Development of Low-friction Factor Sliding Isolation Device

Sliding bearings with low coefficient of friction enable the base isolation system with longer natural period than previous ones and to be effective even for small to medium earthquakes. This paper introduces the sliding bearings with low coefficient of friction, which is almost under 0.03. It is shown that newly developed materials for the sliding bearings contribute to reduce coefficient of friction. Weather resistance and durability under various kinds of conditions are tested for main materials that compose the sliding bearings, and it is proved that these materials have enough performances for practical seismic isolation system exposed to circumstances of outdoor locations. After that, sliding surface pressure dependence, excitation velocity dependence in coefficient of friction, durability and dynamic excitations for practical use sliding bearings designed to support 200 tons of axial force are tested and their practicality is proved. Also it is shown that compression and shear stiffness of single rubber pads put in series on sliding bearings almost fit to the design formulas suggested for general laminated rubber bearings. Finally a design formula and variation of coefficient of friction are considered.