Study on Limits of Height-to-Width Ratio for Base Isolated Buildings Under Earthquake

The limit of height-to-width ratio (HWR) for base-isolated building with the elastomeric rubber bearings is of considerable concern to structural design engineers. And guidelines and codes on this building in the world have to deal with this issue. Nevertheless, until now, no systematical and quantitative study has been done on this problem for the base-isolated buildings. For this reason, the main objective of this paper is to focus on investigations on the limit of the HWR for isolated building with the rubber bearings under different conditions subjected to earthquake excitations. The simplified formulation is derived and some influenced factors, such as the site soil conditions, seismic ground motion intensity, period of the isolated system, period of the superstructure and layout of isolators, are studied and discussed. According to the numerical results, it has been found that the effects of site soil conditions on the HWR limit values are important, in which the softer the site is, the smaller the HWR limit value is under different seismic intensities; the predominant period of isolated building also plays a considerable role in the HWR limit value, namely, the isolated building with a longer period may have a relatively large HWR value; and the stiffness of superstructure affects the HWR limit value little. Furthermore, an effective method to improve the HWR limit value is proposed.