Development of Replaceable Cast Steel Links for Eccentrically Braced Frames

Abstract

Replaceable links for eccentrically braced steel frames (EBFs) decouple the yielding links from the floor beams to facilitate rapid repair or replacement after a seismic event. Replaceable links that are composed of rolled or built-up steel sections are, however, susceptible to the same failure modes as links in conventional EBFs. These failure modes include fracture in the base metal or welds, local buckling, and lateral-torsional buckling, all of which limit the ductility of the link and consequently, the overall ductility of the frame. An extensive numerical analysis study was completed to develop replaceable cast steel link concepts, with practical connection details, that combine the advantages of replaceable links with the geometric freedom and material properties inherent to castings. Results indicate that the unique geometry of the proposed concepts achieves a larger rotation capacity and longer low-cycle fatigue life by evenly distributing flexural yielding over the entire length of the link and minimizing stress concentrations. The replaceable cast steel links have the potential to significantly improve the performance, reliability, robustness, and resilience of EBFs.