Seismic isolation bearing

Abstract

A seismic isolation bearing including a top load plate (11A) for securing the bearing to a structure to be supported, a lower load plate (11B) for securing the bearing assembly to the foundation, and a steel reinforced rubber bearing body (13) sandwiched therebetween. The rubber bearing body (13) performs the bearing and restorative functions of the seismic isolation bearing. A steel midplate (14) extends radially from the middle of the bearing body laminated stack, and includes a plurality of holes (35) proximate the outer circumaference of the midplate. A first series of yield pins (12T) are anchored to the top load plate and extended downwardly toward the bottom load plate, and a second series of yield pins (12B) are anchored to the bottom load plate and extend upwarlly towards to the top load plate. The yield pins (12T, 12B) are received within the oversized holes (35) disposed about the periphery of the midplate. During lateral displacement of the bearing assembly, the midplate (14) deflects and plastically deforms the pins; upon cessation of the applied lateral force, the resilient bearing body urges the assembly back to its original position, plastically reforming the yield pins to their original position. The yield function of the yield pins is thus decoupled from the bearing and restoring function of the bearing body (13).

Dependencies are inferred from the claim text.