Mechanical behaviors of air spring-FPS three-dimensional isolation bearing and isolation performance analysis

Abstract This study proposes a novel air spring–friction pendulum system (FPS) three-dimensional isolation bearing composed of an FPS for horizontal isolation and an air spring for vertical isolation. The bearing has low vertical stiffness and a strong deformation capacity, which can effectively isolate long-period ground motions. A theoretical mechanical model of the three-dimensional isolation bearing is established, and mechanical behavior tests are conducted. Results show that the vertical bearing capacity of the three-dimensional isolation bearing increases linearly with the air pressure and as the applied compression increases, and the horizontal stiffness and force increase with an increase in the vertical load. This study then proposes a design method for the air spring-FPS three-dimensional isolation bearing in the large-span spatial structure. The vibration control effect of the large-span steel tubular truss structure with the three-dimensional isolation bearing under long-period ground motions is investigated. Results reveal that the bearing with low vertical stiffness can effectively isolate long-period ground motions. For the truss structure with air spring-FPS three-dimensional isolation bearing, the horizontal and vertical nodal peak accelerations decrease by 41.9%–87.0% and by 23.1%–43.1%, respectively. In addition, the member peak von Mises stress decreases by 9.8%–29.0%, and the displacement response of the bearing is within the working stroke.