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.
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Published In
Journal of Structural Engineering
Volume 136 • Issue 5 • May 2010
Pages: 543 - 553
Copyright
© 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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