in a coastal area is mainly caused by sea salt particles coming from ocean. Appropriate estimation of such airborne sea salt particles is critically important for a proper anticorrosion management program. At present, the most reasonable simulation of sea salt concentration can be performed as a part of meso scale meteorological analysis. However, accuracy of such simulation is not verified well so far. The objective of this work is to verify and to improve the accuracy of numerical simulation of airborne sea salt particles by introducing enhanced land use data. Other factors affecting accuracy of airborne sea salt concentration will also be discussed.
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土研式捕集タンクへの浮遊粒子の付着挙動の数値シミュレーション
小畑誠
土木学会全国大会 土木学会
Event date： 2013.09
Language：Japanese Presentation type：Oral presentation (general)
Venue：千葉県
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Numerical prediction of ductile crack initiation in a steel column under cyclic loading International conference
Makoto Obata, Hideyuki Fujiwara, Yoshiaki Goto
ASCCS
Event date： 2012.07
Language：English Presentation type：Oral presentation (general)
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局所および広域解析を組み合わせた付着塩分量推定法に関する研究
小畑誠，李国泰，渡辺泰成，後藤芳顯
構造工学シンポジウム 日本学術会議
Event date： 2012.04
Language：Japanese Presentation type：Oral presentation (general)
Venue：東京工業大学
本研究の目的は沿岸域での腐食環境の重要な因子のひとつである付着塩分量の数値的予測のためのひとつの枠組みを提示することにある．本研究では，ある構造物への付着塩分量を推定するために次のような2段階のアプローチを提案する．すなわち構造物の位置の浮遊塩分量は塩分粒子の発生と移流・拡散をより忠実に考慮するために気象解析と連動させる手法をとる．次にその結果をもとに局所的な流体解析を適用し一定期間内の橋梁の各部位に対する付着量を推定する．
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Numerical estimation of corrosion environment by airborne sea salt particles International conference
Liu Chenchen, Makoto Obata
GCCSEE Geoenviornmental Engineering Branch, Chinese Society for Rock Mechanics and Engineering
Event date： 2012.10
Language：English Presentation type：Oral presentation (general)
Venue：Yichang
Anticorrosion of steel bridges has been an increasingly important problem in Japan. For a proper anticorrosion and maintenance program, it is important to estimate corrosion environment of steel bridges. In Japan, airborne sea salt generated from ocean is a predominant factor. Authors have been working on establishing a consistent framework to estimate corrosion environment numerically. It consists of a local and a global approach. While adhesion of airborne sea salt particles to bridge structures are simulated locally by a CFD analysis, the large scale yields a boundary conditions of the local analysis and is given by a part of a mesoscale meteorological analysis. The objective of this work is to numerically investigate reliability of such large scale analysis in estimation of corrosion environment caused by airborne sea salt particles.
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沿岸部の飛来塩分量に及ぼすサーフゾーンの影響に関する研究
横井俊哉，小畑誠
土木学会全国大会 土木学会
Event date： 2012.09
Language：Japanese Presentation type：Oral presentation (general)
Venue：名古屋市
鋼橋や社会基盤構造物の腐食環境予測のために，当該地点での飛来塩分量を把握することが重要である．より合理的かつ柔軟な防蝕のためにはこれを数値的に予測できることが望ましい．日本の沿岸部での飛来塩分は海洋面由来のものであり，海洋面で発生し塩分粒子が風により輸送されることによりもたらされている．このため，著者らは飛来塩分量を気象現象と捉え，近年急速な発達をとげている数値気象モデルを用いて日本各地の飛来塩分量の推定することの可能性について検討を続けてきた．その結果，大まかな季節変動や地域的な変動については既存のモデルで再現しうることを示してきた．しかし，いくつかの観点から観測データをうまく説明できない場合があり，この原因として発生関数，砕波域の問題等について検討し，砕波域の導入の大枠について既に示してきた．ここではより詳細に検討する．
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円形断面鋼製橋脚を持つ連続高架橋模型の２方向加振実験による終局挙動のFE解析 International conference
海老澤健正，後藤芳顯，小畑誠，奥村徹，Li Jiangzhong
土木学会全国大会 土木学会
Event date： 2015.09
Language：Japanese Presentation type：Oral presentation (general)
Venue：岡山大学
１．はじめに： 連続高架橋のレベル 2 地震動に対する耐震設計では，通常，橋脚の損傷のみが許容されているた
め，従来の研究では橋脚単体の終局挙動に関するものがほとんどである．しかし，実際の連続高架橋では，橋脚－
支承(ゴム支承)－上部構造の相互作用が生じる．ここでは，これらの連成挙動をなるべく実状に即した形で再現し た 2 径間連続高架橋模型(s=1/6.7)を用いた水平 2 方向同時加振実験結果
1)に基づき，その終局挙動が FE 解析でどの
程度正確に予測できるかについて検討した．橋脚は円形断面鋼製橋脚を対象とする．橋脚の FE モデルは，すでに単柱橋脚を対象とした静的繰り返し実験 2)，振動台加振実験 3)により解析精度が 確認されている繰り返し構成則に三曲面モデル 4)を導入した非線形シェル要素で
離散化する．なお，高架橋における橋脚の終局挙動については，過去に多く検討 された連成効果のない単柱の加振実験(s=1/8)3)による挙動との比較も行う． -
マルチ振動台を用いた２径間連続高架橋模型の水平２方向加振実験
後藤 芳顯，海老澤 健正，奥村 徹，小畑誠
土木学会全国大会 土木学会
Event date： 2013.09
Language：Japanese Presentation type：Oral presentation (general)
Venue：千葉県
全般
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高解度地表面情報導入による飛来塩分量予測の改良
村上 太郎，福島 雅人，鈴木 誠也，小畑 誠
土木学会全国大会 土木学会
Event date： 2013.09
Language：English Presentation type：Oral presentation (general)
Venue：千葉県
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ゴム材料の弾塑性挙動における降伏曲面の歪みの影響
森井伸一，小畑誠，後藤芳顯
第75回土木学会全国大会 土木学会
Event date： 2019.09
Language：Japanese Presentation type：Oral presentation (general)
Venue：香川大学
橋梁の耐震設計においてはゴム支承が重要な役割を果たしており，その変形特性および破壊特性の的確な評価の必要性が高い．ゴム支承のそれらの特性を知るには数100%におよぶひずみの範囲での，超弾性および塑性挙動を正確に知る必要がある．著者らはこれまでに特にMullins効果に注目して応力ひずみ関係について検討を続けてきた．このとき，塑性モデルとしては移動および等方効果を導入した単純なJ_2流れ理論を用いたが，単純な一方向せん断の結果を再現する材料パラメータがとくにひずみの大きい領域において2方向載荷の結果を再現することができないという問題があった．本研究では塑性モデルに新に降伏曲面の歪みを導入してこの問題を検討する．
Industrial Property Rights
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被測定物の外形測定方法及び外形測定装置
「小畑誠」「後藤芳顯」
Application no：２００９-１０９１２８ Date applied：2009.04
Country of applicant：Domestic Country of acquisition：Domestic
Awards
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第２８回日本道路会議優秀論文賞
2009.10 日本道路協会
「宮本重信」，「北嶋浩」，「牧野芳行」，「奥村茂」，「小畑誠」，「永田和寿」，「篠原正」
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
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土木学会論文賞
2009.04 土木学会
「後藤芳顯」，「江坤生」
Award type：Honored in official journal of a scientific society, scientific journal Country：Japan
Committee Memberships
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土木学会 中部支部長
2019.06 - 2020.06
Committee type：Academic society
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土木学会 土木学会論文集編集委員会A1分冊編集委員長
2016.06 - 2018.06
Committee type：Academic society