Seismic performance of hybrid seismic isolation bearing system: shake table test and nonlinear numerical analysis

Abstract

The hybrid seismic isolation bearing system (HSIBS) is composed of sliding friction bearing and elastomeric bearing, which fulfills the separation of vertical and horizontal force transmission mechanisms. The sliding friction bearing provides vertical support and energy dissipation, while the elastomeric bearing offers self-centering capability. Compared to conventional seismic isolation bearings, such a convenient design of the hybrid bearing system retains higher vertical loading capacity, better flexibility in post-yield stiffness selection, and little interference to traffic during post-earthquake retrofit. Therefore, the system has better adaptability to different seismic design requirements. To evaluate the seismic performance of the bearing system, a 1/3.5 scaled bridge model was designed and subjected to a shake table test. The experimental results demonstrate that the HSIBS exhibits good seismic performance, which significantly reduces the seismic response and residual displacement. Specifically, the maximum deformation of the bearing system is limited to a small level (49 mm), the bridge piers stay within an elastic state under the earthquake input with a peak ground acceleration (PGA) of 0.6 $g$, and the maximum residual displacement of the bearing system is negligible (2.85 mm). In addition, numerical simulations are conducted to verify the test results and analyze the seismic parameters of HSIBS. Parameter optimization of HSIBS is also performed, which achieved the balance of bearing displacement demand and moment of piers, hence enhanced efficiency.