Strength deterioration of circular CFT columns with constant cyclic deflection

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04715
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 23010:Building structures and materials-related
• Research Institution: The University of Kitakyushu
• Principal Investigator: Kido Masae 北九州市立大学, 国際環境工学部, 准教授 (10453226)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 鋼・コンクリート合成構造 / 長周期地震動 / 構造性能 / 耐力劣化

Outline of Final Research Achievements

The purpose of this research is to clarify the effects of the compressive axial force (axial force ratio), the amplitude of the deformation (rotation angle of the member) and the proportion of cross-section (section depth-thickness ratio) on the strength deterioration of concrete filled circular steel tube columns subjected to cyclic loading like the long-period ground motion.
In the case of the section depth-thickness ratio 37, the relationship between the rotation angle and the limit number of repeated cycles is linear on the logarithmic axis based on the results of this research and previous studies. This relationship was formulated by the least-squares method, and we investigated if the Miner’s rule held. The formula evaluated the experimental value conservatively. In the case of the section depth-thickness ratio 45, the strength deteriorated more than the section-depth-thickness ratio 37.

Free Research Field

建築構造

Academic Significance and Societal Importance of the Research Achievements

本研究では，超高層事務所建築物に多用されているコンクリート充填鋼管柱（以後CFT柱と称す）のうち，断面形状が円形の場合を対象とし，南海トラフを震源域とした大地震により起こる長周期地震動を想定した多数回繰返し実験を，柱部材を取り出したモデルにより行い，耐力劣化挙動に及ぼす軸力比，揺れの大きさ，断面寸法の影響を明らかにした．円形CFT柱に関する実験的研究は少なく，耐力劣化挙動に及ぼす影響は定性的にしかわかっていなかったが，本研究により定量的に明らかにすることができた．本研究成果は，長周期地震動も考慮した設計に役立てることができる点で社会的意義がある．