EARTHQUAKEPROOF FLOOR STRUCTURE

PURPOSE: To conduct a vertical motion only in case of an earthquake, and to carry out vertical vibration isolation by forming a conical recessed section to the upper section of a floor and disposing a bearing by a steel ball having a large diameter in a rollable manner while connecting the bearing to a movable section in an extensible manner by a coil spring in a bearing section. CONSTITUTION: A supporting bar 5 comprising a shaft 6 and a jack bolt 7 screwed at the front end of the shaft 6 connects the root end of the shaft 6 to a link ball 8, and is journaled to a boss 11 by a large-sized nut installed on the concrete floor 1 side by a bolt 10 by a bolt 9. A sleeve 15 is fitted on an outer circumference on the journaling section of the shaft 6, a diameter- expanding end section 15a is abutted onto the surface of the boss 11, and a coil spring 17 is wound on an outer circumference between another end of the sleeve 15 and a snap ring 16 fixed onto the intermediate section of the shaft 6 in a collar shape. The supporting bar 5 is interposed between the concrete floor 1 and a floor joist 3 borne by a vibration-isolation mechanism, and used as a bringing-down and erecting means.