Lateral Bracing Forces in Columns with Two Unequal Spans
Publication: Journal of Structural Engineering
Volume 119, Issue 10
Abstract
Elastic columns with two spans of arbitrary length ratio are investigated. The base is pinned and may include a rotational spring. An elastic support acts between the spans, and the top is pinned or supported elastically. An axial load is applied. For perfect columns, the effects of the internal support location and the spring stiffnesses on the critical load and buckling mode are determined. Under special conditions, an ideal spring stiffness exists, such that the elastic supports do not deflect when the column buckles. Imperfect columns with an initial deflection of the same shape as the buckling mode of the corresponding perfect column are also considered. Deflections and bracing forces at the elastic supports are obtained as functions of the axial load, and approximations in terms of the amplification factor are discussed. These results are utilized in a sequel to this paper, which examines design rules for the required stiffness and strength of bracing.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Brush, D. O., and Almroth, B. O. (1975). Buckling of bars, plates, and shells. McGraw‐Hill, New York, N.Y.
2.
Galambos, T. V., ed. (1988). Guide to stability design criteria for metal structures, 4th Ed., Wiley, New York, N.Y.
3.
Guran, A., and Plaut, R. H. (1992). “Stability of a column with a follower load and a load‐dependent elastic support.” Acta Mech., 97(4), 205–214.
4.
McGuire, W. (1968). Steel structures. Prentice‐Hall, Englewood Cliffs, N.J.
5.
Medland, I. C. (1977). “A basis for the design of column bracing.” Struct. Engr., 55(7), 301–307.
6.
Mutton, B. R., and Trahair, N. S. (1975). “Design requirements for column braces.” Civ. Engrg. Trans., Australia, 17(1), 30–36.
7.
Nair, R. S. (1992). “Forces on bracing systems.” Engrg. J., Am. Inst. Steel Constr., 29(1), 45–47.
8.
O'Connor, C. (1979). “Imperfectly braced columns and beams.” Civ. Engrg. Trans., Institution of Engineers, Australia, 21(2), 69–74.
9.
Olhoff, N., and Akesson, B. (1991). “Minimum stiffness of optimally located supports for maximum value of column buckling loads.” Structural Optimization, 3(3), 163–175.
10.
Picard, A., and Beaulieu, D. (1985). “Behaviour of a simple column base connection.” Can. J. Civ. Engrg., 12(1), 126–136.
11.
Plaut, R. H. (1989). “Column buckling when support stiffens under compression.” J. Appl. Mech., Trans. ASME, 56(2), 484.
12.
Plaut, R. H. (1993). “Requirements for lateral bracing of columns with two spans.” J. Struct. Engrg., ASCE, 119, (10).
13.
Plaut, R. H., and Cheng, C.‐C. (1991). “Buckling of frames with load‐dependent supports.” Mechanics computing in 1990's and beyond, H. Adeli and R. L. Sierakowski, eds., Vol. 2, ASCE, New York, N.Y., 871–876.
14.
Rutenberg, A., and Scarlat, A. (1990). “Roof bracing and effective length of columns in one‐story industrial buildings.” J. Struct. Engrg., ASCE, 116(10), 2551–2566.
15.
Salmon, C. G., and Johnson, J. E. (1990). Steel structures: Design and behavior, 3rd Ed., Harper & Row, New York, N.Y.
16.
Stanway, G. S., Chapman, J. C., and Dowling, P. J. (1992). “A simply supported imperfect column with a transverse elastic restraint at any position. Part 1: behaviour.” Proc. Instn. Civ. Engrs., Strucs. and Bldgs., 94(2), 205–216.
17.
Szelag, D., and Mróz, Z. (1978). “Optimal design of elastic beams with unspecified support conditions.” Zeitschrift für angewandte Mathematik und Mechanik, 58(11), 501–510.
18.
Timoshenko, S. P., and Gere, J. M. (1961). Theory of elastic stability, 2d Ed. McGraw‐Hill, New York, N.Y.
19.
Trahair, N. S., and Bradford, M. A. (1988). The behaviour and design of steel structures, 2d Ed. Chapman and Hall, London, England.
20.
Trahair, N. S., and Nethercot, D. A. (1984). “Bracing requirements in thin‐walled structures.” Developments in thin‐walled structures—2, J. Rhodes and A. C. Walker, eds., Elsevier, London, England, 93–130.
21.
Urdal, T. B. (1969). “Bracing of continuous columns.” Engrg. J., Am. Inst. Steel Constr., 6(3), 80–83.
22.
Wang, Y. C., and Nethercot, D. A. (1989). “Bracing effects on 3‐dimensional column subassemblages.” Proc. Instn. Civ. Engrs., Pt. 2, Research and Theory, 87(3), 357–376.
23.
Winter, G. (1960). “Lateral bracing of columns and beams.” Trans., ASCE, 125(1), 807–845.
24.
Yang, J.‐G. (1991). “Lateral bracing forces in compressed two‐span columns with initial curvature,” MS thesis, Virginia Polytechnic Institute and State University, Blacksburg, Va.
25.
Zhang, H.‐Y., Beliveau, J.‐G., and Huston, D. (1993). “Minimum lateral stiffness for equally spaced braces in columns.” J. Engrg. Mech., ASCE, 119(9).
Information & Authors
Information
Published In
Copyright
Copyright © 1993 American Society of Civil Engineers.
History
Received: Jul 14, 1992
Published online: Oct 1, 1993
Published in print: Oct 1993
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.