Analysis of the compound seismic system consisting of ERFPS system and dish spring

A theoretical analyzing approach about ERFPS (Eccentric Rolling Friction Pendulum System) is presented. It starts from formulation of the governing equation according to relative kinematics energy theorem in multiply body dynamics. This system consists of an eccentric roller which is placed in vicinity of two circular concave curve slides to form non-indented contacts. Computation results show that it has the three kinds of necessary capabilities required for an effective isolation system. The relatively long vibration period provides the seismic isolation capability, the gravity provides the reposition capability, and the rolling friction forces at contacting surface on top and bottom plate respectively, provides energy dissipation capability. It is shown that the inter-storey drift resulted from seismic action could be drastically decreased on buildings equipped with ERFPS system. If the rolling friction coefficient is about 0.01, the seismic isolation effectiveness could be as high as 90%. When the coupling effect in two directions is so small that it could be neglected and the dynamic responses could be calculated with respect to each of the individual direction in earthquake engineering.