The Performance Study of a Novel Vertical Variable Stiffness Disc Spring Seismic Isolation Bearing

To effectively adapt to seismic actions in complex earthquake environments and enhance the seismic isolation performance of building structures, this paper divides the disk spring group of traditional disk spring isolation bearings into an upper disk spring group and a lower disk spring group. By arranging different stacking layers, an improved Vertical Variable Stiffness Disk Spring Isolation (VVSDSI) bearing is proposed. The operational performance of this bearing is thoroughly investigated through a theoretical analysis, experimental testing, and numerical simulations. The research results demonstrate the following: (1) under ultimate load conditions, the working stages of the VVSDSI bearing can be divided into two phases. During the isolation phase, the vertical stiffness of the bearing is relatively low, with a value of 11.14 kN/mm, whereas in the protection phase, the vertical stiffness increases significantly to 35.34 kN/mm. (2) During the isolation phase, the preloading displacement exhibits a positive correlation with equivalent stiffness and an equivalent damping ratio, while the loading amplitude shows a negative correlation with these parameters. (3) The theoretical hysteresis model prediction value and numerical model simulation value of the VVSDSI bearing are in good agreement with the measured data, with the maximum errors of the peak load being 6.78% and 10.07%, respectively, which can accurately simulate the mechanical properties of the bearing. Therefore, this research result can provide a theoretical basis and experimental support for the design of vertical seismic isolation systems.