JP2003328589A - Buoyant support unit and base isolation device against vertical earthquake motion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a buoyant support unit applied to a base isolation device against vertical earthquake motion capable realizing a comparatively miniaturized structure and effectively carrying out base isolation against a vertical component of earthquake motion by a simple mechanism. <P>SOLUTION: The buoyant support unit 20 used in the vertical base isolation device 10 carrying out base isolation against the vertical component of the earthquake motion acting on the base isolated structure 11 is composed of a storage container 21, liquid 22 stored in the storage container 21 to apply buoyancy, and a floating body 24 immersed in the liquid 22 and connected with the base isolated structure 11 via a supporting member 23 set with a liquid surface cross-sectional area that is smaller than a body horizontal sectional area. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buoyancy support unit for a seismic isolation device, which is applied to seismically isolate a vertical component of seismic motion among seismic motions acting on buildings and civil engineering structures. The present invention relates to a seismic isolation device for a vertical seismic motion including a buoyancy support unit.

[0002]

2. Description of the Related Art Conventionally, various seismic isolation devices have been put into practical use and proposed to be applied to buildings and civil engineering structures to mitigate the influence of vibration due to seismic waves and minimize damage. Among the conventional seismic isolation devices, the one that has been put into practical use is to isolate and mitigate the horizontal component of the earthquake motion. For the horizontal component of seismic motion, seismic isolation devices such as laminated bearings and ball bearings made of laminated rubber have been put into practical use. It is also possible to obtain a seismic isolation effect by adopting a structure that originally has seismic isolation performance for horizontal components, such as a floating body.

On the other hand, regarding the vertical component of earthquake motion,
A seismic isolation device using a spring has been considered. However, in order to make the natural period of the system longer than the dominant period of earthquake, it is necessary to use a soft spring with a small spring constant. That is, assuming that the natural period is T, the mass of the seismic isolated structure is M, and the spring constant is K, the natural period T is represented by the following mathematical formula, and therefore the seismic isolated structure It is necessary to increase the mass M (value of the numerator) of or to reduce the spring constant K (value of the denominator).

[Equation 1]

As described above, the natural period T is determined by the ratio between the mass M and the spring constant K. Therefore, in order to obtain a seismic isolation effect by setting a relatively long natural period T, for example, about 3 seconds, which is different from the frequency of the earthquake, the natural length of the spring supporting the base-isolated structure is The elongation is as large as 1 m or more. Therefore, in a relatively small seismically isolated structure, it is not realistic because the elongation of the spring occupies a relatively large proportion to the size of the structure, and it is difficult to put it into practical use with ordinary structures. Met.

From this background, the static self-weight of the seismic-isolated structure is reduced by buoyancy, while the mass M at the time of movement is large without being influenced by buoyancy. As a seismic isolation structure for vertical ground motion, a seismically isolated structure is used as a floating body. A conventional seismic isolation device for a vertical seismic motion using a floating body will be briefly described below with reference to FIG. In addition, reference numeral 1 in the drawing
Is a base-isolated structure, 2 is a floating body, 3 is a storage container, 4 is a liquid,
Reference numeral 5 is a spring, 6 is a supporting surface, 7 is a space below the floating body, and 8 is a skirt.

In this conventional example, a part of the floating body 2 integrally connected to the lower portion of the seismic isolated structure 1 is stored up to a predetermined water level in a storage container 3 having an open upper portion. It is submerged in a liquid 4 such as water that gives buoyancy. The seismic isolated structure 1 is elastically supported by a vertical spring 5 whose one end is fixedly supported by a supporting surface 6 such as the ground. Therefore, the total static weight of the seismically isolated structure 1 and the floating body 2 is
The value is a value obtained by subtracting the buoyancy of the liquid 4 from the mass M, and the spring 5 elastically supports this static load. The storage container 3 that stores the liquid 4 is fixed and supported on a support surface 6 such as the ground that is actually subjected to an earthquake motion.

The lower space 7 of the floating body is a space formed on the lower surface of the floating body 2 and filled with a compressive fluid (gas) such as air. The skirt 8 is a plate-like member projecting downward from the bottom surface of the floating body 2. Surrounded by. The lower surface of the floating body lower space 7 is open and is in communication with the liquid 4.

[0008]

By the way, in the above-described conventional seismic isolation device for vertical seismic motion, the fluctuation of the restoring force due to the change of the draft of the floating body 2 shortens the natural period T. Therefore, the storage container 3 and the floating body 2 It is necessary to adopt a large structure with a deep draft.

Explaining this in detail, since the upper part of the floating body 2 is located at a position higher than the liquid surface of the liquid 4, only a part of the floating body 2 is buried in the liquid to generate buoyancy. Moreover, the buoyancy changes with the buried volume that increases and decreases due to the vertical movement of the floating body 2 during seismic isolation, and such buoyancy changes act as the buoyancy spring constant Kf of the mathematical formula shown in [Equation 2]. .

[Equation 2] Therefore, the spring constant component of the denominator increases by the buoyancy spring constant Kf, and since the mass M of the numerator does not fluctuate, the natural period T becomes smaller. In order to reduce the buoyancy fluctuation ratio, in other words, Then, in order to reduce the buoyancy spring constant Kf, the large-sized structure with deep draft described above is required.

Further, in the floating body lower space 7 of the floating body 2 surrounded by the skirt 8, since the seismic isolated structure 1 and the floating body 2 move up and down as a unit, in order to make this function as an effective air spring. Requires a large space in the vertical direction. Therefore, the structures such as the storage container 3 and the floating body 2 still need to be upsized, which makes practical application difficult.

The present invention has been made in view of the above circumstances, and can be realized by a structure having a relatively small size.
It is an object of the present invention to provide a buoyancy support unit and a seismic isolation device for vertical seismic motion, which can effectively isolate the vertical component of seismic motion with a simple mechanism.

[0012]

The present invention adopts the following means in order to solve the above problems. The buoyancy support unit according to claim 1 is a buoyancy support unit for a seismic isolation device that isolates a vertical component of seismic motion acting on a seismic isolated structure such as a building, and a liquid storage container, Through a support member in which the liquid level cross-sectional area between the liquid stored in the storage container and giving buoyancy and the seismic-isolated structure buried in the liquid is set to be smaller than the main body horizontal cross-sectional area. It is characterized in that it is configured to include a floating body connected thereto.

According to such a buoyancy support unit, the entire floating body connected to the seismic-isolated structure via the supporting member whose liquid surface cross-sectional area is set smaller than the horizontal cross-sectional area of the main body is made of liquid. Since it is embedded inside, the buoyancy spring constant Ks (which will be described later) can be reduced only by the support member because the burying volume increases and decreases due to the vertical movement.
(See [Equation 3]) can be reduced (Ks <Kf). When the floating body moves up and down, the mass of the fluid existing above and below the floating body can be added to the mass M as an additional mass Ma (see [Numerical formula 3] described later).

Therefore, in the equation for defining the natural period T, the mass of the numerator becomes large and the spring constant of the denominator becomes smaller than in the conventional case, so that the natural period T becomes large (long).
It becomes possible to do. Further, since the additional mass Ma is increased by increasing the horizontal cross-sectional area of the floating body, it is not necessary to make the structure vertically large.

In the buoyancy support unit according to the first aspect, it is preferable that the support member is one or a plurality of rod-shaped members, whereby a necessary strength is secured with a minimum liquid surface cross-sectional area, and the member is immune. The seismic structure and the floating body can be integrally connected. (Claim 2)

In the buoyancy support unit according to the first or second aspect, it is preferable that the floating body is provided with a buoyancy adjusting mechanism, which acts on the floating body even when the seismic isolated structure changes its own weight. By adjusting the buoyancy, the static weight can be kept constant. (Claim 3)

In the buoyancy support unit according to the present invention, the buoyancy adjusting mechanism includes a gas space forming part provided under the floating body and communicating with the liquid, and a volume varying means of the gas space forming part. What is provided is preferable, and when the amount of gas (pressure) supplied to the gas space forming unit is adjusted by the volume varying means, the space (gas) volume of the gas space forming unit fluctuates. The buoyancy can be adjusted by changing the volume of the floating body buried in the liquid. (Claim 4)

In the buoyancy support unit according to a fourth aspect, it is preferable that the gas space forming portion is divided into a plurality of parts and a dedicated volume varying means is provided for each of the plurality of gas space forming parts, whereby each of the divided gas space forming parts is formed. The space (gas) volume can be adjusted to offset the static tilt for eccentric loads. (Claim 5)

In the buoyancy support unit according to claim 4, it is preferable that the buoyancy adjusting mechanism comprises a bag body disposed in the gas space forming portion and a volume varying means of the bag body. As a result, the number of wall surfaces in the gas space forming portion that come into contact with a gas such as air is reduced, so that the progress of corrosion can be reduced. (Claim 6)

In the buoyancy support unit according to a sixth aspect of the invention, it is preferable that the bag body is divided into a plurality of pieces, and each bag body is provided with its own volume varying means. The volume can be adjusted for each bag to offset the static inclination with respect to the eccentric load, and since the wall surface in the gas space forming portion that comes into contact with a gas such as air is reduced, the progress of corrosion can also be reduced. . (Claim 7)

In the buoyancy support unit according to any one of claims 1 to 7, it is preferable that fins are attached to the floating body, whereby the above-mentioned additional mass Ma can be further increased, and moreover, in the vicinity of the fins. Since the damping force is increased by the flow of the fluid generated at 1, the natural period T can be increased and the response at the resonance point can be reduced. (Claim 8)

The buoyancy support unit according to claim 9 is a seismic isolation device for a vertical seismic motion that isolates a vertical component of the seismic motion acting on a seismic-isolated structure such as a building. The buoyancy support unit according to any one of claims 1 to 3 and an elastic body that elastically supports the seismic isolated structure in the vertical direction.

According to such a seismic isolation device for vertical seismic motion, all of the floating bodies connected to the seismic-isolated structure via a supporting member having a liquid level cross-sectional area smaller than the main body horizontal cross-sectional area. Since the buoyancy support unit for immersing the buoyancy in the liquid is adopted, the buoyancy spring constant Kf can be reduced by minimizing the buoyancy fluctuation by increasing and decreasing the buoyancy volume only by the support member. Further, when the floating body moves up and down, the mass of the fluid existing above and below the floating body can be added to the mass M as the additional mass Ma.

Therefore, in the equation for defining the natural period T, the mass of the numerator is large and the spring constant of the denominator is smaller than in the conventional case, so that the natural period T can be increased. Moreover, since the additional mass Ma increases as the horizontal cross-sectional area of the floating body increases, it is not necessary to make the structure large in the vertical direction, and good seismic isolation performance for the vertical component of seismic motion can be obtained with a simple and compact device configuration. can get.

In the seismic isolation device for vertical seismic motion according to claim 9, seismic isolation means for the horizontal component of the seismic motion acting on the seismic-isolated structure may be provided, whereby the floating structure has Seismic isolation function of the horizontal component
It can be further improved by adding seismic isolation means to the horizontal component of the ground motion. (Claim 10)

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a buoyancy support unit and a seismic isolation device for vertical seismic motion (hereinafter referred to as "vertical seismic isolation device") according to the present invention will be described below with reference to the drawings. <First Embodiment> A first embodiment of the present invention will be described with reference to FIG. In the figure, reference numeral 10 is a vertical seismic isolation device, 11 is a seismic isolated structure, 12 is a support surface, 20 is a buoyancy support unit, and 30 is a spring support guide unit.

The seismic isolated structure 11 is a structure, such as a building or a civil engineering structure, for mitigating the influence of seismic waves. In the illustrated example, the seismic isolated structure 11 is located in a predetermined area in which a computer and various control devices are installed. It is the floor. A seismic isolation device 10 for seismically isolating the vertical component of the seismic motion is installed under the floor for the seismically isolated structure 11.

The seismic isolation device 10 is fixedly installed on a support surface 12 such as the ground that is subjected to the vibration of an earthquake, and is seismically isolated.
1 and a spring support guide unit 30 provided as an elastic body for elastically supporting the seismic isolated structure 11 in the vertical direction.

One of the buoyancy support units 20 stores a liquid, a storage container 21, a liquid 22 which is stored in the storage container 21 to give a buoyancy, and a buoyancy which is completely buried in the liquid 22. At the same time, a floating body 24 is connected to the seismic isolated structure 11 by a support member 23. The storage container 21 is a liquid storage container fixedly installed on the support surface 12, and is filled with a predetermined amount of liquid 22 such as water. The entire volume of the floating body 24 is completely buried in the liquid 22, and the upper surface of the floating body 24 and the seismic isolated structure 11 are integrally connected by one or a plurality of support members 23.

The floating body 24 may be hollow or solid, and it is important that the buoyancy received from the liquid 22 is set appropriately. That is, it is necessary that the buoyancy force received by the floating body 24 and the spring support guide unit 30, which will be described later, cooperate with each other to reliably hold the seismic isolated structure 11 at a predetermined position when the earthquake is normal. The support member 23 is the liquid surface 2 of the liquid 22.
It is preferable that the necessary supporting strength is obtained and the minimum supporting area is obtained so that the total cross-sectional area taken at 2a (hereinafter referred to as "liquid level cross-sectional area") is smaller than the main body horizontal cross-sectional area of the floating body 24. It is set to be the liquid surface cross-sectional area. That is, the supporting member 23 may be a rod-shaped member having a constant cross-section made of a material having excellent strength, and the cross-sectional area may be set as close as possible to the minimum value that satisfies the required strength. In addition, the support member 23 may connect the seismic isolated structure 11 and the floating body 24 by using a rod-shaped member in the vertical direction.

The spring support guide unit 30 elastically supports a vertical static load of the seismic isolated structure 11, and is made of an elastic body such as a spring or rubber.
In the illustrated example, the coil spring 31 that expands and contracts in the vertical direction is supported by the support 32. Support 3
2 is an inner cylinder part 33 fitted to be slidable in the vertical direction.
Also, a sliding member 35 such as a bearing is provided on the sliding surfaces of the inner and outer tubular portions 33, 34 as required. In this case, the lower end surface of the support body 32 (bottom surface of the inner cylindrical portion 33) is fixed to the support surface 12, and the upper end surface (upper surface of the outer cylindrical portion 34) is fixed to the lower surface of the seismic isolated structure 11. The support 32 is provided for the purpose of surely expanding and contracting the coil spring 31 in the vertical direction, and the configuration thereof is not limited to the illustrated example, and may be unnecessary depending on the type of elastic body. In some cases

As described above, the vertical seismic isolation system 10 is constructed by including the buoyancy support unit 20 and the spring support unit 30, but the number and arrangement of the buoyancy support unit 20 and the spring support unit 30 are different. Seismic isolation structure 10
It may be appropriately set in consideration of various conditions so that elastic support and seismic isolation can be achieved in a well-balanced manner in accordance with the shape of the.

In the following, the vertical seismic isolation device 1 having the above-mentioned structure
The action of 0 will be described. When an earthquake occurs, the support surface 12 vibrates due to the earthquake motion. Of these, the horizontal component of the earthquake motion is mitigated by the seismic isolation function of the floating body support unit 20 fixed to the support surface 12. On the other hand, regarding the vertical component of the earthquake motion, the natural period T of the seismically isolated structure 11 is
Seismically isolated by enlarging (longer). This natural period T is represented by the following mathematical formula. In the following mathematical formula, M is the mass of the seismic isolated structure 11, K is the spring constant of the coil spring 31, Ma is the additional mass, and Ks is the buoyancy spring constant.

[Equation 3]

Since the floating body 24 buried in the liquid 22 moves relative to the storage container 21 and the liquid 22 that move up and down together with the support surface 12, the mass of the liquid 22 existing above and below the floating body 24 respectively. The added mass Ma is added to the mass M. Therefore, the value of the natural period T becomes larger as the numerator in the mathematical formula increases by the additional mass Ma. This increase in the additional mass Ma occurs on both sides because the floating body 24 is completely buried in the liquid 22. For example, as shown in the conventional example, when the upper portion is on the liquid surface, only the lower surface side occurs. To do.

Further, as the floating body 24 moves up and down relatively, the buried volume of the support member 23 changes. Since the supporting member 23 in this case is a rod-shaped member having the same cross-sectional shape with the liquid surface cross-sectional area minimized, the volume fluctuation due to the vertical movement of the floating body 24 is also minimized. . Since such volume fluctuations cause buoyancy fluctuations,
When this buoyancy fluctuation is minimized, the buoyancy spring constant Ks is significantly reduced.

That is, as shown in the conventional example, the buoyancy spring constant Kf when the cross-sectional area similar to or substantially the same as the horizontal cross-sectional area of the main body of the floating body moves up and down (volume fluctuation) as the support member.
Compared with the above, the buoyancy spring constant Ks when the support member 23 whose liquid surface cross-sectional area is the required minimum strength moves up and down (volume change) as described above becomes a significantly low (small) value. (Ks <Kf). In this case, all the conditions that are not related to the volume variation associated with the liquid surface cross-sectional area of the support member 23 are the same. As a result, in the denominator of the mathematical formula shown in [Equation 3], the value of the buoyancy spring constant Ks added to the spring constant K becomes significantly smaller than in the conventional case, and thus the natural period T can be increased.

As described above, if the vertical seismic isolation device 10 is adopted, the additional weight Ma is added and the buoyancy spring constant Ks is increased.
Since the numerator in the mathematical expression of [Equation 3] is larger than the conventional one and the denominator is smaller than the conventional one, the natural period T of the seismic-isolated structure 11 is significantly increased. Further, since the additional mass Ma increases as the horizontal cross-sectional area (projected area of the plane) of the floating body 24 increases, it is not necessary to make the storage container 21 a vertically large structure.

<Second Embodiment> Next, the second embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. The same parts as those of the first embodiment shown in FIG.
Detailed description thereof will be omitted. The first feature of the vertical seismic isolation apparatus 10A shown in this embodiment is that the buoyancy support unit 20 is used.
The buoyancy adjusting mechanism is provided on the floating body A of A. This buoyancy adjusting mechanism forms the gas space forming portion 25 on the lower surface side of the floating body 24A as an air chamber having a shape like a bowl, that is, a hollow shape whose lower surface opens and communicates with the liquid 22. A buoyancy adjuster 26 is provided as a volume varying means for adjusting the gas volume of the forming portion 25. The gas space forming unit 25 of the floating body 24A operates the buoyancy adjuster 26 to adjust the amount of gas such as air (pressure).
Can be adjusted to change the substantial space volume in which the liquid 22 does not exist.

The buoyancy adjuster 26 stores or manufactures a gas such as compressed air and supplies a necessary amount to the gas space forming unit 25 via the supply pipe 27, or an excess gas is supplied to the gas space forming unit 25. From the air to the atmosphere, and a known device in which a cylinder filled with compressed air, a compressor, a regulator, an on-off valve and the like are appropriately combined can be used.

If the buoyancy adjuster 26 described above is operated to increase the substantial space volume of the gas space forming portion 25, the internal liquid level 2
Since 2b decreases, the displacement amount of the liquid 22 by the floating body 24A increases, and as a result, the buoyancy of the floating body 24A increases. On the contrary, if the substantial volume of the gas space forming portion 25 is reduced, the internal liquid surface 22b rises and the floating body 24
The displacement amount of the liquid 22 by A is reduced, and as a result, the buoyancy of the floating body 24A is reduced.

By adjusting the buoyancy of the floating body 24A in this manner, the self-weight of the seismic isolated structure 11, that is, the static load acting on the spring support unit 30 can be adjusted. Even if the value changes due to some circumstances, it is not necessary to carry out a large-scale work such as replacing the spring support unit 30, and it is possible to easily cope with it by adjusting the buoyancy. As the buoyancy adjusting mechanism, for example, a bag-shaped member may be fixed to the floating body 24 of the first embodiment described above, and the volume may be changed as necessary to adjust the buoyancy.

A second feature of the second embodiment is that the floating body 24A is provided with fins 28. The fins 28 are plate-like members provided so as to project horizontally or substantially horizontally from the side surface of the floating body 24A.
When such fins 28 are provided, the liquid 2 existing above and below the fins 28 when vertically moving in the liquid 22 is provided.
The mass of 2 is also added to the additional mass Ma. That is, since the additional mass Ma can be set to a larger value as compared with the case without the fin 28, it is effective to further increase the natural period T of the seismic isolated structure 11. Moreover, since the damping force is increased by the flow of the liquid 22 near the fins 28, the response at the resonance point can be reduced.

The fins 28 are mounted not only by the floating body 24A having the air space forming portion 25 described above, but also by the solid or hollow floating body 24 shown in the first embodiment.
It goes without saying that it is also applicable to. Further, in the case of the floating body 24A provided with the air space forming portion 25, as shown in FIG. 2, if the lower surface plate 29 including the communication passage 29a and the fin portion 29b is attached to the lower surface communicating with the liquid 22, the above-mentioned fin 28 The function and effect can be further improved.

As described above, this embodiment is characterized by the floating body 24A which constitutes the floating body unit 20A.
Other components such as the spring support unit 30 are the same as those in the above-described first embodiment.

<Third Embodiment> The third embodiment shown in FIG. 3 is different from the above-described second embodiment in the structure of the buoyancy adjusting mechanism. The same parts as those in the first and second embodiments shown in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted. In the vertical seismic isolation apparatus 10B shown in this embodiment, the membrane bag 50 is arranged in the gas space forming portion 25 provided in the floating body 24B of the buoyancy support unit 20B. This membrane bag 50 is provided with a buoyancy adjuster 2 via a supply pipe 27.
6 is connected, and the volume can be adjusted by the amount of compressed air supplied to the membrane bag 50. Although two sets of the buoyancy adjuster 26 and the supply pipe 27 are provided on the left and right sides in the illustrated example, the numbers are not particularly limited.

Since the membrane bag 50 has sufficient strength to withstand the pressure of the compressed air supplied from the buoyancy adjuster 26, the compressed air supplied from the buoyancy adjuster 26 will not contact the inner wall surface of the gas space forming portion 25. There is no direct contact. Therefore, if air is first removed from the inside of the gas space forming unit 25 and the periphery of the membrane bag 50, the air will be removed by the gas space forming unit 2
Touching the inner wall of 5 can be prevented or minimized. Therefore, it is possible to prevent or suppress the corrosion of the metal forming the wall surface of the gas space forming portion 25 due to the contact with the air, and the vertical seismic isolation device 1
It is effective in improving the durability and reliability of 0B. In addition, the volume variation of the membrane bag 50 is the same as the substantial space volume variation of the gas space forming unit 25 in the above-described second embodiment, and therefore, the action and effect are also the same.

<Fourth Embodiment> The fourth embodiment shown in FIG. 4 is different from the above-described second embodiment in the structure of the buoyancy adjusting mechanism. The same parts as those in the second embodiment shown in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted. The vertical seismic isolation apparatus 10C shown in this embodiment divides the inside of the gas space forming portion 25 provided in the floating body 24C of the buoyancy support unit 20C into a plurality of spaces, and supplies a dedicated buoyancy adjuster 26 and supply to each space. A tube 27 is provided. In the illustrated example, the partition plate 51 is used to form the gas space forming unit 25A.
Dedicated buoyancy adjusters 26A-D and supply pipes 27A-D are connected in order to be divided into 4 to D so that each space volume can be independently adjusted.

With such a structure, the seismic isolated structure 1
When the static eccentric load acts on 1, if the volumes of the gas space forming portions 25A to 25D are adjusted so that large buoyancy is generated at the position where the eccentric load is large, the static inclination with respect to the eccentric load is canceled and eliminated. be able to. That is, the static inclination of the base-isolated structure 11 can be reduced or eliminated. Further, even when the static inclination of the seismic isolated structure 11 changes from the beginning of setting, it can be easily corrected by the operation adjustment of the buoyancy adjusters 26A to 26D.

<Fifth Embodiment> A fifth embodiment shown in FIG. 5 employs a buoyancy adjusting mechanism having a structure in which the above-described third and fourth embodiments are combined. The same parts as those in the embodiment shown in FIGS. 3 and 4 are designated by the same reference numerals, and detailed description thereof will be omitted. In the vertical seismic isolation apparatus 10D shown in this embodiment, four divided membrane bags 50A to 50D are arranged in the gas space forming portion 25 provided in the floating body 24D of the buoyancy support unit 20D. These membrane bags 50A-D
Are respectively buoyancy adjusters 2 via the supply pipes 27A to 27D.
6A to 6D, and the volume can be adjusted independently depending on the amount of compressed air supplied to each of the membrane bags 50A to 50D.

With such a structure, the seismic isolated structure 1
When a static eccentric load is applied to 1, each bag body 50A has a large buoyancy at a position where the eccentric load is large.
By adjusting the volumes of to D independently, the static inclination with respect to the eccentric load can be canceled and eliminated. That is, the static inclination of the seismic isolated structure 11 can be reduced or eliminated, and the area where the wall surface of the gas space forming portion 25 contacts the air can be minimized, so that the corrosion By suppressing, durability and reliability can be improved. Further, when the static inclination of the seismic isolated structure 11 has changed from the initial setting, it can be easily corrected by the operation adjustment of the buoyancy adjusters 26A to 26D.

<Sixth Embodiment> Finally, the sixth embodiment of the present invention.
The embodiment will be described with reference to FIG. The same parts as those in the first to fifth embodiments shown in FIGS. 1 to 5 are designated by the same reference numerals, and detailed description thereof will be omitted. A feature of this embodiment is that, in addition to the vertical seismic isolation device 10E, a dedicated seismic isolation means for the horizontal component of the earthquake motion (hereinafter referred to as "horizontal seismic isolation device") is provided. The buoyancy support unit 20E shown in the figure is obtained by removing the fins 28 of the buoyancy support unit 20A shown in the second embodiment, but, of course, the one provided with the fins 28 is also applicable. The floating body support unit 20 shown in the above embodiment and the floating body support units 20B to 20D shown in the third to fifth embodiments may be adopted, and in any case, it is known to have a seismic isolation function for the horizontal component. Has been.

In the horizontal seismic isolation device 40 shown in the figure, the lower end surface of the spring support unit 30 is fixed on the base material 42 which is installed relative to the support surface 12 via the sphere 41 so as to be relatively movable in each horizontal direction. There is. The periphery of the base material 42 is connected to a damper 43 and a coil spring 44, one end of which is supported by a support fixed to the support surface 12 in each horizontal direction. Further, the upper surface of the base material 42 is connected to the seismic isolated structure 11 via a damper 45.

According to this structure, the vertical seismic isolation device 10B is constituted by the buoyancy support unit 20E and the spring support unit 30 for the vertical component of the earthquake motion.
Functions, the seismic isolation is performed as described in each of the above-described embodiments. On the other hand, for the horizontal component of the earthquake motion, the seismic isolation function of the buoyancy support unit 20E
The horizontal seismic isolation device 40 cooperates with the seismic isolation function to provide seismic isolation. Therefore, it is possible to further effectively isolate the horizontal component, and it is possible to further improve the isolation performance of the seismic isolated structure 11. The horizontal plane new device 40 is not limited to the configuration described above, and other known configurations such as laminated rubber can be appropriately adopted.

As described in the first to sixth embodiments described above, according to the buoyancy support unit and the seismic isolation device for vertical seismic motion of the present invention, the natural period T of the seismically isolated structure 11 is increased.
Since it is possible to increase the numerator of the calculation formula for calculating and to reduce the denominator of the calculation formula, it becomes possible to set the natural period T to be large so as to be different from the frequency of the earthquake and to perform seismic isolation. Further, the additional mass Ma is the floating body 24 and the fin 28.
Since it is increased by setting a large horizontal cross-sectional area, the structures such as the storage container 21 and the floating body 24 do not need to be enlarged in the vertical direction, which is advantageous for practical use. In addition, as described above, the semi-submersible type structure in which the floating body 24 completely buried in the liquid 22 and the seismic-isolated structure 11 on the liquid are connected by the support member 23 is a structure more than the conventional one. It is used in offshore rigs that excavate gas, etc., but the purpose of offshore rigs is to reduce wave power at sea.

In each of the above-described embodiments, the seismic isolated structure 11 has been described as a floor within a predetermined range, but it goes without saying that the structure can be applied to an entire building structure such as a building or a civil engineering structure such as a foundation. Nor. Furthermore, the configuration of the present invention is limited to the above-described embodiment, such as using a suitable liquid other than water as the liquid that gives buoyancy to the floating body, or using a suitable gas other than air for adjusting the buoyancy. However, the present invention can be appropriately modified within the scope of the present invention.

[0056]

The buoyancy support unit and the seismic isolation device for vertical seismic motion according to the present invention have the following effects. According to the buoyancy support unit of claim 1, all the floating bodies connected to the seismic-isolated structure via a supporting member having a liquid surface cross-sectional area smaller than the main body horizontal cross-sectional area are made of liquid. Since it is embedded in the inside, only the supporting member increases or decreases the burying volume due to the vertical movement, so that the buoyancy fluctuation can be minimized and the buoyancy spring constant Ks can be made significantly smaller than the conventional one. Also, when the floating body moves up and down,
The mass of the fluid existing above and below the floating body can be added to the mass M as the additional mass Ma.

Therefore, the natural period T of the seismically isolated structure can be easily set to be different from the seismic frequency, and the seismic isolation performance is good for the vertical component of the seismic motion with a simple and compact device configuration. Can be obtained.

Further, by providing the buoyancy adjusting mechanism on the floating body, even if the self-weight of the seismic isolated structure changes, the static self-weight can be kept constant by adjusting the buoyancy acting on the floating body.

Further, by attaching the fins to the floating body, the above-mentioned additional mass Ma can be further increased, and since the damping force is increased by the flow of the fluid generated near the fins, the natural period T is increased. At the same time, the response at the resonance point can be reduced.

Further, by dividing the gas space forming portion into a plurality of parts and providing a dedicated volume varying means for each of them, the space (gas) volume is adjusted for each of the divided gas space forming parts, and the static inclination with respect to the eccentric load is adjusted. Can be offset
It is possible to reduce the static inclination of the seismic isolation structure with respect to the eccentric load.

If a buoyancy adjusting mechanism including a bag body arranged in the gas space forming section and a volume varying means for the bag body is adopted, the gas space that comes into contact with gas such as air can be used. Since the number of wall surfaces in the forming portion is reduced, it is possible to reduce the progress of corrosion and improve durability and reliability. In this case, if the bag body is divided into a plurality of parts and each bag body is provided with its own volume varying means, the volume of each divided bag body is adjusted to cancel the static inclination with respect to the eccentric load. It is possible to reduce the static inclination of the seismic isolation structure against eccentric load and reduce the wall surface in the gas space forming part that comes into contact with gas such as air, thus reducing the progress of corrosion and durability. And reliability can be improved.

According to the seismic isolation device for vertical seismic motions described in claim 9, the seismic isolated structure is connected to the seismic-isolated structure through a supporting member having a liquid surface cross-sectional area smaller than the main body horizontal cross-sectional area. Since the buoyancy support unit that immerses the entire floating body in the liquid is adopted, the buoyancy spring constant Kf can be reduced by minimizing the buoyancy fluctuation by increasing and decreasing the buoyancy volume only by the support member. it can. Further, when the floating body moves up and down, the mass of the fluid existing above and below the floating body can be added to the mass M as the additional mass Ma.

Further, by providing the seismic isolation means for the horizontal component of the seismic motion acting on the seismically isolated structure, the seismic isolation function of the horizontal component of the floating structure of the buoyancy support unit is It is possible to further improve by adding seismic isolation means for the horizontal component.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a buoyancy support unit and a seismic isolation device for vertical seismic motion according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of a buoyancy support unit and a seismic isolation device for vertical seismic motion according to the present invention.

FIG. 3 is a cross-sectional view showing a third embodiment of a buoyancy support unit and a vertical seismic isolation device according to the present invention.

FIG. 4 is a cross-sectional view showing a fourth embodiment of a buoyancy support unit and a vertical seismic isolation device according to the present invention.

FIG. 5 is a cross-sectional view showing a fifth embodiment of a buoyancy support unit and a vertical seismic isolation device according to the present invention.

FIG. 6 is a sectional view showing a buoyancy support unit and a seismic isolation device for vertical seismic motion according to a sixth embodiment of the present invention.

FIG. 7 is a diagram showing a conventional example of a base isolation structure for a vertical seismic motion using a floating body.

[Explanation of symbols]

10,10A-E Vertical seismic isolation device 11 Seismic isolated structure 12 Support surface 20,20A-E Buoyancy support unit 21 Storage container 22 liquid 23 Support member 24, 24A-E Floating body 25, 25A-D Gas space forming part (air chamber) 26,26A-D Buoyancy adjuster 28 fins 30 Spring support unit 31 Coil spring (elastic body) 32 support 33 Inner tube 34 Outer cylinder 35 Sliding part 40 Horizontal seismic isolation device 41 sphere 42 Base material 50, 50A-D Membrane bag 51 Partition Plate

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16F 15/02 F16F 15/02 L 15/023 15/023 A (72) Inventor Yuji Fukushima Nagasaki City, Nagasaki Prefecture Fukahori-cho 5-717-1 Sanryo Heavy Industries Nagasaki Research Institute F term (reference) 2D046 DA14 2D059 GG15 GG17 GG33 3J048 AA03 AA07 AD05 BG10 CB01 DA01 EA38

Claims (10)

[Claims] 1. A buoyancy support unit for a seismic isolation device for isolating a vertical component of earthquake motion acting on a seismically isolated structure such as a building, comprising a liquid storage container and a liquid storage container. A liquid which is stored and gives buoyancy, and a floating body which is buried in the liquid and is connected to the seismic-isolated structure via a supporting member having a liquid level cross-sectional area set to be smaller than the main body horizontal cross-sectional area. A buoyancy support unit characterized by comprising. 2. The buoyancy support unit according to claim 1, wherein the support member is one or a plurality of rod-shaped members. 3. The buoyancy support unit according to claim 1, wherein the floating body is provided with a buoyancy adjusting mechanism. 4. The buoyancy adjusting mechanism is provided with a gas space forming part provided under the floating body and communicating with the liquid, and a volume varying means of the gas space forming part. The buoyancy support unit according to claim 3. 5. The buoyancy support unit according to claim 4, wherein the gas space forming part is divided into a plurality of parts, each of which is provided with a dedicated volume varying means. 6. The buoyancy support according to claim 4, wherein the buoyancy adjusting mechanism comprises a bag body disposed in the gas space forming portion, and a volume varying means for the bag body. unit. 7. The buoyancy support unit according to claim 6, wherein the bag body is divided into a plurality of pieces, and each bag body is provided with a dedicated volume varying means. 8. The buoyancy support unit according to claim 1, wherein fins are attached to the floating body. 9. A buoyancy support unit according to claim 1, which is a seismic isolation device for vertical seismic motion that seismically isolates a vertical component of seismic motion acting on a seismically isolated structure such as a building. And a seismic isolation device for vertical seismic motion, comprising: an elastic body that elastically supports the seismic isolated structure in a vertical direction. 10. The seismic isolation device for vertical seismic motion according to claim 9, further comprising seismic isolation means for horizontal components of seismic motion acting on the seismically isolated structure.