JPH10252823A - Base isolation structure body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain higher damping performance while reducing a creep quantity by using rubber materials in a central part and a peripheral part of a soft layer, and imparting damping performance lower than the central part and small compressive permanent strain performance to the rubber material of the peripheral part. SOLUTION: A soft layer is divided into a central part and a peripheral part, and respectively characteristically different rubber materials are used. That is, the ratio of damping performance (heq) of the rubber material of the central part of the soft layer to the rubber material of the peripheral part is preferably set to about 1.2 to 5.0, preferably, about 1.2 to 3.0, much preferably, about 1.2 to 1.6. Compressive permanent strain performance smaller than the rubber material of the central part is imparted to the rubber material of the peripheral part. The small compressive permanent strain performance of the rubber material of the peripheral part indicates that compressive permanent strain of 70 deg.C and 22 hours in conformity to JIS K6301 is not more than 70%. In other words, the ratio of compressive permanent strain of the rubber material of the peripheral part of the soft layer to the rubber material of the central part is about 0.1 to 0.9, preferably, about 0.4 to 0.85, much preferably, about 0.6 to 0.8.

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 having higher damping properties while maintaining excellent creep properties.

[0002]

2. Description of the Related Art In recent years, a seismic isolation method using a seismic isolation structure has been attracting attention for the purpose of reducing the input acceleration of vibration to a building generated by an earthquake. This insulates the ground and the building with a soft layer, reduces the natural frequency of the building with respect to the frequency of the ground at the time of the earthquake, reduces the input acceleration of vibration, and is included in the building or in it It minimizes damage to people, machines, etc.

The seismic isolation structure used here is a combination of a soft layer (rubber) and a hard layer (iron plate or the like) alternately.
In order to support the building, it is hard in the vertical direction, and conversely soft in the horizontal direction to reduce the input acceleration of vibration, and has the performance of not breaking even in the case of large horizontal deformation.

However, the conventionally used seismic isolation rubber composition has a very small hysteresis loss. Therefore, the seismic isolation structure using the rubber composition itself has an ability to damp the vibration of the upper structure. Because it is very small, vibration damping was measured by various dampers such as viscous dampers. However, this has the drawback that the structure becomes complicated as a building, and the construction period and cost are disadvantageous.

In order to solve this problem, there has been proposed a structure in which a lead plug is inserted into the center of the seismic isolation structure to increase the energy absorbing ability. However, there is a problem that the micro vibration is transmitted to the upper structure as it is. In addition, there is a seismic isolation structure that uses high-damping rubber as the rubber material of the soft layer, but the high-damping rubber directly supports the large load of the upper structure, resulting in a large amount of creep and poor durability. There is. Therefore, a seismic isolation structure has been proposed in which a through hole is provided in the center of the seismic isolation structure and a high damping rubber material is inserted into the through hole. There was a drawback in that the presence of the hard layer resulted in the separation of the hard layer and the reduction of the load supporting surface. In view of the above, a seismic isolation structure with a small amount of vertical creep as a seismic isolation structure in which a high-damping elastomer is arranged around a bearing body in which hard layers and rubber-like soft layers with small compression set are alternately laminated. Body (JP-A-2-4
No. 9834) has been proposed. However, this seismic isolation structure has a drawback that the load cannot be received unless the size of the bearing that receives the load is increased.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a seismic isolation structure having higher damping while maintaining excellent creep with a small amount of creep.

[0007]

SUMMARY OF THE INVENTION The present invention provides a seismic isolation structure in which a plurality of hard layers and soft layers are alternately laminated.
The soft layer is divided into a central part and a peripheral part, and a rubber material is used for each.The rubber material used for the central part has a higher damping property than the rubber material used for the peripheral part, and the rubber material used for the peripheral part has a higher damping property. The present invention relates to a seismic isolation structure characterized in that the seismic isolation structure has a lower damping property than the central rubber material and a smaller compression set than the central rubber material.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the seismic isolation structure of the present invention,
A hard layer and a soft layer are laminated, and a through hole is not provided at the center at that time, and therefore, the hard layer is not divided. Therefore, the support portion receiving the load in the vertical direction does not become narrow. However, by dividing the soft layer into a central part and a peripheral part, using rubber materials for each, and changing the characteristics of the rubber material used for the central part and the rubber material used for the peripheral part, excellent creep properties and high damping properties are achieved. To achieve. Therefore, the rubber material used for the central part has a higher damping property than the rubber material used for the peripheral part, and the rubber material used for the peripheral part has a higher damping property. It has a compression set (good creep) smaller than that of the rubber material. By doing so, it becomes possible to receive the load in the vertical direction on the entire hard layer and the soft layer, and it is possible to suppress the central rubber from protruding in the horizontal direction. It has become possible to obtain a seismic isolation structure with excellent creep properties, in other words, good durability and higher damping.

The rubber component of the rubber material having an extremely high damping property used in the center of the soft layer of the present invention includes, for example, natural rubber (NR), isoprene rubber (IR), styrene butadiene rubber (SBR), nitrile butadiene rubber (N
BR), ethylene propylene rubber (EPDM or EP
M), polybutadiene rubber (BR), butyl rubber (II
R), halogenated butyl rubber (X-IIR), chloroprene rubber (CR) and the like. The rubber component of the rubber material having high damping property used in the peripheral portion of the soft layer of the present invention, but having a lower damping property than the rubber material in the central portion and a compression set smaller than the rubber material in the central portion. The same as described above can be used. In this case, increasing the amount of silica, carbon and / or tackifier added to the rubber component tends to increase the damping property, while decreasing the amount tends to decrease the compression set.

Here, the extremely high damping property means that a soft layer (rubber) 30 having a diameter of 135 mm × 1 mm made of a rubber composition.
The equivalent damping constant (heq) of a base-isolated structure in which layers and 29 layers of 133 mm x 1 mm hard layers (steel plates) are alternately stacked,
When measured and evaluated by the method described in "Life and Reliability Report of Seismic Isolation Laminated Rubber" (Special Committee for Seismic Isolation Structural Rubber), those with a heq of 18% or more and high attenuation Similarly, the property refers to a material having a heq of 15% or more. In other words, the ratio of the damping property (heq) of the rubber at the center of the soft layer to the rubber at the periphery of the soft layer of the present invention is 1.2 to 1.2.
5.0, preferably 1.2-3.0, more preferably 1.2
The range of ~ 1.6 is preferred. The rubber material used for the peripheral portion of the present invention has a smaller compression set than the rubber material used for the central portion. The small compression set of the rubber material in the periphery is defined by JIS K6301.
70% compression set at 70 ° C for 22 hours
Refers to: Stated another way, the ratio of the compression set of the rubber material at the periphery of the soft layer to the rubber material at the center of the soft layer of the present invention is 0.1 to 0.9, preferably 0.4 to 0.4.
85, more preferably in the range of 0.6 to 0.8.

As described above, in the present invention, the rubber material at the center of the soft layer has a very high damping property, and the rubber material at the periphery has a high damping property, but has a lower damping than the rubber material at the center. It is characterized by having a property and a compression set smaller than that of the rubber material at the center. On the other hand, Japanese Unexamined Patent Publication No.
In the base isolation bearing described in Japanese Patent No. 9834, the rubber material at the peripheral portion has higher damping property than the rubber material at the central portion, which is completely opposite to the present invention. Also, this Japanese Patent Laid-Open No. 2-4
The seismic isolation bearing described in No. 9834 has a problem that the load cannot be received unless the size of the bearing receiving the load is increased.

In the present invention, the area ratio between the central portion and the peripheral portion is preferably in the range of 1: 9 to 8: 2, and more preferably in the range of 2: 8 to 5: 5. In this range, the damping property can be improved, and on the other hand, if a large horizontal shear strain is applied to the seismic isolation structure, early rupture can be prevented. The rubber material at the center may be either vulcanized rubber or unvulcanized rubber, and the rubber material at the periphery is preferably vulcanized rubber. The rubber material at the center may be either bonded or non-bonded to the hard layer, and the rubber material at the periphery is preferably bonded to the hard layer.
The soft layer made of a rubber material having different physical properties in the central part and the peripheral part of the present invention is vulcanized in advance, then laminated with the hard layer and incorporated into the seismic isolation structure, or laminated with the hard layer first. It may be vulcanized after being incorporated into the seismic isolation structure.

In the present invention, on the outer periphery of the seismic isolation structure,
Further, it is preferable to provide a rubber material layer having a large tensile elongation, so that even if a large horizontal shear strain is applied to the seismic isolation structure, it is possible to prevent a crack from being generated on the outer peripheral portion thereof. Examples of the rubber component of the rubber material having a large tensile elongation include natural rubber (NR), isoprene rubber (IR), styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), and polybutadiene rubber (B
R), butyl rubber (IIR), halogenated butyl rubber (X-IIR), chloroprene rubber (CR), ethylene propylene rubber (EPDM or EPM), and the like. These can be used alone or as a blend of two or more. In this case, the amount of reinforcing agent,
The magnitude of the tensile elongation can be adjusted by adjusting the type, rubber crosslinking density, and the like.

In the present invention, a seismic isolation structure having excellent creep properties refers to a structure whose estimated creep rate after 60 years is within 5%. Creep rate: 30 soft layers (rubber) with a diameter of 135 mm x 1 mm and a hard layer (steel) with a diameter of 133 mm x 1 mm
A seismic isolation structure consisting of 29 layers is alternately stacked, with a surface pressure of 50 kgf.
The creep amount was measured by a creep acceleration test (80 ° C.) at 25 ° C. for 60 years, which was obtained from the activation energy E of the rubber material in the surrounding area under the condition of / cm ² , and was obtained by the following equation. Creep rate (%) = (Creep amount / Total rubber thickness) × 100

The rubber composition of the present invention contains a known vulcanizing agent, vulcanization accelerator, vulcanization accelerating aid, vulcanization retarder, coloring agent, reinforcing agent, antioxidant, filler, softener, plasticizer. Agents, activators, tackifiers, lubricants and the like can be added. Examples of the filler include silica, carbon black, clay, talc, mica, calcium carbonate, magnesium carbonate, barium sulfate, aluminum hydroxide, zinc oxide and the like, and various natural or artificial fibers. It is preferable that the amount be 1 to 150 parts by weight based on 100 parts by weight of rubber.

Examples of the softening agent include tall oils mainly containing linoleic acid, oleic acid and abietic acid, pine tar, rapeseed oil, cottonseed oil, peanut oil, castor oil, palm oil,
Plant softeners such as Factis, paraffinic oils, naphthenic oils, and mineral oil softeners such as aromatic oils;
The compounding ratio is 1 to 150 with respect to 100 parts by weight of rubber.
It is preferred to use parts by weight. As plasticizers, phthalic acid type, sebacic acid type, adipic acid type, phosphate ester type,
Epoxy-based, chlorinated paraffin-based, ether-based, thioether-based, polyester-based, polyether-based plasticizers and the like can be mentioned, and the compounding ratio is preferably 1 to 150 parts by weight with respect to 100 parts by weight of rubber.

Examples of the tackifier include an alkylphenol formaldehyde resin, an alkylphenol acetylene resin, a coumarone indene resin, a xylene formaldehyde resin, polybutene, and a rosin derivative. 1-5
It is preferably 0 parts by weight. Examples of the lubricant include stearic acid, metal soap of stearic acid, high melting point wax, low molecular weight polyethylene, polyethylene glycol, octadecylamine and the like.
The amount is preferably 1 to 50 parts by weight based on parts by weight.

The rubber composition of the present invention can be obtained by kneading the above components with a usual processing device, for example, a roll, a Banbury mixer, a kneader or the like.

In the present invention, as the material of the hard layer, metal, ceramics, plastics, FRP, polyurethane, wood, paper board, slate board, decorative board and the like can be used, and among them, steel sheet is preferable. The shape of the hard layer and the soft layer may be circular, square, polygonal such as pentagon, hexagon, or the like. In order to bond such a hard layer and a soft layer, an adhesive or co-vulcanization may be used.

According to the present invention, in a seismic isolation structure in which a plurality of hard layers and soft layers are alternately laminated, a soft layer is divided into a central portion and a peripheral portion, and the rubber material in the central portion and the peripheral portion is made of the rubber composition. A seismic isolation structure characterized by being obtained. It is preferable to provide flanges on the upper and lower surfaces of the laminated structure in which soft layers and hard layers are alternately laminated, and it is also optional to cover the seismic isolation structure with a covering layer. In addition, the hard layer and the soft layer may be provided with holes for passing positioning pins required for positioning the hard layer and the soft layer when the seismic isolation structure is manufactured. Then, when the hole exists in the central portion of the soft layer, and when the rubber material in the central portion is unvulcanized rubber, the rubber may flow at the time of vulcanization. It is preferable to fill the formed holes with vulcanized rubber used in the surrounding rubber or the covering rubber in advance.

[0021]

The present invention will be described below with reference to examples and comparative examples.
It is to be noted that “parts” simply means “parts by weight”. Examples 1 to 4 The diameter 1 which is the area ratio between the central part and the peripheral part described in Table 1 below.
35mm × 1mm soft layer (rubber) 30 layers and diameter 133mm ×
29 layers of 1 mm hard layers (steel plates) were alternately laminated and then vulcanized to obtain the desired seismic isolation structure. At this time, rubber vulcanization,
Rubber-steel vulcanization bonding proceeded simultaneously. Central rubber material 100 parts polyisoprene rubber, 90 parts silica, 4 parts silane coupling agent, 1 part sulfur, vulcanization accelerator (CB
S) 2 parts, 0.3 parts of vulcanization retarder (CTP), zinc white, stearic acid, softener, tackifier, and antioxidant in an amount used in usual rubber compounding, a Banbury mixer To obtain a rubber composition. This rubber material had a damping property of 21.5% and a compression set of 75%.

Peripheral rubber material 100 parts of polyisoprene rubber, 80 parts of silica, 4 parts of silane coupling agent, 1 part of sulfur, vulcanization accelerator (CB
S) 2 parts, 0.3 parts of vulcanization retarder (CTP), zinc white, stearic acid, softener, tackifier, and antioxidant in an amount used in usual rubber compounding, a Banbury mixer To obtain a rubber composition. This rubber material had a damping property of 16.0% and a compression set of 58%. Attenuation (heq) of the rubber at the center to the rubber at the periphery
Ratio = 1.34 The ratio of the compression set of the peripheral rubber to the central rubber = 0.77.

COMPARATIVE EXAMPLE 1 A seismic isolation structure was obtained in the same manner as in the example, except that the entire soft layer was made of a rubber material in the surrounding area. Comparative Example 2 A seismic isolation structure was obtained in the same manner as in Example, except that the soft layer was entirely made of a rubber material at the center. Comparative Example 3 All the soft layers had higher damping properties (1) than the rubber material of Comparative Example 1.
7.6%), and a seismic isolation structure was obtained in the same manner as in the example except that the same rubber material having a large compression set (73%) was used.

[0024]

[Table 1]

In Table 1, the creep rate ratio was represented by an index with the creep rate of Comparative Example 1 being 100. FIG. 1 shows a graph of the creep rate ratio and the damping property in Examples and Comparative Examples. Generally, the creep rate ratio and the damping property have a positive relationship, and as the damping property increases, the creep deteriorates. However, as is clear from FIG. Smaller than things.

From Table 1, it can be seen that Comparative Example 1 in which only the high-damping rubber having good creep properties was a soft layer and Comparative Example 2 in which only the high-damping rubber having a higher damping property was used as the soft layer, the soft layer was located at the center. Divided into peripheral parts, the rubber material used for the central part has a higher damping property than the rubber material used for the peripheral part, the rubber material used for the peripheral part has a higher damping property, but is lower than the rubber material used for the central part Examples 1 to 4 in which a high damping rubber having a damping property and a compression set smaller than that of the rubber material used in the center portion are arranged are high seismic isolation structures having high damping properties and excellent creep properties. I understand. Comparative Example 3, in which the soft layer is made of the same rubber material, has the same damping property as that of Example 2, but shows that the creep property is inferior to that of Example 2.

[0027]

According to the present invention, a seismic isolation structure having a higher damping property while maintaining excellent creep properties with a small amount of creep can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a creep ratio and a damping property in Examples and Comparative Examples.

Claims (7)

[Claims] In a seismic isolation structure in which a plurality of hard layers and soft layers are alternately laminated, a soft layer is divided into a central portion and a peripheral portion, and a rubber material is used for each, and the rubber material used for the central portion is The rubber material used for the peripheral part has a higher damping property, and the rubber material used for the peripheral part has a higher damping property, but has a lower damping property than the rubber material at the center and a compression set smaller than the rubber material at the center. A seismic isolation structure characterized by having. 2. The seismic isolation structure according to claim 1, wherein the ratio of the damping property (heq) of the rubber at the central portion of the soft layer to the rubber at the peripheral portion is in the range of 1.2 to 5.0. 3. The seismic isolation structure according to claim 1, wherein a ratio of a compression set of rubber in a peripheral portion of the soft layer to rubber in a central portion is in a range of 0.1 to 0.9. 4. The area ratio of the central part to the peripheral part is 1: 9 to 8:
2. The seismic isolation structure according to claim 1. 5. The seismic isolation structure according to claim 1, wherein the rubber material at the center is vulcanized rubber or unvulcanized rubber, and the rubber material at the periphery is vulcanized rubber. 6. The seismic isolation structure according to claim 1, wherein the rubber material at the central portion may be either bonded or non-bonded to the hard layer, and the rubber material at the peripheral portion is bonded to the hard layer. 7. The seismic isolation structure according to claim 1, wherein a rubber material layer having a greater tensile elongation is provided on an outer peripheral portion of the seismic isolation structure.