Using the improved inner slider to enhance overturning resistance of DFPB-isolated structure subjected to poundings

The overturning resistance of structures isolated by double friction pendulum bearing (DFPB) would be significantly reduced due to the presence of pounding. To this end, an improved inner slider (IIS) is introduced to enhance the overturning resistance of the DFPB-isolated structure when it is subjected to poundings. Numerical simulations were conducted to investigate the performance of IIS in reducing the potential overturning risk of isolated structure as well as the seismic responses. Influences of displacement ratio, friction coefficient ratio and radius ratio on coefficient of overturning resistance of the structures isolated by DFPB with IIS were also evaluated though parametric studies. The pounding force and its transmission to the superstructure can be significantly mitigated by IIS, and the overturning resistance performance of structures isolated by DFPB with IIS is superior to those isolated by DFPB with traditional inner slider. The threat of overturning for isolated structures is generally greater with lower displacement ratios. Structures equipped with IIS in DFPB experience a decrease in their coefficient of overturning resistance as the friction coefficient increases, and the coefficient of overturning resistance first increases and then decreases with the increase in radius ratio.