Reduced Link Sections for Improving the Ductility of Eccentrically Braced Frame Link-to-Column Connections
Publication: Journal of Structural Engineering
Volume 136, Issue 5
Abstract
Eccentrically braced frames (EBFs) are desirable seismic load resisting systems as they combine the high elastic stiffness of concentrically braced frames with the ductility and stable energy dissipation of moment resisting frames. EBFs with links attached to the columns are particularly appealing for architectural flexibility as they provide multiple locations for placement of doors and hallways. However, previous research has shown that link-to-column connections are prone to failure at low drift levels, due to their susceptibility to fracture at the link flange-to-column welds. This paper investigates the application of the reduced beam section concept for links in eccentrically braced frames to enhance the ductility of link-to-column connections. A design procedure for link section reduction is proposed and preliminary finite-element analyses are conducted on a shear link with various reduced section geometries. A parametric study performed on an array of links having various cross sections and lengths suggests that the reduced link section may substantially reduce the plastic flange strains at the link ends, which can improve the fracture life. The reduction in plastic flange strains is found to be significant for all links, with larger reductions for intermediate and flexural links. Furthermore, the detrimental kinking deformation of the flanges, caused by the large rotation demands in shear links, is moved away from the column face when reduced sections were used. While the analysis results show promise, experimental verification is recommended before the proposed design procedure can be implemented in practice.
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Acknowledgments
The first and third writers acknowledge the support of the University of Washington and the Valle Scholarship and Scandinavian Exchange Program. However, any opinions, findings, conclusions, and recommendations presented in this paper are those of the writers and do not necessarily reflect the views of the sponsors.
References
AISC. (2005a). “Prequalified connections for special and intermediate steel moment resisting frames for seismic applications.” Rep. No. ANSI/AISC 358-05, Chicago.
AISC. (2005b). “Seismic provisions for structural steel buildings.” Rep. No. ANSI/AISC 341-05, Chicago.
Arce, G. (2002). “Impact of higher strength steels on local buckling and overstrength of links in eccentrically braced frames.” MS thesis, Univ. of Texas at Austin, Tex.
Berman, J. W., and Bruneau, M. (2008). “Tubular links for eccentrically braced frames I: Finite-element parametric study.” J. Struct. Eng., 134(5), 692–701.
Choi, J., Stojadinovic, B., and Goel, S. C. (2003). “Design of free flange moment connection.” Eng. J., 40(1), 25–41.
El-Tawil, S., Mikesell, T., and Kunnath, S. K. (2000). “Effect of local details and yield ratio on behavior of FR steel connections.” J. Struct. Eng., 126(1), 79–87.
El-Tawil, S., Mikesell, T. D., Vidarsson, E., and Kunnath, S. K. (1998). “Strength and ductility of FR welded-bolted connections.” Rep. No. SAC/BD-98/01, Applied Technology Council, Redwood City, Calif.
Engelhardt, M. D., Fry, G., Johns, S., Venti, M., and Holliday, S. (2000). “Behavior and design of radius-cut, reduced beam section connections.” Rep. No. SAC 00/17, SAC Joint Venture, Richmond, Calif.
Engelhardt, M. D., Winneberger, T., Zekany, A. J., and Potyraj, T. J. (1998). “Experimental investigation of dogbone moment connections.” Eng. J., 35(4), 128–139.
Hauksdottir, H. O. (2008). “Application of the reduced beam section concept for improving the ductility of certain eccentrically braced frames.” MS thesis, Univ. of Washington, Seattle.
Jones, S. L., Fry, G. T., and Engelhardt, M. D. (2002). “Experimental evaluation of cyclically loaded reduced beam section moment connections.” J. Struct. Eng., 128(4), 441–451.
Kanvinde, A. M., and Deierlein, G. G. (2006). “Void growth model and stress modified critical strain model to predict ductile fracture in structural steels.” J. Struct. Eng., 132(12), 1907–1918.
Kasai, K., and Popov, E. P. (1986). “General behavior of WF steel shear link beams.” J. Struct. Div., 112(2), 362–382.
MSC Software. (2005). MSC. Marc user’s guide, MSC Software Corporation, Santa Ana, Calif.
Okazaki, T. (2004). “Seismic performance of link-to-column connections in steel eccentrically braced frames.” Ph.D. dissertation, Dept. of Civil Engineering, Univ. of Texas at Austin, Tex.
Okazaki, T., Engelhardt, M. D., Nakashima, M., and Suita, K. (2006). “Experimental performance of link-to-column connections in eccentrically braced frames.” J. Struct. Eng., 132(8), 1201–1211.
Richards, P. W., and Uang, C. M. (2005). “Effect of flange width-thickness ratio on eccentrically braced frames link cyclic rotation capacity.” J. Struct. Eng., 131(10), 1546–1552.
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© 2010 ASCE.
History
Received: Jan 22, 2009
Accepted: Nov 4, 2009
Published online: Nov 13, 2009
Published in print: May 2010
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