Stability of Columns in Unbraced Frames
Publication: Journal of Structural Engineering
Volume 123, Issue 7
Abstract
A new design model is presented to derive expressions for the elastic effective length factors for columns in unbraced multistory frames. This model takes into account the effects of boundary conditions at the far ends of the columns above and below the column in question. According to the relative bending stiffness of the girders and columns framing at the far ends, the far end conditions can be modeled as rigid, hinged, or fixed. Because the alignment chart model is based on rigid-far-end conditions, it is not applicable in designing columns with either hinged or fixed-far-end conditions. This refined model rectifies inherent problems associated with currently available solutions caused by both the invalid assumption of constant story drift angles and the errors in mathematical formulation. Using the background of extensive numerical studies, a modified design procedure based on the alignment chart is suggested. The proposed design procedure is characterized by both simplicity and accuracy.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Chen, W. F., and Lui, E. M. (1987). Structural stability: theory and implementation. Elsevier Science Publishing Co., Inc., New York, N.Y.
2.
Chen, W. F., and Lui, E. M. (1991). Stability design of steel frames. CRC Press, Inc., Boca Raton, Fla.
3.
Duan, L., and Chen, W. F.(1988). “Effective length factor for columns in braced frames.”J. Struct. Engrg., ASCE, 114(10), 2357–2370.
4.
Duan, L., and Chen, W. F.(1989). “Effective length factor for columns in unbraced frames.”J. Struct. Engrg., ASCE, 115(1), 149–165.
5.
Galambos, T. V. (1968). Structural members and frames. Prentice-Hall, Inc., London, U.K.
6.
Hajjar, J. F., and White, D. W.(1994). “The accuracy of column stability calculations in unbraced frames and the influence of columns with effective length factor less than one.”AISC Engrg. J., 31(3), 81–97.
7.
Johnston, B. G. (ed.). (1976). Structural stability research council, guide to stability design criteria for metal structures, 3rd Ed., John Wiley & Sons, Inc., New York, N.Y.
8.
Kavanagh, T. C. (1962). “Effective length of framed columns.”Trans., ASCE, 127(II), 81–101.
9.
LeMessurier, W. J.(1977). “A practical method of second order an.” Part 2—Rigid frames.”AISC Engrg. J., 14(2), 49.
10.
Lui, E. M.(1992). “A novel approach for K factor determination.”AISC Engrg. J., 29(4), 150–159.
11.
Yura, J. A.(1971). “The effective length of columns in unbraced frames.”AISC Engrg. J., 8(2), 37–42.
Information & Authors
Information
Published In
Copyright
Copyright © 1997 American Society of Civil Engineers.
History
Published online: Jul 1, 1997
Published in print: Jul 1997
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.