Development of self-stabilizing links for eccentrically braced frames

This paper highlights aspects of the development of self-stabilizing links having tubular cross-sections for use in eccentrically braced frames (EBF's). EBF's utilizing this type of link could be used in bridge piers or other applications where lateral bracing to prevent lateral torsional buckling is difficult to provide. The development of design recommendations for these types of links consisted of three parts, namely, a proof-of-concept experiment, a finite element parametric study, and testing of links with various cross-sectional properties and lengths; the latter two parts are discussed in this paper. The finite element parametric study involved over 200 links with various. cross-sections, lengths, and yield strengths and resulted in recommendations for compactness ratio limits for webs and flanges of links with tubular cross-sections which were valid for a range of typical steel yield strengths. Links with three different tubular cross-sections having compactness ratios near and well below the proposed limits were then investigated experimentally. These links also had various lengths covering the full range of link behavior (i.e., shear to flexural dominated yielding). Fourteen links in total were tested. The results indicated that the proposed design recommendations were adequate to ensure tubular links can achieve plastic rotation levels equivalent to the maximum allowed for wide-flange links considering the loading protocol from the 2005 AISC Seismic Provisions.