Friction Pendulum Systems For Seismic Isolation Of Structures In Near-Fault Regions

Friction pendulum systems are sliding bearings that make use of a spherical concave surface to provide a restoring force and friction force to dissipate earthquake energy.Large sliding displacement of friction pendulum due to near-fault earthquake not only addresses nonlinear dynamic problem for the motion of the pendulum,but makes the horizontal motion of the system related to the negligible vertical ground acceleration.The purpose of this paper is to find a better solution to these problems,the primary research work and conclusions include:1.Integrated models of both the FPB-SDF structure system and the FPB-MDF structure system were proposed and computer programs based on these models were developed.The computer program on the proposed model is verified by comparing the analytical results with SAP2000 for the case of far-field horizontal excitation.2.Numerical results of examples for both SDF structure and MDF structure indicate that the vertical component of ground motion cannot be neglected in estimating seismic horizontal response of FPB-isolated system in near-fault earthquakes.3.Parametric studies of FPB were conducted based on seismic response spectra analysis,which reveal that radius of sliding surface to be 1.5m and friction coefficient to be 0.05 are suggested at least for the initial design scheme in the application in near-fault regions.4.Numerical results show that FPB,if properly designed,is very effective in reducing both the interstory drift and absolute acceleration for each story of the structure.FPB can effectively attenuate the whipping effect due to the uneven distribution of story stiffness along the structural height direction.5.The displacement demand for FPB in near-fault earthquake scenarios could be very large,so the bearing should be large enough to accommodate the motion of the slider along the sliding surface.