This paper demonstrates the applicability of response history analysis based on rigid-plastic models for the seismic assessment and design of steel buildings. The rigid-plastic force-deformation relationship as applied in steel moment-resisting frames (MRF) is re-examined and new rigid-plastic models are developed for concentrically-braced frames and dual structural systems consisting of MRF coupled with braced systems. This paper demonstrates that such rigid-plastic models are able to predict global seismic demands with reasonable accuracy. It is also shown that, the direct relationship that exists between peak displacement and the plastic capacity of rigid-plastic oscillators can be used to define the level of seismic demand for a given performance target. Copyright q 2009 John Wiley & Sons, Ltd.