Seismic performance of brace fuse elements for concentrically steel braced frames

This paper presents the results of a pilot experimental study performed to examine the possibility of using ductile fuse elements to dissipate seismic input energy and reduce the force demand on brace connections in concentrically braced steel frames. These fuse elements are introduced in the bracing members and are designed to yield prior to buckling or yielding of the braces. A total of 21 tests were performed on different fuse elements detailed for two types of bracing members: tapered fuse plates for HSS and double angle bracing members, localized reduction in the cross section of HSS bracing members, and angle splices, also for IISS bracing members. All specimens were subjected to a cyclic quasi-static loading protocol with stepwise deformation increments except two specimens for which a loading history matching more closely the inelastic response of a braced frame structure was used. Some of the specimens experienced local and/or global buckling and exhibited a rather poor performance. Fuse elements for which adequate support had been provided exhibited a stable hysteretic response with high energy dissipation characteristics, large inelastic deformation capacity and beneficial strain hardening behaviour.