Vertical seismic isolated rocking-core system

Mass isolation of structures is an efficient vibration-control technique for reducing earthquake effects on buildings. This paper introduces a vertical seismic isolated rocking-core system (VSI-RCS) in which a controlled rocking-core is separated from the frame by viscous fuses. The controlled rocking-core provides the self-centring capability while the viscous dampers limit the lateral displacement and dissipate the majority of the seismic energy. An analytical solution is proposed for estimation of the optimal damping constant of the dampers along with the corresponding fundamental frequencies and damping ratio of the VSI-RCS. A parametric study was carried out to quantify non-classical dynamic characteristics and spectral analysis was performed to examine the seismic performance of the VSI-RCS compared with rocking-core systems. The proposed formulas were found to be applicable for rapid eigen-analysis and, compared with non-isolated rocking-core systems, proper seismic efficiency of the VSI-RCS was observed.