Double foundation rafts separated by ball bearings, for protection of buildings against earth tremors include support plates with ball bearings on both sides

摘要

A double, reinforced concrete raft foundation has ball bearings (1) between the raft plates (2,3) to allow the upper plate, carrying a building or other structure, to move horizontally in all directions. A U-shaped clamping frame (14) may be attached to the lower plate to restrain the vertical oscillation of the upper plate, and the area of the lower plate is greater than the upper. The minimum 500 mm all-round projected-area clearance of the lower plate is covered by foamed material to ensure freedom of movement of the upper plate. The arrangement can be retrofitted to existing buildings. Piped and cable utilities to and from the building can be made with flexible connectors. Terrace construction buildings can be either supported on a single raft, or individually, if necessary on stepped rafts, at approximately 600 mm spacing. The bearings may be rust-resistant steel, hardened glass or, spherical pebbles. The raft surfaces are preferably coated with rust-resisting hard-rubber or plastics material.