JPH0960333A - Vibration isolation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration isolation device having effective base isolation for a small-scaled lightweight structure such as miniaturized building and eliminating a mold to facilitate the reduction of cost. SOLUTION: This vibration isolation device 1 is equipped with square connection steel plates 5 on both up and down sides for mounting them to the lower surface of a building A and foundation surface B. A device main body 1a is formed by laminating alternately a circular ring-shaped vibration isolation rubber layer 2 and a circular steel plate 3. A coated rubber layer 6 having effective corrosion resistance is wound on the circumference of the device main body 1a. The circular end steel plates 4 having thicker and a slightly larger outside diameter than the steel plate 3 are arranged on both up and down sides of the device main body 1a, and the end steel plate 4 are connected to the connection steel plates 5 by a large number of screw bolts arranged in the circumferential direction at equal intervals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic isolation device installed between a foundation of a building and the ground (ground) to absorb horizontal shaking of the building. The present invention relates to a seismic isolation device suitable for a small-scale, relatively lightweight structure such as a small story building.

[0002]

2. Description of the Related Art This type of seismic isolation device has a structure in which a plurality of steel plates and a plurality of seismic isolation rubber layers are alternately laminated and the side peripheral surfaces thereof are covered with a covering rubber. When the material of the seismic isolation rubber layer is natural rubber, it does not have the function of absorbing the energy of the earthquake, so it may be combined with a damper,
Alternatively, a lead plug, which has the property of absorbing the energy of the earthquake, is loaded in the center of the seismic isolation device. Further, there is a device that does not require a damper or a lead plug by using a high-damping laminated rubber having a function of absorbing energy in the seismic isolation rubber layer.

By the way, the above-mentioned seismic isolation device is generally intended for large-scale heavy buildings such as medium-sized buildings and large-sized buildings. When the outer diameter of the seismic isolation rubber layer becomes small, the bending stress due to horizontal deformation becomes large. Since the seismic isolation rubber layer may be broken too much, the seismic isolation rubber layer and the steel plate whose outer diameter is set to at least 500 mm or more are used in the case of a circular device. In addition, a large number of such seismic isolation devices are used under the foundation of a single building at intervals, but the supporting load per seismic isolation device is around 100 tons at the minimum, and some seismic isolation devices reach several hundreds of tons. In addition, the adhesion of the steel plate and the seismic isolation rubber layer,
It is carried out by heating an unvulcanized base-isolated rubber layer in a mold under a predetermined pressure and vulcanizing it.

The prior art of this type is disclosed in, for example, Japanese Patent Publication No.
There is a device described in No. 11336 public information.

[0005]

However, when the conventional general seismic isolation device described above is applied to a lightweight building such as a small building whose weight is about one tenth of that of a heavy building, The following issues arise.

[0006] Since it is necessary to set the intervals in the lightweight structure to the same level as the conventional one, the number of bases of the seismic isolation device hardly changes, so that the supporting load per seismic isolation device is 1
It will be reduced to around 0 tons, about 1/10 of the conventional level. Therefore, the seismic isolation device may be a small device that is wholly downsized. However, when the rolling acceleration of a lightweight building is reduced in the event of an earthquake to effectively absorb the rolling caused by the earthquake, the deformation capacity of the seismic isolation rubber layer is reduced to that of the conventional structure for heavy buildings. It is necessary to have the same level as in the case of seismic isolation device,
For that purpose, the seismic isolation rubber layer should be at least 20 horizontally.
0 mm to 300 mm must be deformable.

If the rubber hardness of the seismic isolation rubber layer can be set to about 1/10 (for example, 4 to 5 ° in rubber hardness Hs) according to the reduction of the supporting load of the seismic isolation device, the seismic isolation device can be used as a whole. However, there is a limit to the reduction of rubber hardness, and at present, it can be reduced to about 40 ° at most. Therefore, it cannot be implemented by simply reducing the size of the conventional seismic isolation device.

In the conventional seismic isolation device, since a laminated structure of a steel plate and a seismic isolation rubber layer is loaded into a mold and heated, a mold for molding is required. There is a problem that the manufacturing cost of the device increases the manufacturing cost of the device.

The present invention has been made in view of the above points, and is 1) effective for seismic isolation of small-scale and lightweight structures such as small buildings, and 2) is easy to reduce cost without a mold. The challenge is to provide a seismic device.

[0010]

In order to solve the above-mentioned problems, the seismic isolation device of the present invention comprises: a) steel plates and seismic isolation rubber layers which are alternately laminated and whose side peripheral surfaces are covered with a covering rubber. In the seismic isolation device having the above structure, b) the steel plate is circular or regular polygonal, and the seismic isolation rubber layer is ring-shaped corresponding to the shape of the steel plate. The seismic isolation rubber layer in the seismic isolation device of the present invention is made of a high damping laminated rubber having a property that the rubber itself absorbs earthquake energy.

According to the seismic isolation device of the present invention having the above-mentioned structure, unlike the large-scale heavy construction which the conventional seismic isolation device has been intended for, it is lightweight such as a two-story or three-story small building. It reliably supports lightweight structures when they are installed under the foundation of a structure with a certain space between them, and the cross-sectional area is significantly reduced compared to the conventional plate-like base isolation rubber layer. 1/10), and the spring constant is significantly reduced (for example, 1/10). In other words, since the rubber hardness that allows horizontal deformation of the entire seismic isolation rubber layer is proportional to the cross-sectional area, when the rubber hardness is set to the same level as that of the conventional one (for example, 40 ° Hs) However, the rubber hardness allowing the horizontal deformation of the entire seismic isolation rubber layer is significantly reduced (for example, 1/10).

On the other hand, since the outer shape of the ring-shaped seismic isolation rubber layer (the diameter of a circle is the diameter) is the same as that of the conventional one, the bending stress due to the horizontal deformation of the seismic isolation rubber layer is also the same as that of the conventional one. Since it disappears, the deformation ability (deformation amount) corresponding to the shearing deformation in the horizontal direction is secured to about the same level as in the case of heavy construction. Therefore, in the event of an earthquake, a lightweight building on a seismic isolation device has a large amplitude (for example, 20%) with a small acceleration that does not differ from the seismic isolation effect of a conventional seismic isolation device.
About 0 mm), it slowly sways in the horizontal direction, and originally (when no seismic isolation device is installed), the energy of shear deformation in the horizontal direction that originally acted on the lightweight building itself is the seismic isolation rubber layer. It is absorbed and dampened by and prevents damage and buckling of lightweight structures. In addition, since the outer shape can be increased by forming the ring shape, bending stress of the base isolation rubber layer (mainly tensile stress acting on the base isolation rubber layer) can be suppressed. Therefore, at room temperature as described in claim 2. Can be adhered to steel plate with adhesive.

As described in claim 2, c) it is preferable that the seismic isolation rubber plate is formed by punching a vulcanized plate-shaped rubber into a ring shape and bonded to the steel plate at room temperature with an adhesive. .

According to the seismic isolation device described above,
In other words, since it is not necessary to use a mold for bonding (laminating) the steel plate and the seismic isolation rubber layer, an expensive mold is not required and the vulcanization process is omitted. Therefore, manufacturing is easy and significant cost reduction is achieved. To be Further, when the seismic isolation rubber layer is vulcanized and bonded to the steel plate, the quality of the rubber varies, but since the vulcanized rubber layer is bonded at room temperature, the quality of the rubber is stable and the quality of the seismic isolation device is also stable.

As described in claim 3, d) it is desirable to provide an opening at the center of the steel plate.

According to the above-described seismic isolation device, a large number of ring-shaped seismic isolation rubber layers and a large number of steel plates are aligned with each other by passing the central opening of the steel plate through a vertically extending core rod. The layers can be stacked alternately, and the stacking work can be performed efficiently. Further, since air escapes from the central opening when laminating the steel sheet and the ring-shaped seismic isolation rubber layer, air does not collect in the seismic isolation rubber layer between the steel sheets.

As described in claim 4, the steel plate can be formed in a ring shape corresponding to the shape of the seismic isolation rubber layer. The thickness of the steel plate needs to be thicker than that of a circular plate or a polygonal plate.

According to the above-mentioned seismic isolation device, not only the seismic isolation rubber layer but also the steel plates laminated with the seismic isolation rubber layer are formed in a ring shape, so that the seismic isolation device can be easily handled and the device can be easily manufactured. . When the steel plate is formed into a ring shape, bending stress due to horizontal deformation during an earthquake increases, but it can be dealt with by increasing the plate thickness.

[0019]

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

FIG. 1 shows one seismic isolation device installed between the lower surface of a low-rise building (2 to 3 floors) and the foundation surface. The left half of FIG. 1 (a) is a sectional view. The right half shows a front view, and FIG. 1 (b) is a sectional view taken along line bb of FIG. 1 (a). FIG.
FIG. 2A is a perspective view showing a section of a device body of a seismic isolation device with a part cut away, and FIG. 2B is a perspective view showing a circular ring-shaped seismic isolation rubber layer and a circular steel plate.

As shown in FIG. 1, the seismic isolation device 1 is a building A.
Square bonding steel plates 5 for attachment to the lower surface of the base and the base surface B are provided on both upper and lower surfaces. The device body 1a has a structure in which circular ring-shaped seismic isolation rubber layers 2 and circular steel plates 3 are alternately laminated. In this example, a high damping seismic isolation rubber is used for the seismic isolation rubber layer 2, but this high damping seismic isolation rubber has both a “load supporting function” and a “spring function” and a “damping function” at the same time. A coating rubber layer 6 effective for rust prevention is wound around the apparatus main body 1a. Further, circular end steel plates 4 that are thicker and have a slightly larger outer diameter than the other steel plates 3 are arranged on both upper and lower surfaces of the apparatus main body 1a, and each end steel plate 4 is arranged at equal intervals in the circumferential direction. The screw bolts 4a are connected to the joining steel plate 5, but each of the screw bolts 4a is screwed to the screw item 4b from the joining steel plate 5 side toward the end steel plate 4. Then, bolt holes 5b are formed in each corner of the laminated steel plate 5, and the anchor bolts 5a passed through the bolt holes 5b are fixed to the lower surface (reinforced concrete portion) of the building A and the foundation surface (reinforced concrete portion). As a result, the seismic isolation device 1 is provided between the lower surface of the building A and the foundation surface B.

In the seismic isolation device 1 according to this embodiment, the seismic isolation rubber layer 2 and the circular steel plate 3 of the device body 1a are laminated as follows. That is, a vulcanized seismic isolation rubber plate is punched into a ring shape by a press machine, and the ring-shaped seismic isolation rubber layer 2 is adhered to the outer peripheral edge portion of the circular steel plate 3 by using an adhesive to laminate them at room temperature. . As shown in FIG. 2, an opening 3a is provided in the central portion of the steel plate 3, and the ring-shaped seismic isolation rubber layer 2 is attached to the steel plates 3 and 3 while aligning the vertically standing mandrel through the opening 3a of the steel plate 3. It is interposed between them. At this time, air escapes from the opening 3a of the steel plate 3, so that the air is prevented from accumulating between the steel plates 3 and 3 in the seismic isolation rubber layer 2. In this way, a predetermined number of the seismic isolation rubber layer 2 and the circular steel plate 3 are integrally laminated, and then the covering rubber 6 (FIG. 1) is wound around the side peripheral surface thereof using an adhesive.

Although one embodiment has been shown above, the seismic isolation device of the present invention can be implemented as follows.

1) The ring-shaped seismic isolation rubber layer 2 and the steel plate 3 are formed into polygons corresponding to each other.

2) Increase the rigidity by increasing the thickness of the steel plate 3,
It is formed in a ring shape corresponding to the seismic isolation rubber layer 2, and the ring-shaped seismic isolation rubber layers 2 and the steel plates 3 are alternately laminated. In this case, in addition to the method of adhering at room temperature with an adhesive as shown in the above embodiment, vulcanization adhering may be performed as in 3).

3) A concave mold having an inner diameter slightly larger than the outer diameters of the steel plate 3 and the seismic isolation rubber layer 2 and a convex mold having an outer diameter slightly smaller than the inner diameters of the steel plate 3 and the seismic isolation rubber layer 2. Using the unvulcanized seismic isolation rubber layer 2 and the steel plate 3 alternately stacked around the convex mold, the unvulcanized coated rubber layer 6 is provided around the seismic isolation rubber layer 2 and the steel plate 3. It is wound, inserted together with the convex mold into the concave mold, and vulcanized and adhered by heating under pressure.

[0027]

[Examples] The dimensions of each component in this example will be specifically described. Vertical support load of seismic isolation device 1: 7 tons / unit Horizontal spring rigidity (spring constant) of seismic isolation device 1 (device body 1a) ): 67 kg / cm Seismic isolation rubber layer 2: outer diameter x inner diameter x thickness x number of sheets = 520 mm x 4
87 mm x 2 mm x 70 sheets Physical property value of seismic isolation rubber layer 2: Rubber hardness 40 ° Hs equivalent; G (shear elastic modulus) = 4.0k
g / cm ² , k (correction coefficient) = 0.89, E∞ (bulk modulus) = 20400 kg / cm ² Steel plate 3: outer diameter × thickness × number of sheets = 520 mm × 0.8 mm × 69
Sheet End Steel Plate 4: Outer Diameter x Thickness x Number of Sheets = 520mm x 12mm x 2
Sheet Laminated Steel Plate 5: Vertical x Horizontal x Thickness x Number of Sheets = 540 mm x 54
0mm x 25mm x 2 pieces Screw bolt 4a: outer diameter x number x location = 10mm x 12 pieces x
2 places Anchor bolt 5a: outer diameter x number x places = 28 mm x 4 pieces x 2 places According to the seismic isolation device 1 of the above-mentioned example, the steel plate 3 reliably supports a vertical load of about 7 tons per unit of the device. In addition, since the thickness of the steel plate 3 and the seismic isolation rubber layer 2 is made as thin as possible and the number of laminated layers is greatly increased, the rigidity of the rubber is increased, but the entire seismic isolation rubber layer is made of a single rubber. Since it deforms in the horizontal direction with almost the same softness as the state, the horizontal deformation ability is sufficiently secured. Therefore, in the event of an earthquake, the lightweight building (building) A supported by the seismic isolation device 1 shakes slowly in the horizontal direction with a small amplitude and a large amplitude, and shear deformation in the horizontal direction occurs. Energy is absorbed and attenuated by the seismic isolation rubber layer 2, and damage or buckling of the lightweight building A is prevented.

Here, how each of the numerical values in the above embodiment is obtained will be described based on the calculation formula.

Assuming that the weight W of the small building A is 28 tons,
As shown in FIG. 3, seismic isolation devices 1 are installed at the four corners of the lower surface of the small building A. Therefore, the vertical support load per seismic isolation device / unit will be 7 tons. Here, empirically, the target natural frequency T = 2 seconds by the seismic isolation device 1 and the equivalent damping ratio h
Set e = 0.15. In addition, from the response analysis based on typical earthquake waveforms in the past, the maximum horizontal deformation amount of the seismic isolation rubber layer 2 (deformation capacity of the seismic isolation device 1) δ _max = 300 mm. ◎ Design conditions for seismic isolation device 1: Pv = W / 4 = 7 ton = 7000 kg Horizontal spring constant K, K = m (2π / T) ² , m = Pv / g K = (Pv / g) × (2π / T) ² = 7000/980 x (2π /
2) ² = 70.5 kg / cm ◎ Physical properties of rubber used for the seismic isolation rubber layer 2: equivalent to rubber hardness of 40 ° Hs; G (shear elastic modulus) = 4.0 kg /
cm ² , k (correction coefficient) = 0.89, E∞ (bulk modulus) = 2
0400kg / cm ² Allowable stress for rubber design; compression σ _c = 500kg / cm ² , tensile
(Rubber) σ _t = 20 kg / cm ² , shear τ = 20 kg / cm ² , tensile (rubber adhesive surface) σ _b = 15 kg / cm ² ◎ Design of the seismic isolation device 1: Dimensions of the following members based on experience rules Etc. are tentatively assumed as follows. Seismic isolation rubber layer outer diameter (mm) x inner diameter (mm) x thickness (mm) x number of sheets = 52
0 × 487 (inner diameter) × 2 × 70 Steel plate outer diameter (mm) × thickness (mm) × number of sheets = 520 × 0.8 × 69 Cross-section area of seismic isolation rubber layer A = π / 4 × (52 ² −48.7 ² ) = 261cm ² Spring constant Kh = 67kg / cm …… Value calculated based on Lindley's formula [However, spring constant Kh = (4.0 × 261) /14=74.6kg/cm assuming no compression)

◎ Strength (stress) of seismic isolation rubber layer 2 If horizontal deformation δ = 30 cm and spring constant Kh = 67 kg / cm, shear stress τ = Ph / A = Kh · δ / A = 67 × 30 ÷ 261 = ^{7.7kg / cm 2 <20kg / cm} 2 ( allowable shear stress) compressive stress _{^{σ Cmax = + σ h bc +}} σ v bc + σ v c = + 16 / π · Kh · δ · (H / D 1 3) · 1 / {1 − (D ₂ / D ₁ ) ⁴ } ・ {1 + Pv / Kh ・ 1 / H} + Pv / A = 66kg / cm ² <500kg / cm ² (Allowable compressive stress) Tensile stress σ _tmax = σ ^h _bt + σ ^v _bt − _{^{σ v c = + 16 / π}} · Kh · δ · (H / D 1 3) · 1 / {1 - (D 2 / D 1) 4} · {1 + Pv / Kh · 1 / H} -Pv / A = 12kg / cm ² <15kg / cm ² (Allowable tensile stress of rubber bonded surface) In order to suppress the tensile stress σ _t due to horizontal deformation of the seismic isolation rubber layer 2 from the above formula, the outer diameter of the seismic isolation rubber layer 2 (D ₁ )
It is confirmed that increasing the value is effective.

[0031]

[Comparative Example] The physical properties of the seismic isolation rubber layer 2 are the same as those in the above example.

Target period: T = 2.0 to 2.2 seconds Vertical support load: A type; Pv = 70 tons B type; Pv = 7 tons This embodiment; Pv = 7 tons Heavy construction For lightweight construction A type B type This example Target spring constant: 580 ■ 700kg / cm 58 ■ 70kg / cm 58 ■ 70kg / cm Seismic isolation rubber layer outer diameter (mm) × thickness (mm) × number of sheets: 520 × 6 × 22 180 × 3 × 45 520 × 487 (inner diameter) × 2 × 70 Steel plate outer diameter (mm) × thickness (mm) × number of sheets: 520 × 2.8 × 21 180 × 1.2 × 44 520 × 0.8 × 69 rubber layer cross-sectional area : 2123cm ² 254.5cm ² 261cm ² Total rubber layer height: 132mm 135mm 140mm Rubber layer / steel plate total height: 190.8mm 187.8mm 195.2mm Spring constant: 646kg / cm 66kg / cm 67kg / cm Maximum stress horizontal deformation δ (mm) δ = 200, δ = 300 δ = 200, δ = 300 δ = 200, δ = 300 Surface pressure σ _LO (kg / cm ² ): 33 (δ = 0) 28 (δ = 0) 27 (δ = 0) Shear stress τ (kg / cm ² ): 6 9 5 8 5 8 Compressive stress σ _c (kg / cm ² ): 93 123 171 243 53 66 Tensile stress σ _t (kg / cm ² ): 27 57 116 188 -1 12 bonding method: vulcanization More sigma _t in-available / sigma _t excessive and incapable / sigma _t is cold bonding friendly small ◎ A type high damping seismic isolation rubber device of the conventional structure using the ◎ B type rubber layer section a conventional structure Equipment reduced in size and applied to lightweight construction

As can be seen from the above comparison results, the conventional type A seismic isolation device for heavy buildings has been reduced in size as a whole, and in particular, the cross-sectional area of the seismic isolation rubber layer has been reduced to apply to lightweight construction. To obtain a possible horizontal spring constant (horizontal spring rigidity), the tensile stress σ _t is 20 kg / cm ² which is the allowable tensile stress of the rubber even when the horizontal deformation amount δ is set to 200 mm, for example.
It means that it cannot be implemented because it goes far beyond. The tensile stress σ _{t of} the conventional A type exceeds the allowable tensile stress of the rubber, but this is because the outer diameter of the seismic isolation rubber layer is set to the minimum value of 520 mm for easy comparison. Actually, it is set to 600 to 700 mm or more, so that it falls within the range of allowable tensile stress.

On the other hand, in the seismic isolation device according to the embodiment of the present invention, when the horizontal deformation amount δ is set to 200 mm, the tensile stress σ _t becomes-(minus) and becomes the compressive stress,
When the horizontal deformation amount δ is set to 300 mm, the tensile stress σ _t is 12 kg / cm ² , which is the allowable tensile stress of the rubber bonded surface of 20 k / cm ^2.
Since it will be g / cm ² or less, not only can it be fully implemented,
Although the bonding ability is slightly lower than that of vulcanization bonding, room temperature bonding using an adhesive that has the advantage of eliminating the need for molds becomes possible. In addition, the numerical value shown above is an example to the last,
The weight of the building on which the seismic isolation device is to be installed (to be exact,
It goes without saying that it can be arbitrarily set according to the vertical support load per unit). Further, although the seismic isolation device of the present invention is particularly suitable for a lightweight building, it can be applied to a comparatively heavy building such as a middle floor building.

[0035]

As is apparent from the above description,
The seismic isolation device of the present invention has the following excellent effects. (1) It is particularly effective for seismic isolation of small and lightweight structures such as small buildings. In addition, since the seismic isolation rubber layer has a ring-shaped cross-sectional area, it is possible to increase the outer shape, so the bending stress of the seismic isolation rubber layer can be suppressed, which improves durability and ensures stable long-term use. it can.

(2) In the device according to the second aspect, it is not necessary to use a mold for adhering (laminating) the steel plate and the seismic isolation rubber layer, so that the manufacturing is easy and the cost can be largely reduced.
Also, since the vulcanized seismic isolation rubber layer is bonded at room temperature, the quality of the rubber is stable and the quality of the seismic isolation device is also stable.

(3) In the device according to the third aspect, a plurality of ring-shaped seismic isolation rubber layers and a plurality of steel plates are cored by passing a central opening of the steel plate through a core rod standing upright in the vertical direction. Can be stacked alternately, and the stacking work can be done efficiently, and when stacking the steel plate and the ring-shaped seismic isolation rubber layer, air escapes from the center opening, so Air does not collect in the.

(4) In the device according to claim 4, not only the seismic isolation rubber layer but also the steel plates laminated with the seismic isolation rubber layer are formed in a ring shape, so that the device is easy to handle and the device can be manufactured. It will be easy.

[Brief description of drawings]

1 shows one of the seismic isolation devices according to an embodiment of the present invention installed between a lower surface of a low-rise building (2 to 3 floors) and a foundation surface, and FIG. The left half shows a sectional view, the right half shows a front view, and FIG. 1B is a sectional view taken along line bb of FIG. 1A.

FIG. 2 (a) is a perspective view in which a part of the device body of the seismic isolation device is cut away to show a cross section, and FIG. 2 (b) is a perspective view showing a circular ring-shaped seismic isolation rubber layer and a circular steel plate. It is a figure.

FIG. 3 is a front view schematically showing a state where a seismic isolation device is installed between the lower surface of a two-story building and the foundation surface.

[Explanation of symbols]

 1 seismic isolation device 1a device body 2 seismic isolation rubber layer 3 steel plate 4 end steel plate 5 joining steel plate 6 coated rubber A small building (lightweight building) B foundation surface

Claims (4)

[Claims] 1. A seismic isolation device having a structure in which steel plates and seismic isolation rubber layers are alternately laminated, and side surfaces thereof are covered with a covering rubber, wherein the steel plates are circular or regular polygonal. A seismic isolation device, wherein the seismic rubber layer has a ring shape corresponding to the shape of the steel plate. 2. The seismic isolation device according to claim 1, wherein the seismic isolation rubber layer is formed by punching a vulcanized plate-shaped rubber into a ring shape and is bonded to the steel plate at room temperature with an adhesive. 3. The seismic isolation device according to claim 1, wherein an opening is provided in the central portion of the steel plate. 4. The seismic isolation device according to claim 1, wherein the steel plate is formed in a ring shape corresponding to the shape of the seismic isolation rubber layer.