JP2000065135A - Laminated rubber support - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a long period of a natural period without impairing the other various performances by setting a primary shape factor, a secondary shape factor, the ratio of a diameter to a thickness and rubber hardness of a rubber-like elastic plate to respective specific values. SOLUTION: In a support of this laminated rubber, when a diameter of a rubber-like elastic plate 10 is denoted by D, a thickness of the robber-like elastic plate 10 is denoted by (h'), the total thickness Σh' of the rubber-like elastic plate 10 is denoted by (h), a thickness of a hard plate 9 is denoted by (t) and a diameter of a central hole when there is a central hole extending by penetrating through the laminated layer in a base isolation laminated body is denoted by (d), a primary shape factor S1 decided by S1=(D-d)/4h' and S2=D/h is set >=35, a secondary shape factor S2 is <5, the ratio D/t of a diameter D of a rubber elastic body to a thickness (t) is set <150, and rubber hardness of the rubber-like elastic plate 10 is set <=50. Thus, the support of this laminated rubber can attain a long period of a natural period without impairing the other various performances, particularly, buckling performance, and can exhibit excellent base isolation performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a seismic isolation bearing that reduces the acceleration of vibrations input to structures, various devices, arts and crafts, etc. due to, for example, earthquakes, mechanical vibrations, or traffic vibrations. Related to laminated rubber bearings.

[0002]

2. Description of the Related Art Acceleration of vibration applied to structures such as buildings, bridges, tanks, etc., and devices such as electronic computers, medical devices, security devices, precision manufacturing devices, analytical and analytical devices, and arts and crafts. For example, as shown in FIG. 6, a laminated rubber bearing in which a hard plate a such as a steel plate and a rubber-like elastic plate b are alternately laminated and joined as shown in FIG. 6 is known.

[0003] Further, as one of the parameters that determine the shape of such a laminated rubber bearing, there is the secondary shape coefficient S ₂ defined by the following equation, the secondary shape factor S ₂ is the loading capacity and the horizontal rigidity involvement, laminated rubber bearing as secondary shape factor S ₂ is increased becomes flat, horizontal rigidity is subtracted with increases the loading capability, etc. becomes difficult to cause buckling or bending deformation. S ₂ = D / h (where D is the diameter of the rubber-like elastic plate and h is the total thickness of the rubber-like elastic plate)

Therefore, as the laminated rubber bearing, a rubber bearing having a relatively stable structure in which the secondary shape factor S ₂ exceeds 5 has conventionally been used.

[0005]

On the other hand, in the field of construction in recent years, as an effective seismic isolation structure, the direction of making the natural period T of a base-isolated building longer is oriented. It is hoped that it will be more than seconds.

Here, it is well known that the natural period T of the base-isolated building is given by the following equation from the horizontal rigidity of the laminated rubber bearing. T = 2π√ ｛W / (KH · g)｝ ≒ 2π√ ｛(D ·
σ) / (S ₂ · G · g) 中 where T: natural period of the building based on the horizontal rigidity of the laminated rubber bearing W: gross building weight KH: horizontal rigidity of the laminated rubber bearing g: gravitational acceleration D: rubbery Elastic plate diameter σ: Surface pressure of laminated rubber bearing G: Shear modulus of rubbery elastic plate S ₂ : Secondary shape factor of laminated rubber bearing

From the above equation, it can be understood that the natural period T can be made longer by changing the geometric dimensions such as the surface pressure σ, the diameter D and the secondary shape factor S ₂ , or the shear modulus G. However, these are all severe directions in the use environment of the laminated rubber bearing.

That is, increasing the surface pressure σ causes an increase in the amount of creep and at the same time lowers the buckling characteristics such that buckling is likely to occur during smaller horizontal shear deformation. Further, lowering the shear modulus G causes difficulty in the production process and increases the amount of creep. The secondary shape factor S ₂
As described above, if the number of the laminated rubber bearings is reduced to less than 5, the buckling or bending deformation is likely to occur, and the loading capacity is reduced.

However, from this viewpoint, as shown in Table 1, in a laminated rubber bearing having a diameter D of, for example, 70 cm, the shear modulus G of the rubber is usually 4 kgf / cm ² -6.
kgf / cm ² , maximum surface pressure σ is 100 kgf / cm
^Since it is set to about ₂ , the natural period T is surely shorter than 4 seconds when the secondary shape coefficient S2 is 5 or more. As described above, it is extremely difficult to achieve a longer period of 4 seconds or more with the conventional laminated rubber bearing, and it was not possible to sufficiently exhibit the seismic isolation performance.

[0010]

[Table 1]

In view of such circumstances, the present inventor has conducted research.
As a result of stacking, the secondary shape factor S_TwoWhere is reduced to less than 5
Of buckling / bending deformation and reduction of loading capacity
Increases the thickness t of the hard plate to provide sufficient rigidity to each hard plate.
While the primary shape factor S ₁To increase the laminated rubber bearing
Increased vertical and bending stiffness and horizontal spring constant
Can be solved by keeping the surface pressure dependency of
I was able to find out.

That is, according to the present invention, the secondary shape factor S _{2 is set} to 5
After realizing a longer period, the buckling / bending deformation and the reduction of the loading capacity can be improved by setting the thickness of the hard plate and the primary shape factor S _1. It is intended to provide a laminated rubber bearing that can be achieved without impairing other performances.

As is well known, the primary shape factor S ₁ is defined as a ratio between the restrained area of the rubber-like elastic plate and the free surface area (side area) and is one of the parameters of the laminated rubber bearing determined by the following equation. Yes, when this becomes large,
As the bending stiffness increases, the deformation due to the surface pressure is suppressed. As a result, the fluctuation of the horizontal spring constant, that is, the dependency of the horizontal spring constant on the surface pressure is reduced and stabilized. S ₁ = (D−d) / 4h ′ (where h ′ is the thickness of the rubber-like elastic plate, and d is the diameter of the center hole c when the base-isolated laminate has a center hole c (shown in the figure)). is there.)

[0014]

In order to achieve the above object, the invention of claim 1 of the present application provides a seismic isolation laminate in which a plurality of hard plates and rubber-like elastic plates are alternately laminated and joined. A laminated rubber bearing comprising: a rubber-like elastic plate having a diameter of D, a rubber-like elastic plate having a thickness of h ′, a rubber-like elastic plate having a total thickness of h, and a hard plate having a thickness of t; When the seismic isolation laminate has a center hole extending through the stack and the diameter of the center hole is d, a primary shape factor S ₁ determined by the following equation:
Is 35 or more, the secondary shape factor S ₂ is less than 5, and the diameter D
The ratio D / t between the thickness and the thickness t is smaller than 150, and the rubber hardness Hd of the rubber-like elastic plate is 50 degrees or less. S ₁ = (D−d) / 4h ′ − (1) S ₂ = D / h − (2)

In the invention of claim 2, the seismic isolation laminate does not have the center hole.

In the invention according to claim 3, the seismic isolation laminate has the center hole, and the diameter d of the center hole is 0.05 times or less the diameter D of the rubber-like elastic plate. It is characterized by.

Further, in the invention according to claim 4, the seismic isolation laminate is characterized in that the outer peripheral surface of the rubber-like elastic plate is located at a distance L inward from the outer peripheral surface of the hard plate. A gap portion having no rubber-like elastic plate is formed in a region near the outer periphery, and an outer peripheral surface of the seismic isolation laminate is covered with an outer rubber layer integrally vulcanized with the seismic isolation laminate. I have.

According to the fifth aspect of the present invention, each of the outer peripheral surfaces of the rubber-like elastic plate and the hard plate has substantially the same shape, and the rubber-like elastic plate is provided in a region near the outer periphery which is inwardly separated from the outer peripheral surface by a distance L. The plate forms a non-adhesion portion that is not adhered to the hard plate, and an outer peripheral surface of the seismic isolation laminate is covered with a skin rubber layer integrally vulcanized with the seismic isolation laminate.

In the invention of claim 6, the distance L is at least 1.0 times the thickness h 'of the rubber-like elastic plate.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are cross-sectional views of a laminated rubber bearing 1 of the present application. The laminated rubber bearing 1 has a seismic isolation laminate 5 in which a plurality of hard plates 9 and rubber-like elastic plates 10 are alternately laminated and joined. The outer peripheral surface of the seismic isolation laminate 5 has
In this example, the outer rubber layer 6 is integrally covered with the seismic isolation laminate 5 to be covered and protected by the outer rubber layer 6.

The fixed plate 3 is attached to the upper and lower connecting plates 2 arranged at the uppermost and lowermost stages of the seismic isolation laminate 5 on the laminated rubber bearing 1 by using connecting fittings 13 such as bolts. At the same time, the laminated rubber bearing 1 is fixed to the lower structure 4L as a foundation and the upper structure 4U as a building, for example, via the fixing plate 3, respectively.

The hard plate 9 is made of a rigid metal plate such as a steel plate. The connecting plate 2 is thicker than the hard plate 9, for example, approximately the same as the fixed plate 3. It is formed of a thick plate body of the order. As long as the plate has the same rigidity and strength as the metal plate, plates made of various materials such as ceramics and synthetic resin can be used.
The hard plate 9 has an outer peripheral surface 9s having a circular shape with no directivity, that is, a contour shape of an outer edge of the hard plate 9 so as to cope with swings in various directions.

As the rubber-like elastic plate 10, various rubber materials can be used, but it is necessary to have excellent mechanical strength, long-term stability of elastic modulus, long-term stability of deformation capacity, and creep resistance. Yes, for example, natural rubber (NR), chloroprene rubber (CR) and the like can be preferably used. In particular, since natural rubber is inexpensive and is superior to chloroprene rubber in characteristics other than weather resistance, it is more preferable to use a natural rubber-based material in which this natural rubber is blended in an amount of 90 phr or more.

As shown in FIG. 2 in an enlarged manner, the rubber-like elastic plate 10 has an outer peripheral surface 10 s recessed by a distance L from the outer peripheral surface 9 s of the hard plate 9 in this embodiment. By locating (aside), a gap portion 14 in which the rubber-like elastic plate 10 does not exist between the hard plates 9 is formed in a region near the outer periphery. The entire upper surface and lower surface of the rubber-like elastic plate 10 are joined to the hard plate 9 and the upper and lower connecting plates 2 by known means such as vulcanization bonding.

Next, the outer rubber layer 6 is formed in a straight cylindrical shape along each outer peripheral surface 9 s of the hard plate 9, and therefore, between the outer peripheral surface 10 s of the rubber-like elastic plate 10 and the outer peripheral surface 10 s. It is possible to form a hollow portion 15 that is separated and non-adhesive. The outer rubber layer 6 hermetically covers and protects the outer peripheral surface of the seismic isolation laminate 5 by bonding at least to the outer peripheral surfaces of the upper and lower connecting plates 2. It is preferable to adhere to the outer peripheral surface 9s of each hard plate 9 in order to uniformly increase the thickness over the entire surface and to prevent peeling.

The outer rubber layer 6 has excellent weather resistance, for example, chloroprene rubber (CR), butyl rubber (IIR)
, Halogenated butyl rubber (X-IIR), ethylene propylene rubber (EPM, EPDM), urethane rubber (U), silicon rubber
(Q), fluoro rubber (FKM), polysulfide rubber (T), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM),
Synthetic rubber materials such as ethylene vinyl acetate rubber (EVM) and epichlorohydrin rubber (ECO) can be used, but chloroprene rubber (CR), butyl rubber (IIR), butyl rubber (X-IIR), ethylene Propylene rubber
(EPM, EPDM) are preferred.

Of these, chloroprene rubber (CR) is the same kind of rubber material that is integrally vulcanized and bonded to the natural rubber, and includes butyl rubber (IIR) and halogenated butyl rubber (X-II
R) and ethylene propylene rubber (EPM, EPDM) are different types of rubber materials that are not integrally vulcanized with the natural rubber.
Also, in view of being amorphous, nitrile rubber (NB
R), butadiene rubber (BR), ethylene propylene rubber (EPD
M), silicone rubber (Q), acrylic rubber (ACM), and epichlorohydrin rubber (ECO) are preferred.

In the laminated rubber bearing 1 of the present application, as shown in FIG. 2, the diameter of the rubber-like elastic plate 10 is D, the thickness of the rubber-like elastic plate 10 is h ′, and the total thickness of the rubber-like elastic plate 10 is Δh. ′ Is h, the thickness of the hard plate 9 is t, and the diameter of the center hole 11 when the seismic isolation laminate 5 has a center hole 11 extending through the stack is d, (1), (2)
The primary shape factor S ₁ determined by
₂ is less than 5, and the ratio D / t of the diameter D to the thickness t is 15
0, and the rubber hardness Hd of the rubber-like elastic plate 10
Is set to 50 degrees or less. S ₁ = (D−d) / 4h ′ − (1) S ₂ = D / h − (2)

As described above, in the present application, since the secondary shape coefficient S ₂ is reduced to less than 5, the natural period T can be made longer. Moreover, since the total thickness h is larger for the same diameter D, the allowable horizontal shear strain amount and the linear region of the horizontal spring constant are increased, and as a result, the horizontal deformation performance can be improved.

On the other hand, by setting the secondary shape factor S ₂ <5, buckling and bending deformation tend to occur and the loading capacity tends to decrease. Therefore, the ratio D / t <150 and the primary shape factor S ₁ ≧ 35.

Here, setting the ratio D / t <150 means that the thickness t of the hard plate 9 per sheet is increased to a value larger than the value of D / 150. Sufficient rigidity and strength can be provided, and buckling and bending deformation are suppressed. The primary shape factor S ₁ is related to the vertical / bending stiffness as described above. By setting S ₁ ≧ 35, the vertical / bending stiffness of the entire seismic isolation laminate 5 is increased, and the ratio D /
In combination with the setting of t <150, buckling and bending deformation are effectively suppressed.

As a result, for example, as shown in FIG.
Is as large as 300 kgf / cm ² , the generation of buckling can be suppressed and a stable hysteresis curve can be exhibited up to a horizontal strain rate δ / h of 400%.

By setting S ₂ ≧ 35, the dependency of the horizontal spring constant on the surface pressure can be reduced, and seismic isolation performance can be stably exhibited.

The rubber hardness Hd has a certain correlation with the elastic modulus of the rubber. In general, as the rubber hardness Hd increases, the elastic modulus tends to increase, which tends to hinder the elongation of the natural period T. Therefore, by restricting the rubber hardness Hd (JISA hardness) to 50 degrees or less, it is possible to eliminate an adverse effect on the long period and obtain an appropriate value of the horizontal spring constant.

If the secondary shape factor S ₂ is 5 or more and the rubber hardness Hd is more than 50 degrees, the long period cannot be sufficiently achieved, the primary shape factor S ₁ is less than 35, and the ratio D / t
When it is 150 or more, buckling and bending deformation when high surface pressure and high shear strain act cannot be suppressed. In addition, ・ The upper limit of the primary shape factor S ₁ is preferably 45 or less, because the number of laminations increases for bearings having the same total rubber thickness,
This is because the cost increases. The lower limit of the secondary shape factor S ₂ is preferably 30 or more, because the surface pressure dependency and the strain dependency increase. The lower limit of the ratio D / t is preferably 20 or more, because the surface pressure dependency and the strain dependency increase. -The lower limit of the rubber hardness Hd is preferably 20 or more, because the creep amount increases in proportion to the decrease in hardness.

When the seismic isolation laminate 5 has the center hole 11, the effect of the regulation of the primary shape factor S ₁ and the ratio D / t is reduced, for example, the degree of stress generated in the hard plate 9 is increased. Therefore, in the laminated rubber bearing 1 of the present invention, it is preferable that the center hole 11 is not formed, and when it is necessary to form the center hole 11, the diameter d is equal to the rubber-like elastic plate 1.
It should be kept to no more than 0.05 times, more preferably no more than 0.03 times the diameter D of 0.

On the other hand, as a result of the study by the present inventors, the outer peripheral surface 10 s of the rubber-like elastic plate 10 and the outer peripheral surface 9 s of the hard plate 9 have the same shape, and the entire surface is adhered.
In the case, when a large horizontal deformation occurs due to an earthquake or the like, stress concentrates on the outer peripheral edge of the hard plate 9 and a soft horizontal spring constant required for the seismic isolation device cannot be obtained. It has been found that the rubber-like elastic plate 10 tends to be easily damaged. In particular, when the outer rubber layer 6 and the rubber-like elastic plate 10 are bonded and integrated, the movement (deformation) of the rubber-like elastic plate 10 is hindered by the outer rubber layer 6, so that the horizontal spring constant has an effect. As a result, it was found that the surface pressure dependency was further worsened.

On the other hand, in this embodiment, since the hollow portion 15 in which the rubber-like elastic plate 10 does not exist is formed near the outer periphery of the hard plate 9, stress concentration at the outer peripheral edge of the hard plate 9 is avoided, and The movement of the rubber-like elastic plate 10 is smoothed, for example, the fixation and unification of the outer rubber layer 6 and the rubber-like elastic plate 10 can be prevented, a soft horizontal spring constant is secured, damage from the outer peripheral edge is suppressed, and the horizontal spring constant is reduced. The decrease in the surface pressure dependency can be improved.

When the distance L between the hollow portions 15 is less than 1.0 times the thickness h 'of the rubber, the avoidance of stress concentration is insufficient. If the distance L is too large, the rubber-like elastic plate 1
Since the actual bonding area of 0 is reduced, durability and strength are adversely affected. Therefore, the upper limit thereof is preferably 2.0 times or less the rubber thickness h '.

Further, since the outer peripheral portion of the hard plate 9 facing the hollow portion 15 can support the protrusion from the end of the rubber-like elastic plate 10 which occurs when a large horizontal shear deformation occurs while receiving a vertical load, Sinking in the direction is suppressed, and surface pressure dependency is also improved. In particular, as shown in FIG. 4, the protrusion 6 </ b> A filled in the hollow portion 15 is formed on the inner surface of the outer rubber layer 6.
Is formed, the depression can be suppressed more reliably, and the surface pressure dependency can be further improved. At this time, the protrusion 6A
In order to avoid adhesion between the rubber material and the rubber-like elastic plate 10, a release agent may be applied before vulcanization, or the outer rubber layer 6 may be formed of the different rubber material that does not vulcanize and adhere to the natural rubber. preferable. When the hollow portion 15 is provided as shown in FIG.
Since there is no fear of vulcanization adhesion, the same type of rubber material can be used as the outer rubber layer 6. Further, besides the rubber material, if the material has excellent weather resistance and flexibility, for example, polyethylene or polypropylene And various synthetic resin materials such as polyamide.

FIG. 5 shows another embodiment of the present invention. In the drawing, the rubber-like elastic plate 10 shows a case where the outer peripheral surface 10 s has a contour shape substantially the same as the outer peripheral surface 9 s of the hard plate 9. That is, the outer peripheral surfaces 9 s and 10 s are flush with each other, and the outer peripheral surface 10 s of the rubber-like elastic plate 10 is
And surface contact in a non-adhered state. This non-adhered state can be easily formed by using a rubber material different from the rubber-like elastic plate 10 as the outer rubber layer 6 as described above, and when the same type of rubber material is used, it is vulcanized. It can be formed by applying a release agent before.

In this case as well, it is preferable to avoid stress concentration at the outer peripheral edge of the hard plate 9, and the rubber-like elastic region is provided inward from the outer peripheral surface 9 s of the hard plate 9 at the distance L. The plate 10 forms a non-bonded portion 16 that is not bonded to the hard plate 9. This non-adhered portion 16 can also be formed by applying a release agent before vulcanization.
In FIG. 5, in order to distinguish the non-bonded state from the bonded state,
The non-bonded portion 16 is illustrated with a minute gap.

Since the laminated rubber bearing 1 of the present invention can be formed by simultaneous vulcanization of the outer rubber layer 6 and the seismic isolation laminate 5 as in the prior art, efficient production can be achieved without increasing the number of production steps. In addition, since the outer skin rubber layer 6 is vulcanized and bonded to the side surface of the hard plate 9, it exhibits superior performance in terms of adhesive strength and durability as compared with, for example, a case where a tape of a weather-resistant material is wound around to form the outer skin. However, if simultaneous vulcanization is difficult, the outer rubber layer 6 may be formed in a process different from that of the seismic isolation laminate 5 or a tape may be wound around the molded seismic isolation laminate 5 to form the outer skin. good.

[0044]

Since the laminated rubber bearing of the present invention is constructed as described above, it is possible to achieve a longer natural period T without impairing other performances, especially buckling performance, etc. It can demonstrate seismic performance.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a laminated rubber bearing of the present application.

FIG. 2 is an enlarged partial cross-sectional view of a region near the outer periphery.

FIG. 3 is a diagram comparing a horizontal load-horizontal distortion rate curve between an example and comparative examples 1 and 2;

FIG. 4 is an enlarged cross-sectional view showing another embodiment near the outer periphery.

FIG. 5 is an enlarged cross-sectional view showing still another embodiment of a region near the outer periphery.

FIG. 6 is a cross-sectional view illustrating a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laminated rubber bearing 5 Seismic isolation laminated body 6 Outer rubber layer 9 Hard plate 10 Rubbery elastic plate 11 Center hole 14 Gap 16 Non-adhesion

Claims (6)

[Claims] 1. A laminated rubber bearing comprising a seismic isolation laminate in which a plurality of hard plates and rubber-like elastic plates are alternately laminated and joined, wherein the rubber-like elastic plate has a diameter of D, The thickness of the elastic plate is h ', the total thickness of the rubbery elastic plate is h, the thickness of the hard plate is t, and the center when the seismic isolation laminate has a center hole extending through the laminate. When the diameter of the hole is d, the primary shape factor S ₁ determined by the following equation is 35 or more, the secondary shape factor S ₂ is less than 5, and the ratio D / D of the diameter D to the thickness t is D / D.
The laminated rubber bearing, wherein t is smaller than 150 and the rubber hardness Hd of the rubber-like elastic plate is 50 degrees or less. S ₁ = (D−d) / 4h ′ − (1) S ₂ = D / h − (2) 2. The laminated rubber bearing according to claim 1, wherein said seismic isolation laminate does not have said center hole. 3. The seismic isolation laminate has the center hole, and the diameter d of the center hole is 0.05 times or less the diameter D of the rubber-like elastic plate. 1. The laminated rubber bearing according to 1. 4. The seismic isolation laminate is characterized in that the rubber-like elastic plate is located between the hard plates by positioning the outer peripheral surface of the rubber-like elastic plate at a distance L inward from the outer peripheral surface of the hard plate. 3. An outer peripheral surface of the seismic isolation laminate is covered with an outer rubber layer integrally vulcanized with the seismic isolation laminate, wherein no gap is formed in a region near the outer periphery.
Or the laminated rubber bearing according to 3. 5. The rubber-like elastic plate and the hard plate have substantially the same outer peripheral surface, and the rubber-like elastic plate is attached to the hard plate in a region near the outer periphery which is inwardly separated by a distance L from the outer peripheral surface. The non-adhesive portion which is not adhered is formed, and an outer peripheral surface of the seismic isolation laminate is covered with a skin rubber layer integrally vulcanized with the seismic isolation laminate.
The described laminated rubber bearing. 6. The laminated rubber bearing according to claim 4, wherein the distance L is at least 1.0 times the thickness h ′ of the rubber-like elastic plate.