Shaking table tests and numerical studies on the effect of viscous dampers on an isolated RC building by friction pendulum bearings

Base isolation is an effective way for diminishing the response of a structure to seismic action. However, this results in large displacements for isolators, particularly for buildings located in near-fault sites. Viscous dampers (VDs) are often used as supplementary devices to reduce those displacements, but there is a potential for significant increases in story drift and floor acceleration of the superstructure. This paper aims to investigate the effect of viscous dampers on a base-isolated 16-storey reinforced concrete (RC) framed structure with friction pendulum bearings (FPBs) through shaking table tests and numerical simulations. First, the similitude design method for small scaled test models was introduced, including the stiffness-based method for FPBs and the energy-based method for VDs. Then a shaking table test for the isolated structure using FPBs was conducted. Experimental and numerical results were utilized to investigate the effect of VDs on both the displacement of the isolators and the response of the superstructure. It is concluded that VDs do not significantly influence either the isolation displacements or the structural response in a small earthquake, but isolator displacements can be remarkably controlled in a strong earthquake at the expense of a slight increase in the superstructure response.