Horizontal floor response spectra of base-isolated buildings due to vertical excitation

摘要

A mechanism of horizontal floor response spectra amplification in the vicinity of higher modes' frequencies is investigated. It is demonstrated, by means of a simple two-degrees-of-freedom model, that in the case of unsymmetrical superstructure, such amplification may occur because of the coupling between vertical excitation and horizontal response of the non-isolated modes. This phenomenon is further illustrated by the results of analyses of a model of a nuclear plant.