Steel EBF and MRF 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. Furthermore, it is difficult to assess the extent of this damage since no measure of the cumulative inelastic action that has taken place during an earthquake is usually possible, and hence whether the structure can survive another earthquake. The objective of this research is to address these drawbacks by introducing an innovative approach consisting of designing MRFs and EBFs with replaceable nonlinear links at the locations of expected inelastic action. The research program combines analytical and large-scale experimental studies to develop, assess and validate guidelines for the design of the replaceable nonlinear link and its connection.