Near-fault seismic performance of triple variable friction pendulum bearing

The current paper investigates the effect of Variable Friction System (VFS) on the response of Triple Friction Pendulum Bearing (TFPB) under normal and parallel components of near-fault ground motions. The Triple Variable Friction Pendulum Bearing (TVFPB), a developed TFPB, is proposed in this study. The variation of the frictional force on sliding surfaces of TVFPB is such that up to a certain value of displacement, the friction coefficient increases and then decreases with further increase in displacement. In order to verify the effectiveness of VFS, the analytical seismic responses are compared with the response of the same system supported on conventional TFPB. Based on the results, it can be concluded that the usage of VFS is quiet effective in reducing the displacement of isolation system. Moreover, by comparing the superstructure demands, it is observed that for stiff bearings with smaller displacement capacity, the incorporation of VFS will result in lower superstructure demands, whereas for flexible bearings with larger displacement capacity, superstructure demands are increased