This paper described the results of the static loading tests using a half-scale thick rubber bearing to investigate the fundamental characteristics such as horizontal and vertical restoring force of a rubber bearing applied to a Sodium-cooled-Fast-Reactor (SFR). Since the SFR has thin-walled component structures, a seismic isolation system is employed to mitigate the seismic force. A rubber bearing with thick rubber layers is used for the seismic isolation system applied to the SFR, it was developed aiming for isolation of not only horizontal response acceleration, but also vertical response acceleration. The thick rubber bearing of 1600 mm in diameter full-scale was designed to provide about a 10000 kN rated load with a horizontal natural period of 3.4 s and a vertical one of 0.125 s. Moreover, a linear strain limit of the thick rubber bearing was designed to accept a horizontal displacement of 700 mm or more in order to ensure a double safety margin for response displacements against a design basis ground motion. The static loading tests were performed using a half-scale thick rubber bearing with a diameter of 800 mm to investigate the horizontal/vertical stiffness, damping ratio, a linear strain limit in horizontal direction and a tensile yield stress in the vertical direction. The fundamental characteristic of rubber bearings employed to the SFR and the validity of a design formula became clear through the static loading tests.

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