A model for the hysteretic behavior of materials and structures is presented. This model is based on an approach which views the system as consisting of a series of ideal elastoplastic elements. The steady-state dynamic response of the model when subjected to trigonometric excitation is determined. The effect of the roundedness of the hysteresis loop on the nature of the response is investigated, and steady-state results, predicted by the theoretical model, are compared with experimental results from an actual structure.