Earthquaker protection system and method of installing same

DETAILED DESCRIPTION I claim: 1.
In a system for isolating a superstructure from its substructure to prevent damage to the superstructure from horizontal seismically induced inertial forces acting between the superstructure and the substructure, wherein a plurality of columns and/or walls support the superstructure above the substructure and each of the columns and/or walls is respectively detached from the substructure in an approximately horizontal plane thereby defining the superstructure above the locus of such detachment and the substructure below the locus of such detachment, the combination of: sliding means disposed at the locus of detachment between the superstructure and the substructure, to permit relative horizontal movement therebetween, said sliding means including bearing plate means operably attached to either the superstructure or the substructure and sliding members operably attached to the other; control means acting in series with sliding means between the superstructure and the substructure, at one or more contact points for each column or wall support, to exert an adjustable and calibratible range of horizontal drag force or opposite braking force, in opposition to any horizontal relative motion due to the relative velocity of the substructure with respect to the superstructure; and biasing means in parallel and not in series with said control means with respect to said superstructure and said substructure, said biasing means acting as very low stiffness horizontal springs in opposition to any horizontal motion due to relative displacement of the substructure with respect to the superstructure, which stiffness is sufficiently high enough to urge the superstructure to near its original position relative to the substructure under the influence of continued shaking motions, while being sufficiently low enough, relative to the total building mass and the calibrated sliding friction force, that it limits or prevents the transmission of significant harmonic resonance from the substructure to the superstructure