Dynamic Characteristics of a Sliding Bearing Using Lubricant Material for Base Isolation of Light Structures

The authors have been developed a system for base isolation of a wooden house and a prefabricate house. It consists of sliding bearings and laminated rubber bearings. There are two types of sliding bearings, one has the coefficient of friction of 0.046, the other has 0.06. Each of sliding bearings supports 30 ∼ 40kN of vertical load, the surface pressure of the sliding shoe is 10 ∼ 12 N/mm² (10∼12MPa). The horizontal stiffness of the laminated rubber bearing is 38.5N/mm. For base isolation of an ordinary wooden house, 12 ∼ 16 sliding bearings and 4 ∼ 6 laminated rubber bearings are used. If the mass of a wooden house is 40ton and it is supported by 16 sliding bearings of the coefficient of friction of 0.046 and attached by 4 laminated rubber bearings with the horizontal stiffness of 38.5 N/mm, therefore it has 0.249 of the equivalent damping factor and 3.2 second of the natural period. As for the base isolated houses which are used this system, 500 houses have been constructed in Japan currently by the August of 2002 (Takahashi, 2002). As an advanced system of this base isolation system, we have developed a new type of the base isolation system of sliding bearing using silicone lubrication materials and rubber spring devices.