Static structures (e.g. – buildings) – Means compensating earth-transmitted force – Relative motion means between a structure and its foundation
Patent
1996-10-18
1998-06-09
Canfield, Robert
Static structures (e.g., buildings)
Means compensating earth-transmitted force
Relative motion means between a structure and its foundation
521677, 525731, E04B 198
Patent
active
057618569
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an apparatus which is disposed between two structures so as to reduce vibration acceleration for the structure by absorbing relative horizontal vibrations between the two structures, and more particularly to a vibration isolating apparatus for reducing earthquake input acceleration by damping seismic energy so as to prevent damage to a structure such as a building, a bridge, or the like and to a vibration isolating system using at least one such vibration isolating apparatus.
BACKGROUND ART
As a vibrational energy absorber, one described in, for instance, Japanese Patent Application Publication No. 17984/1986 is known, and this vibrational energy absorber is fixed between two structures and has a lead member which undergoes plastic deformation as a shearing force is applied thereto. The lead member of such a vibrational energy absorber satisfactorily absorbs the vibrational energy in its plastic deformation without causing cracks or the like. After the deformation, however, the lead member of such a vibrational energy absorber does not return the absorbed energy to the structure unlike an ordinary spring, and maintains its deformed state, so that it is difficult to return the structure to its original position.
An elastic body serving as a vibration isolating apparatus in which elastic plates, which constitute elastic material layers and are formed of rubber or the like, and metal plates, which constitute rigid material layers, are alternately superposed one on top of another, and these members are bonded to each other by vulcanization or the like and are thereby secured to each other, reduces earthquake input acceleration and by and large protects the structure from the damaging force of an earthquake. However, such an elastic body has a low vibrational energy absorbing capability, and from the standpoint of earthquake engineering and vibration engineering there are various practical problems such as in that if the elastic body is used singly as a vibration isolating apparatus, in comparison with the above-described lead member a long time is required until the vibrations of the structure subjected to seismic vibrations subside.
Accordingly, a vibration isolating apparatus which is comprised of an elastic body and a cylindrical lead member disposed in and passed through the elastic body, has also been proposed in the aforementioned publication so as to be provided with the vibrational energy absorbing capability in the plastic deformation of the lead member and the earthquake-input-acceleration reducing capability and the restoring capability of the elastic body.
A vibration isolating apparatus 5 shown in FIGS. 1 and 2 is comprised of an annular elastic body 3 in which elastic plates 1, which constitute elastic material layers and are formed of rubber or the like, and annular rigid plates 2, which constitute rigid material layers, are alternately superposed one on top of another and are secured to each other; a cylindrical lead member 4 which is disposed in a hollow portion 12 defined by a cylindrical inner peripheral surface 9 of the elastic body 3; and flange plates 18 and 19 which are respectively attached to a lower surface and an upper surface of the elastic body 3 by means of bolts or the like by abutting respectively against a lower surface and an upper surface of the cylindrical lead member 4. The vibration isolating apparatus 5 is used in a state in which the flange plate 18 side is fixed to one structure such as a base, and the other structure such as a building is placed on the flange plate 19 side so as to receive a normal load X from the building or the like via the flange plate 19.
In such a vibration isolating apparatus 5, unless the cylindrical lead member 4 disposed in the hollow portion 12 is restrained by the elastic body 3 without a gap, in the event that a lateral force (horizontal force) F due to an earthquake has occurred, a gap is produced between the inner peripheral surface 9 of the elastic body 3 and the cylindrical outer peri
REFERENCES:
patent: 4117637 (1978-10-01), Robinsons
patent: 4499694 (1985-02-01), Buckel et al.
patent: 4899323 (1990-02-01), Fukahori et al.
patent: 5324117 (1994-06-01), Matsushita et al.
Kishizono Tsukasa
Robinson William Henry
Shimoda Ikuo
Canfield Robert
Oiles Corporation
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