Abstract This paper outlines a methodology to incorporate low-cycle fatigue in seismic risk evaluation of steel structures. The method is based on a simple cumulative damage model in which damage due to each plastic excursion is approximated by a Coffin-Manson type relationship. The parameters in this model are treated as random variables with distributions that are obtained from studies on the nonlinear seismic behavior of bilinear single-degree-of-freedom oscillators. The method is used to obtain an equivalent ‘single-excursion’ ductility demand which represents the same damage state as the low-cycle fatigue model. The proposed approach presents a realistic means of seismic risk evaluation and will provide a basis for establishing safer and more reliable steel structures.