STABILITY INDEX AND EFFECTIVE LENGTH FACTOR

• KIDO Masae

  Faculty of Environmental Eng., The University of Kitakyushu

• TSUDA Keigo

  The University of Kitakyushu

Bibliographic Information

Other Title

• 安定性指標と座屈長さ係数
• Examination in two-span plane frames
• －2スパン平面骨組における検討－

Abstract

1. Introduction The objective of this study is to examine the properties of the stability index SI, and the relations among the effective length factors obtained from different buckling conditions. Overview of the relations among the stability indexes (SI and _GSI) and the effective length factors (γ_exact, _SIγ, _SIγ *, _Gγ, _Gγ˜ and _Gγ˜* ) is shown in Fig. 1. The targets are rectangular 2-span plane frames, and total 96 frames are examined, taking the condition of the column base, number of story, stiffness ratio, stiffness ratio reduction factor and distribution of the story shear as the parameters.   2. Stability index and effective length factors Stability indexes SI and _GSI are calculated by Eqs. (1) and (12). For the overall structural system, the effective length factors _SIγ and _Gγ˜ are calculated by Eqs. (5) and (17), respectively. For the buckling of the story, the effective length factors _SIγ* and _Gγ˜* are calculated by Eqs.(9) and (19), respectively. The exact effective length factors γ_exact are calculated by the buckling slope-deflection method or the finite element method.   3. Results Effects of story shear distribution and column base are shown in Figs. 6, 7 and Fig. 8, respectively. Comparison between the stability index SI obtained by the first-order lateral load elastic analysis and approximate _GSI obtained by G factor is shown in Figs. 9, 10, 11, and 12. Comparison of effective length factor between _SIγ and γ_exact is shown in Fig. 13, and comparison of effective length factor between _Gγ˜ and γ_exact is shown in Fig. 14.   4. Conclusions The conclusions derived from this study are as follows: 1) The effects of the story shear distribution on the stability index are hardly observed (see Figs. 6 and 7). For frames with four stories or more, the stability index above the 4th story is almost same among the fixed base and pin base frame (see Fig. 8). 2) In the intermediate-stories, the approximate stability index _GSI obtained by G factor can be applicable as the stability index (see Figs. 9 10, 11, and 12). 3) The buckling-associated-story obtained from stability index _GSI agrees well with that obtained from stability index SI (see Table 3). 4) Effective length factors obtained by using the stability index agree fairly well with the exact factors about within 5% error (see Fig. 13). 5) The effective length factors _Gγ˜ estimate the exact values γ_exact up to 1.12 times (fixed base) and 1.2 times (pin base) (see Fig. 14). 6) In the intermediate-stories, the effective length factors _Gγ˜* can estimate the factors _SIγ*.

Journal

• Journal of Structural and Construction Engineering (Transactions of AIJ)

  Journal of Structural and Construction Engineering (Transactions of AIJ) 86 (786), 1259-1270, 2021-08-30

  Architectural Institute of Japan

Keywords

• PΔ effect
• frame stability
• amplification factor
• effective length factor
• stability index

Details

• CRID: 1390852174972328704
• NII Article ID: 130008080425
• DOI: 10.3130/aijs.86.1259
• ISSN: 18818153
• ISSN: 13404202
• Web Site: https://www.jstage.jst.go.jp/article/aijs/86/786/86_1259/_pdf
• Text Lang: ja
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed