Effects of Geometric Imperfections on Flexural Buckling Resistance of Laterally Braced Columns
Publication: Journal of Structural Engineering
Volume 142, Issue 9
Abstract
This paper deals with the effects of geometric imperfections on flexural inelastic buckling resistance of axially loaded columns with equally spaced lateral braces and presents a simplified way of forming the critical geometric imperfection for finite-element analyses, which leads to rational results for buckling resistances. First, laterally braced columns with geometric imperfections formed by the traditional single half sine wave or the eigenbuckling modes were analyzed by FEM to illustrate the effect of different imperfection shapes. Second, geometric imperfections of columns acquired from measurements in laboratory tests were adopted, and the statistical characteristic and probability distribution of initial deflections along the column length were obtained; then, extensive numerical results from finite-element analyses were obtained through random imperfection simulations. Last, the comparison was made between statistical results based on the random imperfections and those based on eigenbuckling modes to propose a critical geometric imperfection shape as a linear superposition of a limited number of scaled eigenbuckling modes, making it possible to obtain a rational buckling resistance result by one-time analysis, which is safe but not too conservative. The commonly used lowest eigenbuckling mode or equivalent sine shape for initial geometric imperfections do not provide a rational prediction for the inelastic buckling resistance of laterally braced columns. The critical geometric imperfection shape presented in this paper can be used in advanced analysis for inelastic buckling resistance of braced columns.
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Acknowledgments
This work has been supported by the National Natural Science Foundation of China (Grant No. 51278273) and the China Postdoctoral Science Foundation (Grant No. 2012M5104 57) awarded to the first author.
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Published In
Journal of Structural Engineering
Volume 142 • Issue 9 • September 2016
Copyright
© 2016 American Society of Civil Engineers.
History
Received: May 24, 2015
Accepted: Jan 5, 2016
Published online: Mar 22, 2016
Discussion open until: Aug 22, 2016
Published in print: Sep 1, 2016
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