JP6994951B2 - Seismic isolation device - Google Patents

Description

The present invention relates to a seismic isolation device.

Rolling bearings and sliding bearings provided between the lower structure and the upper structure can support the axial force from the upper structure and allow the lower structure and the upper structure to be relatively displaced. It is widely used in seismic devices (see, for example, Patent Documents 1 and 2).
The rolling bearing is configured so that a rolling portion such as a sphere or a roller rolls on the sliding surface of the lower structure, and the coefficient of friction μ with the sliding surface can be realized with a very small value (for example, μ≈0.005). There is a feature.
The sliding bearing is configured so that the sliding portion provided with the low friction material slides on the sliding surface of the lower structure, and has a feature that a large load capacity equal to or higher than that of the laminated rubber bearing can be realized at low cost.

Japanese Unexamined Patent Publication No. 2017-110447 JP-A-2017-166518

However, rolling bearings generally have a problem that the load capacity is small and a large axial force cannot be supported. Further, since the rolling bearing is composed of high-precision machine parts, there is a problem that it is not easy to increase the load capacity and it is costly.

On the other hand, sliding bearings generally have a large load capacity and can support a large axial force, but it is difficult to set the coefficient of friction with the sliding surface to a small value such as the coefficient of friction between the rolling bearing and the sliding surface. Is.
In addition, the coefficient of friction of the sliding bearing has the property of depending on the surface pressure of the sliding surface, and the axial force acting on the bearing is small and large when the surface pressure is low, and when the axial force acting is large and the surface pressure is low. Has the property of becoming smaller.
For example, the coefficient of friction μ of the low friction slip support currently on the market is 0.014 when the reference surface pressure is 20 MPa (20 N / mm ² ), but when the reference surface pressure is 1/4, 5 MPa. Is 0.029, which is about twice as high as that in the case of a reference surface pressure of 20 MPa (20 N / mm ² ). Furthermore, the coefficient of friction μ of the slip support is 0.07 when the reference surface pressure is 1 MPa, which is 1/20, which is about 5 times higher than that when the reference surface pressure is 20 MPa (20 N / mm ² ). When the surface pressure is 1/200, 0.1 MPa, it becomes 0.24, which is about 17 times that of the reference surface pressure of 20 MPa (20 N / mm ² ), which is no longer low friction. It ends up.

As described above, the rolling bearing has a problem that the load capacity is small and it is difficult to support it at a high axial force, and the sliding bearing has a problem that the coefficient of friction with the sliding surface becomes large at a low axial force. .. For these reasons, with the current rolling bearings and sliding bearings, it is not possible to rationally build bearings with stable performance (low friction) from low axial forces to high axial forces.
Further, since the rolling bearing is composed of high-precision machine parts, there is a problem that the cost increases when trying to increase the load capacity.

Therefore, an object of the present invention is to provide a seismic isolation device capable of stably maintaining performance and suppressing costs regardless of the magnitude of the acting axial force.

In order to achieve the above object, the seismic isolation device according to the present invention is a seismic isolation device provided between a lower structure that can be relatively displaced in the horizontal direction and the upper structure, and is located below the upper structure. A rolling bearing that is connected and has a rolling portion that can roll horizontally along a sliding surface provided on the lower structure, and a rolling bearing that is parallel to the rolling bearing and is connected to the lower side of the upper structure and the sliding portion. A sliding bearing having a sliding portion that can slide horizontally along a surface, and when the axial force acting from the superstructure is equal to or less than a predetermined value, the rolling portion is the sliding surface. When the sliding portion is separated from the sliding surface and the axial force acting on the rolling bearing and the sliding bearing exceeds the predetermined value, the sliding portion becomes rollable. The rolling portion comes into contact with the sliding surface so that the sliding surface can be rolled, and the sliding portion comes into contact with the sliding surface to make the sliding surface slidable.

In the sliding part, the axial force acting on the superstructure is large, and the larger the surface pressure on the sliding surface, the smaller the coefficient of friction on the sliding surface, and the smaller the axial force acting on the superstructure, the smaller the surface pressure on the sliding surface. The smaller the value, the larger the coefficient of friction on the slip surface.
In the present invention, in the sliding support, when the axial force acting from the superstructure exceeds a predetermined value, the sliding portion allows the sliding portion to slide on the sliding surface, and the axial force acting from the superstructure has a predetermined value. Below, when the friction coefficient between the sliding portion and the sliding surface is large because the surface pressure is small and the surface pressure is small, the sliding portion is separated from the sliding surface. Therefore, the sliding bearing slides on the sliding surface only when the surface pressure is large and the coefficient of friction with the sliding surface can be kept small.
On the other hand, since the change in the coefficient of friction of the rolling portion with the sliding surface due to the change in the axial force acting from the superstructure is small, the friction with the sliding surface regardless of the magnitude of the axial force acting from the superstructure. The coefficient can be maintained at a substantially constant small value.

When the axial force acting from the superstructure is small, the friction coefficient with the sliding surface is small. Only the rolling support can roll on the sliding surface while supporting the axial force, and when the axial force acting from the superstructure is large. The rolling support, which has a small friction coefficient with the sliding surface, and the sliding support, which has a large surface pressure on the sliding surface and a small friction coefficient with the sliding surface, can roll the sliding surface while supporting the axial force. Therefore, the coefficient of friction with the sliding surface can be kept small regardless of the magnitude of the axial force acting on the superstructure. As a result, the performance of the seismic isolation device can be stably maintained regardless of the magnitude of the axial force acting on the superstructure.

In addition, the cost of rolling bearings tends to increase if a structure that generally supports a large axial force is attempted.
In the present invention, when the axial force acting from the superstructure exceeds a predetermined value, the axial force is supported only by the rolling bearings, but the axial force acting from the superstructure has a predetermined value. If it is larger than that, not only the rolling bearings but also both the rolling bearings and the sliding bearings support the axial force. Therefore, even if the axial force acting from the superstructure becomes large, the axial force is borne by both the rolling bearings and the sliding bearings, so that the axial force borne by the rolling bearings can be reduced, and the rolling bearings can be used. Such costs can be reduced.

Further, in the seismic isolation device according to the present invention, the rolling bearing is on the lower side of the superstructure via an urging member that urges the rolling bearing and the superstructure so as to be separated from each other in the vertical direction. When the axial force acting from the superstructure is equal to or less than the predetermined value, the sliding portion is arranged above the rolling portion by the urging force of the urging member and from the sliding surface. When the axial force acting from the superstructure is separated and exceeds the predetermined value, the urging member is compressed so that the sliding portion has the same height as the rolling portion and comes into contact with the sliding surface. You may do so.
With such a configuration, it is possible to switch between a state in which only the rolling portion can slide on the sliding surface and a state in which both the rolling portion and the sliding portion can slide on the sliding surface. It can be easily done by the axial force acting on the body.

According to the present invention, it is possible to stably maintain the performance regardless of the magnitude of the acting axial force, and it is possible to obtain a device with reduced cost.

It is a schematic diagram which shows an example of the seismic isolation device by embodiment of this invention, and is the figure which shows the case where the acting axial force is small. It is an exploded view of the seismic isolation device by embodiment of this invention. It is a schematic diagram which shows an example of the seismic isolation device by embodiment of this invention, and is the figure which shows the case where the acting axial force is large. It is a graph which shows the relationship between the axial force and the friction coefficient of each of a rolling bearing and a sliding bearing.

Hereinafter, the seismic isolation device according to the embodiment of the present invention will be described with reference to FIGS. 1 to 4.
As shown in FIG. 1, the seismic isolation device 1 according to the present embodiment is provided in the seismic isolation layer 13 between the lower structure 11 and the upper structure 12 which are separated in the vertical direction and can be relatively displaced in the horizontal direction. There is. In the present embodiment, the seismic isolation layer 13 is provided with a plurality of seismic isolation devices 1.
As shown in FIGS. 1 and 2, the seismic isolation device 1 has a rolling bearing 2 and a sliding bearing 3 arranged in parallel. In the present embodiment, the sliding bearing 3 is formed in a tubular shape penetrating in the vertical direction, and the rolling bearing 2 is arranged inside the sliding bearing 3 and surrounded by the sliding bearing 3.
The rolling bearing 2 is connected to the lower side of the upper structure 12 via a compression spring (urging member) 4, and is configured to be able to roll the upper surface 11a of the lower structure 11. The sliding bearing 3 is connected to the lower side of the upper structure 12 and is configured to be slidable on the upper surface 11a of the lower structure 11.
The upper surface 11a of the lower structure 11 is formed on a horizontal surface, and for example, a stainless steel plate or the like is provided to form a sliding surface 5.

The rolling bearing 2 is a bearing (rolling portion) 21 such as a steel ball or a roller that can roll on the sliding surface 5, and a bearing support portion that supports the bearing 21 and is connected to the superstructure 12 via a compression spring 4. 22 and.
The bearing support portion 22 is provided above the bearing 21 and supports the bearing 21 so as to be rollable from above. A notch 23 that opens to the lower side and the outside (slip bearing 3 side) is formed on the side portion of the bearing support portion 22. Of the surfaces constituting the notch portion 23, the surface facing downward is referred to as a downward surface 23a. The downward surface 23a is formed in a substantially horizontal plane.

The compression spring 4 is provided between the bearing support portion 22 and the upper structure 12, and urges the bearing support portion 22 and the upper structure 12 in a direction that separates them in the vertical direction. As the compression spring 4 expands and contracts, the dimensions from the lower surface 12a of the upper structure 12 to the lower end 21a of the bearing 21 change. As the compression spring 4, a disc spring, a coil spring, or a leaf spring shown in FIG. 2 is suitable.
In the present embodiment, when the load capacity (supporting axial force) acting on the rolling bearing 2 is N ₁ , the coefficient of friction μ ₁ between the bearing 21 and the sliding surface 5 is set to be μ ₁ ≤ 0.006. There is.

The sliding bearing 3 has a sliding portion 31 slidable on the sliding surface 5 and a sliding portion support portion 32 that supports the sliding portion 31 and is connected to the superstructure 12.
The lower surface of the sliding portion support portion 32 is formed in a horizontal plane, and the sliding portion 31 is provided along the lower surface. The sliding portion 31 is formed by applying a Teflon (registered trademark) coating to the lower surface of the sliding portion support portion 32 or attaching a Teflon (registered trademark) tape. The sliding portion 31 is formed on substantially the entire lower surface of the sliding portion support portion 32.
On the lower side of the sliding portion support portion 32, a jaw portion 33 protruding inward (rolling bearing 2 side) is formed. The upper surface 33a of the jaw portion 33 is formed in a substantially horizontal plane. The jaw portion 33 is provided inside the notch portion 23 of the bearing support portion 22, and the upper surface 33a of the jaw portion 33 is arranged so as to face the lower side of the downward surface 23a of the notch portion 23 in the vertical direction. ing.

When the rolling bearing 2 is displaced in the vertical direction with respect to the superstructure 12 due to the expansion and contraction of the compression spring 4, the sliding bearing 3 is not displaced in the vertical direction with respect to the superstructure 12, so that the downward surface 23a of the notch 23 is formed. It is displaced in the vertical direction with respect to the upper surface 33a of the jaw portion 33.
Therefore, when the compression spring 4 expands and the rolling bearing 2 is displaced downward so as to be separated from the upper structure 12, the downward surface 23a of the notch portion 23 approaches the upper surface 33a of the jaw portion 33, and the compression spring 4 Compresses and the rolling bearing 2 is displaced upward so as to be close to the superstructure 12, the downward surface 23a of the notch 23 is separated from the upper surface 33a of the jaw 33.
The upper surface 33a of the jaw portion 33 and the downward surface 23a of the notch portion 23 are in contact with each other when they are close to each other, and a gap is formed between them when they are separated from each other.

The dimensions from the lower surface 12a of the upper structure 12 to the lower surface 31a of the sliding portion 31 are set so as to always have _a constant value h1.
In the present embodiment, when the load capacity (supporting axial force) acting on the sliding bearing 3 is N ₂ , the coefficient of friction μ ₂ between the sliding portion 31 and the sliding surface 5 is 0.01 ≤ μ ₂ ≤ 0.1. It is set to be. When the contact area between the sliding portion 31 and the sliding surface 5 is A at the reference surface pressure σ ₀ , the withstand load N ₂ is N ₂ = A · σ ₀ > 10N ₁ . In this way, the load capacity of the sliding bearing 3 is set to an order of magnitude larger than the load capacity of the rolling bearing 2.

In the rolling bearing 2 and the sliding bearing 3, as shown in FIG. 1, when the compression spring 4 is extended and the downward surface 23a of the notch 23 and the upper surface 33a of the jaw portion 33 of the sliding bearing 3 come into contact with each other, the rolling bearing 2 and the sliding bearing 3 are brought into contact with each other. The lower end portion 21a of the bearing 21 of the rolling bearing 2 is arranged below the lower surface 31a of the sliding portion 31 of the sliding bearing 3. At this time, the dimension h2 from the lower surface 12a of the upper structure 12 to the lower end portion 21a of the bearing 21 of the rolling bearing ₂ is the dimension from the lower surface 12a of the upper structure 12 to the lower surface 31a of the sliding portion 31 of the sliding bearing 3. It is larger than h ₁ .
When the compression spring 4 extends and abuts on the upper surface 33a of the jaw 33 of the sliding bearing 3, the downward surface 23a of the notch 23 of the bearing support 22 cannot be displaced below the upper surface 33a of the jaw 33. It is configured as follows. Therefore, the maximum dimension from the lower surface 12a of the upper structure 12 to the lower end 21a of the bearing 21 of the rolling bearing ₂ is h2. At this time, the force urged by the extended compression spring 4 is N ₁ ′.

In such a seismic isolation device 1, when the axial force N received from above is a predetermined value N ₁ ′ or less (N ≦ N ₁ ′), the notch portion of the bearing support portion 22 is provided by the urging force of the compression spring 4. The downward surface 23a of the 23 is kept in contact with the upper surface 33a of the jaw portion 33 of the sliding bearing 3, and the lower surface 12a of the upper structure 12 and the upper surface 11a of the lower structure 11 (the upper surface 5a of the sliding surface 5) are formed. The interval is configured to be maintained at h ₂ above.
On the other hand, when the axial force N received from above is larger than the predetermined value N ₁ ′ (N> N ₁ ′), the axial force N received from above by the compression spring 4 is predetermined as shown in FIG. The downward surface 23a of the notch 23 of the bearing support 22 is separated from the upper surface 33a of the jaw 33 of the sliding bearing 3 by being compressed more than the case of N ₁ ′ or less, and the sliding portion 31 of the sliding bearing 3 is separated from the upper surface 33a. The upper structure 12 is close to the lower structure 11 until the lower surface 31a comes into contact with the sliding surface 5. When the lower surface 31a of the sliding portion 31 of the sliding bearing 3 comes into contact with the sliding surface 5, the distance between the lower surface 12a of the upper structure 12 and the upper surface 11a of the lower structure 11 slides from the lower surface 12a of the upper structure 12. The dimension of the portion 31 up to the lower surface 31a is the same as h ₁ , and the compression spring 4 is compressed so that the distance from the lower surface 12a of the upper structure 12 to the lower end portion 21a of the bearing 21 of the rolling bearing 2 is also h ₁ . ..

As described above, when the axial force N received from above is a predetermined value N ₁ ′ or less (N ≦ N ₁ ′), the distance between the lower surface 12a of the upper structure 12 and the upper surface 11a of the lower structure 11 is h ₂ . Therefore, the lower end portion 21a of the bearing 21 comes into contact with the sliding surface 5, but the lower surface 31a of the sliding portion 31 is separated from the sliding surface 5. At this time, the distance between the lower surface 31a of the sliding portion 31 of the sliding bearing 3 and the sliding surface 5 of the lower structure 11 is set to be, for example, about 0.2 to 0.5 mm.
When the upper structure 12 and the lower structure 11 are relatively displaced in the horizontal direction in this state, the bearing 21 rolls on the sliding surface 5, and the sliding portion 31 does not slide on the sliding surface 5.
As a result, the frictional resistance between the seismic isolation device 1 and the sliding surface 5 is only the frictional resistance between the bearing 21 of the rolling bearing 2 and the sliding surface 5, so that the friction coefficient is μ ₁ (μ ₁ ≤ 0.006). Will be due to.
At this time, the relationship between the axial force N, the frictional resistance force Q, the friction coefficient μ ₁ , and the apparent friction coefficient _μe received from above is given by the following equation (1).

On the other hand, when the axial force N received from above is larger than the predetermined value N ₁ ′ (N> N ₁ ′), the distance between the lower surface 12a of the upper structure 12 and the upper surface 11a of the lower structure 11 is h. The lower end portion 21a of the bearing 21 of the rolling bearing 2 abuts on the sliding surface ₅ , and the lower surface 31a of the sliding portion 31 of the sliding bearing 3 also abuts on the sliding surface 5. At this time, the compression spring 4 of the rolling bearing 2 contracts, but since the amount of compression is small, the force N ₁ ′ urged from the compression spring 4 to the rolling bearing 2 hardly changes.
When the upper structure 12 and the lower structure 11 are relatively displaced in the horizontal direction in this state, the bearing 21 rolls on the sliding surface 5, and the sliding portion 31 slides on the sliding surface 5.
As a result, the frictional resistance between the seismic isolation device 1 and the sliding surface 5 is the frictional resistance between the bearing 21 of the rolling support 2 and the sliding surface 5 and the frictional resistance between the sliding portion 31 of the sliding support 3 and the sliding surface 5. Since it is a force, it is based on the friction coefficient μ ₁ (μ ₁ ≤ 0.006) and the friction coefficient μ ₂ (0.01 ≤ μ ₂ ≤ 0.1).
At this time, the relationship between the axial force N, the frictional resistance force Q, the friction coefficient μ ₁ , the friction coefficient μ ₂ , and the apparent friction coefficient μ _e received from above is given by the following equation (2).

The friction coefficient μ ₂ of the slip support 3 has a surface pressure dependence that the friction coefficient μ ₂ decreases as the degree of compressive stress from the slip surface 5 increases. Assuming that the contact area A between the sliding surface 5 and the sliding material and the friction coefficient μ ₀ = 0.014 of the reference surface pressure σ ₀ = 20 MPa (20 N / mm ² ), the friction coefficient μ ₂ at the surface pressure σ is as follows. It is represented by the equation (3).

Here, it is assumed that the load capacity N ₂ = A · σ ₀ with respect to the reference surface pressure of the sliding bearing 3 and the axial force N ₁ ′ = N 2/20 acting on the rolling bearing ₂ . Assuming that the coefficient of friction of the rolling bearing 2 is μ ₁ = 0.006 and the axial force acting on the entire bearing (seismic isolation device 1) is N = αN ₂ , the following equation (4) is established.

Further, the apparent friction coefficient _μe is given by the following equations (5) and (6).

On the other hand, when the seismic isolation device 1 is composed of only the sliding bearing 3, the following equation (7) is obtained from σ / σ ₀ = α regardless of the axial force.

FIG. 4 shows the results of comparison between the seismic isolation device 1 composed of both the rolling bearings 2 and the sliding bearings 3 (rolling and sliding bearings) of the present embodiment and the conventional seismic isolation device composed of only the sliding bearings. ..
In FIG. 4, it is defined as follows.

_μe : Friction coefficient of the entire bearing = Friction resistance force of the entire bearing Q / Total axial force acting on the bearing N
α: Axial force ratio = Total axial force acting on the bearing N / Yield strength at reference surface pressure of sliding bearing N ₂
N ₂ = A · σ ₀
σ ₀ : Reference surface pressure (20 MPa in this embodiment)
A: Contact area of the sliding part with the sliding material

The conventional seismic isolation device consisting only of sliding bearings has a large coefficient of friction when the axial force is low. On the other hand, in the seismic isolation device 1 composed of both the rolling bearing 2 and the sliding bearing 3 of the present embodiment, an excessive friction coefficient does not occur even if the axial force is small, and the friction coefficient does not depend on the axial force. Can be made smaller.

When the axial force ratio α ≦ 1/20 = 0.05, only the rolling bearing 2 rolls on the sliding surface 5, and the sliding bearing 3 does not slide on the sliding surface 5, so that the friction coefficient μ _e is μ _e . = 0.006, which is a constant value.
When the axial force ratio α> 1/20 = 0.05, the rolling support 2 rolls on the sliding surface 5 and the sliding support 3 also slides on the sliding surface 5, so that the coefficient of friction increases, but the shaft The coefficient of friction μ _e is μ _e <0.04 regardless of the force ratio.
When only the sliding bearing 3 is used without using the rolling bearing 2 for the seismic isolation device 1, when the axial force ratio α ≦ 0.1, the friction coefficient between the sliding portion 31 and the sliding surface 5 is the axial force. It increases sharply as it decreases, but if the axial force ratio α> 0.2, it can be seen that the friction coefficient is almost the same as when both the rolling bearing 2 and the sliding bearing 3 are used for the seismic isolation device 1. ..

Next, the operation and effect of the seismic isolation device 1 according to the above-described embodiment will be described with reference to the drawings.
The sliding portion 31 has a large axial force acting on the upper structure 12, and the larger the surface pressure on the sliding surface 5, the smaller the coefficient of friction with the sliding surface 5, and the smaller the axial force acting on the upper structure 12. The smaller the surface pressure with respect to the sliding surface 5, the larger the coefficient of friction with the sliding surface 5.
In the sliding support 3 according to the embodiment of the present invention, when the axial force acting from the superstructure 12 exceeds a predetermined value and the friction coefficient between the sliding portion 31 and the sliding surface 5 with respect to the axial force becomes small. The sliding portion 31 makes the sliding surface 5 slidable, the axial force acting from the superstructure 12 is small below a predetermined value, and the friction coefficient between the sliding portion 31 and the sliding surface 5 with respect to this axial force is When it becomes large, the sliding portion 31 is separated from the sliding surface 5, so that the sliding portion 31 does not slide. Therefore, the sliding bearing 3 slides on the sliding surface 5 only when the friction coefficient of the entire bearing can be kept small.
On the other hand, since the change in the coefficient of friction of the bearing 21 with the sliding surface 5 due to the change in the axial force acting on the superstructure 12 is small, it is equal to or less than a predetermined value regardless of the magnitude of the axial force acting on the superstructure 12. It is possible to support the axial force of the above and maintain the coefficient of friction with the sliding surface 5 at a substantially constant small value.

When the axial force acting from the superstructure 12 is small, only the rolling support 2 having a small coefficient of friction with the sliding surface 5 can roll on the sliding surface 5, and when the axial force acting from the superstructure 12 is large. The rolling support 2 having a small friction coefficient with the sliding surface 5 and the sliding support 3 having a small friction coefficient with the sliding surface 5 due to a large surface pressure with respect to the sliding surface 5 can roll the sliding surface 5. Therefore, the coefficient of friction with the sliding surface 5 can be kept small regardless of the magnitude of the axial force acting on the superstructure 12. As a result, the performance of the seismic isolation device 1 can be stably maintained regardless of the magnitude of the axial force acting on the superstructure 12.

Further, the rolling bearing 2 generally tends to increase in cost if it is attempted to have a structure that supports a large axial force.
In the present invention, when the axial force acting from the superstructure 12 is smaller than a predetermined value, the axial force is supported only by the rolling bearing 2, but the axial force acting from the superstructure 12 is predetermined. When the value exceeds the value, the axial force is supported not only by the rolling bearing 2 but also by both the rolling bearing 2 and the sliding bearing 3. Therefore, even if the axial force acting on the superstructure 12 becomes large, the axial force is borne by both the rolling bearing 2 and the sliding bearing 3, so that the axial force borne by the rolling bearing 2 can be leveled off. , The cost required for the rolling bearing 2 can be reduced.

Further, in the seismic isolation device 1 according to the present embodiment, the rolling bearing 2 is under the upper structure 12 via a compression spring 4 that urges the rolling bearing 2 and the upper structure 12 so as to be separated from each other in the vertical direction. When the axial force that is connected to the side and acts from the superstructure 12 is less than or equal to a predetermined value, the sliding portion 31 is arranged above the bearing 21 by the urging force of the compression spring 4 and acts from the superstructure 12. When the axial force to be applied exceeds a predetermined value, the compression spring 4 is compressed and the sliding portion 31 has the same height as the bearing 21.
With such a configuration, switching between a state in which only the bearing 21 can slide on the sliding surface 5 and a state in which both the bearing 21 and the sliding portion 31 can slide on the sliding surface 5 can be switched to the upper part. It can be easily switched by the axial force acting on the structure 12.

Although the embodiment of the seismic isolation device 1 according to the present invention has been described above, the present invention is not limited to the above embodiment and can be appropriately modified without departing from the spirit of the present invention.
For example, in the above embodiment, the seismic isolation layer 13 is provided with a plurality of seismic isolation devices 1, but the seismic isolation layer 13 may be provided with only one seismic isolation device 1 or a rolling bearing. It may be used in combination with a seismic isolation device consisting only of bearings.
Further, in the above embodiment, the compression spring is used as a switching mechanism between a state in which only the bearing 21 is slidable on the sliding surface 5 and a state in which both the bearing 21 and the sliding portion 31 are slidable on the sliding surface 5. Although 4 is used, a mechanism using a member other than the compression spring 4 may be used.

1 Seismic isolation device 2 Rolling bearings 3 Sliding bearings 4 Compression springs (urgency members)
5 Sliding surface 11 Lower structure 12 Upper structure 21 Bearing (rolling part)
31 Sliding part

Claims (2)

In the seismic isolation device provided between the lower structure that can be displaced relative to the horizontal direction and the upper structure.
A rolling bearing provided with a rolling portion connected to the lower side of the upper structure and capable of rolling horizontally along a sliding surface provided on the lower structure.
It has a sliding bearing that is parallel to the rolling bearing, is connected to the underside of the superstructure, and has a sliding portion that can slide horizontally along the sliding surface.
When the axial force acting from the superstructure is equal to or less than a predetermined value, the rolling portion comes into contact with the sliding surface to enable rolling of the sliding surface, and the sliding portion is in contact with the sliding surface. Separated,
When the axial force acting on the rolling bearing and the sliding bearing exceeds the predetermined value, the rolling portion comes into contact with the sliding surface to enable rolling on the sliding surface, and the sliding portion becomes capable of rolling. A seismic isolation device characterized in that it comes into contact with the sliding surface and makes the sliding surface slidable. The rolling bearing is connected to the underside of the superstructure via an urging member that urges the rolling bearing and the superstructure to be vertically separated from each other.
When the axial force acting on the superstructure is equal to or less than the predetermined value, the sliding portion is arranged above the rolling portion by the urging force of the urging member and separated from the sliding surface. When the axial force acting from the superstructure exceeds the predetermined value, the urging member is compressed so that the sliding portion has the same height as the rolling portion and comes into contact with the sliding surface. The seismic isolation device according to claim 1.

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