JPH09195571A - Seismic isolation structure using a mixture of low friction sliding bearing and laminated rubber bearing - Google Patents

Abstract

(57) [Abstract] [Problem] In a seismic isolation bearing in which sliding friction bearings and laminated rubber bearings are mixed, the Coulomb friction coefficient is reduced, smooth and effective damping is obtained, and damping characteristics are easily adjusted. A seismic isolation structure that mixes low friction sliding bearings and laminated rubber bearings,
Another object of the present invention is to provide a seismic isolation system that uses the seismic isolation system and a velocity proportional damping device (oil damper) together. SOLUTION: A low friction sliding bearing and a laminated rubber bearing are used in combination, and an oil-impregnated polyacetal resin or polytetrafluoroethylene resin plate is used as a lubricant for the sliding friction bearing. In some cases, the sliding surface is lubricated. If the laminated rubber bearing is allowed to break, it is possible to use a sliding bearing that is 1-2 cm lower than the main sliding friction bearing as a backup bearing and use it together with an oil damper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic isolation structure for buildings, which is a mixture of low friction sliding bearings and laminated rubber bearings.

[0002]

2. Description of the Related Art Conventionally, sliding bearings or laminated rubber bearings have often been used individually as seismic isolation bearings. However, in consideration of the fact that it is relatively free to set various elements such as yield shear force and seismic isolation period related to seismic isolation performance and it is easy to extend the period, sliding friction bearing and laminated rubber bearing are used in combination. The structure is in the limelight.

Already in New Zealand, An Introductio
n to Seismic Isolation (1993) has a simple description of the relationship, but this document does not have a specific description. In Japan, in the collection of lectures from the Architectural Institute of Japan (August 1995),
"Development of design method of seismic isolation structure by compound bearing method (Part 1
Outline of construction method and basic theory) "has been published, but in this document the Coulomb friction coefficient of sliding bearings is about µ = 0.1 to 0.15.

Generally, for seismic isolation, vibrations with a short period of seismic input are dominant, so the natural oscillation period of the seismic isolation system is lengthened.

A method of insulating the ground from a building.

A method of absorbing input seismic energy.

There is

According to the present invention, means for insulating the ground and the building which are subject to seismic vibration by sliding bearings, means for lengthening the natural vibration period of the building with laminated rubber bearings, and oil dampers for absorbing vibration energy. It is possible to combine the means for doing so, and it is possible to easily adjust the damping performance of the earthquake input.

If an energy absorption damper of a displacement velocity proportional type such as an oil dynamometer is used here, a smooth seismic response can be obtained without causing jerking due to a drastic change in rigidity when the displacement changes direction as in the case of a sliding bearing alone. It becomes a property. Further, the damping performance does not decrease with an increase in the displacement as in the case of the sliding bearing alone, and a certain damping performance is secured regardless of the displacement.

Since the sliding bearing is mixed with the laminated rubber bearing, the natural vibration period of the building seismic isolation system is longer (about 6 sec) than that of the laminated rubber bearing alone, and the natural vibration period is long ( It can be applied to high-rise buildings and excellent design seismic motions with long-period components, and exhibits a high seismic isolation effect.

Next, the characteristics of the seismic isolation system which is a mixture of the low friction sliding bearing and the laminated rubber bearing will be described.

The natural vibration period T of the seismic isolation system is T = T _{R /} (1−α) ^1/2 (1) T _R = lamination Natural vibration period of rubber bearing α = load bearing ratio of sliding bearing Equivalent viscous damping constant H _eq of the base isolation system is H _eq = h _eq +4 μαW / πK _R δ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (2) = H _eq + 31.6μαT _R ² /δ...(3) h _eq = Equivalent viscous damping constant of laminated rubber bearing δ = Displacement K _R = Equivalent rigidity of laminated rubber bearing at displacement δ μ = Coulomb friction coefficient of sliding bearing W = Weight of building Equivalent sliding friction coefficient of the seismic isolation system μ _eq is μ _eq = αμ (4) Therefore, considering only a seismic isolation system that mixes low friction sliding bearings and laminated rubber bearings, increasing the equivalent viscous damping coefficient H _eq of the system is equivalent to the system equivalent sliding friction coefficient μ _eq = α μ
(Equation (4)) needs to be increased. However, it has already been mentioned that increasing the equivalent sliding friction coefficient μ _eq of the system increases Coulomb friction and makes seismic isolation more jerky. In order to release the jerky seismic isolation and to secure the state in which the building, which is the characteristic of the sliding bearing, is insulated from the ground while ensuring a proper natural vibration period, the equivalent sliding friction coefficient μ _{eq of the system} , That is, it is preferable that the Coulomb friction coefficient μ of the sliding bearing is small. Reducing the load bearing ratio α of the sliding bearing acts in the direction of shortening the natural vibration period of the seismic isolation system, as shown in equation (1), and further reduces the number of sliding bearings. It impairs the characteristics as a complicated mixed structure.

Therefore, the present invention provides a seismic isolation structure in which a low friction sliding bearing whose seismic isolation characteristics can be easily adjusted and a laminated rubber bearing are mixed, and in particular, the Coulomb friction coefficient of the sliding bearing is suppressed to a low level so that an oil damper is provided. It is an object to provide a seismic isolation structure that is used together.

[0014]

[Means for Solving the Problem] A seismic isolation structure characterized by using a plurality of low friction sliding bearings and a plurality of laminated rubber bearings, respectively. 1 to 1 to be received and low friction sliding bearing receiving the load
It is also possible to mix backup slide bearings, which have a low height of 2 cm and are initially unloaded. A conventional general sliding bearing can be used for this backup sliding bearing.

The seismic isolation structure, which uses a mixture of low friction sliding bearings and laminated rubber bearings, may be a combination of a plurality of low friction sliding bearings and laminated rubber bearings and an oil damper. is there.

The low-friction sliding bearing has a stainless steel plate attached to the seismically isolated side, a base is provided on the base side, and a rubber pad is provided on the base.
A structure in which an intermediate plate, an oil-impregnated polyacetal resin or a polytetrafluoroethylene-based resin plate is sequentially stacked, a load is applied by abutting on the stainless plate, and the oil-impregnated polyacetal resin or polytetrafluoroethylene-based resin plate and a stainless plate are slid. Alternatively, a base may be attached to the seismically isolated side, a rubber pad, an intermediate plate, an oil-impregnated polyacetal resin or a polytetrafluoroethylene resin plate may be sequentially loaded and unloaded, and a stainless steel plate may be attached to the foundation side. A lubricating oil frame is provided around the lubricating oil frame, the lubricating oil frame is filled with lubricating oil, and the oil-impregnated polyacetal resin or polytetrafluoroethylene resin plate slides on the stainless steel plate in the lubricating oil. It is also possible.

As described above, as the sliding material for the low-friction sliding bearing, the oil-containing polyacetal resin and the tetrafluoroethylene resin whose sliding surface is lubricated with lubricating oil are used, but they are used in the surface pressure and lubrication state where the friction coefficient is 0.05 or less. Therefore, it is desirable to use the surface pressure at 300 Kgf / cm ² or more. Then, the oil-impregnated polyacetal resin can obtain a friction coefficient of 0.05 or less without lubrication. As the laminated rubber bearing mixed with the sliding bearing, a low-damping laminated rubber bearing, a high-damping laminated rubber bearing, and a lead-containing laminated rubber bearing may be used alone or in combination. As an additional damper, it is preferable not to use an elasto-plastic damper as the additional damper, because the elasto-plastic damper has a reduced damping performance as the displacement increases and does not exhibit the required damping capacity when necessary.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 (a) is a plan view in which a sliding bearing is arranged in the center of a building under high load, and FIG. 2 is a plan view in which the sliding bearing is arranged in the periphery of a building under low load. Yes □
Indicates a sliding bearing, and ○ indicates a laminated rubber bearing. FIG. 1B is a plan view in which laminated rubber bearings and sliding bearings are randomly arranged.

FIG. 3 is a diagram of a sliding bearing using an oil-impregnated polyacetal resin. A stainless steel plate 3 is attached to the seismically isolated side 1, a base 4 is attached to the foundation side 2, and the base 4 is mounted on the base 4. The rubber pad 5, the intermediate plate 6, and the lubricant 7 (oil-impregnated polyacetal resin) are stacked in this order to form a structure that receives a load from the seismic isolated side.

FIG. 4 is a diagram of a sliding bearing using a tetrafluoroethylene resin whose sliding surface is lubricated with lubricating oil. A base 4, a rubber pad 5, an intermediate plate 6, and a lubricant 7 (in this case, a tetrafluoroethylene-based resin but an oil-impregnated polyacetal resin may be used) are sequentially stacked on the seismic isolated side 1, and a stainless plate 3 is mounted on the foundation side 2. A lubricating oil frame 8 is attached so as to surround the stainless steel plate 3, the lubricating oil is filled therein, and the lubricant 7 is loaded on the stainless steel plate 3 from the seismic isolated side.
The structure to receive the load of.

FIG. 5 is a diagram showing the natural vibration period T of the base isolation system and the natural vibration period T _R of the laminated rubber bearing with the load bearing ratio α of the sliding bearing as a parameter.

FIG. 6 is a diagram showing the natural vibration period T of the seismic isolation system and the load bearing ratio α of the sliding bearing as a parameter of the natural vibration period T _R of the laminated rubber bearing.

FIG. 7 is a horizontal axis the ratio H _eq / h _eq equivalent viscous damping constant h _eq of the laminated rubber bearing of equivalent viscous damping constant for the laminated rubber bearing with the equivalent viscous damping constant seismic isolation system, the displacement δ parameters FIG.

FIG. 8 shows a ratio H _eq / h _eq between the equivalent viscous damping coefficient of the base isolation system and the equivalent viscous damping coefficient of the laminated rubber bearing, and the load bearing ratio α of the sliding bearing as the horizontal axis. It is the figure which represented _heq as a parameter.

Even if the seismic isolation device is excessively displaced on soft ground or the like, the allowable displacement of the sliding bearing itself is basically unlimited, so it is safe to set the stainless steel plate large enough. In this case, however, if the laminated rubber bearing is designed to be fractured, the laminated rubber bearing must be backed up. It is also possible to use a conventional simple sliding bearing for this back-up. The slide bearing for backup should be installed close to the laminated rubber bearing with a clearance of 1-2 cm above and below the seismically isolated side and the foundation side. When the laminated rubber bearing is broken, the backup sliding bearing supports the load instead of the laminated rubber bearing and slides horizontally to achieve the seismic isolation function.

According to the present invention, the seismic isolation system can have a friction coefficient of about 0.02. Therefore, it becomes easy to adjust the damping performance of the seismic isolation system. The seismic isolation performance can be improved by reducing the damping property due to Coulomb friction and by using a viscous damping device (oil damper) proportional to the displacement speed. On the other hand, in the case of an elasto-plastic damper, the damping performance decreases as the displacement increases, and sufficient damping cannot be obtained when damping is required. Oil dampers provide constant damping regardless of displacement. In addition, it is possible to design a non-linear damper such that damping performance increases with increasing displacement. Moreover, even if the spring constant of the laminated rubber bearing is reduced and the natural vibration period is extended, a seismic isolation system with little residual deformation after an earthquake is possible. With a conventional sliding bearing with a friction coefficient of about 0.1,
Large residual deformation may remain.

[0028]

The effects of the present invention are as follows.

By mixing the low friction sliding bearing and the laminated rubber bearing, the natural vibration period of the seismic isolation system is extended as compared with the case where only the laminated rubber bearing is used. (See FIG. 5 and FIG. 6) For example, a natural vibration period of 6 sec is possible for a high-rise building with a common natural vibration period of 3 sec. Therefore, even if long-period ground motion is predominant on soft ground, the building escapes the resonant response. Even if the seismic isolation device is excessively displaced, the allowable displacement of the sliding bearing itself is basically unlimited, so it is safe to set the stainless steel plate large enough. In this case, however, if the laminated rubber bearing is designed to be fractured, the laminated rubber bearing must be backed up. It is also possible to use a conventional simple sliding bearing for this back-up. The slide bearing for backup should be installed close to the laminated rubber bearing with a clearance of 1-2 cm above and below the seismically isolated side and the foundation side. When the laminated rubber bearing is broken, the backup sliding bearing supports the load instead of the laminated rubber and slides horizontally to achieve the seismic isolation function.

By using the low friction sliding bearing and the laminated rubber bearing together, compared to the case of only the sliding friction bearing,
The coefficient of friction of the seismic isolation system decreases. When only the conventional sliding bearing is used, the friction coefficient is about 0.1 to 0.15, but according to the present invention, it can be 0.02. Therefore, it becomes easy to adjust the damping performance of the seismic isolation system. The seismic isolation performance can be improved by reducing the damping property due to Coulomb friction and by using a viscous damping device (oil damper) proportional to the displacement speed. On the other hand, in the case of an elasto-plastic damper, the damping performance decreases as the displacement increases, and sufficient damping cannot be obtained when damping is required. Oil dampers provide constant damping regardless of displacement. In addition, it is possible to design a non-linear damper such that damping performance increases with increasing displacement. Moreover, even if the spring constant of the laminated rubber bearing is reduced and the natural vibration period is extended, a seismic isolation system with little residual deformation after an earthquake is possible. A conventional sliding bearing with a friction coefficient of about 0.1 may have large residual deformation.

The sliding bearing of the present invention has a surface pressure of 1000 Kgf / cm.
Withstand pressure load up to ² , design load from 1000 Tonf to tens of To
It is possible to design bearings with a wide range of capacity up to nf, and it is easy to handle low loads that are difficult to design with laminated rubber bearings.

The sliding bearing is extremely compact, has good workability, and is inexpensive.

[Brief description of the drawings]

FIG. 1 (a) is a plan view in which a sliding bearing is arranged at the center of a building under high load. (B) is a plan view in which laminated rubber bearings and sliding bearings are randomly arranged.

FIG. 2 is a plan view in which sliding bearings are arranged in the peripheral portion of a building having a low load.

FIG. 3 is a diagram of a sliding bearing using an oil-containing polyacetal resin.

FIG. 4 is a diagram of a sliding bearing using a tetrafluoroethylene-based resin whose sliding surface is lubricated with lubricating oil.

FIG. 5 is a diagram showing the natural vibration period T of the seismic isolation system and the natural vibration period T _R of the laminated rubber bearing using the load bearing ratio α of the sliding bearing as a parameter.

FIG. 6 is a diagram showing the natural vibration period T of the seismic isolation system and the load bearing ratio α of the sliding bearing with the natural vibration period T _R of the laminated rubber bearing as a parameter.

Table 7 an equivalent viscous damping constant h _eq of laminated rubber bearing ratio H _eq / h _eq equivalent viscous damping constant equivalent viscous damping constant for the laminated rubber bearing of MenShinkei the horizontal axis, the displacement δ as a parameter FIG.

[FIG. 8] Ratio of equivalent viscous damping coefficient of base isolation system to equivalent viscous damping coefficient of laminated rubber bearing H _eq / h _eq is load bearing ratio α of sliding bearing as horizontal axis Equivalent viscous damping constant of laminated rubber bearing h _eq It is the figure which represented using as a parameter.

[Explanation of symbols]

1 …… Seismically isolated side, 2 …… Foundation side, 3 …… Stainless steel plate,
4 ... Stand, 5 ... Rubber pad, 6 ... Intermediate plate, 7
...... Lubricant, 8 ...... Lubricant oil frame, 9 ...... Lubricant oil

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Eiji Takaoka Eiji Takaoka 2-19-1 Tobita-cho, Chofu-shi, Tokyo Kashima Construction Co., Ltd. Technical Research Institute (72) Inventor Masayoshi Ikenaga 8 Kirihara-cho, Fujisawa-shi, Kanagawa OILES Engineering Co., Ltd. Fujisawa Business Co., Ltd.

Claims (5)

[Claims] 1. A seismic isolation structure comprising a mixture of low-friction sliding bearings and laminated rubber bearings, wherein a plurality of low-friction sliding bearings and laminated rubber bearings are mixed together. 2. A low-friction sliding bearing is one that receives an initial load and a low-friction sliding bearing that receives the load is 1 to 2c.
2. A seismic isolation structure using a low friction sliding bearing and a laminated rubber bearing as a mixture according to claim 1, characterized in that a back-up sliding bearing having a low height and not initially receiving a load is mixed. 3. The low-friction sliding bearing and the laminated rubber bearing according to claim 1 or 2, wherein a plurality of low-friction sliding bearings and laminated rubber bearings are used together with an oil damper. A seismic isolation structure that is a mixture of 4. A stainless steel plate is attached to the seismic isolated side, a base is provided on the foundation side, and a rubber pad, an intermediate plate, an oil-impregnated polyacetal resin or a polytetrafluoroethylene-based resin plate is sequentially stacked on the base, and the stainless steel plate is attached. The low friction slide bearing and the laminated rubber according to claim 1, 2 or 3, wherein the plate is brought into contact with a plate to receive a load and slides between the oil-containing polyacetal resin or polytetrafluoroethylene resin plate and the stainless plate. A seismic isolation structure with mixed bearings. 5. A base is attached to the seismically isolated side, a rubber pad, an intermediate plate, an oil-impregnated polyacetal resin or a polytetrafluoroethylene-based resin plate is sequentially loaded and unloaded, and a stainless plate is attached to the foundation side, and the periphery of the stainless plate is attached. A lubricating oil frame is provided, the lubricating oil frame is filled with lubricating oil, and the oil-impregnated polyacetal resin or polytetrafluoroethylene resin plate slides on the stainless steel plate in the lubricating oil. A seismic isolation structure comprising a mixture of the low friction sliding bearing according to claim 1, 2 or 3 and the laminated rubber bearing.