Static structures (e.g. – buildings) – Means compensating earth-transmitted force – Relative motion means between a structure and its foundation
Reexamination Certificate
1999-12-01
2001-05-08
Friedman, Carl D. (Department: 3635)
Static structures (e.g., buildings)
Means compensating earth-transmitted force
Relative motion means between a structure and its foundation
C052S167100, C052S167300
Reexamination Certificate
active
06226935
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a seismic isolator which comprises vibrating units arranged in a multiplexed manner around a core member suspended from an upper structure, and which is adapted to cut off horizontal vibration of a lower structure.
2. Description of the Related Art
A seismic isolator which comprises a core member suspended from an upper structure, and vibrating units arranged in a multiplexed manner around the core member, and which is adapted to cut of f horizontal vibration of a lower structure, as disclosed in Japanese Patent Publication Nos. 16330/1979, 40842/1979, 574/1988 and 21780/1988 is characterized in that a plurality of frustoconical vibrating units of different scales are arranged in a multiplexed manner with adjacent vibrating units combined with one another by suspension members, a vertical load of the upper structure being borne as a compressive force by the core member and vibrating units, and as a tensile force by suspension members provided among the vibrating units, whereby the upper structure is substantially supported in a suspended state on the lower structure.
Owing to a plurality of vibrating units arranged in a multiplexed manner, a pendulum length larger than a distance between the upper and lower structures is secured. Since a vibration cycle corresponding to the pendulum length equal to the sum of a total length of all of the suspension members is given to the upper structure, the vibration cycle of the upper structure increases to a high level to cut off horizontal vibration of the lower structure.
The vibrating units are formed cylindrically, and the compressive force bearing portions of the vibrating units are formed of face bars. Therefore, in order that the vibrating units positioned relatively on the outer circumferential side support the inner circumferential side vibration units without hindering the relative displacement of the latter vibration units, it is necessary that the vibrating units on the outer circumferential side be larger than those on the inner circumferential side. Therefore, it is necessary that the radius of the vibrating units positioned on the outermost circumferential side be so large that corresponds to the sum of the amplitude of vibrating units, and the area occupied by a seismic isolator generally tends to increase.
SUMMARY OF THE INVENTION
The present invention has been achieved by developing the above-described seismic isolator, and proposes a seismic isolator of the type which does not cause an increase in the area occupied thereby, and a seismic isolator of the same construction to which a function of absorbing a seismic impact force is added.
In the previously-described seismic isolator, compressive force bearing portions constitute vibrating units, and adjacent vibrating units are combined with one another by suspension members constituting tensile force bearing members. According to the present invention, vibration units are formed of suspension members constituting tensile force bearing members, and frames and bases to which both end portions of the suspension members are joined, and adjacent vibrating units are joined together by compressive force bearing members, which comprises wire rods, whereby the necessity of increasing the area of lower end portions of the vibrating units is eliminated to reduce the area occupied by the seismic isolator comprising vibrating units arranged in a multiplexed manner.
The seismic isolator comprises a core member bearing a vertical load of the upper structure as a compressive force, and a plurality of vibrating units arranged in a multiplexed manner around the core member, the vibrating units comprising frames positioned on a relatively upper side, bases positioned below the frames, and suspension members provided between the frames and bases, supporting the bases in a suspending state and bearing the vertical load of the upper structure as a tensile force.
The vibrating units positioned on the relatively inner circumferential side are supported on the vibrating units positioned on the outer circumferential side thereof via diagonal members constituting compressive force bearing members. The diagonal members are provided between the frames of the vibrating units positioned on the relatively inner circumferential side and the bases of the vibrating units positioned on the outer circumferential side, bear the vertical load of the upper structure as a compressive force, and support the inner circumferential side vibrating units on the outer circumferential side vibrating units.
A lower end portion of the core member is joined to the bases of the vibrating units positioned on the innermost circumferential side, and the vibrating units positioned on the outermost circumferential side are supported on the lower structure directly via the diagonal members provided between the relative frames and the lower structure, or on the lower structure via the diagonal members and the relative bases.
The core member extends through the frames of all of the vibration units, and is relatively displaced with respect to the frames when the upper and lower structures are relatively displaced with respect to each other, so that the frames are formed so as to have holes which do not hinder the relative displacement of the core member.
The vertical load of the upper structure is transmitted from the core member to the bases joined thereto, and the vertical load transmitted to these bases to the relative frames on the upper side via the suspension members. The resultant load is further transmitted to the bases of the outer circumferential side vibrating units, which support these frames, via the relative diagonal members, and finally from the frames of the vibrating units positioned on the outermost circumferential side to the lower structure via the relative diagonal members or via the relative diagonal members and bases.
The upper structure is virtually put in a condition in which it is supported in a suspended state on the lower structure via a suspension member the length of which corresponds to the sum of a total length of all of the suspension members, and a vibration cycle corresponding to a pendulum length equal to the sum of a total length of all of the suspension members is given to the upper structure to increase the cycle thereof to a high level, and cut off the horizontal vibration of the lower structure.
When the upper structure is relatively displaced with respect to the lower structure due to the vibration of the latter structure, the bases of the vibrating units on the innermost circumferential side to which the core member is joined are relatively displaced with the upper structure with respect to the relative frames on the upper side, while the frames of the vibrating units on the innermost circumferential side and the bases of the vibrating units on the outer circumferential side joined thereto via the relative diagonal members are relatively displaced with respect to the relative frames on the upper side. In the whole of the seismic isolator, relative displacement corresponding to the sum of amounts of relative displacement of the bases of all vibrating units occurring with respect to the frames on the upper side occurs between the upper and lower structures.
When the bases of the vibrating units are relatively displaced with respect to the frames at the time of occurrence of vibration of the lower structure with the shapes and sizes in plan of adjacent vibrating units identical with each other, the bases cannot collide with compressive force bearing members to be displaced, when the compressive force bearing members are face bars. According to the present invention, the diagonal members constituting compressive force bearing members are wire rods. Therefore, when the direction of adjacent vibrating units is regulated, hollow spaces allowing the displacement of the bases occurs around therearound, so that the bases can be relatively displaced with respect to the frames even when the shapes and sizes of adjacent vibr
Kitayama Naomi
Kojima Teiji
Kuramochi Haruo
Kuramochi Michio
Narita Ryosuke
Chavez Patrick J.
Friedman Carl D.
NEC System Integration & Construction, Ltd.
Pearne & Gordon LLP
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