Interaction among Flexural, Local, and Out-of-Plane Bucklings in Hysteretic Behavior of Steel Braces

Research Project

Project/Area Number	08455259
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Research Field	Building structures/materials
Research Institution	KYOTO UNIVERSITY
Principal Investigator	NONAKA Taijiro Kyoto Univ., Disaster Prevention Research Institute, Professor, 防災研究所, 教授 (60027224)
Co-Investigator(Kenkyū-buntansha)	IWAI Satoshi Disater Prevention Research Institute, Research Associate, 防災研究所, 助手 (60184850) NAKASHIMA Masayoshi Kyoto Univ.Disaster Prevention Research Institute, Associate Professor, 防災研究所, 助教授 (00207771)
Project Period (FY)	1996 – 1997
Project Status	Completed (Fiscal Year 1997)
Budget Amount *help	¥6,000,000 (Direct Cost: ¥6,000,000) Fiscal Year 1997: ¥1,300,000 (Direct Cost: ¥1,300,000) Fiscal Year 1996: ¥4,700,000 (Direct Cost: ¥4,700,000)
Keywords	Steel Structure / Brace / Wide-Flange Section / Experiment / Hysteresis / Lateral-Torsional Deformation
Research Abstract	The goal of this study is to quantify the hysteretic characteristics of steel braces that involve interaction among flexural, local, and out-of-plane bucklings. To obtain basic information on these characteristics a series of quasi-static loading tests were carried out, and accuracy and limitation of analytic solutions were examined through comparison between the experimental and analytical results. In the tests, two width-to-thickness ratios (to examine the effect of local buckling), two cross-sections (wide-flange and narrow-flange sections), four slenderness ratios (to examine the strength deterioration in the post-buckling range), and two ratios of eccentricity were chosen. It was found from the tests that (a) both in-plane and out-of-plane deformations were notable for narrow-flange sections, whereas for wide-flange sections, in-plane deformation was dominant in small deformations, out-of-plane deformation grew in medium magnitudes of deformation, and again in-plane deformation promoted in large deformations ; (b) out-of-plane deformation including significant torsion was more pronounced for larger slenderness ratios ; (c) shorter braces broke earlier (with smaller ductility) due to the growth of local deformation ; and (d) strong correlation was observed between the breakage and cumulative plastic strain. Comparison between the test and analysis revealed that both the maximum strength and strength degradation in the post-buckling range can be estimated reasonably by the analysis, and the analysis can trace the hysteresis when in-plane deformation dominates, but the analysis fails in tracing the hysteretic behavior of braces in which out-of-plane deformation is large.