Effective Length Factor for Columns in Braced Frames
Publication: Journal of Structural Engineering
Volume 114, Issue 10
Abstract
The alignment chart used in the present AISC and CAN3‐M84 specifications defines the column effective length factor K in terms of the relative joint bending stiffness ratio at each end of the column. In the development of the alignment chart, the far ends of columns above and below the column being considered are assumed to be rigidly jointed. In practice, some columns are not rigidly connected. A direct use of the alignment chart without any modifications results in an effective length factor that can be either too conservative or even unsafe depending on the boundary conditions of the restraining columns. This paper derives the general effective length factor equations for columns in braced frames, corresponding to five different boundary conditions of top and bottom columns. A simple modification of the present alignment chart for the determination of a more accurate K‐value for the design of columns in braced frames is proposed. The procedure is illustrated by several numerical examples.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Bleich, F. (1952). Buckling strength of metal structures. McGraw‐Hill, New York, N.Y.
2.
Bridge, R. Q., and Fraser, D. J. (1987). “Improved G‐factor method for evaluating effective lengths of columns.” J. Struct. Engrg., ASCE, 113(6), 1341–1356.
3.
Chen, W. F., and Lui, E. M. (1987). Structural stability: theory and implementation. Elsevier, New York, N.Y.
4.
Galambos, T. V. (1968). Structural members and frames. Prentice‐Hall International, London, U.K.
5.
Iffland, J. S. B. (1978). “High rise building column design.” J. Struct. Div., ASCE, 104(9), 1469–1483.
6.
Johnson, D. E. (1960). “Lateral stability of frames by energy method.” J. Engrg. Mech. Div., ASCE, 95(4), 23–41.
7.
Johnston, B. G., ed. (1976). Structural stability research council, guide to stability design criteria for metal structures. 3rd Ed., John Wiley & Sons, New York, N.Y.
8.
Load and resistance factor design specification for structural steel buildings. (1986). American Institute of Steel Construction, Chicago, Ill.
9.
Specification for the design, fabrication and erection of structural steel for buildings. (1978). American Institute of Steel Construction, Chicago, Ill.
10.
“Steel Structures for Buildings (Limit States Design). “(1984). CAN3‐S16.1‐M84, Canadian Standards Association, Rexdale, Ontario, Canada.
11.
Winter, G., et al. (1948). “Buckling of trusses and rigid frames.” Cornell University, Ithaca, N.Y. Engineering Experimental Station, Cornell Univ. Bull. No. 36
Information & Authors
Information
Published In
Copyright
Copyright © 1988 ASCE.
History
Published online: Oct 1, 1988
Published in print: Oct 1988
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.