Plastic Torsion Analysis of Monosymmetric and Point-Symmetric Beams
Publication: Journal of Structural Engineering
Volume 125, Issue 2
Abstract
This paper extends a simple method of analyzing the plastic torsion collapse of compact equal flange I-section beams to monosymmetric and point-symmetric beams. The method can be used manually, is much easier than elastic analysis, and is no more difficult than the plastic collapse analysis of beams in bending. The use of plastic torsion analysis avoids the conservatism of first yield analysis and design because it accounts for the spread of plasticity through the cross section and the redistribution of torque that occurs in redundant members after the first hinge forms. Designs based on plastic analyses of torsion will lead to significant economies over the first yield designs based on elastic analysis. Equations are developed in this paper for the uniform torsion plastic torques and for the plastic bimoments of monosymmetric I-sections, lipped and unlipped channels, and equal flange lipped angles, and of point-symmetric lipped and unlipped Z-sections. A worked example of the plastic torsion collapse and design of a lipped channel is present.
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References
1.
Akesson, B., and Backlund, J. ( 1972). “Numerische berechnung des platischen wlassowschen wolbwiderstandsmomentes Zw der normierten walzprofile IPBI, IPB, IPBv, IPE, I, U, und Z.” Publ. No. 24, Institut fur Festigkeitslehre, Chalmers Technische Hochschule, Goteburg.
2.
Akesson, B., and Backlund, J. ( 1973). “Plastisches wlassowsches wolbwiderstandsmoment offener walzprofile.” Der Stahlbau, 42(1), 13–19.
3.
AS4100 —1990 steel structures. (1990). Standards Australia, Sydney.
4.
Billinghurst, A., Williams, J. R. L., Chen, G., and Trahair, N. S. ( 1992). “Inelastic uniform torsion of steel members.” Comp. and Struct., 42(6), 887–894.
5.
Dinno, K. S., and Merchant, W. ( 1965). “A procedure for calculating the plastic collapse of I-sections under bending and torsion.” The Struct. Engr., 43(7), 219–221.
6.
Farwell Jr., C. R., and Galambos, T. V. (1969). “Nonuniform torsion of steel beams in elastic range.”J. Struct. Div., ASCE, 95(12), 2813–2829.
7.
Horne, M. R. ( 1979). Plastic theory of structures, 2nd Ed., Pergamon, Tarrytown, N.Y.
8.
Lundgren, K. ( 1976). “Vlasov torsion of elastic-ideally-plastic beams of thin-walled open cross-section.” Int. J. Mech. Sci., 18(3), 105–109.
9.
Nadai, A. ( 1931). Plasticity . McGraw-Hill, New York.
10.
Neal, B. G. ( 1977). The plastic methods of structural analysis, 3rd Ed., Chapman & Hall, London.
11.
Osterrieder, P., Werner, F., and Kretzschmar, J. ( 1997). “Plastic flexural-torsional buckling design of beams with open thin-walled cross sections.” Proc., 5th Int. Colloquium on Stability and Ductility of Steel Struct., 475–482.
12.
Pi, Y.-L., and Trahair, N. S. (1994a). “Inelastic bending and torsion of steel I-beams.”J. Struct. Engrg., ASCE, 120(12), 3397–3417.
13.
Pi, Y.-L., and Trahair, N. S. ( 1994b). “Steel member design for combined torsion and bending.” Australian Civ. Engrg. Trans., Institution of Engineers, Australia, CE36(4), 325–330.
14.
Pi, Y.-L., and Trahair, N. S. ( 1994c). “Torsion design of steel members.” Australian Civ. Engrg. Trans., Institution of Engineers, Australia, CE36(4), 319–324.
15.
Pi, Y.-L., and Trahair, N. S. (1995a). “Inelastic torsion of steel I-section beams.”J. Struct. Engrg., ASCE, 121(4), 609–620.
16.
Pi, Y.-L., and Trahair, N. S. (1995b). “Plastic collapse analysis of torsion.”J. Struct. Engrg., ASCE, 121(10), 1389–1395.
17.
Timoshenko, S. P. ( 1953). “Theory of bending, torsion, and buckling of thin-walled members of open cross-section.” Collected papers of Stephen P. Timoshenko. McGraw-Hill, New York.
18.
Timoshenko, S. P., and Goodier, J. N. ( 1970). Theory of elasticity, 3rd Ed., McGraw-Hill, New York.
19.
Trahair, N. S., and Bradford, M. A. ( 1998). The behaviour and design of steel structures, 3rd Australian Ed., E & FN Spon, London.
20.
Trahair, N. S., and Pi, Y.-L. ( 1996). “Simplified torsion design of compact I-beams.” Steel Constr., 30(1), 2–19.
21.
Trahair, N. S., and Pi, Y.-L. ( 1997). “Torsion, bending, and buckling of steel beams.” Engrg. Struct., 19(5), 372–377.
22.
Vlasov, V. Z. ( 1961). Thin-walled beams, 2nd Ed., Israel Program for Scientific Translations, Jerusalem.
23.
Zbirohowski-Koscia, K. ( 1967). Thin-walled beams . Crosby Lockwood, London.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 125 • Issue 2 • February 1999
Pages: 175 - 182
History
Received: Apr 13, 1998
Published online: Feb 1, 1999
Published in print: Feb 1999
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