Base isolation has become a widely accepted method for earthquake resistant design of structures. However, the research in the field has been generally restricted to one-dimensional motion. Structural response is not limited to this one-dimensional motion, and the torsional effect of multidimensional motion contributes to the horizontal displacements. A three-dimensional structure can not be modeled with multiple one-dimensional analyses; rather, a complete three-dimensional analysis must be undertaken, as shown in this study.Four separate analyses for the calculation of the dynamic response of a base-isolated structure will be presented in this study. The first two analysis procedures are for a single-story base-isolated structure. The last two procedures are for a multi-story base-isolated structure. The first procedure for each structure assumes a fully linear response, in which the bearings and the superstructure remain in the linear elastic range of response. The second procedure allows for a non-linear response from the bearings, in which each individual bearing may yield, changing the effective stiffness value.The structural response for each of these cases will be calculated using computer analysis and compared with one another and also with a single-degree of freedom system. The results will be discussed at the end of this study
