Seismic Design and Performance of Steel Moment-Resisting Frames with Nonlinear Replaceable Links

Abstract

Although moment resisting frames (MRFs) designed according to the latest seismic codes can provide life safety during a design level earthquake, they are expected to sustain significant damage at flexural yielding locations in the beams. The design of the beams for strength and drift control considerations are also interlinked, often resulting in overdesign of other elements, such as diaphragms and foundations. These drawbacks can be mitigated by introducing replaceable links at the locations of expected inelastic action. A five-story prototype MRF building with replaceable links in a high-seismic zone was designed. Four full-scale beam-to-column subassemblages representing the first floor exterior connections in the prototype building were experimentally evaluated. The results demonstrated that MRFs with replaceable flexural links can provide strength and ductility equivalent to existing MRFs while minimizing the effect of the added links on the elastic stiffness of the system. Finite-element models were then developed to capture the observed experimental responses, including local buckling, bolt slipping, and bolt bearing.