A Horizontal Stiffener Detailing for Shear Links at the Link-to-Column Connection in Eccentrically Braced Frames

Abstract

This study investigates the performance and viability of a horizontal stiffener detailing (HSD) to (1) be used at the link-to-column connection in a D-braced eccentrically braced frame layout where conventional link-to-column connections show poor performance, (2) minimize the overstrength factor of shear links caused by the hardening of link flanges, and (3) mitigate an undesirable failure mechanism previously observed in shear links fabricated using ASTM A992 steel. HSD and conventional stiffener detailing (CSD) were tested using W460×60 sections under two loading protocols, including one simulating near-collapse excitation. While the flanges of CSD shear links are greatly stiffened by vertical stiffeners, webs of HSD shear links exhibit inelastic buckling at large rotation angles. This allows the flanges to freely deform, thereby reducing the likelihood of brittle fracture at the flange connections, as well as undesirable link overstrength induced by the flange contribution. This study shows that the horizontal stiffener configuration developed a ductile failure mechanism resulting from gradually increasing local buckling in the web. The strength degradation of links with horizontal stiffener detailing was much more gradual due to the ever-increasing web buckling, unlike the sudden brittle fracture at the flange-to-column face of links with CSD. This research shows that the HSD is a viable and economic alternative for shear links, which has the potential to decrease welding in the shear link while exhibiting adequate seismic performance. HSD also maintains a low overstrength factor and utilizes a simplistic design approach. Finally, the bolted extended end-plate connection and its details at the link ends used in the test experiment provided a viable solution for replaceable links.