In this paper, the authors studied the characteristics of simulated long period earthquake ground motions and their effects on the responses of base-isolated buildings. Analytical structural building models for response analyses were generated based on the data about exisiting base-isolated buildings. Earthquake response analyese were carried out for the building models subjected to long period earthquake ground motions to find how the design parameters and the input motions affect the maximum earthquake responses and the margins of seismic safety. The response analyses indicate that the design earthquake motion for base-isolated buildings should be provided as an energy spectrum as well as a response spectrum.
