Torsional response behavior of base-isolated FBR reactor building during earthquake excitation.

This paper describes an analytical evaluation of the effect of torsional motion on seismic responses of base-isolated FBR buildings which were designed conceptually in an applicability study of base isolation systems. Dynamic response coupling with torsional motion induced by obliquely incident earthquake input and by eccentricity in the structure was evaluated by response analyses, taking the biaxial nonlinearity of base isolation devices into account. As a result, it is shown that the effect of the torsional motion on the response of the building, devices, and the floor response spectra is not so large from a seismic design standpoint.