JP7382528B1 - Seismic isolation structure - Google Patents

Abstract

[Problem] To provide a seismic isolation device that can absorb vibrations in the front, rear, left, and right (horizontal) directions with a small number of dampers. [Solution] A seismic isolation structure that supports a seismically isolated object, including an upper rolling surface that swings horizontally with the seismically isolated object, a lower rolling surface that swings horizontally with the ground, A support ball that rolls between an upper rolling surface and the lower rolling surface, and a biasing means that applies a biasing force to the support ball to bias the support ball to a predetermined position, The biasing means is characterized in that it applies a biasing force directly to the support ball. [Selection diagram] Figure 1

Description

The present invention relates to a seismic isolation structure equipped with a rolling support, and more particularly to a seismic isolation structure having a biasing means for biasing a seismically isolated object in a direction opposite to the direction of vibration.

Generally, a seismic isolation device is comprised of an isolator that converts large, fast vibrations into small, slow vibrations, and a damper that absorbs vibration energy and converges the vibrations in a short time. Laminated seismic isolation rubber, sliding material (sliding bearing), bearing (rolling bearing), etc. are used for the isolator, and coil springs, oil dampers, etc. are used for the damper (Patent Document 1, Patent Document 2). .

For example, in Patent Document 1, single ball rolling bearings are provided at the four corners of a steel frame frame, support receiving SUS flat plates are horizontally fixed at the four corners of the foundation pressure plate, and a concrete stand with an embedded anchor for the fixed end of the tension spring is provided. , a seismic isolation device has been proposed that combines a single ball rolling bearing with tension springs arranged to prevent the X and Y directions of the steel frame frame, as well as uplift and resonance, and the expansion and contraction action of the tension springs.

Further, Patent Document 2 includes a rolling element that rolls between a pair of upper and lower plate members, a retainer that holds the rolling element between the pair of upper and lower plate members, and a pinion is provided in the retainer. A rolling bearing device has been proposed in which a pair of upper and lower plate members is provided with a rack that engages with a pinion. The rolling bearing device of Patent Document 2 is configured to absorb vibration energy using laminated rubber and an oil damper.

JP2022-017135 Publication Publication Japanese Patent Application Publication No. 2016-003681

However, in the seismic isolation devices of Patent Document 1 and Patent Document 2, the damper made of a coil spring or oil damper exerts elastic force only in one direction, so it covers vibrations in each of the three directions: up, down, front, back, left, and right. There is a problem that a damper is required, making the device complicated and large-scale.
The present invention has been made in view of this problem, and aims to provide a seismic isolation device that can absorb vibrations in the front, rear, left, and right (horizontal) directions with a small number of dampers.

The inventions made to solve the above problems are as follows.
A seismic isolation structure that supports a seismically isolated object,
an upper rolling surface that swings horizontally together with the seismically isolated object;
A lower rolling surface that swings horizontally with the ground;
a support ball rolling between an upper rolling surface and the lower rolling surface;
a biasing means for applying a biasing force to the support ball to bias the support ball to a predetermined position;
The biasing force is a tensile force acting between the predetermined position and the support ball,
The biasing means includes an elastic body that expands and contracts in the longitudinal direction,
The upper rolling surface consists of a lower surface of a bottom made of a plate-like member,
The bottom floor has an insertion hole through which the biasing means is inserted,
When the biasing means is inserted into the insertion hole, one longitudinal end thereof is fixed on the upper surface side of the bottom floor, and the other longitudinal end side is connected to the support ball on the lower side of the bottom floor. and
In the biasing means, one longitudinal end of a non-stretchable linear body is joined to the other longitudinal end of the elastic body, and the other longitudinal end of the linear body is connected to the support ball. A seismic isolation structure characterized by being fixed to.

Since the seismic isolation structure according to the present invention exerts a biasing force directly on the support ball in this way, one biasing means can cover vibrations in all directions.

In the seismic isolation structure of the present invention, the biasing means includes a linear elastic body connecting the base point (fixing device) of the bottom floor and the biasing point (adhesion point) of the support ball, so that the support ball can roll in any direction. Even if the support ball is moved, the support ball can be returned to its original position by the biasing force of the linear elastic body.

In particular, it is preferable that the support ball is provided with a groove extending in the meridian direction from the apex (adhesion point) where the biasing means is fixed to the bottom point. By providing such a groove, the elastic body and the linear body, which have been elongated due to vibrations such as an earthquake, can be reliably wound up with the support ball, thereby ensuring a seismic isolation effect even against large amplitude earthquakes. I can demonstrate it.

In the seismic isolation structure of the present invention, it is preferable that the bottom floor and the support ball have a hollow structure, and that the seismic isolation object installed on the bottom floor can be floated by buoyancy. With such a configuration, it is possible to reduce damage caused by flooding caused by tsunamis and the like that occur due to large earthquakes.

Furthermore, the seismic isolation structure of the present invention is
A seismic isolation structure that supports a seismically isolated object,
an upper rolling surface that swings horizontally together with the seismically isolated object;
A lower rolling surface that swings horizontally with the ground;
a support ball rolling between an upper rolling surface and the lower rolling surface;
a biasing means that applies a biasing force to the support ball to bias the support ball to a predetermined position, the biasing force being a tensile force acting between the predetermined position and the support ball;
The support ball is made of a magnetic metal, and a magnetic member made of a magnetic metal or a magnet is provided at the predetermined position of the bottom bed, and the support ball is The ball is attracted to the magnetically attracted member, thereby being biased toward the predetermined position. In this configuration, while the biasing structure of the present invention is composed of a magnetic member and a magnetic metal ball, by using a sturdy magnetic metal support ball, even a huge and heavy seismically isolated object can be firmly supported. It can be supported. In addition, in this configuration, the magnetically attracted member and the support ball are kept stationary due to the mutual magnetic attraction, but if a force exceeding this magnetic force is applied due to an earthquake or the like, the support ball will rotate.

In the seismic isolation structure of the present invention, the support ball receiver firmly holds the support ball, so that the object to be seismically isolated can be firmly fixed in a static state where no earthquake occurs. Furthermore, it is preferable that the support ball receiver supports the support ball via a bearing. The bearings allow the supporting balls to roll smoothly, so higher seismic isolation and damping effects can be expected.

Furthermore, the seismic isolation structure of the present invention is
A seismic isolation structure that supports a seismically isolated object,
an upper rolling surface that swings horizontally together with the seismically isolated object;
A lower rolling surface that swings horizontally with the ground;
a support ball rolling between an upper rolling surface and the lower rolling surface;
a biasing means that applies a biasing force to the support ball to bias the support ball to a predetermined position, the biasing force being a tensile force acting between the predetermined position and the support ball;
The support ball is made of a non-magnetic material and has a hollow structure, and has a magnet therein, and a magnetic member made of a magnetic metal or a magnet is provided at the predetermined position of the bottom bed. The support ball is attracted to the magnetic member through a support ball receiver provided on the outside, and is urged to the predetermined position. Also in this case, it is particularly preferable that the support ball receiver is a bearing.

The seismic isolation structure of the present invention provides sufficient seismic isolation and damping effects with a simple configuration, so it can be expected to protect a variety of seismically isolated objects from damage caused by earthquakes, from small fixtures to large buildings. .

FIG. 1 is a perspective view of a seismic isolation structure according to a first embodiment of the present invention. FIG. 2 is a front view of the base isolation structure shown in FIG. 1. FIG. FIG. 2 is a top view of the base isolation structure of FIG. 1. FIG. 2 is a top view showing a state in which the base isolation structure of FIG. 1 is subjected to force due to horizontal vibration of the ground. It is a front view of the seismic isolation structure of 2nd Embodiment of this invention. 6 is a sectional view taken along line AA in FIG. 5. FIG. It is a perspective view from below of the seismic isolation structure of 3rd Embodiment of this invention. 8 is a front view of the base isolation structure of FIG. 7. FIG. 9 is a sectional view taken along line BB in FIG. 8. FIG. It is a structural example of the support ball in the seismic isolation structure based on 4th Embodiment of this invention.

Embodiments of the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the following embodiments.

(First embodiment)
A seismic isolation structure 1 according to a first embodiment of the present invention is shown in FIGS. 1 to 4 . The seismic isolation structure 1 includes an upper rolling surface 21 forming the lower surface of the bottom floor 2, a support ball 3, a biasing means 4, and a lower rolling surface 22. Further, the lower rolling surface 22 is a leveled horizontal surface made of concrete. Here, "upper side" and "lower side" are expressions with respect to the support ball 3 in a seismic isolation structure installed on the ground or the like.

The bottom floor 2 is made of a rectangular plate-like member that spreads in the horizontal direction, supports a seismically isolated object A (not shown) on its upper surface, and forms an upper rolling surface 21 on its lower surface. At the four corners of the bottom floor 2, insertion holes 7 through which the linear bodies 5 are inserted are provided. The four corners of the lower surface (upper rolling surface 21) of the bottom floor 2 are provided with depressions 8 centered around the insertion holes 7 to accommodate the support balls 3. The support ball 3 is housed in the depression 8 during normal times when no earthquake occurs. The recess 8 that accommodates the support ball 3 has a spherical shape with approximately the same diameter as the support ball 3, the diameter of the lower opening is smaller than the diameter of the support ball 3, and the depth is smaller than the radius of the support ball 3. It is being A fixture 6 formed by bending a metal wire into an inverted V shape is protruded from the upper surface of the bottom floor 2. A total of four fixtures 6 are provided, two each along the long sides of the bottom floor 2.

The biasing means 4 includes an elastic body 41 that is provided at one end in the longitudinal direction (left-right direction in FIG. 2) and made of annular rubber, and a linear body 5 that is provided at the other end in the longitudinal direction and has no elasticity. It is equipped with The biasing means 4 hooks the elastic body 41 on one end to the fixture 6, connects the linear body 5 on the other end to the adhesive point 30 on the surface of the support ball 3 through the insertion hole 7, and 41 is configured to expand and contract in the longitudinal direction of the biasing means 4. The elastic body 41 can be made of any known material. To give some examples, the elastic body 41 is made of natural rubber, synthetic rubber, synthetic resin elastomer, etc.

The linear body 5 is not particularly limited as long as it has a linear shape and is not stretchable, and any known material can be used, such as thread, string, rope, metal wire, chain, etc. The linear body 5 is used with an appropriate length and thickness depending on the magnitude of vibration expected in the seismically isolated object, location conditions, etc.

Given the intended use of seismic isolation structures, regular maintenance and inspection are essential to ensure that they function reliably in times of emergency. In the seismic isolation structure according to this embodiment, since the elastic body 41 and the linear body 5 are arranged on the upper surface of the bottom floor 2, the states of the elastic body 41 and the linear body 5 can be easily checked from above the bottom floor 2. This can be confirmed, and operations such as repair or replacement can be performed from above the bottom floor 2 if necessary, making maintenance and inspection easier.

One end of the linear body 5 passes through an insertion hole 7 made in the bottom floor 2 and reaches the back surface (upper rolling surface 21) of the bottom floor 2, where it is joined at an adhesive point 30 of the support ball 3.

In addition, in a state where no external force such as an earthquake is applied (hereinafter referred to as a "static state"), the four support balls 3 are in contact with the ground while being accommodated in the depressions 8, and the elastic body 41 is relaxed. Instead, the tension received from the support ball 3 is added.

Note that since the lengths of the elastic body 41 and the linear body 5 on the upper surface of the bottom floor 2 are constant, the range in which the support ball 3 can roll is limited.

FIG. 3 shows the state of the base isolation structure 1 in a static state, and FIG. 4 shows the state of the base isolation structure 1 when subjected to horizontal force due to an earthquake or the like. As shown in FIG. 4, the support ball 3 detaches from the depression 8 and rolls against the bottom floor 2 under the force in the horizontal direction, thereby suppressing the transmission of ground shaking to the bottom floor 2. Therefore, the bottom bed 2 hardly moves in the horizontal direction. In this way, earthquake vibrations to the seismically isolated object installed on the bottom floor 2 are reduced.

In the seismic isolation structure 1, even if the bottom floor 2 receives force in any horizontal direction and the support ball 3 rolls in any horizontal direction with respect to the bottom floor 2, the elastic body 41 is subjected to a tensile force in the linear direction connecting the fixture 6 and the insertion hole 7, so vibrations in any direction can be suppressed. As shown in FIGS. 1 to 3, by arranging two sets of support balls 3 and elastic bodies 41 so as to face each other on the same straight line, the effect of suppressing vibrations received by the bottom floor 2 is enhanced.

In the example of FIG. 1, the constituent parts of the seismic isolation structure including the support ball 3, the elastic body 41, the linear body 5, and the fixture 6 are provided at four locations on one floor surface. Further, although the supporting balls 3 are provided near the four corners of the lower surface of the rectangular bottom floor 2, the positions and number thereof are arbitrary. However, from the viewpoint of stably supporting the seismically isolated object placed on the bottom floor 2, it is preferable to provide the supporting balls 3 at three or more locations.

The bottom floor 2 can be made of any type of material, such as metal plates, wooden plates, reinforced concrete, composite materials, or a combination of different materials, as long as it has sufficient strength to support the weight of the seismically isolated object. In this embodiment, the seismically isolated object A is installed on the bottom floor 2 so as not to cover the biasing means 4.

Furthermore, the base isolation structure 1 of the present invention may be provided by using the floor part of the base isolation object A as the bottom floor 2 of the present invention, or the base isolation structure 1 of the present invention may be provided separately from the floor part of the base isolation target A. It may be placed on a bottom floor 2 provided with a seismic structure 1.

The material of the support ball 3 is not particularly limited as long as it has sufficient strength to support the weight of the base floor 2 and the seismically isolated object on it, and wood, stone, etc. can be used depending on the weight of the seismically isolated object. , resin, metal, etc. can be used as appropriate, but when supporting heavy objects such as buildings, metal is preferable because of its excellent strength and durability.

When horizontal shaking is applied to the ground supporting the seismic isolation structure shown in Figures 1 to 3, the seismically isolated object tries to stay in its original position due to inertia due to its mass, so the seismic isolation structure is fixed to the structure. The bottom bed 2 is oriented relative to the ground in the opposite direction to the rocking direction of the ground, and the support ball 3 is removed from its position in the static state and rolls in the rocking direction of the ground. Then, the pulling force of the biasing means 4 acts to return the support ball 3 to its resting position. In the case of an earthquake, this process repeats. In this way, the vibrations of the bottom floor 2 and the vibration damping object A are suppressed.

In this embodiment, if the bottom floor 2 and the support ball 3 are made into a hollow structure so that the seismically isolated object installed on the bottom floor 2 can be floated, it is possible to prevent tsunamis that are likely to occur due to a large earthquake. It also corresponds to In other words, it is possible to avoid water damage to seismically isolated objects caused by tsunamis and the like.

In the example shown in FIGS. 1 to 3, a depression 8 is provided in a portion where the bottom floor 2 contacts the support ball 3. Since the top of the support ball 3 fits into the recess 8, the stability of the seismic isolation structure 1 in a static state is well maintained. In FIGS. 1 to 4, the depth of the recess is slightly exaggerated to make it easier to understand the installation state of the recess 8 and the contact state of the recess 8 and the support ball 3. If the depth of the depression becomes extremely large, it is assumed that pitching vibrations will occur when the support ball 3 is displaced from the depression 8 due to the horizontal shaking of an earthquake. By appropriately designing the depth of the depression 8, it is possible to achieve both stability in a static state and suppression of pitching vibration when the support ball 3 escapes from the depression 8 during an earthquake.

(Second embodiment)
5 and 6 show an example of a structure in which the base isolation structure shown in FIGS. 1 to 3 does not have a recess 8 in the bottom floor 2 to maintain stability in a static state. In the examples shown in FIGS. 5 and 6, the bottom floor 2 is not provided with a recess for accommodating the support ball 3, and the upper end of the support ball 3 is cut out horizontally. In the static state, the support ball 3 is in contact with the bottom floor 2 at this horizontal portion. This maintains the stability of the seismically isolated object in a static state.

(Third embodiment)
A seismic isolation structure according to the third embodiment is shown in FIGS. 7 and 8. In this embodiment, a magnetic member 11 is fixed to the bottom floor 2 by an internal fixture 15, and a support ball 3 is housed in a support ball receiver 12 provided to surround the magnetic member 11. . Here, since the support ball 3 is made of magnetic metal, the support ball 3 and the magnetized member 11 are attracted to each other by magnetic force, and the attractive force acts as a biasing means for the seismic isolation structure.

A known magnetic member can be used. The stronger the magnetic force acting on the support ball 3, the better the function as a biasing means. In addition to permanent magnets, electromagnets can also be used as magnets that can be used in the magnetizing member. Examples of magnetic metals that can be used in the magnetizing member include iron, nickel, and alloys made of these.

In the examples shown in FIGS. 7 and 8, the support ball 3 supports the bottom floor 2 via the support ball receiver 12. The presence of such a support ball receiver 12 allows the support ball 3 to support the magnetic member 11 fixed to the bottom floor 2 even if it protrudes from the bottom floor 2. In addition, by providing a gap between the magnetic member 11 and the support ball 3, not only is there no need to provide a space for storing the magnetic member 11 in the bottom floor 2, but also the surface of the bottom bed 2 is Since the magnetic member 11 can be installed as an afterthought, the seismic isolation structure 1 can be manufactured more easily.

In this embodiment, as shown in FIG. 9(a), the support ball 3 is made of solid magnetic metal and the support ball receiver 12 is provided with a bearing 13, and as shown in FIG. 9(b), In the second embodiment, the support ball 3 is made of a non-magnetic material and has a hollow structure, and the magnet 14 is housed inside the support ball 3 in a free state relative to the support ball 3, and the support ball receiver 12 is provided with a bearing 13 (Fig. 9(b), the magnets 14 face each other on the inner wall of the support ball 3 due to the force of being attracted by the magnetic member 11), as shown in FIG. 9(c), the support ball 3 is made of hollow magnetic metal. This includes a mode in which the bottom floor 2 is supported via a support ball receiver 12 without a bearing.

In the example shown in FIGS. 9A and 9B with the bearing 13, the support ball 3 is in contact with the bearing 13, so the friction between the support ball 3 and the support ball receiver 12 is small and the support ball 3 moves smoothly. . In addition, in the example shown in Fig. 2(c) without a bearing, the part of the support ball receiver 12 that contacts the support ball 3 is chamfered, so the support ball 3 can move smoothly as in the case with a bearing. can.

In this embodiment, the seismic isolation structure composed of the magnetic member 11, the support ball receiver 12, and the support balls 3 made of magnetic metal is provided near the four corners of the lower surface of the rectangular bottom floor 2, but the location and number can be determined arbitrarily. It is. However, from the viewpoint of stably supporting the seismically isolated object placed on the bottom floor, it is preferable to provide the support balls 3 at three or more locations.

Although the present invention has been described above using a plurality of embodiments using FIGS. 1 to 9, these embodiments may be used in combination. Although it is possible to adopt a method in which biasing means of different configurations are provided on a single bottom floor, it is also possible to use a method in which a single seismically isolated object is placed on a plurality of seismic isolation structures each equipped with a different biasing means. It is possible.

As an example of combining a plurality of seismic isolation structures of the present invention, a combination of the seismic isolation structure shown in FIG. 2 or 5 and the seismic isolation structure shown in FIG. 8 can be cited. For example, a structure consisting of a magnetic member 11, a support ball receiver 12, and a support ball 3 as shown in FIGS. 9(a) to 9(c) is placed between the support balls 3 shown in FIG. Install. A seismic isolation structure including the elastic body 41 has a higher seismic isolation effect against strong shaking than a seismic isolation structure biased by magnetic force.On the other hand, in a seismic isolation structure including the support ball receiver 12, the support ball receiver 12 is a support ball. 3 is firmly held, so it is highly effective in keeping it stationary in a static state. By combining the two, it can remain completely stationary when there is almost no vibration, and even if it is subjected to large horizontal vibrations, it can reliably suppress it.

In addition, by using such a combination, it is possible to omit the recess 8 provided in Fig. 2 and the horizontal surface of the support ball 3 provided in Fig. 5, resulting in the effects of process simplification and cost reduction. You can also expect

(Fourth embodiment)
Finally, in the case where the biasing means 4 is composed of the elastic body 41 and the linear body 5 as in the first and second embodiments, it is possible to reliably cope with the case where the amplitude of external vibrations caused by an earthquake or the like is large. An embodiment will be described. When external vibrations of large amplitude are received, the distance that the support ball 3 moves due to the external vibrations also increases. At this time, the linear body 5 is wound around the support ball 3, but if the length of the winding, that is, the moving distance of the support ball 3 is considerably larger than the circumferential length of the support ball 3, the linear body 5 will be wrapped around the support ball 3 in double, triple, etc. fashion. At this time, if the surface of the support ball 3 is smooth, the linear body 5 will not be able to tightly wrap around the surface of the support ball 3. If the linear body 5 is not tightly wrapped around the surface of the support ball 3, the rubber elasticity will restore the body all at once, which will be inconvenient.

Therefore, it is conceivable to provide a groove on the surface of the support ball 3 as a measure to prevent such a situation. An example of this is shown in FIG. FIG. 10(a) is a front view of the support ball 3, and FIG. 10(b) is a top view. The linear body 5 is joined to the bonding point 30. The bottom floor, linear bodies, etc. other than the spherical body 3 are omitted.

As can be seen in FIG. 10(b), the surface of the spherical body 3 is provided with 16 grooves 31 arranged at equal angles from the adhesive point 30 (vertex 3a) to the bottom point 3b for fixing the linear body 5. It is being With such a structure, when an earthquake with large amplitude occurs, the linear body 5 and the elastic body 41 can be reliably wound around the spherical body 3 to absorb vibrations. In addition, since the horizontal surfaces (the apex surface 32 and the bottom surface 33) are in contact with the upper rolling surface 21 and the lower rolling surface 22, stability in a static state is increased.

The lower rolling surface 22 of the seismic isolation structure of the present invention is preferably a flat horizontal surface so that the support ball 3 can easily roll. When used as a seismic isolation structure for a building, other components may be installed on a surface leveled with concrete or the like as the lower rolling surface 22. Further, the lower rolling surface 22 may be formed by appropriately placing an iron plate or the like on the surface cured horizontally with concrete or the like. When using the device with fixtures, furniture, etc. placed thereon, other components are installed on the floor surface of the room as the lower rolling surface 22. In this case, if a carpet or the like is laid on the floor surface, the carpet or the like functions as the lower rolling surface 22.

Examples of objects to be seismically isolated to which the seismic isolation structure of the present invention can be applied include buildings such as detached houses and condominiums, furniture such as chests of drawers, and fixtures such as display shelves and OA desks. In addition, the invention can also be suitably applied to analytical instruments that require isolation from minute vibrations during use, such as large-scale scanning electron microscopes (SEMs).

As described above, the present invention is not limited to the embodiments described above. It goes without saying that the present invention includes design changes that do not depart from the gist of the present invention, including various modifications and modifications that can be conceived by a person having ordinary knowledge in the field of the present invention. .

1 Seismic isolation structure 2 Bottom floor 21 Upper rolling surface 22 Lower rolling surface 3 Support ball 3a Vertex 3b Bottom point 4 Biasing means 41 Elastic body 5 Linear body 6 Fixture 7 Insertion hole 8 Recess 11 Magnetic member 12 Support ball receiver 13 Bearing 14 Magnet 15 Internal fixture 30 Adhesive point 31 Groove 32 Top surface 33 Bottom point surface

Claims (7)

A seismic isolation structure that supports a seismically isolated object,
an upper rolling surface that swings horizontally together with the seismically isolated object;
A lower rolling surface that swings horizontally with the ground;
a support ball rolling between an upper rolling surface and the lower rolling surface;
a biasing means for applying a biasing force to the support ball to bias the support ball to a predetermined position;
The biasing force is a tensile force acting between the predetermined position and the support ball ,
The biasing means includes an elastic body that expands and contracts in the longitudinal direction,
The upper rolling surface consists of a lower surface of a bottom made of a plate-like member,
The bottom floor has an insertion hole through which the biasing means is inserted,
When the biasing means is inserted into the insertion hole, one longitudinal end thereof is fixed on the upper surface side of the bottom floor, and the other longitudinal end side is connected to the support ball on the lower side of the bottom floor. and
In the biasing means, one longitudinal end of a non-stretchable linear body is joined to the other longitudinal end of the elastic body, and the other longitudinal end of the linear body is connected to the support ball. A seismic isolation structure characterized by being fixed to . 2. The seismic isolation structure according to claim 1 , wherein the bottom floor and/or the support ball have a hollow structure, and can float a seismically isolated object installed on the bottom floor by buoyancy. 2. The seismic isolation structure according to claim 1 , wherein the support ball is provided with a groove extending in a meridian direction from an apex to a bottom point at which the biasing means is fixed. A seismic isolation structure that supports a seismically isolated object,
an upper rolling surface that swings horizontally together with the seismically isolated object;
A lower rolling surface that swings horizontally with the ground;
a support ball rolling between an upper rolling surface and the lower rolling surface;
a biasing means that applies a biasing force to the support ball to bias the support ball to a predetermined position, the biasing force being a tensile force acting between the predetermined position and the support ball;
The support ball is made of a magnetic metal, and a magnetic member made of a magnetic metal or a magnet is provided at the predetermined position of the upper rolling surface, and a support ball holder provided on the outside thereof, The seismic isolation structure is biased to the predetermined position by the support ball being attracted to the magnetic member. A seismic isolation structure that supports a seismically isolated object,
an upper rolling surface that swings horizontally together with the seismically isolated object;
A lower rolling surface that swings horizontally with the ground;
a support ball rolling between an upper rolling surface and the lower rolling surface;
a biasing means that applies a biasing force to the support ball to bias the support ball to a predetermined position, the biasing force being a tensile force acting between the predetermined position and the support ball;
The support ball is made of a non-magnetic material and has a hollow structure, and has a magnet therein, and a magnetic member made of a magnetic metal or a magnet is provided at the predetermined position of the upper rolling surface, Further, the seismic isolation structure is biased to the predetermined position by attracting the support ball to the magnetic member via a support ball receiver provided on the outside thereof. The seismic isolation structure according to claim 4 or 5 , wherein the upper rolling surface is provided with a support ball receiver that allows the support ball to roll. The seismic isolation structure according to claim 6 , wherein the support ball receiver supports the support ball via a bearing.

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