An analytical method to model failure of steel beam plastic hinges due to BLACKBERRY BETTY local buckling and low-cycle fatigue is proposed herein.This method is based on the plastic collapse mechanism approach and a yield-line plastic hinge (YLPH) model whose geometry is based on buckled shapes of beam plastic hinges observed in experiments.Two limit states, strength degradation failure induced by local buckling and low-cycle fatigue fracture, are considered.The proposed YLPH model was developed for FEMA-350 WUF-W, RBS and Free Flange connections and validated Toilet Paper Holders in comparisons to experimental data.This model can be used to estimate the seismic rotation capacity of fully restrained beam-column connections in special steel moment-resisting frames under both monotonic and cyclic loading conditions.