JP2023077438A - Laminate rubber seismic isolation bearing - Google Patents

Abstract

To provide a laminate rubber seismic isolation bearing capable of improving weather resistance without using cover rubber.SOLUTION: A laminate rubber seismic isolation bearing comprises a laminate rubber body formed by alternately laminating a rubber plate and a rigid plate, and a pair of flange plates connected to the upper and lower end surfaces of the laminate rubber body. The thickness of the outer peripheral part of the rigid plate is larger than the thickness of a body part, which is the central side of the rigid plate. According to such a configuration, it is possible to reduce an area where the rubber plate is exposed to outside air and improve weather resistance without using cover rubber.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a laminated rubber type seismic isolation bearing.

Laminated rubber-type seismic isolation bearings (hereinafter sometimes simply referred to as "seismic isolation bearings") are known as seismic isolation devices that protect structures such as building structures and civil engineering structures from earthquake vibrations (vibration). ing. In general, a seismic isolation bearing comprises a laminated rubber body in which rubber plates and metal plates are alternately laminated. placed in the gap between

Since seismic isolation bearings are used in a state where they are exposed to the outside air, there is concern that the rubber plates may deteriorate due to the effects of oxygen, ozone, and ultraviolet rays. If the deteriorated rubber plate peels off or cracks, there is a risk of degrading the performance of the seismic isolation bearing. Therefore, in order to ensure the performance of seismic isolation bearings even after long-term use, it is essential to take measures to improve weather resistance and suppress deterioration of rubber plates.

Conventionally, there has been known a method of covering the outer peripheral surface of a laminated rubber body with a cover rubber made of a rubber material having excellent weather resistance to prevent the rubber plate from coming into contact with the outside air (for example, Patent Document 1). However, in such a method, it is necessary to prepare a rubber member for forming the cover rubber and to attach it to the laminated rubber body, which is inconvenient in that the number of members and the number of man-hours increase.

JP-A-62-83138

The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a laminated rubber-type seismic isolation bearing capable of improving weather resistance without using a cover rubber.

A laminated rubber type seismic isolation bearing of the present disclosure includes a laminated rubber body formed by alternately laminating rubber plates and rigid plates, and a pair of flange plates joined to upper and lower end surfaces of the laminated rubber body. , the thickness of the outer peripheral portion of the rigid plate is larger than the thickness of the body portion which is the central side of the rigid plate.

Longitudinal cross-sectional view schematically showing an example of the laminated rubber type seismic isolation bearing of the present disclosure Enlarged view of the area surrounded by the rectangular frame RF in FIG. Longitudinal cross-sectional view showing a seismic isolation bearing deformed in the horizontal direction FIG. 11 is a vertical cross-sectional view showing the outer peripheral portion of a rigid plate in another embodiment of the present disclosure; FIG. 11 is a vertical cross-sectional view showing the outer peripheral portion of a rigid plate in another embodiment of the present disclosure; A vertical cross-sectional view showing a main part of a seismic isolation bearing in another embodiment of the present disclosure A vertical cross-sectional view showing a main part of a seismic isolation bearing in another embodiment of the present disclosure

An embodiment of the laminated rubber type seismic isolation bearing of the present disclosure will be described with reference to the drawings.

A laminated rubber-type seismic isolation bearing 1 (hereinafter sometimes simply referred to as a "seismic isolation bearing 1") shown in FIG. and a pair of flange plates 11 and 12 joined to the upper and lower end faces of the laminated rubber body 10 . The seismic isolation bearing 1 is formed in a columnar shape as a whole. In this embodiment, the seismic isolation bearing 1 is formed in a columnar shape, but it is not limited to this, and may be formed in a prismatic shape that forms a quadrangle or a hexagon in plan view, for example.

The seismic isolation bearing 1 is installed in a gap between a lower structure (eg, building foundation) (not shown) and an upper structure (eg, building frame) (not shown). The seismic isolation bearing 1 is attached to a lower structure via a flange plate 11 and attached to an upper structure via a flange plate 12 . Between those structures and the flange plates 11 and 12, a sliding plate, a mounting flange, or the like may be interposed, if necessary. It should be noted that FIG. 1 shows the seismic isolation bearing 1 in an unloaded state, not subjected to the loads associated with installation in such gaps. Unless otherwise specified, the dimensions of the gap 30g and the rubber plate 20, which will be described later, refer to the dimensions in the no-load state before the seismic isolation bearing 1 is installed in the gap.

The laminated rubber body 10 does not cover its outer peripheral surface with rubber. That is, the seismic isolation bearing 1 does not use a cover rubber. The laminated rubber body 10 is configured using a plurality of rubber plates 20 and a plurality of rigid plates 30 . In this embodiment, nine rubber plates 21-29 and eight rigid plates 31-38 are used. In this specification, while each rubber plate is referred to individually as "rubber plates 21 to 29", they are collectively referred to as "rubber plate 20". Further, while each rigid plate is individually referred to as "rigid plates 31 to 38", they are collectively referred to as "rigid plate 30".

The rubber plate 20 is preferably made of a rubber material having excellent creep resistance. Although not particularly limited, the rubber plate 20 is formed of a rubber material based on natural rubber, and it is also possible to use various synthetic rubbers in combination therewith. Examples of synthetic rubbers include diene rubbers such as isoprene rubber, butadiene rubber, styrene-butadiene rubber and butyl rubber, and olefin rubbers such as ethylene propylene rubber. The rigid plate 30 is made of a metal plate such as a steel plate. However, it is not limited to this, and can be formed of a non-metallic plate material such as ceramic, plastic, or fiber-reinforced plastic.

FIG. 2 is an enlarged view of the area surrounded by the rectangular frame RF in FIG. In this embodiment, since the rigid plates 31 to 38 have the same shape, the “rigid plate 30” may be described with reference to the rigid plates 37 and 38 shown in FIG. Similarly, the “rubber plate 20” may be described with reference to the rubber plates 28 and 29 shown in FIG. In the seismic isolation bearing 1 of the present embodiment, the thickness Tp of the outer peripheral portion 30p of the rigid plate 30 is greater than the thickness Tb of the main body portion 30b on the center side (left side in FIG. 2) of the rigid plate 30 . That is, the relationship of Tp>Tb is established. As a result, although the cover rubber is not used, the area where the rubber plate 20 is exposed to the outside air can be reduced and the weather resistance can be improved.

On the outer peripheral surface of the laminated rubber body 10, a gap 30g is formed between the outer peripheral portions 30p of the rigid plates 30 arranged in the vertical direction. The gap 30g is formed between the outer peripheral portion of the flange plate 11 and the outer peripheral portion 30p of the rigid plate 30 (rigid plate 31), and between the outer peripheral portion 12p of the flange plate 12 and the outer peripheral portion 30p of the rigid plate 30 (rigid plate 38). is also formed between By forming such a gap 30g, the flexural deformation of the seismic isolation bearing 1 in the vertical direction becomes possible. Also, since the thickness Tp is larger than the thickness Tb, the size of the gap 30g is smaller than the thickness T20 of the rubber plate 20 . As a result, the area where the rubber plate 20 is exposed to the outside air can be reduced compared to the case where it is not so.

The size of the gap 30g is not particularly limited, and can be appropriately set in consideration of the bending deformation of the seismic isolation bearing 1 and the like. However, from the viewpoint of improving the weather resistance by reducing the area where the rubber plate 20 is exposed to the outside air, the gap 30g is preferably 20% or less of the thickness T20 of the rubber plate 20, and more preferably 10% or less. . From the same point of view, the gap 30g is preferably 10 mm or less, more preferably 5 mm or less. However, it is preferable that the gap 30g exceeds 0 mm so that bending deformation in the vertical direction can be exhibited. In a loaded state after the seismic isolation bearing 1 is installed in the gap, the gap 30g may be substantially 0 mm, but preferably exceeds 0 mm from the viewpoint of ensuring bending deformation in the vertical direction. The thickness Tp of the outer peripheral portion 30p is preferably two times or more, more preferably three times or more, the thickness Tb of the main body portion 30b. Thickness Tb is, for example, 3.2 to 4.5 mm.

The upper and lower surfaces of the main body portion 30b of the rigid plate 30 are formed of flat surfaces extending in the horizontal direction. A main body portion 20b, which is the center side of the rubber plate 20, is laminated on the main body portion 30b. The upper and lower surfaces of the main body portion 20b of the rubber plate 20 are formed as flat surfaces extending in the horizontal direction. The thickness T20 is the thickness of the main body portion 20b and corresponds to the gap between the main body portions 30b of the rigid plate 30. As shown in FIG. Thickness T20 is, for example, 3.3 to 12 mm. From the viewpoint of sufficiently securing the area of the body portion 20b extending with the thickness T20, the length Lp of the outer peripheral portion 30p is preferably 20% or less of the length Lb (see FIG. 1) of the body portion 30b. Moreover, it is more preferable that the length Lp is 10 mm or more.

The outer peripheral portion 30p of the rigid plate 30 has a stepped side surface 30s whose thickness gradually increases from the main body portion 30b toward the outer peripheral side (right side in FIG. 2). The outer peripheral portion 30p is composed of a thickness changing portion 30X including the stepped side surface 30s and a constant thickness portion 30Y including the outer peripheral end 30e of the rigid plate 30. As shown in FIG. Since the seismic isolation bearing 1 has a step due to the difference in thickness between the main body portion 30b and the outer peripheral portion 30p, when bending deformation occurs in the horizontal direction as shown in FIG. works. In this embodiment, by gradually increasing the thickness of the rigid plate 30 on the stepped side surface 30s, the shear stress applied to the rubber body 20 can be reduced, and damage to the rubber body 20 can be suppressed. . From this point of view, the inclination angle θ of the stepped side surface 30s is preferably 90 degrees or less, more preferably 67.5 degrees or less, and even more preferably 45 degrees or less.

In this embodiment, the thickness of the outer peripheral portion 12p of the flange plate 12 is greater than the thickness of the main body portion 12b, which is the center side of the flange plate 12. As shown in FIG. The thickness of the body portion 12b is, for example, 25 to 38 mm. As shown in FIG. 2, by increasing the thickness of the outer peripheral portion 12p of the flange plate 12, the gap 30g can be reduced without increasing the height h of the step on the upper surface of the rigid plate . This is convenient for reducing shear stress acting on the rubber body 20 described above. In this embodiment, the portion of the outer peripheral portion 12p that faces the outer peripheral portion 30p of the rigid plate 30 is partially thickened. good. The same configuration is used between the flange plate 11 and the lower surface of the rigid plate 31, and the thickness of the outer peripheral portion of the flange plate 11 is greater than the thickness of the main body portion of the flange plate 11 on the center side.

As shown in FIG. 2, the outer peripheral portion of the rubber plate 20 preferably enters the gap 30g. According to this configuration, the gap between the rigid plates 30 (or the flange plates 11 and 12) (especially the gap between the main body portions 30b) is properly filled with rubber, thereby ensuring the seismic isolation function. It is suitable for The rubber that has entered the gap 30g may reach the outer peripheral edge 30e of the rigid plate 30, or may protrude from the outer peripheral edge 30e. Alternatively, the outer peripheral edge of the rubber plate 20 may be made flush with the outer peripheral edge 30e of the rigid plate 30 by cutting off the rubber protruding from the outer peripheral edge 30e.

In this embodiment, the outer peripheral portion 30p of the rigid plate 30 has a shape in which the thickness is increased on both sides in the vertical direction with respect to the body portion 30b of the rigid plate 30 . As shown in FIG. 2, the rigid plate 30 has a raised surface (stepped side surface 30s) directed upward from the upper surface of the main body portion 30b and a raised surface (stepped side surface 30s) directed downward from the lower surface of the main body portion 30b. By increasing the thickness on both sides in the vertical direction in this manner, the gap 30g can be reduced without increasing the height h of the step between the upper and lower surfaces of the rigid plate 38 . This is convenient for reducing shear stress acting on the rubber body 20 described above.

As described above, the seismic isolation bearing 1 of this embodiment includes the laminated rubber body 10 formed by alternately laminating the rubber plates 20 and the rigid plates 30, and the upper and lower end faces of the laminated rubber body 10. The thickness Tp of the outer peripheral portion 30p of the rigid plate 30 is larger than the thickness Tb of the body portion 30b on the center side of the rigid plate 30. As shown in FIG. According to such a configuration, even if cover rubber is not used, the area where the rubber plate 20 is exposed to the outside air can be reduced, and the weather resistance can be improved.

As in the present embodiment, the outer peripheral portion 30p of the rigid plate 30 preferably has a stepped side surface 30s whose thickness gradually increases from the body portion 30b of the rigid plate 30 toward the outer peripheral side. According to such a configuration, it is possible to reduce the shear stress acting on the rubber body 20 when the seismic isolation bearing 1 is flexurally deformed in the horizontal direction, thereby suppressing damage to the rubber body 20 .

As in the present embodiment, it is preferable that the thickness of the outer peripheral portions 11p and 12p of the flange plates 11 and 12 is larger than the thickness of the main body portions 11b and 12b on the center side of the flange plates 11 and 12 . With such a configuration, the gap 30g can be reduced without increasing the height h of the step on the upper surface of the rigid plate 38 or the lower surface of the rigid plate 31, which is convenient for reducing the shear stress acting on the rubber body 20. is good.

As in this embodiment, the outer peripheral portion of the rubber plate 20 preferably enters the gap 30g between the outer peripheral portions 30p of the plurality of rigid plates 30 aligned in the vertical direction. According to such a configuration, the rubber is appropriately filled between the rigid plates 30 (especially the gap between the main body portions 30b), which is suitable for securing the seismic isolation function.

As in the present embodiment, the outer peripheral portion 30p of the rigid plate 30 preferably has a shape in which the thickness is increased on both sides in the vertical direction with respect to the body portion 30b of the rigid plate 30 . With this configuration, the gap 30g can be reduced without increasing the height h of the step between the upper and lower surfaces of the rigid plate 30, which is convenient for reducing the shear stress acting on the rubber body 20.

The seismic isolation bearing 1 is not limited to the configuration of the embodiment described above, and is not limited to the effects described above. In addition, the seismic isolation bearing 1 can be modified in various ways without departing from its gist. For example, one or a plurality of configurations may be arbitrarily selected from configurations according to modified examples described later, and employed in place of or in addition to the above-described embodiments. Modifications shown in [1] to [4] below can be configured in the same manner as the above-described embodiment except for the configuration described below, so common points will be omitted and differences will be mainly described. The same reference numerals are assigned to the configurations that have already been described in the above-described embodiments, and redundant descriptions are omitted.

[1] In the above-described embodiment, the thickness of the rigid plate 30 gradually increases linearly (tapered) on the side surface 30s of the step. It may be in the form shown. In the example of (A), the thickness of the rigid plate 30 gradually increases in the shape of a convex arc. In the example of (B), the thickness of the rigid plate 30 gradually increases in the shape of a concave arc. In these cases, the inclination angle θ of the stepped side surface 30s may be obtained, for example, based on a straight line connecting the start point and end point of the arc. In the example of (C), the rigid plate 30 does not have the stepped side surface 30s. In the example of (D), an inclined surface is provided at the corner between the body portion 30b and the outer peripheral portion 30p in the example of (C). In the example of (E), a small step is provided at the corner between the body portion 30b and the outer peripheral portion 30p in the example of (C).

[2] In the above-described embodiment, the outer peripheral portion 30p of the rigid plate 30 includes the thickness changing portion 30X and the constant thickness portion 30Y. As shown in C), the outer peripheral portion 30p may not have the constant thickness portion 30Y. In addition, in the example of (A), the stepped side surface 30s shown in FIG. 2 is provided in the thickness change portion 30X. In the example of (B), the stepped side surface 30s shown in FIG. 4A is provided in the thickness change portion 30X. In the example of (C), the stepped side surface 30s shown in FIG. 4B is provided in the thickness change portion 30X.

[3] In the above-described embodiment, the outer peripheral portion 30p of the rigid plate 30 has a shape in which the thickness is increased on both sides in the vertical direction with respect to the main body portion 30b. It may be in the form shown. The outer peripheral portion 30p of the rigid plate 30 shown in FIG. 6 has a shape in which the thickness is increased only on the upper side (that is, one side in the vertical direction) with respect to the main body portion 30b. With such a configuration, it is not necessary to increase the thickness of the outer peripheral portion of the flange plate 12 , so that a general plate material having a constant thickness can be used for the flange plate 12 . In the example of FIG. 6, the thickness is increased only on the upper side, but instead of this, the thickness may be increased only on the lower side.

[4] In the above-described embodiment, the rigid plates 31 to 38 have the same shape. For example, in the example of FIG. 7, the outer peripheral portion 30p having a thicker thickness only on the lower side is applied to the rigid plates 31 to 33, the outer peripheral portion 30p having a thicker thickness on both the upper and lower sides is applied to the rigid plates 34 and 35, and the upper side The outer peripheral portion 30p, which is only thicker than the other, is applied to the rigid plates 36-38. According to such a configuration, there is an advantage that a general plate material having a constant thickness can be used for the pair of flange plates 11 and 12 .

1 Laminated rubber type seismic isolation bearing 10 Laminated rubber body 11 Flange plate 12 Flange plate 20 Rubber plate 21-29 Rubber plate 30 Rigid plate 30b Body portion 30g Gap 30p Peripheral portion 30s Step side surface 31-38 Rigid plate

Claims (5)

A laminated rubber body formed by alternately laminating rubber plates and rigid plates, and a pair of flange plates joined to both upper and lower end surfaces of the laminated rubber body,
A laminated rubber type seismic isolation bearing, wherein the thickness of the outer peripheral portion of the rigid plate is greater than the thickness of the main body portion of the rigid plate, which is located on the center side of the rigid plate. 2. The laminated rubber type seismic isolation bearing according to claim 1, wherein the outer peripheral portion of said rigid plate has a stepped side surface whose thickness gradually increases from the body portion of said rigid plate toward the outer peripheral side. The laminated rubber type seismic isolation bearing according to claim 1 or 2, wherein the thickness of the outer peripheral portion of the flange plate is larger than the thickness of the body portion on the center side of the flange plate. The laminated rubber type seismic isolation bearing according to any one of claims 1 to 3, wherein the outer peripheral portion of said rubber plate is inserted into a gap between the outer peripheral portions of said plurality of rigid plates arranged in the vertical direction. The laminated rubber type seismic isolation bearing according to any one of claims 1 to 4, wherein the outer peripheral portion of said rigid plate has a shape in which the thickness is increased on both sides in the vertical direction with respect to the body portion of said rigid plate.

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