Effective Length Factor of Columns in Semirigid and Unbraced Frames
Publication: Journal of Structural Engineering
Volume 123, Issue 3
Abstract
In current engineering practice, to evaluate the stability of columns in frames with rigid and semirigid connections, one must estimate the effective length factor (K-factor) of columns considering the effects of the nonlinear moment-rotation characteristics of beam-to-column connections. Herein, using the alignment chart approach and based on a recent study on the stability of semirigid frames and the concept of Shanley's inelastic column buckling theory, the governing equations on the K-factor of columns for various boundary conditions with rigid and semirigid beam-to-column connections are derived for unbraced frames. With a proper evaluation of the tangent connection stiffness for semirigid beam-to-column connections at buckling state and with the introduction of the modified relative stiffness factors, the alignment chart in the present American Institute of Steel Construction-load and resistance factor design specification can be applied to find the corresponding column K-factor in semirigid frames. This is described in the present paper. Furthermore, using a semirigid and unbraced portal frame example, the effects of the nonlinear moment-rotation characteristics of connections on the K-factor are numerically studied and the K-factors obtained by two simplified methods are also compared with the present method.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Barakat, M., and Chen, W. F.(1990). “Practical analysis of semi-rigid frames.”Engrg. J., AISC, 27(2), 54–68.
2.
Bjorhovde, R.(1984). “Effect of end restraint on column strength—practical applications.”Engrg. J., AISC, 212(1), 1–13.
3.
Chen, W. F., and Lui, E. M. (1991). Stability design of steel frames. CRC Press, Inc., Boca Raton, Fla.
4.
Driscoll, G. C.(1976). “Effective length of columns with semi-rigid connections.”Engrg. J., AISC, 13(4), 109–115.
5.
Duan, L., and Chen, W. F.(1989). “Effective length factor for columns in unbraced frames.”J. Struct. Engrg., ASCE, 115(1), 149–165.
6.
Goto, Y., and Chen, W. F.(1987). “On the computer-based design analysis for flexibly jointed frames.”J. Constr. Steel Res., 8, 203–231.
7.
Goto, Y., Suzuki, S., and Chen, W. F.(1993). “Stability behavior of semi-rigid sway frames.”Engrg. Struct., 15(3), 209–219.
8.
King, W. S., and Chen, W. F.(1993). “LRFD analysis for semi-rigid frame design.”Engrg. J., AISC, 30(4), 130–140.
9.
Kishi, N., and Chen, W. F.(1990). “Moment-rotation relations of semi-rigid connections with angles.”J. Struct. Engrg., ASCE, 116(7), 1813–1834.
10.
Kishi, N., Chen, W. F., Goto, Y., and Matsuoka, K. G. (1993a). “Design aid of semi-rigid connections for frame analysis.”Engrg. J., 30(3), 90–107
11.
Kishi, N., Chen, W. F., Goto, Y., and Matsuoka, K. G.(1994b). “Analysis program for the design of flexibly jointed frames.”Comp. and Struct., 49(4), 705–713.
12.
Lui, E. M. (1985). “Effects of connection flexibility and panel zone deformation on the behavior of plane steel frames,” PhD thesis, School of Civ. Engrg., Purdue Univ., West Lafayette, Ind.
13.
Manual of steel construction—load and resistance factor design, 1st Ed. (1986). American Institute of Steel Construction, Chicago.
14.
Manual of steel construction–load and resistance factor design, 2nd Ed. (1994). American Institute of Steel Construction, Chicago.
15.
Richard, R. M., and Abbott, B. J.(1975). “Versatile elastic-plastic stress-strain formula.”J. Engrg. Mech., ASCE, 101(4), 511–515.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 123 • Issue 3 • March 1997
Pages: 313 - 320
Copyright
Copyright © 1997 American Society of Civil Engineers.
History
Published online: Mar 1, 1997
Published in print: Mar 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.