2001 Fiscal Year Final Research Report Summary
Correlation Between Loading Rate, Temperature Rise, and Material Properties Changes in Plastic Rotation Capacity of Steel Welded Beam-to-Column Connections
| Project/Area Number |
12450224
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Building structures/materials
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
NAKASHIMA Masayoshi Disaster Prevention Research Institute, Prof., 防災研究所, 教授 (00207771)
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| Co-Investigator(Kenkyū-buntansha) |
MORI Yasuhiro Graduate School of Engineering, Nagoya Univ., Assoc. Prof., 大学院・工学研究科, 助教授 (30262877)
MINAMI Fumiyoshi Graduate School of Engineering, Osaka Univ., Assoc. Prof., 大学院・工学研究科, 助教授 (60135663)
HOKOI Shuichi Graduate School of Engineering, KYOTO UNIVERSITY, Prof., 大学院・工学研究科, 教授 (80111938)
KANAO Iori Disaster Prevention Research Institute, JSPS Research Fellow, 防災研究所, 特別研究員(PD)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Steel Beam-to-Column Connections / Plastic strain / Heat Input / Fracture Toughness / Ductility Capacity / Heat Conduction |
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| Research Abstract |
This study focuses on the quantification of complex interaction between loading rate, temperature rise, and material's property changes regarding the plastic rotation capacity of steel welded beam-to-column connections.The background of this study is the possible linkage, starting from dynamic loading, energy dissipated by plastificatiori, conversion of the dissipated energy to thermal energy, temperature rise due to thermal energy, change in material's toughness caused by the temperature rise, change in material's ductility, and eventual change in plastic rotation capacity of connections. To this end, dynamic loading tests applied to real-scale beam-to-column subassemblages, detailed nonlinear finite element analysis, and numerical heat conduction analysis were conducted, and the following findings were obtained.
(1) Cumulative plastic strains and temperature-rise are correlated strongly ; the classical hypothesis that the plane section remains plane is not applicable in the proximity
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of beam end ; and vertical stiffeners arranged to avoid local buckling also altered the local strain distributions.
(2) Detailed nonlinear finite element analysis supported the experimental findings, and it was found that the primary reasons for complexity of strain distributions are the flexibility of column flange (in its out-of-plane bending) and the existence of weld access holes.
(3) The heat conduction analysis indicated that heat convection to air is negligible in the loading rate expected during earthquakes but that heat transfer within the steel material is conspicuous. The analysis also verified that the temperature rise in the very proximity of beam end is smaller than the temperature rise in regions slightly away from the end, and it is due to the existence of the non-plastified column attached to the beam end.
(4) Proposed also was a procedure to estimate the thermal energy distributions (i.e., the cumulative plastic strain distribution) from the measurement of temperatures at discrete locations. This procedure is to provide a new, reliable measuring index for the purpose of structural health monitoring. Less
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