Gakuji NAGAI
Research Associate, Institute of Industrial Science, The University of Tokyo
Japanese | English

Last update on April 9, 2002

A member of Prof. Katsuhiko WATANABE's Lab. (Institute of Industrial Science, The University of Tokyo)


 My Dissertation

"Finite Element Procedure for Failure Simulation of Mesoscopic Structure in Concrete Materials"
supervised by Assoc. Prof. Takahiro YAMADA (Yokohama National University) and Prof. A. Wada (Structural Engineering Research Center, Tokyo Institute of Technology)
 

Motivation

Objective

Approach

Current Status

The first stage of the nonlinearity before commpressive peak can be simulated.
  • Movie (QuickTime 2.2MB) of tensile damage progression on the interfaces between coarse aggregates and mortar with macroscopic uni-axial compression applied. (Currently, tensile failures on the interfaces are only modeled in the sense of continuum iso-tropic damage model)
  • Future Works

    All is to capture the compressive peak in macoroscopic scale only with tensile failures in mesoscopic scale and furthermore to simulate post-peak behaviors


    Publications & Presentations

    Some papers are available in pdf format and all presentations are automatically generated by MS-PowerPoint

    Journal papers

    in English

    1. G. Nagai, T. Yamada and A. Wada: "Accurate Modeling and Fast Solver for the Stress Analysis of Concrete Materials Based on Digital Image Processing Technique", International Journal for Computational Civil and Structural Engineering, Vol. 1, 2001 in printing (paper)
    2. J. Fish, W. Chen and G. Nagai: "Nonlocal Dispersive Model For Wave Propagation In Heterogeneous Media. Part 1: One-Dimensional Case", International Journal for Numerical Methods in Engineering, 2001 (submitting)
    3. J. Fish, W. Chen and G. Nagai: "Nonlocal Dispersive Model For Wave Propagation In Heterogeneous Media. Part 2: Multi-Dimensional Case", International Journal for Numerical Methods in Engineering, 2001 (submitting)
    4. in Japanese

    5. G. Nagai, T. Yamada and A. Wada: "On a Finite Element Procedure Based on the Real 3-Dimensional Image for Concrete Materials", Journal of Structural and Construction Engineering (Transactions of AIJ), No. 509, pp. 77-82, 1998.7
    6. G. Nagai, T. Yamada and A. Wada: "On a Nonlinear Finite Element Analysis Procedure Based on Hierarchical Digital Image for Concrete Materials with Consideration of Coarse-Aggregates-and-Mortar Interface",Journal of Structural and Construction Engineering (Transactions of AIJ), No. 528, pp. 91-98, 2000.2

    Refereed conference papers

    in English

    1. G. Nagai, T. Yamada and A. Wada: "Stress Analysis of Concrete Material Based on Geometrically Accurate Finite Element Modeling", Fracture Mechanics of Concrete Structures, Proceedings FRAMCOS-3 (eds H. Mihashi and K. Rokugo), AEDIFICATIO Publishers, pp. 1077-1086, 1998.10 (paper, presentation)
    2. in Japanese

    3. G. Nagai, T. Yamada and A. Wada: "Image-Based Finite Element Analysis of Compressive Failure of Concrete Materials", Proceedings of the Japan Concrete Institute, Vol. 21, No. 3, pp. 157-162, 1999.7

    Conference papers (not all)

      in English

    1. G. Nagai, T. Yamada and A. Wada: "Finite Element Analysis of Concrete Material Based on the 3-dimensional real image data", in CD-ROM, 4th World Congress on Computational Mechanics (WCCM4), Buenos Aires, 1998.7
    2. G. Nagai, T. Yamada and A. Wada: "Three-dimensional Nonlinear Finite Element Analysis of the Macroscopic Compressive Failure of Concrete Materials Based on Real Digital Image", 8th International Conference on Computing in Civil & Building Engineering (ICCCBE2000), pp. 449-456, California, 2000.8 (paper, presentation)
    3. G. Nagai, T. Yamada and A. Wada: "3-D Mesoscopic Failure Simulation of Concrete Materials by Using Image-Based Finite Element Method", The 20th International Congress of Theoretical and Applied Mechanics (ICTAM2000), Chicago, 2000.8 (poster)
    4. G. Nagai, T. Yamada and A. Wada: "A 3-D Finite Element Modeling of Mesoscopic Structure in Concrete Materials for Compressive Failure Simulation", Fracture Mechanics of Concrete Structures, Proceedings FRAMCOS-4 (eds R. de  Borst), AEDIFICATIO Publishers, 2001.5 (in preparing)
    5. in Japanese

    6. G. Nagai, T. Yamada and A. Wada: "Finite Element Analysis of Concrete Materials Based on Digital Image Data", Proceedings of the Conference on Computational Engineering and Science, Vol. 2, No. 3, pp. 1103-1106, 1997.5
    7. G. Nagai, T. Yamada and A. Wada: "Development of a Mixed Finite Element Containing Smooth Interface for Digital Image-Based Mesh", Proceedings of the Conference on Computational Engineering and Science, Vol. 3, pp. 393-396, 1998.5
    8. G. Nagai, T. Yamada and A. Wada: "Numerical Analysis of Macroscopic Compressive Behavior of Concrete Materials Caused by Tensile Failure in Microscopic Structure", Proceedings of the Conference on Computational Engineering and Science, Vol. 4, No. 2, pp. 729-732, 1999.5
    9. G. Nagai, T. Yamada and A. Wada: "Three-Dimensional Image-Based Finite Element Procedure for the Compressive Failure Simulation of Concrete Materials", Proceedings of the Conference on Computational Engineering and Science, Vol. 5, 2000.5

    Miscellaneous articles

    in Japanese

    1. G. Nagai, T. Yamada and A. Wada: "Numerical Modeling of Concrete Materials", KEISAN KOGAKU (Journal of the Japan Society of Computational Engineering and Science), Vol. 4, No. 3, pp. 18-23, 1999.9
    2. G. Nagai: Cover figure, Concrete Journal, Japan Concrete Institute, Vol. 37, No. 9, 1999.9
    3. T. Yamada and G. Nagai: "Mesoscopic Simulation of Concrete Materials by Using Image-Based Finite Element Method", Concrete Journal, Japan Concrete Institute, Vol. 38, No. 1, pp. 64, 2000.1


    Personal Resume

    Education

    April 1991 - March 1995
    Department of Architecture, Faculty of Engineering, Science University of Tokyo, Japan
    Bachelor degree of Engineering
    Graduation project: Development of a program for 3-D nonlinear analysis of building frames
    Keywords: Winkler Model, Fiber Beam Element
    April 1995 - March 1997
    Department of Environmental and Physical Engineering, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Japan
    Master degree of Engineering
    April 1997 - March 2000
    Department of Environmental and Physical Engineering, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Japan
    Doctor degree of Engineering
    Thesis: gFinite Element Procedure for Failure Simulation of Mesoscopic Structure in Concrete Materialsh (Compressed PDF files in Japanese)
    Keywords: 3-D, Composite Materials, Multi-Scale Problem, Digital Image Processing, Mixed Finite Element, Parallel Computing
    April 2000 - March 2001
    Research Fellow, Structural Engineering Research Center, Tokyo Institute of Technology, Japan
    July 2000 - May 2001
    Visiting Scholar, Dept. of Civil Engineering, Rensselaer Polytechnic Institute, USA

    Scholarships and Grants

    Awards

    Academic Memberships

    Institute of Industrial Science, University of Tokyo
    4-1-6, Komaba, Meguro, Tokyo 153-8505, JAPAN
    e-mail: gakuji@iis.u-tokyo.ac.jp
    phone/fax: +81-3-5452-6128/6129