Inelastic Effective Length Factor of Nonsway Reinforced Concrete Columns
Publication: Journal of Structural Engineering
Volume 135, Issue 9
Abstract
This paper proposes a new equation for the effective length factor ( -factor) for reinforced concrete columns in braced frames. The new formula is valid both for normal and high-strength concrete. The equation was obtained from a sensitivity analysis performed on a two-dimensional nonlinear finite-element numerical model that takes into account the inelastic behavior of the concrete columns (cracking, yielding, and second order effects). The numerical model was calibrated with 44 experimental tests performed by the writers’ research group. A comparative study was carried out between the numerical model and different national design codes, displaying important differences with respect to all of them: the ACI code (from 37 to −3%), the Spanish code EHE (from 26 to −9.26%), and the Eurocode 2 (from 14 to −14%). It was decided to propose two additional simplified equations: one for checking and the second for design.
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Acknowledgments
The writers express their sincere gratitude to the Spanish “Ministerio de Fomento” for help provided through Project No. UNSPECIFIED13-12-2001 and “Ministerio de Educación” through Grant No UNSPECIFIEDBIA2005-255.
References
American Concrete Institute. (2005). “Building code requirements for structural concrete and commentary.” ACI 318-05, ACI Committee 318, Farmington Hills, Mich.
Aristizábal-Ochoa, J. D. (1994). “K-factor for columns in any type of construction: Nonparadoxical approach.” J. Struct. Eng., 120(4), 1272–1290.
Bazant, Z. P., and Xiang, Y. (1997). “Inelastic buckling of concrete column in braced frame.” J. Struct. Eng., 123(5), 634–642.
Bendito, A. (2006). “Estudio numérico del pandeo inelástico de soportes de hormigón armado intraslacionales.” Ph.D. dissertation, Universitat Jaume I, Castellon, Spain (in Spanish).
Breen, J. E., MacGregor, J. G., and Pfrang, E. O. (1972). “Determination of effective length factors for slender concrete columns.” J. Am. Concr. Inst., 69(11), 669–672.
Broms, B., and Viest, I. M. (1961). “Long reinforced concrete columns: A symposium.” Trans. Am. Soc. Civ. Eng., 126(2), 308–400.
Cervenka, V. (1998). “Applied brittle analysis of concrete structures.” Proc., 5th Int. Conf. on Fracture Mechanics of Concrete Structures, Freiburg, Germany, Vol. 4, 1107–1116.
Cranston, W. B. (1972). “Analysis and design of reinforced concrete columns.” Research Rep. No. 20, Cement and Concrete Association, London.
Disque, R. O. (1973). “Inelastic k-factor in design.” Eng. J., 10(2), 33–35.
Duan, L., and Chen, W. F. (1999). “Effective length factors of compression members.” Structural engineering handbook, C. Wai-Fah, ed., CRC, Boca Raton, Fla.
EHE. (1999). Instrucción de hormigón estructural, Ministerio de Fomento, Spain (in Spanish).
European Committee for Standardization. (2004). “Eurocode 2: Design of concrete structures: Part 1.” EC-2 ENV-1992-1-1.
Furlong, R. W. (1998).“Discussion: Inelastic buckling of concrete column in braced frame.” J. Struct. Eng., 124(6), 721–722.
Hu, X. Y., Zhou, R. G., King, W. S., Duan, L., and Chen, W. F. (1993). “On effective length factor of framed columns in ACI code.” ACI Struct. J., 90(2), 135–143.
MacGregor, J. G., Breen, J. E., and Pfrang, E. O. (1970). “Design of slender concrete columns.” J. Am. Concr. Inst., 67(1), 6–28.
Shanley, F. R. (1947). “Inelastic column theory.” J. Aeronaut. Sci., 14(5), 261–268.
Traver, J., and Bonet, J. L. (2002), “Cálculo del factor de amplificación de momentos en soportes esbeltos intraslacionales de hormigón armado en flexo-compresión esviada.” MS thesis, Technical University of Valencia, Spain (in Spanish).
Yura, J. A. (1971). “The effective length of columns in unbraced frames.” Eng. J., 8(2), 37–42.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 135 • Issue 9 • September 2009
Pages: 1034 - 1039
Copyright
© 2009 ASCE.
History
Received: Oct 2, 2007
Accepted: May 11, 2009
Published online: Aug 14, 2009
Published in print: Sep 2009
Notes
Note. Associate Editor: Dat Duthinh
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