JPH0729395B2 - Seismic isolation structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a seismic isolation structure in which a plurality of hard plates and soft plates having viscoelastic properties are alternately laminated, and particularly to seismic isolation. The present invention relates to a seismic isolation structure having a damping effect as well as an effect.

[Prior Art] A structure in which a hard plate such as a copper plate and a soft plate having a viscoelastic property such as rubber are laminated is widely used as a support member that requires vibration damping and vibration absorbing properties.

The effect of such a base isolation structure is that it is soft in the lateral direction between a rigid building such as concrete and the foundation.
That is, by inserting a base isolation structure having a small shear rigidity, the natural period of the concrete building is shifted from the period of the earthquake. Therefore, due to the seismic isolation design in which the seismic isolation structure is inserted between the building and the base, the acceleration that the building receives due to the earthquake becomes extremely small. .

However, since the slow rolling of the building remains as it is, if the amount of rolling is large, it causes a collision between the building and other structures and destruction of equipment such as water pipes, gas pipes, and wiring.

Therefore, conventionally, in order to reduce the rolling displacement, the seismic isolation structure and the damper are generally installed side by side and used.

In addition, by hollowing out the inside of the seismic isolation structure, embedding lead in this part, and utilizing the plastic deformation of lead during an earthquake to impart a damping effect to the seismic isolation structure, the seismic isolation effect and damper effect ( It is also considered to combine the damping effect).

[Problems to be Solved by the Invention] However, the method of installing the seismic isolation structure and the damper in parallel is not an advantageous method because the installation work is complicated and the cost is significantly increased.

In addition, the seismic isolation structure containing lead is difficult to remove because the hard plate such as a steel plate damages lead when the seismic isolation structure is largely deformed in the event of a large earthquake, and the damaged lead damages the soft plate such as rubber. It is easy to cause breakage of the entire seismic structure. Moreover, the damaged lead is easily broken by repeated large deformation.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a seismic isolation structure in which a plurality of hard plates and soft plates are attached to each other. Hysteresis ratio during tensile deformation is 0.15 ~
0.60 5Hz, 0.01% deformation at −10 ℃, 30 ℃ Storage elastic modulus E _(-10) , E ₍₃₀₎ ratio E _(-10) / E ₍₃₀₎ composed of material that satisfies 1.0 ~ 3.0 It is something that is done.

As a method of imparting a damping effect to the seismic isolation structure, the present inventors combine the seismic isolation effect and the damping effect by imparting a high hysteresis loss to the material itself that constitutes the soft plate of the seismic isolation structure. As a result of repeated studies on the above, the following was found.

That is, when considering only the function as a damper, a material having a large hysteresis loss is preferable. However, when the hysteresis loss becomes large, creep becomes large and the temperature dependence of the elastic modulus also becomes large, which causes undesirable side effects as a seismic isolation structure that supports a building. Therefore, the constituent material of the soft plate is required to have a hysteresis loss characteristic within a specific size range and a small temperature dependence of the elastic modulus.

Based on such knowledge, the present invention finds that the material satisfying the above requirements (1) to (3) is optimal as a material for a soft plate, which can exhibit both a seismic isolation effect and a damping effect, and has been completed. It is a thing.

[Operation] In the present invention, the material that composes the soft plate and satisfies the above requirements (1) to (3) exhibits a good damping effect together with an excellent seismic isolation effect.

Therefore, according to the seismic isolation structure of the present invention, the sway transmitted to the building is mitigated, and the building can be supported stably and reliably.

Embodiments Embodiments will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view of a base isolation structure 1 according to an embodiment of the present invention. This seismic isolation structure 1 is configured by alternately laminating soft plates 2 such as rubber having viscoelastic properties and hard plates 3 having rigidity such as steel plates.

Therefore, in the present invention, the soft plate 2 has a hysteresis ratio of 0.15 to 100 at a tensile deformation of 25 ° C.
0.60 5Hz, 0.01% deformation at −10 ℃, 30 ℃ Storage elastic modulus E _(-10) , E ₍₃₀₎ ratio E _(-10) / E ₍₃₀₎ composed of material that satisfies 1.0 ~ 3.0 Has been done.

The reasons for the above limitation will be described below.

Generally, the loss tangent tan δ value is used as a measure of the hysteresis loss characteristic and the attenuation characteristic of a material. However, as is well known, tan δ is a quantity measured as a response delay to a stimulus with a small amplitude, and the tan δ of a material used for a seismic isolation structure that undergoes large deformation of 100 to 200% during an earthquake It is unsuitable as a parameter that describes the hysteresis loss characteristic.

Therefore, in the present invention, the hysteresis ratio (h ₁₀₀ ) of the material at 25 ° C. and 100% tensile deformation is used as the measure of loss characteristics. In addition, at a tensile speed of 200 mm / min, h ₁₀₀ is the stress-strain curve in FIG. Is given by the area ratio of.

It is desirable that h ₁₀₀ is as large as possible for the damper (damping) effect as described above, but this inevitably increases the plastic deformation of the material. Therefore, the range of h ₁₀₀ at 25 ° C. for making both properties good is 0.15 ≦ h ₁₀₀ ≦ 0.60, preferably 0.20 ≦ h ₁₀₀ ≦ 0.55, and more preferably 0.22 ≦ h ₁₀₀ ≦ 0.50.

Temperature dependence of elastic modulus of material As is well known, the most important effect on seismic isolation characteristics is
Vertical spring constant and horizontal spring constant of the base isolation structure, which are directly proportional to the elastic modulus of the material.

On the other hand, looking at the usage status of the seismic isolation structure, it is generally used in a state where it is always exposed to the outside air. It is highly conceivable that the environmental conditions will be -10 ℃ in winter and 30 ℃ in summer. In such a situation, a rubber material or the like has a more or less elastic modulus that is temperature-dependent, and tends to be harder at lower temperatures.
Furthermore, as the amount of material loss increases, the temperature dependence tends to increase.

In the present invention, the temperature dependence of the elastic modulus of the material is small, 5 Hz, the value at -10 ° C. for dynamic measured storage modulus E 0.01% strain E _(-10) value at a 30 ° C. E _{( 30)} Preferably More preferably Is preferred.

As the soft plate material satisfying the above conditions, various rubber materials can be mentioned, for example, ethylene propylene rubber (EPR, EPDM), nitrile rubber (NBR), butyl rubber, halogenated butyl rubber, chloroprene rubber (CR), Natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR) and the like can be mentioned.
Of these, halogenated butyl rubber, EPR, EPD
M, CR, NR, IR, BR and SBR are preferable, and it is most preferable to use a mixture of two or more thereof.

Among the rubber materials, SBR containing a large amount of styrene, which has a large temperature dependence of the elastic modulus even if the loss amount is large, is not preferable.

In the present invention, needless to say, the rubber material may be mixed with a compounding material such as various fillers, plasticizers, softeners, and oils in order to impart the properties of to.

In the present invention, as the material of the hard plate 3, metal, ceramics, plastics, FRP, polyurethane, wood, paper plate, slate plate, decorative plate and the like can be used.

Further, the shape of the hard plate and the soft plate may be a circle, a square, or a polygon such as a pentagon or a hexagon.

To bond such a hard plate and a soft plate, an adhesive may be used or co-vulcanization may be performed.

Since the seismic isolation structure is constantly exposed to the outside air during use, it is subject to long-term deterioration due to air, humidity, ozone, ultraviolet rays, radiation for nuclear power, and sea breeze at seaside. Further, since it supports the building, it is constantly subjected to a compressive load, and even under normal conditions, a considerable tensile stress is applied to the surface portion of the rubber layer. In addition, during a large earthquake, the rubber layer is locally subjected to tensile strain of 100-200%. However, deterioration progresses further due to such tensile stress and tensile strain.

Therefore, as shown in FIG. 3, the seismic isolation structure 1
The outer peripheral edge portions of the hard plate 3 and the soft plate 2 are preferably covered with a coating layer 4 of a rubber material having excellent weather resistance.

The rubber material of the coating layer 4 is preferably a rubber-like polymer having excellent weather resistance, and examples thereof include butyl rubber, acrylic rubber, polyurethane, silicone rubber, fluororubber, polysulfide rubber, ethylene propylene rubber (ERP and EPDM), and hypalon. , Chlorinated polyethylene, ethylene vinyl acetate rubber, epichlorohydrin rubber, chloroprene rubber and the like. Of these, butyl rubber, polyurethane, ethylene propylene rubber, hypalon, chlorinated polyethylene, ethylene vinyl acetate rubber, and chloroprene rubber are particularly effective from the viewpoint of weather resistance. Furthermore, when considering the adhesiveness with the rubber that constitutes the soft plate, butyl rubber,
Ethylene propylene rubber and chloroprene rubber are desirable, and ethylene propylene rubber is most preferably used.

These rubber materials may be used alone or in combination of two or more. Further, it may be blended with a commercially available rubber such as natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber or the like in order to improve elongation and other properties. Further, these rubber materials may be mixed with various fillers, antioxidants, plasticizers, softeners, oils and other compounds commonly used in rubber materials.

Generally, the thicker the coating layer 4 formed of such a rubber material is, the higher the internal protection effect is.
On the other hand, there are problems such as high cost and delayed vulcanization. From the above, the thickness of the coating layer 4 is 1 to
It is preferably 30 mm, desirably 2 to 20 mm, especially 3 to 15 mm. However, when fire resistance is required for the seismic isolation structure, the coating layer can have a thickness exceeding 30 mm.

It is important that the coating layer 4 is firmly bonded to the hard plate 3 and the soft plate 2, but the bonding is performed between the rubber material of the soft plate 2 (hereinafter sometimes referred to as “internal rubber”) and the coating layer 4. A method of simultaneously vulcanizing and adhering a rubber material (hereinafter sometimes referred to as "coated rubber").

A two-stage vulcanization bonding method in which only the internal rubber is vulcanized first and then the coated rubber is vulcanized and bonded.

A method in which internal rubber and coated rubber are separately vulcanized and then bonded with an adhesive.

It can be done easily. At the time of adhesion, if the adhesion between the internal rubber and the covering rubber is poor, a third rubber layer having good adhesiveness with respect to both may be interposed therebetween.
Further, an additive for improving adhesiveness may be blended with the internal rubber and / or the coated rubber.

In the present invention, as the material of the hard plate 3, metal, ceramics, plastics, FRP, polyurethane, wood, paper plate, slate plate, decorative plate and the like can be used. As the soft plate 2, various vulcanized rubbers, unvulcanized rubbers, organic materials such as plastics, foams thereof,
Various materials such as inorganic materials such as asphalt and clay, and mixed materials thereof can be used.

Further, the shape of the hard plate and the soft plate may be circular, rectangular, or polygonal such as pentagon and hexagon.

To bond such a hard plate and a soft plate, an adhesive or co-vulcanization may be used.

By the way, the seismic isolation structure undergoes large shear deformation due to, for example, shaking of the building when an earthquake occurs. Particularly, in the surface layer portion of the soft plate on the flange mounting side of the seismic isolation structure, this shear deformation causes an extremely large local strain, which causes damage or breakage of the seismic isolation structure.

Since this local strain is caused by bending deformation of the hard plate on the flange mounting side, in order to prevent this, in the present invention, the flexural rigidity of the hard plate on the flange mounting side is set higher than that on the center side. To do.

II Make the tensile stress of the soft plate on the flange mounting side higher than that on the center side.

It is preferable to adopt at least one of the above configurations.

In the case of I configuration, the hard plate is S ₁ from the flange mounting side,
S ₂ , S ₃ …… S _M (S _M is a hard plate in the center)
The flexural stiffness in _{25 ℃, E S1, E S2} , E S3 case of the ...... E _SM, flexural rigidity E _S1 of hard plate S ₁ is hard plates S _M flexural rigidity E _SM
As opposed to Preferably More preferably So that

The flexural rigidity E _S2 of the hard plate S ₂ whereas flexural rigidity E _SM of hard plate S _M, Preferably Is desirable.

Furthermore the flexural rigidity E _S3 also hard plates S _3, hard plate optionally S _M
It may be higher than the bending stiffness E _{SM of} .

In this case, the bending stiffness E _S1 , of the hard plates S ₁ , S ₂ , S ₃ …… S _M ,
E _S2 , E _S3 …… E _SM is E _S1 ≧ E _S2 ≧ E _S3 ≧ …… E _SM (however, E
Except when _S1 = E _S2 = E _S3 = ... = E _SM . ), Or E _S1 , E _S3 and E _S7 (bending rigidity of the _seventh hard plate S ₇ from the flange side) may be set to be larger than E _SM at random. good. In the present invention, in short, it suffices that the bending rigidity of the flange side is higher than the bending rigidity of the hard plate on the center side, and the bending rigidity of each hard plate is estimated to be a vibration added to the base isolation structure, etc. It is appropriately set according to the direction and degree.

There is no particular limitation on the method for making the bending rigidity of the hard plate on the flange side higher than that on the center side, but increasing the plate thickness by using a hard plate of the same material as the center side, and increasing the plate thickness The method of using a hard plate made of a material having higher bending rigidity is suitable. For, generally the thickness of the same material of the plate is a bending stiffness 2 ^triple doubles, plate thickness having a flexural rigidity in need is readily determined by calculation.

In the case of the II configuration, place the soft plate from the flange mounting side to R ₁ ,
And _{R 2, R 3 ...... R M} (R M soft plate in the center), each of
Tensile stress at 100% elongation at 25 ℃ (Modulus100)
_Are respectively E _R1 , E _R2 , E _R3 ...... E _RM , the tensile stress E _R1 of the soft plate R ₁ is the stress E _RM of the soft plate R _M , Preferably More preferably Is preferred.

The tensile stress E _R2 of the soft plate R ₂ is the tensile stress E R ₂ of the soft plate R _{M.
To RM} Preferably Is preferred.

Further tensile stress E _R3 soft plate R ₃ may optionally soft plate R _M
It may be higher than the tensile stress E _{RM of} .

In this case, the soft plate _{R 1, R 2, R 3} ...... R M of tensile stress E _R1, E
_R2 , E _R3 ...... E _RM is E _R1 ≧ E _R2 ≧ E _R3 ≧ …… ≧ E _RM (however,
Except when E _R1 = E _R2 = E _R3 = ... = E _RM . ), Or E _R1 , E _R3 , and E _R7 (tensile stress of the _seventh soft plate R ₇ from the flange side) may be set to be larger than E _RM .

There is no particular limitation on the method for making the tensile stress of the soft plate on the flange side higher than that on the center side, but it is a base material of the same quality as the center side, and the compounding amount of the filler, etc. is increased. The method of using a soft plate made of a material having a high tensile stress is suitable.

In the present invention, the soft plate R _{M at} the center has a temperature of 25 ° C. and 100%.
The tensile stress E _RM during extension is preferably 5 to 40 kg / cm ² .

By doing so, the occurrence of local strain due to bending deformation of the hard plate near the flange is reduced, and damage and breakage of the seismic isolation structure due to local strain are reduced, which is extremely advantageous.

The seismic isolation structure of the present invention as described above has characteristics such as vibration isolation (vibration prevention and damping) in addition to the seismic isolation function.

[Advantages of the Invention] As described in detail above, the seismic isolation structure of the present invention has a seismic isolation effect and a damper effect. The degree of is reduced. Therefore, even when a large earthquake occurs, it is possible to prevent the building from colliding with other structures and the damage of equipment such as water pipes, gas pipes, and pipes.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a seismic isolation structure according to an embodiment of the present invention,
FIG. 2 is a graph showing a stress-strain curve of a material, and FIG. 3 is a longitudinal sectional view of a seismic isolation structure according to another embodiment of the present invention. 1 ... Seismic isolation structure, 2 ... Soft plate, 3 ... Hard plate, 4 ... Coating layer.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area E04H 9/02 331 A 9023-2E F16F 1/30 8917-3J

Claims (1)

[Claims] 1. In a seismic isolation structure in which a plurality of hard plates having rigidity and soft plates having viscoelastic properties are alternately laminated, the material forming the soft plates satisfies the following: Seismic isolation structure characterized by being present. Hysteresis ratio at 100% tensile deformation at 25 ℃ is 0.15〜
The ratio E _(-10) / E ₍₃₀₎ of storage elastic moduli E _(-10) and E ₍₃₀₎ at 0.60 5Hz, 0.01% deformation at -10 ° C and 30 ° C is 1.0 to 3.0.