COMPOUND SEISMIC ISOLATION STRUCTURE

PROBLEM TO BE SOLVED: To realize a high seismic isolation performance even for a structure built on soft ground and also against a large-scale earthquake by arranging seismic isolation devices by elastic slide bearing and oil dampers side by side between the upper and lower structures of the structure with an adequate ratio between them. SOLUTION: Seismic isolation devices 2 by elastic slide bearings are arranged at both the ends portions in a longitudinal direction and at a central part at each column position between the ground and a structure 1, and also seismic isolation devices 3 having a friction force greater than that of the seismic isolation device 2 are arranged between them. And an oil damper 4 is arranged at both the short sides of the structure 1. In a small-scale earthquake, a slide member 11 absorbs a relative displacement between the upper and lower structures 6, 9 by the elastic deformation of elastic bearing portion 10 and the viscous resistance of the oil damper 4. Against a large-scale earthquake, the seismic energy is efficiently absorbed by the frictional resistance between the slide member 11 and slide plate 7 and the viscous resistance of the oil damper 4. By arranging the seismic isolation devices 2, 3, 4 by adequately combining them, a high seismic isolation performance can be obtained even for a structure built on soft ground.