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Engineering educational research section Civil and Environmental Engineering Program |
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MORITA Chihiro
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Degree 【 display / non-display 】
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博士（工学） ( 1996.7 九州大学 )
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工学修士 ( 1990.3 長崎大学 )
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工学士 ( 1988.3 長崎大学 )
Research Areas 【 display / non-display 】
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Social Infrastructure (Civil Engineering, Architecture, Disaster Prevention) / Structure engineering and earthquake engineering
Papers 【 display / non-display 】
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Cyclic constitutive modeling of multiaxial elasto-plastic behavior in lean duplex stainless steel Reviewed
Horisawa E., Sugiura K., Kitane Y., Morita C.
Journal of Constructional Steel Research 246 2026.11
Publishing type：Research paper (scientific journal) Publisher：Journal of Constructional Steel Research
This study investigates the cyclic elasto-plastic behavior of structural stainless steels, including lean duplex stainless steel, under combined axial-torsional loading. Cyclic loading tests were conducted using thin-walled tubular specimens of SUS821L1 and SUS304. The experiments revealed anisotropic yield surfaces extended in the shear direction for the lean duplex stainless steel. Additionally, the stainless steels exhibited degradation of Young's modulus with plastic strain accumulation, and significant multiaxial ratcheting behavior. Based on these findings, a cyclic plasticity model was developed by extending the bounding-surface framework. The proposed model introduces three key mechanisms: anisotropic yield surface and the evolution of anisotropy, degradation of Young's modulus, and non-proportional hardening under multiaxial loading. Model parameters were identified through regression fitting of experimental data obtained under uniaxial and multiaxial cyclic loading. The model was validated by comparing predicted and measured stress-strain responses, including ratcheting behavior under cyclic axial strain with constant shear stress and cyclic shear strain with constant axial stress. The simulation results show peak stress differences within 6.6% for SUS821L1 and 8.8% for SUS304 under multiaxial loading conditions, confirming that the model can capture the influence of anisotropy and biaxial loading path on the cyclic response of stainless steels. This study provides a reliable basis for simulating the multiaxial deformation behavior of lean duplex stainless steel under variable loading conditions.
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Morimoto A., Nakano A., Morita C.
International Journal of Steel Structures 2026.9
Publishing type：Research paper (scientific journal) Publisher：International Journal of Steel Structures
Atmospheric exposure tests were conducted to evaluate the long-term corrosion behavior of Zn–30mass%Al thermal-sprayed coatings, Zn thermal-sprayed coatings, and hot-dip galvanized Zn coatings under different airborne salt environmental conditions, and an accelerated outdoor exposure test using artificial seawater was additionally carried out. The corrosion characteristics of each coating were assessed through surface appearance observation, coating thickness measurements, XRD patterns, and cross-sectional analysis using scanning electron microscopy and energy-dispersive X-ray spectroscopy. As a result, corrosion products were observed in all coatings, with distinct differences in their morphology and progression depending on coating composition and thickness. The Zn–30mass%Al thermal-sprayed coating exhibited negligible thickness reduction (< 5%) and no significant microstructural degradation, even under severe airborne salt conditions, demonstrating superior long-term corrosion resistance. In the case of Zn thermal-sprayed coatings, an oxide layer formed in environments subject to severe corrosion. Furthermore, the thinner the coating, the thicker the oxide layer formed, and more defects and voids were observed within the coating. A continuous decrease in the thickness of the hot-dip galvanized coating was observed at both test sites. It is believed that, because the coating surface is smooth, the oxide layer is easily removed by factors such as rainfall. The findings highlight the importance of coating composition and thickness in enhancing the durability of zinc-based protective coatings in airborne salt environments.
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STUDY ON CORROSION PREDICTION OF WEATHERING STEEL USING WAPPEN TYPE EXPOSURE TEST Reviewed
NAKASHIMA Kazutoshi, IMAI Atsumi, YASUNAMI Hiromichi, KANO Isamu, TAKAGI Masahide, MORITA Chihiro, IWASAKI Eiji
Japanese Journal of JSCE 82 ( 5 ) 2026.5
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society of Civil Engineers
The wappen-type exposure test is an exposure testing method that utilizes small and lightweight steel specimens and has primarily been used for assessing the condition of weathering steel bridges. This study summarizes the results of wappen-type exposure tests conducted on 51 bridges nationwide, presenting fundamental information on the trends, characteristics, and errors of the data obtained. Furthermore, taking into account the unique features of the wappen-type exposure test, we propose a simpler yet more accurate evaluation method as well as a standardized testing procedure.
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Axial-torsional testing and cyclic plasticity modelling of wire arc additively manufactured steel Reviewed International coauthorship
Horisawa E., Meng X., Gardner L., Kitane Y., Sugiura K., Morita C.
Journal of Constructional Steel Research 238 2026.3
Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Constructional Steel Research
Wire arc additive manufacturing (WAAM) is a metal 3D printing technique with the potential to produce structural steel elements in a cost-effective fashion. However, there is currently a paucity of data concerning the mechanical behaviour of WAAM steel under uniaxial and multiaxial cyclic loading. This study aims to address this gap via a comprehensive experimental investigation and constitutive modelling of the multiaxial cyclic behaviour of WAAM steel. Cyclic testing featuring axial and torsional loading was conducted on WAAM Grade ER70S-6 steel, and a constitutive model to describe the multiaxial cyclic behaviour of the examined material is proposed. First, radial loading in the biaxial stress plane was conducted to identify the shape of the initial yield surface and the strain development paths of the material. Uniaxial and biaxial cyclic loading tests were performed to investigate the hardening of the material. The experimental results show that WAAM steel exhibits a von Mises isotropic yield surface, with plastic strain developing in the direction normal to the yield surface. The proposed modified two-surface plasticity model accurately reproduces both the uniaxial and multiaxial cyclic stress-strain responses, while offering improved accuracy for the multiaxial ratcheting behaviour compared with the conventional model. The results of this study show that the classical plasticity theory used for conventional steel is also applicable to WAAM steel.
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Proposal for the structure and management method of a rapid-erectable emergency temporary bridge Reviewed
Hiraike Tsutomu, Sasaki Takanobu, Tomioka Yoshikazu, Honda Shuichi, Chikahiro Yuki, Watanabe Shinya, Watanabe Hiroshi, Hirasawa Hideyuki, Morita Chihiro
Journal of Structural Engineering, A 72A 818 - 830 2026.3
Authorship：Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society of Civil Engineers
Books 【 display / non-display 】
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Corrosion behavior of Al–based thermal–sprayed coatings for marine bridges
Morimoto A., Nakano A., Horisawa E., Morita C.（ Role： Joint author）
Moving Toward Smart Resilient and Sustainable Bridges 2026 （ ISBN:9781041311737, 9781041313687, 9781003778677 ）
Book type：Scholarly book
To ensure the durability of steel bridges exposed to marine atmospheric environments, the corrosion behavior of Zn–30 mass% Al thermal sprayed coating and Al–5 mass% Mg thermal sprayed coating was comparatively evaluated. A three-year atmospheric exposure test was conducted at two coastal sites in Okinawa and Miyazaki Prefecture. Furthermore, the effects of adhering salt deposits were investigated through an accelerated outdoor exposure test using artificial seawater. Zn-Al thermal sprayed coating produced white corrosion products, but no corrosion reaching the substrate was observed. On the other hand, with Al-Mg thermal sprayed coating, red rust formed on test specimens with a coating thickness of 30 µm, but no corrosion was observed on the substrate for coating thickness of 60 µm or greater. Although Okinawa Prefecture had a high level of airborne salt deposition, no significant differences were observed in the types of corrosion products. Based on these results, Zn–30 mass% Al thermal sprayed coating demonstrates stable corrosion protection performance for steel bridges in marine environments. When applying Al–5 mass% Mg thermal sprayed coating, it is important to ensure a coating thickness of at least 60 µm. These findings provide fundamental data for specifying coating systems for steel bridges exposed to marine environments.
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Mechanical behavior of thick coatings deposited by high-pressure cold spray
Horisawa E., Matsumura M., Matsumoto R., Morita C.（ Role： Joint author）
Moving Toward Smart Resilient and Sustainable Bridges 2026 （ ISBN:9781041311737, 9781041313687, 9781003778677 ）
Book type：Scholarly book
Cold spray is a coating technology in which supersonic powder particles form dense coatings with minimal thermal degradation, making it applicable to the corrosion protection of steel bridges. This study investigates its potential for the mechanical repair and reinforcement of steel structures by depositing thick coatings of 316L stainless steel and pure aluminum on carbon steel substrates. Coatings with a thickness of approximately 2.3 mm were successfully formed on round bars. Compression tests showed that the stainless steel coating exhibits significant strain hardening and a continuous yielding stress-strain curve, with an estimated elastic modulus of 136 GPa. In contrast, tensile tests showed that coatings underwent brittle fracture and delamination at low strains (0.14% to 0.21%), occurring almost simultaneously with substrate yielding. The estimated tensile elastic modulus was lower than the compressive one (78.4 GPa for stainless steel), which is attributed to the presence of internal pores and micro-cracks opening under tension.
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これだけは知っておきたい橋梁メンテナンスのための構造工学入門
委員長：岩城一郎 他（ Role： Joint author）
建設図書 2019.5
Language：Japanese Book type：Textbook, survey, introduction
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耐候性鋼橋梁の可能性と新しい技術
主査：山口栄輝 他（ Role： Joint author）
日本鋼構造協会 テクニカルレポート 2006.10
Language：Japanese Book type：Scholarly book
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ロマンを訪ねて～九州橋紀行
九州橋梁・構造工学研究会 主査：﨑元達郎 他（ Role： Joint author）
西日本新聞社 1995.7
Language：Japanese Book type：General book, introductory book for general audience
MISC 【 display / non-display 】
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進化するRC構造物の非破壊検査2003 非破壊検査の手法【目で見る】3D Invited
森田千尋，出水享
建築技術 ( 881 ) 101 - 102 2023.6
Authorship：Lead author, Corresponding author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal)
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進化するRC構造物の非破壊検査2003 非破壊検査の手法【表面で計測する】光学的ひずみ計測 Invited
森田千尋，出水享
建築技術 ( 881 ) 122 - 123 2023.6
Authorship：Lead author, Corresponding author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal)
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デジタル画像相関法を用いた橋梁の亀裂・変位・ひずみ計測に関する研究 Invited
出水享，松田浩，伊藤幸広，森田千尋
光技術コンタクト 60 ( 2 ) 32 - 39 2022.2
Authorship：Last author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal)
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「橋の日」の制定・活動と47都道府県橋の日運動の支援 Invited
森田千尋
土木学会誌 ( 8月 ) 60 - 61 2021.8
Authorship：Lead author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal)
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宮崎大学工学部で行った高校生「総合的な探究の時間」の評価
田村宏樹、森田千尋、盆子原康博、荒井昌和、菅本和寛、坂本眞人、石津貴弘
宮崎大学工学部紀要 49 17 - 22 2020.9
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (bulletin of university, research institution)
Presentations 【 display / non-display 】
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九州・山口地区における耐候性鋼橋梁の20年後の追跡調査
末田純聖，森田千尋，堀澤英太郎，中島和俊，安井賢太郎
令和7年度土木学会西部支部研究発表会
Event date： 2026.3.7
Language：Japanese Presentation type：Oral presentation (general)
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CFRPを用いたダム洪水吐ゲートの補強効果に関する研究
高野紗羽，森田千尋，堀澤英太郎，池田昌史
令和7年度公募型卒業研究テーマ成果発表会
Event date： 2026.2.19
Language：Japanese Presentation type：Oral presentation (general)
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Study on atmospheric corrosion properties of Zn-30mass% Al and Zn arc thermal sprayed coatings International conference
Ayame Morimoto, Atsushi Nakano, Chihiro Morita
The 13th International Symposium on Steel Structures & The 14th Pacific Structural Steel Conference 2025.11.21
Event date： 2025.11.19 - 2025.11.22
Language：English Presentation type：Oral presentation (general)
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低温溶射により肉盛された鋼材および溶射被膜の力学的特性
堀澤英太郎、松本理佐、松村政秀、森田千尋
土木学会第80回年次学術講演会 2025.9.11
Event date： 2025.9.10 - 2025.9.12
Language：Japanese Presentation type：Oral presentation (general)
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三次元計測技術を用いた鋼構造部材モデルの寸法精度の検証
細石波留斗、池内亮磨、森田千尋、堀澤英太郎、安井賢太郎、出水享
土木学会第80回年次学術講演会 2025.9.12
Event date： 2025.9.10 - 2025.9.12
Language：Japanese Presentation type：Poster presentation
Awards 【 display / non-display 】
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令和7年度公募型卒業研究テーマ成果発表会最優秀賞
2026.2 一般社団法人高等教育コンソーシアム宮崎 CFRPを用いたダム洪水吐ゲートの補強効果に関する研究
高野紗羽，森田千尋，堀澤英太郎，池田昌史
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
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令和6年度土木学会西部支部研究発表会優秀講演賞
2025.3 公益社団法人土木学会西部支部
永田琥太郎，中丸ゆかり，安井賢太郎，森田千尋，川畑琉皇，重井徳貴
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
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令和6年度土木学会西部支部研究発表会優秀講演賞
2025.3 公益社団法人土木学会西部支部
森本菖，森田千尋，中野敦，堀澤英太郎，押川渡，米沢昇
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
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令和6年度土木学会西部支部研究発表会優秀講演賞
2025.3 公益社団法人土木学会西部支部
宮崎琉太郎，森田千尋，中野敦，堀澤英太郎，博多屋智志，森本菖
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
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令和6年度土木学会全国大会第79回年次学術講演会優秀発表賞
2024.10 公益社団法人土木学会
森本菖，森田千尋，中野敦，堀澤英太郎，押川渡，米沢昇
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
Grant-in-Aid for Scientific Research 【 display / non-display 】
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耐候性鋼のさび外観評点区分の検討と三次元データを用いた橋梁の健全度評価手法の構築
Grant number：24K07642 2024.04 - 2027.03
独立行政法人日本学術振興会 科学研究費基金 基盤研究(C)
Authorship：Principal investigator
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3次元データを用いたインフラ構造物の点検・診断システムの高度化・高精度化
Grant number：22K04268 2022.04 - 2025.03
独立行政法人日本学術振興会 科学研究費基金 基盤研究(C)
Authorship：Coinvestigator(s)
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地方橋梁の三次元モデルの構築と効率的・効果的な復元設計による維持管理環境の創出
Grant number：20K04666 2020.04 - 2023.03
独立行政法人日本学術振興会 科学研究費補助金 基盤研究(C)
Authorship：Principal investigator
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橋梁狭隘箇所の変状認識を目的とするGNSSを採用したUAV自律航行システムの開発
Grant number：18K04305 2020.04 - 2021.03
科学研究費補助金 基盤研究(C)
Authorship：Coinvestigator(s)
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３次元データを用いたインフラ構造物の革新的点検・診断システムの開発
Grant number：19K04556 2019.04 - 2021.03
科学研究費補助金 基盤研究(C)
Authorship：Coinvestigator(s)
Available Technology 【 display / non-display 】
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多視点画像解析を用いた構造物の3次元モデル化と橋梁点検への活用
防食技術（溶射、機能性防錆塗装システム）の腐食性評価に関する研究
耐候性鋼橋梁の健全度評価手法に関する研究Home Page： 土木環境プログラム
Related fields where technical consultation is available：・橋梁（特に鋼橋梁）の点検、診断、補修・補強に関する内容
・構造物の構造解析、実験Message： 構造物（特に鋼橋梁）の維持管理に関する研究を行っています。これらに関するご相談に対応できると思います。
また、学び直し講座として、橋梁点検技術者養成講座を実施しています。