Seismic design of EBF steel frames using replaceable nonlinear links

Steel EBF structures designed according to the latest seismic design specification are expected to sustain damage during a design level earthquake through repeated inelastic deformation and localized buckling. Repair is therefore expected to be costly and disruptive, even if the structure has met its goal of providing life safety during an earthquake. To address these drawbacks, the design of EBFs with replaceable nonlinear links introduced at the locations of expected inelastic action is investigated in this paper. First, the concept of replaceable nonlinear links is presented. Two full-scale shear links, consisting of a pair of back-to-back channel sections bolted on either side of the web of the connecting floor beam were tested following an incremental cyclic loading protocol for verification of strength and ductility. The links exhibited good ductile behavior, developing stable shear yielding of the channel panels. The bolted connections were found to be critical in the design of these links. The first specimen failed at the connection level, while the second, with a reinforced connection reached a link rotation of 0.11 radians.