Papers - OBATA Makoto
-
Numerical approach to the ductile fracture of steel members Reviewed
M.OBATA, A.MIZUTANI, Y.GOTO
Proc. of the Second International Conference on Advances in Steel Structures, Hong Kong, China, December 15-17, 1999 2 1021 - 1027 1999.04
Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings)
-
The verification of plastic constitutive relation and its application to FEM analysis of plastic fracture of steel members Reviewed
M. OBATA, A. MIZUTANI, Y. GOTO
J. Struct. Engineering, JSCE 626 ( 626 ) 185 - 196 1999.04
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society of Civil Engineers
As observed in the Hyogoken Nanbu Earthquake, brittle fracture is often triggered by preceding ductile fracture of steel members. The estimation of ultimate behaviors and deformation capacity of steel structures, therefore, critically depends on the ductile characteristics of its members. However, no reliable numerical method to investigate the ductile fracture of members is available because of the lack of the understandings of the quantitative aspects of such material characteristics. The objective of this work is to show a basic approach to a practical numerical analysis of ductile fracture. In the present work, we determined Gurson's model parameters using the proposed method to show that the FEM analysis with Gurson's model could be a suitable tool for the estimation of ductility limit of steel members.
-
Mechanical behaviors of a shock absorbing bridge restrainer plate Reviewed
M. OBATA, T. KURIHARA, Y. GOTO
J. Structural Mechanics and Earthquake Engineering, JSCE 612 239 - 250 1999.04
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)
-
FEM analysis for hysteretic behavior of thin-walled columns Reviewed
Y. GOTO, Q. WANG, M. OBATA
J. of Struct Engrg., ASCE 124 1290 - 1301 1998.04
Language：English Publishing type：Research paper (scientific journal)
-
A rigorous method for the analysis of localization of axisymmetric buckling patterns in thick cylindrical shells Reviewed
Y.GOTO, C.ZHANG, Q.WANG, M.OBATA
Thin-walled structures 31 73 - 88 1998.04
Language：English Publishing type：Research paper (scientific journal)
-
The failure mechanism and the pull-out strength of a bond-type anchor near a free edge Reviewed
M. OBATA, M. INOUE, Y. GOTO
Mech. Mater. 28 113 - 122 1998.04
Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)
-
Y. GOTO, Q. WANG, N. TAKAHASHI, M. OBATA
J. Structural Mechanics and Earthquake Engineering, JSCE 591 189 - 206 1998.04
Language：Japanese Publishing type：Research paper (scientific journal)
-
Cyclic loading test on steel pier base-to-footing connections with small edge distance Reviewed
Y. GOTO, T. KAMIJO, H. FUJIWARA, M. OBATA
J. Struct. Engineering, JSCE 44A 1271 - 1280 1998.04
Language：Japanese Publishing type：Research paper (scientific journal)
-
M. OBATA, A. MIZUTANI, Y. GOTO
J. Struct. Engineering, JSCE 44A 29 - 36 1998.04
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)
-
FEM analysis for hysteretic behavior of thin-walled columns Reviewed
Yoshiaki Goto, Qingyun Wang, Makoto Obata
Journal of Structural Engineering 124 ( 11 ) 1290 - 1301 1998
Language：English Publishing type：Research paper (scientific journal) Publisher：American Society of Civil Engineers (ASCE)
An accurate finite-element-method-based analysis to predict the ultimate hysteretic behavior of thin-walled steel columns subjected to seismic loading is presented in this paper. For this purpose, we develop the three-surface cyclic metal plasticity model. The three-surface model includes less material parameters and internal variables for the ease of its implementation in the finite-element method analysis. This model is characterized by a discontinuous surface inserted between the yield surface and the bounding surface. The discontinuous surface is used to express the yield plateau and the change of hardening coefficient. Most material parameters in the three-surface model can be determined by the tensile coupon test. However, three parameters independent of material types are calibrated by the existing cyclic loading test results of thin-walled steel columns. This is to improve the accuracy of this analysis specifically in the simulation of the localized buckling behavior, which accompanies extremely large plastic strains.
-
Effect of constitutive models on the hysteretic behavior of thin-walled steel bridge piers subjected to seismic loading Reviewed
Y.GOTO, Q.WANG, M. OBATA
Proc. of the 7th International Conference on Computing in Civil and Building Engineering, Seoul, Korea, August 19-21, 1997 1 381 - 386 1997.04
Language：English Publishing type：Research paper (international conference proceedings)
-
A new experimental method to determine elasto-plastic material parameters Reviewed
M.OBATA, A. MIZUTANI, Y. GOTO
Proc. of the 7th International Conference on Computing in Civil and Building Engineering, Seoul, Korea, August 19-21, 1997 2 805 - 810 1997.04
Language：English Publishing type：Research paper (international conference proceedings)
-
Prevention of the fall out of bridge girders by slit-type restrainers Reviewed
M.OBATA, T. KURIHARA, Y. GOTO
Proc. of the Second International Conference on Behavior of Steel Structures in Seismic Areas, Kyoto, Japan, Aug. 3-8, 1997 947 - 954 1997.04
Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings)
-
Localization of axisymmetric plastic buckling patterns in thick cylindrical shells under monotonic/cyclic loading Reviewed
C.H. ZHANG, Y. GOTO, K. ONO, M. OBATA
Proc. of the 5th International Colloquium on Stability and Ductility of Steel Structures, Nagoya, Japan, July 29-30, 1997 1 441 - 448 1997.04
Language：English Publishing type：Research paper (international conference proceedings)
-
Analysis of strain localization of solids under cyclic loading using a corner theory of plasticity Reviewed
M.OBATA, T. SHOJI, Y. GOTO
Proc. of the 5th International Colloquium on Stability and Ductility of Steel Structures, Nagoya, Japan, July 29-30, 1997 2 817 - 824 1997.04
Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings)
-
A new experimental method to determine elasto-plastic material parameters Reviewed
M Obata, A Mizutani, Y Goto
PROCEEDINGS OF THE SEVENTH INTERNATIONAL CONFERENCE ON COMPUTING IN CIVIL AND BUILDING ENGINEERING, VOLS 1-4 2 805 - 810 1997
Language：English Publishing type：Research paper (international conference proceedings) Publisher：TECHNO-PRESS
The objective of this work is to propose a new experimental method to amend the current shortcomings regarding the determination of material parameters with the aids of FEM-based inverse analysis. The outline of the proposed method is as follows. In uni-axial tension test, we use a non-standard specimen that allows non-uniform deformation, Instead of strain, we measure displacement between appropriate two points together with external load. So obtained load-displacement curve indirectly reflects all the consequences of multi-axial plastic deformation. Then, we apply FEM-based inverse analysis to obtain the material parameters to reproduce the closest load-displacement curve to the observed one. This method provides a consistent way to determine the material parameters by a simple uniaxial test.
-
Effect of constitutive models on the hysteretic behavior of thin-walled steel bridge piers subjected to seismic loading Reviewed
Y Goto, QY Wang, M Obata
PROCEEDINGS OF THE SEVENTH INTERNATIONAL CONFERENCE ON COMPUTING IN CIVIL AND BUILDING ENGINEERING, VOLS 1-4 1 381 - 386 1997
Language：English Publishing type：Research paper (international conference proceedings) Publisher：TECHNO-PRESS
We herein present a three surface cyclic steel plasticity model and implement it in the FEM analysis in order to predict the ultimate hysteretic behavior of thin-walled steel columns subjected to seismic loading, The three-surface model is devised to include less material parameters and internal variables for the ease of its implementation in FEM. This model is characterized by two parameters independent of material types which is calibrated by the cyclic loading tests for thin-walled steel columns, These two parameters are used to improve the accuracy of our analysis specifically in the simulation of the local buckling behavior under extremely large plastic strains.
-
Effect of free edge on the pull-out strength of bond type anchor bolt Reviewed
M. OBATA, M. INOUE, Y. GOTO
J. Struct. Engineering, JSCE 42A 1131 - 1138 1996.04
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)
-
Experimental stduy of energy absorbing restrainer tie plates Reviewed
M. OBATA, K. OHMI, Y. GOTO
J. of Construction Steel 4 385 - 390 1996.04
Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)
-
Analysis of the ultimate behavior of a slit-type bridge restrainer Reviewed
M. OBATA, T. KURIHARA, Y. GOTO
Proc. of International Conference on Advances in Steel Structures, Hong Kong, December 11-14, 1996 1 559 - 564 1996.04
Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings)
