JPH1068215A - Floor base isolation construction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to make natural period of a floor material a long period even if the spring constant is not made lower and to reduce cost. SOLUTION: This floor quake relieving construction is of a structure to intervene a plural number of laminated rubbers 15 between a floor slab 12 and a frame 14 including a floor material 13 arranged at intervals. In this case, an oscillation period in the horizontal direction is designed to be prolonged by reducing the number of arrangements of the laminated rubbers 15 and increasing the load of the respective laminated rubbers and frame 14 deflection is prevented by arranging sliding bearings 16 of friction coefficient as close as possible to zero by the reduced quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floor seismic isolation structure using a seismic isolation structure such as laminated rubber.

[0002]

2. Description of the Related Art A floor seismic isolation structure is designed to provide seismic isolation not for the entire building but for the floor, not for the entire building, such as floors for precision equipment such as computers and operating room floors. It is used to reduce the acceleration of seismic isolation floor against seismic waves.

As a conventional floor seismic isolation structure, a natural vibration period of the floor is shifted to a long period side with respect to a vibration period peculiar to the building by using a seismic isolation structure such as a soft laminated rubber, so that a horizontal direction is obtained. A method of reducing response acceleration is generally adopted. Further, in order to suppress the response displacement of the floor, a method of absorbing seismic energy input from the building to the floor by using an oil damper to suppress vibration of the floor has been adopted.

A conventional floor seismic isolation structure will be described with reference to FIGS. 4 and 5. FIG. FIG. 4 is a plan view of a conventional floor seismic isolation structure, and FIG.
FIG. As shown in the figure, in the conventional floor seismic isolation structure, a plurality of laminated rubbers 3 are interposed between a floor slab 1 and a mount 2 made of H-section steel or the like, and a floor laid on the upper side of the mount 2 is provided. The material 4 is provided with a computer device 5 that is vulnerable to vibration. In addition, as a vibration damping structure for suppressing a response displacement of the gantry 2 including the floor material 4 to an earthquake or the like,
An oil damper 6 is installed between each floor slab 1 and the gantry.

[0005] With this floor seismic isolation structure, the natural period of the gantry 2 including the floor material is shifted in the horizontal direction to the long period side using the soft laminated rubber 3 with respect to the natural period of the building, and the response acceleration in the horizontal direction is reduced. Had to be reduced.

[0006]

By the way, the natural period T in the seismic isolation structure of the floor is expressed by the following equation, where the spring constant K of the elastic body such as laminated rubber in the horizontal direction and the mass of the floor etc. are M. You. T = 2π (M / K) ^1/2 (1) From equation (1), in order to increase the natural period of the floor or the like, the mass M of the floor or the like is increased or the spring constant K is increased. Should be reduced.

[0007] When the mounting weight (mass on the sprung mass) is large, such as in a building or a bridge, the spring constant for prolonging the natural period is relatively large, and is within the range of the design of a normal laminated rubber. In the case of seismic isolation, the sprung mass is extremely smaller than that of the entire building, etc.In order to extend the natural period of the floor with seismic isolation rubber, it is necessary to increase the sprung mass by adding a mass member. , Or the spring constant of the seismic isolation rubber must be considerably smaller for lighter floors. When the mass is added, there is a problem that the cost of attaching the mass member is increased.

For this reason, in the case of floor seismic isolation, the spring constant of the seismic isolation rubber must be selected to be small in accordance with the lightweight floor. This increases the height of the rubber, that is, increases the number of layers. However, when the height of the laminated rubber is high and the spring constant is small, the horizontal displacement becomes large, the center of the load in the vertical direction of the laminated rubber is largely shifted, and a so-called buckling phenomenon occurs. Therefore, it is difficult to increase the natural period in floor seismic isolation using only the conventional laminated rubber.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low-cost seismic isolation structure that can extend the natural period of the floor structure without reducing the spring constant more than necessary in the seismic isolation of the floor.

[0010]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies and as a result, while adopting a structure having the same spring constant of a seismic isolation structure such as laminated rubber as before, The focus was on increasing the load on individual seismic isolation structures. That is, since the gantry including the floor is a structure supported by a plurality of seismic isolation structures, the number of seismic isolation structures is reduced in place of the conventional structure with mass members, and A method of increasing the load was adopted. As a result, it was found that the natural period of the gantry including the floor material in the horizontal direction was prolonged, and the seismic isolation performance was improved.

[0011] However, in this case, the space between the seismic isolation structures serving as floor supports becomes too large, and the possibility that the gantry is bent is increased. In order to suppress the deflection of the gantry, a method of increasing the gantry or the floor strength can be considered.

In view of the above, the present inventors have focused on a structure in which a supporting member in place of the reduced seismic isolation structure is disposed between the seismic isolation structures such as laminated rubber, and the seismic isolation performance is maintained. However, this support member can be displaced in response to the response displacement of the seismic isolation structure such as laminated rubber, and in order to sufficiently exhibit the performance of the seismic isolation structure such as laminated rubber, It is desired that the member be capable of suppressing the vibration damping function in the horizontal direction as much as possible.

The present inventor has adopted a structure in which a slip bearing is disposed between the seismic isolation structures instead of the reduced seismic isolation structure as a seismic isolation structure satisfying these conditions.
If this sliding bearing is adopted, the load on each seismic isolation structure such as laminated rubber will increase, and the natural period in the horizontal direction can be extended, and the load distribution of each seismic isolation structure will increase. Accordingly, the support structure can prevent the floor from bending even if the space between the seismic isolation structures increases.

Therefore, in the present invention, in a floor seismic isolation structure in which a plurality of seismic isolation structures are arranged at an interval between a floor slab and a gantry including a floor, the period in the horizontal direction is increased. In order to reduce the number of the seismic isolation structures, a floor seismic isolation structure is adopted, in which a sliding bearing is arranged between the seismic isolation structures to prevent bending of the gantry. It was done.

Here, as the seismic isolation structure, a structure in which a large number of hard plates having rigidity and soft plates having viscoelastic properties are alternately laminated is generally used. Rigid materials such as plastic, hard polyurethane, wood, and paper board can be used. Further, as the soft plate, plastic, clay, and the like can be used in addition to thermoplastic rubber, urethane rubber, various vulcanized rubbers, unvulcanized rubber, and the like. However, in the case of unvulcanized rubber or clay, a restoring force cannot be obtained without elasticity even if it is viscous. Therefore, it is conceivable to use these materials together with an elastic material.

As the most common seismic isolation structure, laminated rubber can be used, and this laminated rubber may have a structure in which a large number of rubber plates and metal plates are alternately laminated. it can.

The sliding bearing can be composed of, for example, a columnar member fixed to the gantry side and a sliding material fixed to the lower end, and a sliding plate fixed to the floor slab side. However, in order to sufficiently exhibit the performance of the seismic isolation structure, it is desirable that the slide bearing has a function of only supporting the gantry.

That is, the present invention provides a seismic isolation structure in which both the upper and lower surfaces are fixed, assuming that the vertical load is shared between the seismic isolation structure and the slide bearing, and the horizontal rigidity (spring constant) acts. (Laminated rubber) only, and by sliding the movable surface of the sliding bearing relative to the fixed surface, the rigidity (spring constant) in the horizontal direction does not act on the sliding bearing.

Therefore, in order to make the sliding bearing body easily move in the horizontal direction under the load shared in the vertical direction, the movable surface and the fixed surface of the sliding bearing member must be made of a combination of relatively slippery materials. There is. For this reason, it is desired that the movable surface and the fixed surface of the sliding bearing body be selected from materials having an extremely small coefficient of friction.

Therefore, in the present invention, it is possible to adopt a structure in which the friction coefficient of the sliding bearing body approaches zero as much as possible. For this structure, if a material that reduces friction such as polytetrafluoroethylene is selected for the sliding material, and a mirror-like smooth plate such as a stainless steel plate is used as the sliding plate, the friction coefficient can be reduced to about 0.05. be able to.

[0021]

An embodiment of the present invention will be described below with reference to the drawings. 1 is a plan view of a floor seismic isolation structure showing an embodiment of the present invention, FIG. 2 is a front view thereof, and FIG.
FIG.

As shown in the figure, a floor seismic isolation structure 11 according to the present invention has a plurality of laminated rubber 15 as a seismic isolation structure between a floor slab 12 and a gantry 14 including a floor member 13. In the floor seismic isolation structure with the arrangement interposed therebetween, the number of the laminated rubbers 15 is reduced in order to increase the horizontal period, and the bending of the gantry 14 between the laminated rubbers 15 is reduced by the reduced number of the laminated rubbers 15. The sliding bearing body 16 for prevention is arranged.

The floor slab 12 is a concrete floor generally cast on a foundation or a beam of a building, and a pedestal 14 is provided above the floor slab 12 via a floor isolation structure 11.
Is laid. The gantry 14 is formed by arranging H-shaped steels in a lattice, and a floor material 13 is laid on the upper side of the pedestal 17 via a pedestal 17. The pedestal 17 is a floor material 13
Of a well-known structure having an adjustment bolt for adjusting the flat soil of the pedestal 17.
Electrical wiring and the like are laid in a space formed between the first and third wires.

The laminated rubber 15 is reduced by two from the conventional arrangement of six laminated rubbers 3 shown in FIG. 4 to eliminate the laminated rubber at the intermediate portion of the pedestal 14. The sliding bearing body 16 is arranged so that the load applied to each laminated rubber 15 is made larger than that of the laminated rubber 3 shown in FIG. That is, although the laminated rubber having the same characteristics as the laminated rubber shown in FIG. 4 is used, the load borne by one laminated rubber is increased by reducing the number of laminated rubbers. .

The structure of the laminated rubber 15 is not different from that of the conventional rubber shown in FIG.
The laminated rubber 15 has a cylindrical shape in which a large number of rubber plates 20 and metal plates 21 are alternately laminated between upper and lower flanges 18 and 19. The laminated rubber 15 is formed by integrally bonding upper and lower flanges 18, 19, a rubber plate 20, and a metal plate 21 when the rubber plate is vulcanized. The upper end flange 18 of the laminated rubber 15 is fixed to the gantry 14, and the lower end flange 19 is fixed to the floor slab 12.

The laminated rubber 15 is manufactured by appropriately selecting its performance as a light-load seismic isolation structure, and has an outer diameter of 100 to 400 mm and a height of 150 to 350 mm. You. Since the height from the floor slab 12 to the floor material 13 is generally suppressed to 500 to 600 mm,
Height of gantry 14 (150-200 mm), pedestal 1
7 (about 200 mm), the laminated rubber 1
This is because the height of 5 is naturally set.

The rubber properties of the laminated rubber 15 are appropriately selected in order to obtain desired properties. For example,
In the case of the laminated rubber 15 for a vertical load of 1.5 tons, if the outer diameter is 170 mm, the inner diameter is 140 mm, the height is 250 mm, and the total rubber thickness is 171 mm, the surface pressure is 1 depending on the rubber characteristics.
2 kgf / cm ² , horizontal allowable deformation 150 mm, horizontal natural frequency 1.62 Hz, horizontal rigidity 22.9 kg
f / cm is obtained. In addition, laminated rubber 1 for 5.0 tons
In No. 5, if the outer diameter is 290 mm, the inner diameter is 200 mm, the height is 273 mm, and the total rubber thickness is 175 mm, the surface pressure is 16.5 kgf / cm ² , the allowable deformation in the horizontal direction is 180 mm, and the natural vibration in the horizontal direction is determined according to the rubber characteristics. Number 2.2H
z, a horizontal rigidity of 42 kgf / cm is obtained. The laminated rubber 15 is not limited to the dimensions and characteristics shown in the above specific examples,
It goes without saying that dimensions and characteristics suitable for light loads can be appropriately selected. Table 1 shows an example.

[0028]

[Table 1]

The sliding bearing body 16 is fixed to the gantry 13 and has a sliding member 22 fixed at the lower end as a columnar member 23 as a movable part made of a steel plate, and a sliding plate as a fixed part fixed to the floor slab 12 side. 24. Sliding material 22
A material that reduces friction, such as polytetrafluoroethylene (trade name: Teflon), is selected. The sliding plate 24 is a mirror-like smooth plate, such as a stainless steel plate (SUS304), and has a friction coefficient μ. The configuration is reduced to about 0.05.

That is, the sliding support 16 is provided with the floor material 13.
And is set so as to hardly receive the load from the gantry 14. At the time of vibration input such as an earthquake, the gantry 14 is set so as to hardly exhibit the vibration damping function.
And, it is installed so as to exhibit performance only to reinforce the deflection on the floor material 13. Therefore, by selecting the material of the sliding member 22 and the sliding plate 24, the friction coefficient of the sliding support 16 can be made as close to zero as possible.

An oil damper 26 having a well-known structure is provided between the floor slab 12 and the gantry 14 as a vibration damping structure for suppressing a displacement of the gantry 14 in response to an earthquake or the like. FIG. 3 shows a state in which the computer device 27 is installed on the floor material 13.

In the above structure, the number of laminated rubbers 15 as the seismic isolation structure is reduced as compared with the conventional seismic isolation structure shown in FIG. Is increased. The natural period T in the floor seismic isolation structure is expressed as the mass M of the floor or the like and the horizontal spring constant K of the laminated rubber 15 (1).
When applied to the equation, the natural period T will increase. T = 2π (M / K) ^1/2 ............ (1)

Accordingly, the seismic isolation performance is improved as compared with the conventional floor seismic isolation structure shown in FIG. This is, as before,
As the dummy mass, it is not necessary to use a heavy material for the gantry 14, the floor material 13, and the like, and a lightweight material can be used as the gantry weight, so that low cost can be realized.

In the floor seismic isolation structure shown in FIG.
In order to exert the seismic isolation performance equivalent to the present invention, the height of the laminated rubber 15 must be higher than that of the present invention, but in this case, the stand itself must be designed in order to suppress the floor height. Need to be done. In this regard, in the present invention, since the seismic isolation performance is improved with a simple configuration merely by reducing the number of laminated rubbers, the design and manufacture of the gantry becomes easy, and the construction of the seismic isolation structure is also easily performed. As a result, the overall cost can be kept low.

Furthermore, with the decrease in the number of the laminated rubbers 15, the deflection which may occur in the center of the gantry 14 can be maintained by the use of the slide bearings 16, and the strength of the floor itself can be sufficiently satisfied.

[0036]

As is apparent from the above description, according to the present invention, the seismic isolation performance is greatly improved by a simple configuration in which the number of seismic isolation structures, such as laminated rubber, is reduced compared to the prior art. In addition to the seismic isolation structure, which has reduced the strength of the gantry due to the decrease of the seismic isolation structure, a sliding bearing that functions only to prevent deflection of the gantry is used. It is possible to provide a floor seismic isolation structure which is easy to manufacture and can sufficiently satisfy the strength of the floor itself.

[Brief description of the drawings]

FIG. 1 is a plan view of a floor seismic isolation structure showing an embodiment of the present invention.

FIG. 2 is a front view of the same.

FIG. 3 is an enlarged front view of the same main part.

FIG. 4 is a plan view of a conventional floor seismic isolation structure.

FIG. 5 is a front view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Floor seismic isolation structure 12 Floor slab 13 Flooring material 14 Stand 15 Laminated rubber 16 Slip support 17 Pedestal 18 Flange 19 Flange 20 Rubber plate 21 Metal plate 22 Slipper 23 Slipper

Claims (2)

[Claims] 1. A floor seismic isolation structure in which a plurality of seismic isolation structures are arranged at intervals between a floor slab and a gantry including a floor. A floor seismic isolation structure characterized in that the number of seismic structures is reduced, and a sliding bearing for preventing bending of a gantry is provided between the seismic isolation structures by the reduced number of seismic isolation structures. . 2. The floor seismic isolation structure according to claim 1, wherein the coefficient of friction of the sliding bearing body is as close to zero as possible.