Effect of Triple Friction Pendulum Isolators and Supplemental Viscous Dampers on Seismic Isolated RC Buildings under Near-Fault Excitations

The isolating system absorbs part of the earthquake energy before transferring it to the structure, by shifting the natural period of the isolated structure. This period shift results in a reduction in the inertial forces. It is clear that the effects of near-fault (NF) ground motions with large velocity pulses can bring the seismic isolation devices to critical working conditions. In this study, two three-dimensional RC buildings which are supported by TPB isolators are idealized. Various triple friction pendulum bearing configurations are selected for isolation systems. There are also viscous dampers to limit the excess deformation of isolators. Nonlinear time history analyses were performed by using Opensees to study the influence of supplemental dampers on structural responses such as isolator displacements and max drifts under ten near-fault ground motion records. The results show noticeable reduction in isolator displacement when using dampers. However, maximum drift rise considerably. Moreover by increasing the period range or reducing the damping ratio of isolation system maximum drift reduces but the displacement of isolators increase.

Keywords:

Base Isolation , Triple Pendulum Bearing , Supplemental Viscous Damper , Near-Fault Earthquake