Seismic isolation structure

Abstract

To provide a seismic isolation device that can absorb vibration in the front / back and left / right (horizontal) directions with only a small number of dampers.SOLUTION: A seismic isolation structure that supports a target to be seismically isolated includes an upper rolling surface that oscillates horizontally together with the target to be seismically isolated, a lower rolling surface that oscillates horizontally together with the ground, support balls that roll between the upper rolling surface and the lower rolling surface, and energizing means that exerts energizing force on the support balls to energize them to predetermined positions, wherein the energizing means exerts energizing force directly on the support balls.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a seismic isolation structure equipped with a rolling bearing, and further to a seismic isolation structure having a biasing means for biasing an object to be isolated in a direction opposite to the direction of vibration. [Background technology]

[0002] Generally, seismic isolation devices are composed of an isolator that converts large, fast vibrations into small, slow vibrations, and a damper that absorbs vibration energy and converges the vibration in a short time. The isolator uses laminated seismic isolation rubber, sliding materials (sliding bearings), bearings (rolling bearings), etc., while the damper uses coil springs, oil dampers, etc. (Patent Document 1, Patent Document 2).

[0003] For example, Patent Document 1 proposes a seismic isolation device that combines single-ball rolling bearings at the four corners of a steel frame frame, horizontally fixing SUS flat support plates to the four corners of the foundation pressure plate, and providing anchor-embedded concrete risers for the fixed ends of the tension springs, with tension springs arranged to prevent the steel frame frame from lifting up in the X and Y directions and to prevent resonance, and the expansion and contraction action of the tension springs.

[0004] Also, Patent Document 2 proposes a rolling bearing device that includes a rolling body that rolls between a pair of upper and lower plate members, a cage that holds the rolling body between the pair of upper and lower plate members, a pinion on the cage, and a rack that meshes with the pinion on the pair of upper and lower plate members. The rolling bearing device of Patent Document 2 is configured to absorb vibration energy by laminated rubber and an oil damper. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-017135 A [Patent Document 2] JP 2016-003681 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the seismic isolation devices of Patent Documents 1 and 2, the dampers consisting of coil springs or oil dampers are limited to exerting elastic force in one direction, so dampers are required to cover vibrations in each of the three directions (up / down, front / back, left / right), which poses the problem that the devices become complex and large-scale. The present invention has been made in view of the above problems, and has an object to provide a seismic isolation device capable of absorbing vibrations in the front-rear and left-right (horizontal) directions with a small number of dampers. [Means for solving the problem]

[0007] The invention made to solve the above problems is as follows: A seismic isolation structure supporting an object to be isolated from seismic forces comprises an upper rolling surface that oscillates horizontally together with the object to be isolated from seismic forces, a lower rolling surface that oscillates horizontally together with the ground, support balls that roll between the upper rolling surface and the lower rolling surface, and biasing means that exerts a biasing force on the support balls to bias the support balls to a predetermined position, the biasing means directly exerting a biasing force on the support balls.

[0008] The seismic isolation structure according to the present invention exerts a biasing force directly on the support balls in this way, so that a single biasing means can cover vibrations in all directions.

[0009] In the seismic isolation structure of the present invention, the biasing means consists of a linear elastic body that connects the base point (fixing device) of the bottom floor and the biasing point (adhesion point) of the support ball, and regardless of the direction in which the support ball rolls, the biasing force of the linear elastic body can return the support ball to its original position.

[0010] In particular, it is preferable that the support ball is provided with a groove 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 that are stretched by vibrations such as earthquakes can be reliably wound up by the support ball, so that the seismic isolation effect can be reliably achieved even against earthquakes of large amplitude.

[0011] In the seismic isolation structure of the present invention, it is preferable that the bottom floor and the support spheres are hollow so that the seismic isolation object placed on the bottom floor can be floated by buoyancy. With such a configuration, it is also possible to reduce the damage caused by flooding due to tsunamis that occur with a large earthquake.

[0012] In addition, in the seismic isolation structure of the present invention, the support balls are made of magnetic metal, a magnetic member made of a magnetic metal or a magnet is provided at the predetermined position of the floor, and the support balls are biased to the predetermined position by being attracted to the magnetic member via a support ball receiver provided on the outside of the magnetic member. In this configuration, the biasing structure of the present invention is composed of a magnetic member and a magnetic metal ball, and by using a sturdy magnetic metal support ball, even a large and heavy seismic isolation object can be firmly supported. In this configuration, the magnetic member and the support ball are kept stationary by the magnetic attraction force acting on each other, but the support balls will rotate if a force greater than this magnetic force is applied due to an earthquake or the like.

[0013] In the seismic isolation structure of the present invention, the support ball receiver firmly holds the support ball, so that the object to be isolated can be firmly fixed in a static state without the occurrence of an earthquake. Furthermore, it is preferable that the support ball receiver supports the support ball via a bearing. The bearing allows the support ball to roll smoothly, so a higher seismic isolation and vibration reduction effect can be expected.

[0014] In the seismic isolation structure of the present invention, the support balls are made of a non-magnetic material, have a hollow structure, have magnets inside, and are provided at the predetermined positions of the floor with magnetic metal or magnetic members, and the support balls are urged to the predetermined positions by being attracted to the magnetic members via the support ball receivers provided on the outside. In this case, it is particularly preferable that the support ball receivers are bearings. Effect of the Invention

[0015] The seismic isolation structure of the present invention provides sufficient seismic isolation and vibration damping effects with a simple configuration, and is therefore expected to protect a wide range of seismic isolation objects, from small fixtures to large buildings, from earthquake damage. [Brief description of the drawings]

[0016] [Figure 1] 1 is a perspective view of a seismic isolation structure according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a front view of the seismic isolation structure of FIG. [Diagram 3] FIG. 2 is a top view of the seismic isolation structure of FIG. [Figure 4] 2 is a top view showing a state in which the base isolation structure of FIG. 1 is subjected to a force due to horizontal vibration of the ground. [Diagram 5] FIG. 4 is a front view of a seismic isolation structure according to a second embodiment of the present invention. [Figure 6] 6 is a cross-sectional view taken along line AA in FIG. 5. [Figure 7] FIG. 11 is a perspective view of a seismic isolation structure according to a third embodiment of the present invention, viewed from below. [Figure 8] FIG. 8 is a front view of the seismic isolation structure of FIG. [Figure 9] 9 is a cross-sectional view of FIG. 8 taken along line B-B. [Figure 10] 13 is a structural example of a support ball in a seismic isolation structure according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment.

[0018] (First embodiment) A seismic isolation structure 1 according to a first embodiment of the present invention is shown in Fig. 1 to Fig. 6. The seismic isolation structure 1 comprises an upper rolling surface 21 forming the lower surface of a base floor 2, a support ball 3, an urging means 4, and a lower rolling surface 22. The lower rolling surface 22 is a horizontal surface made of leveled concrete. Here, the terms "upper side" and "lower side" refer to the support ball 3 in the seismic isolation structure installed on the ground or the like.

[0019] The bottom floor 2 is made of a rectangular plate-like member extending horizontally, supports the seismic isolation object A (not shown) on its upper surface, and forms the upper rolling surface 21 on its lower surface. The four corners of the bottom floor 2 are provided with insertion holes 7 through which the linear body 5 is inserted. The four corners of the lower surface (upper rolling surface 21) of the bottom floor 2 are provided with recesses 8 that accommodate the support balls 3, with the insertion holes 7 at their centers. The support balls 3 are stored in the recesses 8 during normal times when no earthquakes occur. The recesses 8 that accommodate the support balls 3 are spherical with approximately the same diameter as the support balls 3, with the diameter of the lower opening smaller than the diameter of the support balls 3 and the depth smaller than the radius of the support balls 3. The upper surface of the bottom floor 2 is provided with a fixing device 6 formed by bending a metal wire into an inverted V shape. A total of four fixing devices 6 are provided, two on each long side of the bottom floor 2.

[0020] The biasing means 4 is provided at one end in the longitudinal direction (left-right direction in FIG. 2) and includes an elastic body 41 made of annular rubber, and a linear body 5 that does not have stretchability and is provided at the other end in the longitudinal direction. The biasing means 4 is configured such that the elastic body 41 at one end is hooked onto a fixing tool 6, and the linear body 5 at the other end is connected to an adhesive point 30 on the surface of the support ball 3 via an insertion hole 7, so that the elastic body 41 stretches in the longitudinal direction of the biasing means 4. Any known material can be used for the elastic body 41. Some examples of the elastic body 41 include natural rubber, synthetic rubber, and synthetic resin elastomer.

[0021] The linear body 5 is not particularly limited as long as it is linear and has no elasticity, 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 according to the magnitude of vibration expected in the seismic isolation object, the location conditions, etc.

[0022] Considering the purpose of use, regular maintenance and inspection are essential for a seismic isolation structure to function reliably in the event of an emergency. In the seismic isolation structure according to this embodiment, the elastic body 41 and the linear body 5 are arranged on the upper surface of the base floor 2, so that the state of the elastic body 41 and the linear body 5 can be easily checked from above the base floor 2, and repairs, replacements, and other operations can be performed from above the base floor 2 as necessary, which has the effect of facilitating maintenance and inspection.

[0023] One end of the linear body 5 passes through an insertion hole 7 opened 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 .

[0024] In a state where no external force due to an earthquake or the like is applied (hereinafter referred to as the "static state"), the four support balls 3 are housed in the recesses 8 and are in contact with the ground, the elastic body 41 is not relaxed, and tension is applied from the support balls 3.

[0025] In addition, 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 rolls is limited.

[0026] Figure 3 shows the state of the seismic isolation structure 1 in a static state, while Figure 4 shows the state of the seismic isolation structure 1 when subjected to a horizontal force due to an earthquake or the like. As shown in Figure 4, when subjected to a horizontal force, the support balls 3 leave the depressions 8 and roll relative to the base floor 2, thereby preventing the transmission of ground vibrations to the base floor 2, so that the base floor 2 barely moves in the horizontal direction. In this way, earthquake vibrations on the seismic isolation object placed on the base floor 2 are reduced.

[0027] In the seismic isolation structure 1, even if the bottom floor 2 receives a force in any horizontal direction and the support balls 3 roll in any horizontal direction relative to the bottom floor 2, the elastic bodies 41 receive a tensile force in the linear direction connecting the fixing devices 6 and the insertion holes 7, so that vibrations in any direction can be suppressed. As shown in Figures 1 to 3, by arranging two sets of combinations of support balls 3 and elastic bodies 41 facing each other on the same straight line, the effect of suppressing vibrations received by the bottom floor 2 is increased.

[0028] In the example of Fig. 1, the components of the seismic isolation structure, consisting of the support spheres 3, elastic bodies 41, linear bodies 5, and fixing devices 6, are provided in four locations on one floor surface. Also, the support spheres 3 are provided near the four corners of the underside of the rectangular bottom floor 2, but the locations and number are arbitrary. However, from the viewpoint of stably supporting the seismic isolation object placed on the bottom floor 2, it is preferable to provide the support spheres 3 in three or more locations.

[0029] The base floor 2 can be made of any material, such as metal plates, wood plates, reinforced concrete, composite materials, or a combination of different materials, as long as it has sufficient strength to support the weight of the seismic isolation object. In this embodiment, the seismic isolation object A is placed on the base floor 2 so as not to cover the biasing means 4.

[0030] In addition, the floor portion of the seismic isolation object A may be treated as the bottom floor 2 of the present invention and the seismic isolation structure 1 of the present invention may be provided, or the floor portion of the seismic isolation object A may be placed on a bottom floor 2 equipped with the seismic isolation structure 1 of the present invention separately from the floor portion of the seismic isolation object A.

[0031] There are no particular restrictions on the material of the support sphere 3 as long as it has sufficient strength to support the weight of the base floor 2 and the object to be isolated above it; wood, stone, resin, metal, etc. can be used as appropriate depending on the weight of the object to be isolated; however, when supporting heavy objects such as buildings, it is preferable to use a metal, which has excellent strength and durability.

[0032] When horizontal shaking is applied to the ground supporting the seismic isolation structure of Figures 1 to 3, the object to be isolated will tend to remain in its original position due to the inertia of its mass, so the base floor 2 fixed to the seismic isolation structure will move in the opposite direction to the ground shaking relative to the ground, and the support balls 3 will move away from their static position and roll in the direction of the ground shaking. Then, the pulling force of the biasing means 4 will act, returning the support balls 3 to their static position. In the event of an earthquake, this process will be repeated. In this way, the vibration of the base floor 2 and the object to be vibration-controlled A will be suppressed.

[0033] In this embodiment, if the bottom floor 2 and the support balls 3 are made hollow so that the seismic isolation object placed on the bottom floor 2 can be floated, it can also be used to deal with tsunamis that may occur due to large earthquakes. In other words, it is possible to prevent flooding damage to the seismic isolation object caused by a tsunami.

[0034] In the example shown in Figures 1 to 3, a recess 8 is provided at the portion where the bottom floor 2 contacts the support ball 3. The support ball 3 has its top fitted into the recess 8, so that the stability of the seismic isolation structure 1 in a static state is well maintained. In Figures 1 to 4, the depth of the recess 8 is slightly exaggerated to make it easier to understand the installation state of the recess 8 and the state in which the recess 8 contacts the support ball 3. If the depth of the recess is extremely large, it is expected that vertical vibration will occur when the support ball 3 shifts from the recess 8 due to horizontal shaking of an earthquake. By appropriately designing the depth of the recess 8, it is possible to achieve both stability in a static state and suppression of vertical vibration when the support ball 3 escapes from the recess 8 during an earthquake.

[0035] Second embodiment Figures 5 and 6 show an example of a structure for maintaining stability in a static state in the seismic isolation structure shown in Figures 1 to 3 without providing a recess 8 in the bottom floor 2. In the example of Figures 5 and 6, the bottom floor 2 does not have a recess for accommodating the support ball 3, and the upper end of the support ball 3 is cut off horizontally. In a static state, the support ball 3 is in contact with the bottom floor 2 at this horizontal portion. This maintains the stability of the seismic isolation object in a static state.

[0036] Third embodiment A seismic isolation structure according to a third embodiment is shown in Figures 7 and 8. In this embodiment, a magnetic member 11 is fixed to the bottom floor 2 by an internal fixing device 15, and a support ball 3 is housed in a support ball receiver 12 provided so as to surround the magnetic member 11. Here, since the support ball 3 is made of a magnetic metal, the support ball 3 and the magnetic member 11 attract each other by magnetic force, and this attractive force acts as the biasing means of the seismic isolation structure.

[0037] Known magnetic members can be used. The stronger the magnetic force acting on the support ball 3, the better the function as a biasing means. As magnets that can be used as magnetic members, in addition to permanent magnets, electromagnets can also be used. As magnetic metals that can be used as magnetic members, iron, nickel, and alloys made of these can be mentioned.

[0038] In the examples of Figures 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 enables the magnetic member 11 fixed to the bottom floor 2 to be supported by the support ball 3 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 it not necessary to provide a space for storing the magnetic member 11 in the bottom floor 2, but the magnetic member 11 can be installed on the surface of the bottom floor 2 later, making it easier to manufacture the seismic isolation structure 1.

[0039] This embodiment includes an embodiment in which the support ball 3 is a solid magnetic metal and the support ball receiver 12 is equipped with a bearing 13, as shown in Figure 9(a); an embodiment in which the support ball 3 is made of a non-magnetic material and has a hollow structure, a magnet 14 is housed inside it in a free state relative to the support ball 3, and the support ball receiver 12 is equipped with a bearing 13, as shown in Figure 9(b) (in the example of Figure 9(b), the magnet 14 faces the inner wall of the support ball 3 due to the force of being attracted to the magnetic member 11), and an embodiment in which the support ball 3 is a hollow magnetic metal and supports the bottom bed 2 via a support ball receiver 12 without a bearing, as shown in Figure 9(c).

[0040] In the examples of Figure 9 (a) and (b) which have bearings 13, the support ball 3 abuts against the bearing 13, so there is little friction between the support ball 3 and the support ball receiver 12, and the support ball 3 moves smoothly. In the example of Figure 9 (c) which does not have a bearing, the part of the support ball receiver 12 which abuts against the support ball 3 is chamfered, so the support ball 3 can move smoothly, just like when it has a bearing.

[0041] In this embodiment, the seismic isolation structure consisting of the magnetic members 11, the support ball receivers 12, and the support balls 3 made of magnetic metal are provided near the four corners of the lower surface of the rectangular bottom floor 2, but the positions and number of the support balls are arbitrary. However, from the viewpoint of stably supporting the seismic isolation object placed on the bottom floor, it is preferable to provide the support balls 3 in three or more places.

[0042] Although the present invention has been described above with reference to several embodiments using Figures 1 to 9, these embodiments may be used in combination. It is also possible to adopt a method of providing biasing means of different configurations on one bottom floor, but it is also possible to place one seismic isolation object on several seismic isolation structures each equipped with a different biasing means.

[0043] 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 FIG. 5 and the seismic isolation structure shown in FIG. 8 can be given. For example, a structure consisting of a magnetic member 11, a support ball receiver 12, and a support ball 3 as shown in FIG. 9(a) to FIG. 9(c) is installed between the support balls 3 shown in FIG. 2. A seismic isolation structure including an elastic body 41 has a higher seismic isolation effect against strong shaking than a seismic isolation structure that is biased by magnetic force, while a seismic isolation structure including a support ball receiver 12 has a high effect of keeping the structure stationary in a static state because the support ball receiver 12 firmly holds the support ball 3. By combining the two, the structure can be kept completely stationary when there is almost no vibration, and can reliably suppress large horizontal vibrations even if they are received.

[0044] Furthermore, by using such a combination, the recess 8 in FIG. 2 and the horizontal surface of the support ball 3 in FIG. 5 can be omitted, which is expected to simplify the process and reduce costs.

[0045] (Fourth embodiment) Finally, an embodiment that can reliably cope with large amplitude external vibrations caused by earthquakes or the like when the biasing means 4 is composed of an elastic body 41 and a linear body 5 as in the first and second embodiments will be described. When subjected to large amplitude external vibrations, the movement distance of the support ball 3 increases accordingly. At this time, the linear body 5 is wound around the support ball 3, but if the length of the winding, i.e., the movement distance of the support ball 3, becomes considerably larger than the perimeter of the support ball 3, the linear body 5 is wound around the support ball 3 in double, triple, etc. At this time, if the surface of the support ball 3 is smooth, the linear body 5 cannot be firmly wound around the surface of the support ball 3. If the linear body 5 is not firmly wound around the surface of the support ball 3, it will suddenly return to its original shape due to rubber elasticity, which is not good.

[0046] One way to prevent this is to provide grooves on the surface of the support ball 3. An example of this is shown in Figure 10. Figure 10(a) is a front view of the support ball 3, and Figure 10(b) is a top view. The linear body 5 is joined to the adhesive point 30. The bottom floor, linear body, etc. other than the spherical body 3 are omitted.

[0047] As can be seen in Figure 10(b), the surface of the spherical body 3 has 16 grooves 31 arranged at equal angles from the adhesive point 30 (vertex 3a) that fixes the linear body 5 to the bottom point 3b. With this structure, when a large-amplitude earthquake occurs, the linear body 5 and elastic body 41 can be securely wound up by the spherical body 3 to eliminate vibration. In addition, the horizontal surfaces (vertex surface 32, bottom surface 33) are in contact with the upper rolling surface 21 and the lower rolling surface 22, which increases stability in a static state.

[0048] The lower rolling surface 22 of the seismic isolation structure of the present invention is preferably a flat horizontal surface so that the support balls 3 can easily roll. When used as a seismic isolation structure for a building, the ground can be leveled and the surface cured horizontally with concrete or the like can be used as the lower rolling surface 22, and other components can be installed on top of it. Also, an iron plate or the like can be placed appropriately on the surface cured horizontally with concrete or the like to serve as the lower rolling surface 22. When used to place fixtures, furniture, or the like on it, the indoor floor surface can be used as the lower rolling surface 22, and other components can be installed on top of it. 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.

[0049] Examples of seismic isolation objects to which the seismic isolation structure of the present invention can be applied include buildings such as detached houses and apartments, furniture such as chests of drawers, and fixtures such as display shelves and office automation desks. In addition, the structure can be suitably applied to analytical equipment that needs to be isolated from minute vibrations during use, such as large scanning electron microscopes (SEMs).

[0050] The present invention is not limited to the above-described embodiment. It goes without saying that the present invention includes design changes within the scope of the present invention, including various modifications and alterations that can be conceived by a person having ordinary knowledge in the field of the present invention, without departing from the gist of the present invention. [Explanation of symbols]

[0051] 1. Seismic isolation structure 2 Substrate 21 Upper rolling surface 22 Lower rolling surface 3 Support ball 3a Vertex 3b bottom point 4. Actuation means 41 Elastic Body 5 linear body 6 Fixtures 7 Insertion hole 8. Depression 11 Magnetic member 12 Support ball holder 13 Bearings 14. Magnets 15 Internal Fixtures 30 adhesive points 31 Groove 32 Vertex Face 33 Bottom Point Surface

Claims

1. A seismic isolation structure for supporting an object to be isolated, An upper rolling surface that oscillates horizontally together with the seismic isolation object; A lower rolling surface that oscillates horizontally together with the ground; A support ball that rolls between an upper rolling surface and the lower rolling surface; and a biasing means for applying a biasing force to the support ball to bias the support ball to a predetermined position. A seismic isolation structure characterized in that the biasing force is a tensile force acting between the specified position and the support ball.

2. The biasing means includes an elastic body that expands and contracts in a longitudinal direction, The upper rolling surface is a lower surface of a bottom floor made of a plate-shaped member, The bottom floor has an insertion hole through which the elastic body is inserted, The seismic isolation structure described in claim 1, wherein, when the elastic body is inserted into the insertion hole, one longitudinal end is fixed to the upper surface side of the base floor, and the other longitudinal end is connected to the support ball on the underside of the base floor.

3. The seismic isolation structure described in claim 2, wherein the biasing means comprises a linear body having a non-elastic property, one end of which is joined to the other end of the elastic body in the longitudinal direction, and the other end of the linear body is fixed to the support ball.

4. 4. A seismic isolation structure according to claim 2 or 3, wherein the base floor and / or the support spheres have a hollow structure, and an object to be isolated placed on the base floor can be floated by buoyancy.

5. 4. The seismic isolation structure according to claim 2, wherein the support ball is provided with a groove extending in a meridian direction from a vertex where the biasing means is fixed to a bottom point.

6. The seismic isolation structure described in claim 1, wherein the support balls are 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 the support balls are attracted to the magnetic member via a support ball receiver provided on the outside, thereby urging the support balls to the predetermined position.

7. The seismic isolation structure described in claim 1, wherein the support ball is made of a non-magnetic material, has a hollow structure, has a magnet inside, and a magnetic member made of a magnetic metal or a magnet is provided at the specified position on the upper rolling surface, and the support ball is attracted to the magnetic member via a support ball receiver provided on the outside, thereby urging the support ball to the specified position.

8. The seismic isolation structure according to claim 6 or 7, further comprising a support ball receiver on the upper rolling surface, on which the support ball can roll.

9. The seismic isolation structure according to claim 8 , wherein the support ball receiver supports the support ball via a bearing.

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