Iterative system buckling analysis, considering a fictitious axial force to determine effective length factors for multi-story frames

Choi, Dongho; Yoo, Hongki

doi:10.1016/j.engstruct.2008.10.008

Cited by 13 publications

(8 citation statements)

References 24 publications

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“…For LC 1, the buckling loads and the K-factors of columns in all stories are the same since all columns have the same axial forces. As can be seen in Tables 7 to 9, the present results agree very well with those by Choi and Yoo (2009) for α =0. It can also be found from Table 7 that the tangential forces make the buckling loads be increased by 21.14% and the K-factors be decreased by 9.13%.…”

Section: Three-bay Seven-story Framessupporting

confidence: 93%

“…For comparison, the results obtained by Choi and Yoo (2009), as a special case, who used the system buckling approach based on the numerical eigenvalue computation for the conservative frame (α =0) are presented. For LC 1, the buckling loads and the K-factors of columns in all stories are the same since all columns have the same axial forces.…”

Section: Three-bay Seven-story Framesmentioning

confidence: 99%

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System buckling analysis for multi-story frames subjected to nonconservative forces

Kim

Choi

2015

Int J Steel Struct

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The evaluation of the effective length factor (K-factor) of columns based on the system buckling approach is a convenient tool in the stability design of multi-story frames. This method is superior to other analytical approaches, such as isolated subassembly and story-based approaches, in that inter-column and inter-story interactions are inherently taken into account. In this study, in order to investigate the effect of nonconservative forces on buckling loads and K-factors for the single-and multistory framed structures, the system buckling approach is presented. For this purpose, the finite element model, based on the Hamilton's principle, is formulated for the stability analysis of framed structures subjected to nonconservative forces. In numerical examples, buckling loads and K-factors for single-and multi-story frames subjected to conservative or nonconservative forces are evaluated and compared with those obtained by other researchers. Especially the effect of the stiffness ratio of girder to column on K-factors is investigated for nonconservative systems.

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Section: Three-bay Seven-story Framessupporting

confidence: 93%

Section: Three-bay Seven-story Framesmentioning

confidence: 99%

System buckling analysis for multi-story frames subjected to nonconservative forces

Kim

Choi

2015

Int J Steel Struct

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“…For braced frames, critical force of each story is the minimum one of critical forces of columns in the story. For unbraced frames, story critical forces can be obtained by story-buckling method (Yura [11], White and Hajjar [12], Xu and Liu [13], Choi and Yoo [14]). For the load distribution in Frame Type 1, 2 and 4, the story critical force is given by…”

Section: Calculation Of Critical Load Using Modified Approachesmentioning

confidence: 99%

Modified Approaches for Calculation of Effective Length Factor of Frames

Chen¹,

Chuan²

2015

Volume 11 Number 1

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As a crucial factor for stability calculation of frames, the effective length factor is generally determined by the traditional approaches in most current design codes, but some assumptions imposed do not reflect the real frame buckling behaviors. In this paper modified approaches are proposed based on the change of some unreasonable assumptions of the traditional approaches mainly in two aspects. Firstly, the premise that all frame columns buckle simultaneously is changed into an individual column buckling mode in braced frames, or story buckling mode in both braced and unbraced frames. Secondly, actual distribution of axial forces of columns is taken into account, so that the stability functions of columns may not be identical. Moreover, approximate formulas for calculation of the effective length factor are obtained based on the modified approaches, by which a series of numerical analysis is carried out. Numerical analysis results demonstrate that the modified approaches improve the accuracy well compared with the traditional ones.

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“…On the other side, the concept of inelastic buckling analysis was also applied to the numerical method. By utilizing empirical column strength curves and the stiffness reduction factor, iterative eigenvalue analysis was performed by several researchers (Iwasaki, 2001;Choi and Yoo, 2009;Choi et al, 2005;Choi et al, 2007). Since this numerical method, which is based on simple eigenvalue analysis, can determine the effective lengths of all members in a frame only by utilizing the Euler buckling equation and the minimum eigenvalue of a system, the method may be effectively applied to complex threedimensional frames.…”

Section: Introductionmentioning

confidence: 99%

Iterative eigenvalue analysis for stability design of three-dimensional frames considering a fictitious axial force factor

Choi

Jung

et al. 2010

International Journal of Steel Structures

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In design of steel frames, it is well known that the Euler buckling equation with eigenvalue analysis may lead to unexpectedly large effective lengths of members that have relatively small axial force. This paper illustrated the use of a fictitious axial force factor to overcome the problem mentioned above. Considering a fictitious axial force factor, the illustrated method determines the elastic and inelastic effective lengths of each member in three-dimensional steel frames based on iterative schemes and the stiffness reduction factors. To verify the validity of the illustrated method, the effective lengths of example frames by the proposed method were compared with those of previously established methods. The results show that the proposed method gives reasonable effective lengths of all members in space frames, and can be a good substitute for previously established methods.

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Iterative system buckling analysis, considering a fictitious axial force to determine effective length factors for multi-story frames

Cited by 13 publications

References 24 publications

System buckling analysis for multi-story frames subjected to nonconservative forces

System buckling analysis for multi-story frames subjected to nonconservative forces

Modified Approaches for Calculation of Effective Length Factor of Frames

Iterative eigenvalue analysis for stability design of three-dimensional frames considering a fictitious axial force factor

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