JP2012202549A - Base isolation structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base isolation structure that can appropriately obtain a base isolation effect even when the weight of a body to be supported is changed.SOLUTION: The base isolation structure 10 includes: a first laminated rubber body 12 whose one end in a laminating direction is fixed to a base part 54 and other end in the laminating direction is fixed to the body to be supported; a second laminated rubber body 20 arranged separately from the first laminated rubber body in parallel, whose one end in the laminating direction is fixed to one of the base part 54 and the body to be supported and other end in the laminating direction is arranged separately from the other one of the base part 54 and the body to be supported; and an elastic body 30 arranged between the other of the base part 54 and the body to be supported and the other end of the second laminated rubber body 20 while being abutted on both of them, and has a spring constant lower than that of the first laminated rubber body 12 and the second laminated rubber body 20.

Description

  The present invention relates to a seismic isolation structure.

  Conventionally, seismic isolation structures have been used to protect buildings and structures from vibrations such as earthquakes. For example, as a seismic isolation structure, a structure in which a structure is supported by a laminated body in which an elastic plate and a metal plate are laminated together is known. In such a seismic isolation structure, horizontal vibration is isolated mainly by shear deformation of the elastic plate (see, for example, Patent Documents 1 to 3).

  By the way, since the seismic isolation characteristics of the seismic isolation device change depending on the weight of the structure to be supported, it is designed to obtain the predetermined seismic isolation characteristics in consideration of the load received from the supported target. ing.

However, when the weight of the support to be supported changes, for example, it is difficult to maintain the seismic isolation characteristics in a supported body whose weight changes depending on the amount of contents such as a tank or a water tank. It was difficult to obtain the seismic isolation effect.

Patent Document 4 describes a laminated rubber bearing that changes the rigidity of the laminated rubber by horizontal deformation of the laminated rubber. However, the laminated rubber support of Patent Document 4 has a configuration in which a horizontal force does not act on the second laminated rubber and the third laminated rubber on the outer periphery unless the horizontal deformation of the central first laminated rubber exceeds a certain amount. Yes. Therefore, if the weight of the supported body changes, the seismic isolation characteristics change, and it is difficult to obtain a desired seismic isolation effect.

JP2003-147993A Special table 2006-514181 Registered utility model 312118 JP-A-2-16230

  The object of the present invention has been made in consideration of the above facts, and is to provide a seismic isolation structure capable of obtaining an appropriate seismic isolation effect even if there is a change in the weight of the supported target to be supported. The purpose is to provide.

  In order to achieve the above object, the seismic isolation structure according to claim 1 is configured such that elastic plates and metal plates are alternately laminated, one end in the laminating direction is fixed to the base, and the other end in the laminating direction is supported. A first laminated rubber body fixed to the first laminated rubber body and spaced apart from the first laminated rubber and arranged in parallel, and elastic plates and metal plates are alternately laminated in the same direction as the lamination direction, and one end of the lamination direction is A second laminated rubber body fixed to one of the base or the supported body and having the other end spaced apart from the other of the base or the supported body; the other of the base or the supported body and the second laminated rubber body And an elastic body having a spring constant lower than that of the first laminated rubber body and the second laminated rubber body.

  In the seismic isolation structure according to claim 1, one end of the first laminated rubber body is fixed to the base, and the other end is fixed to the supported body. The second laminated rubber body is arranged such that one end in the laminating direction is fixed to the base or the supported body and the other end is separated from the other of the base or the supported body. Here, the to-be-supported body means the structure supported by the seismic isolation structure. The base means the foundation and foundation on which the seismic isolation structure is installed. The fixing here may be direct fixing or indirect fixing via another member such as a mounting plate.

  An elastic body is disposed between the other end of the second laminated rubber body and the base or the other of the supported body. The elastic body is in contact with the second laminated rubber body and the supported body, and the spring constant is lower than that of the first laminated rubber body and the second laminated rubber body.

  When the load from the supported body is relatively small and the amount of compression of the elastic body is small, the first laminated rubber body and the elastic body mainly undergo shear deformation due to the relative movement in the horizontal direction of the supported body and the base, so that Demonstrate the seismic effect. As the load from the supported body increases, a shearing force is transmitted to the second laminated rubber body in accordance with the load, and the second laminated rubber body also undergoes shear deformation.

  When the load from the supported body is relatively large and the amount of compression of the elastic body is large, both the first laminated rubber body and the second laminated rubber body undergo shear deformation due to relative movement of the supported body and the base in the horizontal direction. , Demonstrates seismic isolation effect.

Here, considering the seismic isolation characteristics of the seismic isolation structure, seismic isolation period T, the load m from the supported body, and the relationship between the horizontal direction of the spring constant k _h of the laminated rubber body, of formula (1) It becomes like this.

Therefore, when a load m is changed, in order to ensure the desired seismic isolation period T may be increased in the horizontal direction of the spring constant k _h of the laminated rubber body with increasing load m from the supported body.

  According to the seismic isolation structure of claim 1, as described above, the shearing force transmitted to the second laminated rubber body increases as the load from the supported body increases. The spring constant of increases. Therefore, the seismic isolation characteristic can be maintained as compared with the case where the horizontal spring constant of the seismic isolation structure is constant.

  The seismic isolation structure according to claim 2 is characterized in that the second laminated rubber body is disposed so as to surround an outer periphery of the first laminated rubber body.

  As described above, by arranging the first laminated rubber body and the second laminated rubber body, particularly when the load from the supported body is small, the seismic isolation effect stabilized by the first laminated rubber body arranged on the inner side. Can be demonstrated.

  The seismic isolation structure according to claim 3 is characterized in that the first laminated rubber body has a columnar shape, and the second laminated rubber body has a cylindrical shape surrounding the first laminated rubber body.

  Thus, a more stable seismic isolation effect can be exhibited by making the first laminated rubber body into a columnar shape and the second laminated rubber body into a cylindrical shape surrounding the first laminated rubber body.

  As described above, according to the seismic isolation structure of the present invention, the seismic isolation effect can be appropriately obtained even if there is a change in the weight of the supported body to be supported.

It is a perspective view of the seismic isolation structure which concerns on this embodiment. It is the partially broken view which looked at the seismic isolation structure which concerns on this embodiment from the upper side. It is sectional drawing of the seismic isolation structure which concerns on this embodiment. It is a graph which shows the relationship between the displacement of the elastic body of this embodiment, and the shear force which acts on a 2nd laminated rubber body. It is sectional drawing which shows the state (small water storage amount) in which the seismic isolation structure which concerns on this embodiment was installed. It is sectional drawing which shows the operation state (small amount of water storage) of the seismic isolation structure which concerns on this embodiment. It is sectional drawing which shows the state (in the amount of water storage) in which the seismic isolation structure which concerns on this embodiment was installed. It is sectional drawing which shows the operation state (in the amount of stored water) of the seismic isolation structure which concerns on this embodiment. It is sectional drawing which shows the state (water storage amount many) in which the seismic isolation structure which concerns on this embodiment was installed. It is sectional drawing which shows the operation state (large amount of water storage) of the seismic isolation structure which concerns on this embodiment. It is a figure which shows the modification (A)-(C) of the elastic body of the seismic isolation structure which concerns on this embodiment. It is a figure which shows the modification (D) (E) of the elastic body of the seismic isolation structure which concerns on this embodiment. It is the partially broken figure which looked at the seismic isolation structure which concerns on the modification of this embodiment from the upper side.

  Hereinafter, the seismic isolation structure 10 which concerns on 1st Embodiment of this invention is demonstrated with reference to drawings.

  1 to 3 show a seismic isolation structure 10 according to an embodiment of the present invention. As shown in FIG. 5, the seismic isolation structure 10 is disposed between a supported body (water tank 56) that is a support target of the seismic isolation structure 10 and a base 54 where the seismic isolation structure 10 is installed. ing. Especially the seismic isolation structure 10 of this embodiment can be used suitably for seismic isolation of a tank, a water tank, etc. with which the change of the weight is assumed beforehand. In the present embodiment, a case where the water tank 56 is supported as a supported body will be described as an example.

  The seismic isolation structure 10 of the present embodiment includes a first laminated rubber body 12, a second laminated rubber body 20, an elastic body 30, and mounting plates 14A and 14B.

  As shown in FIG. 3, the first laminated rubber body 12 includes a plurality of disk-shaped first metal plates 18 and a plurality of disk-shaped first elastic plates 16 in the thickness direction (arrow B direction). It is set as the cylindrical laminated body laminated | stacked alternately. The first elastic plate 16 is made of a rubber material. The first metal plate 18 and the first elastic plate 16 are firmly integrated by vulcanization adhesion. In this way, not only the first elastic plate 16 but also the first metal plates 18 are alternately laminated so that a predetermined rigidity is applied to a load in the vertical direction (arrow B direction). With respect to the load in the horizontal direction, the spring function is exhibited and a predetermined deformation amount can be secured.

  The outer diameter of the first metal plate 18 is smaller than the outer diameter of the first laminated rubber body 12, and a covering rubber 19 is disposed in a cylindrical shape on the outer edge of the first metal plate 18. The first metal plate 18 is covered with the covering rubber 19, and the first metal plate 18 is not exposed to the outside to prevent deterioration.

  A second laminated rubber body 20 is disposed on the outer periphery of the first laminated rubber body 12. The second laminated rubber body 20 has a cylindrical shape, and is disposed so as to surround the first laminated rubber body 12 and away from the first laminated rubber body 12. A space R is formed between the first laminated rubber body 12 and the second laminated rubber body 20.

  The second laminated rubber body 20 has a cylindrical shape in which a plurality of ring-plate-like second metal plates 28 and a plurality of ring-plate-like second elastic plates 26 are alternately laminated in the thickness direction (arrow B direction). It is made into the laminated body. The second elastic plate 26 is made of a rubber material. The second metal plate 28 and the second elastic plate 16 are firmly integrated by vulcanization adhesion. As described above, not only the second elastic plate 26 but also the second metal plates 28 are alternately stacked, thereby having a predetermined rigidity with respect to a load in the vertical direction (arrow B direction). With respect to the load in the horizontal direction, the spring function is exhibited and a predetermined deformation amount can be secured. The height of the second laminated rubber body 20 in the lamination direction B is lower than that of the first laminated rubber body 12.

  The outer diameter of the second metal plate 28 is smaller than the outer diameter of the second laminated rubber body 20, and a covering rubber 29 is arranged in a cylindrical shape on the outer edge of the second metal plate 28. The inner diameter of the second metal plate 28 is made larger than the inner diameter of the second laminated rubber body 20, and the covering rubber 29 is arranged in a cylindrical shape on the inner wall of the second metal plate 28. The second metal plate 28 is covered with the covering rubber 29, so that the second metal plate 28 is not exposed to the outside and the deterioration is prevented.

  An elastic body 30 is laminated on the upper end of the second laminated rubber body 20. The elastic body 30 is made of a rubber material, and is formed in a ring shape over the entire circumference so as to cover the upper end surface of the second laminated rubber body 20. The elastic body 30 has a lower end portion (an end portion on the second laminated rubber body 20 side) wider than an upper end portion (an end portion on the mounting plate 14B side), and the inner peripheral wall 30A has a concave shape of R. . The spring constant of the elastic body 30 in the stacking direction S (vertical direction) is set to be smaller than the spring constant of the first stacked rubber body 12 and the second stacked rubber body 20 in the same direction (stacking direction S).

  Mounting plates 14A and 14B are disposed on both ends of the first laminated rubber body 12 and the second laminated rubber body 20 in the thickness direction (arrow B direction). The mounting plates 14A and 14B are made of thick annular steel plates.

  The first laminated rubber body 12 has a lower end fixed to the mounting plate 14A and an upper end fixed to the mounting plate 14B. The lower end of the second laminated rubber body 20 is fixed to the mounting plate 14A. The elastic body 30 laminated on the second laminated rubber body 20 has an upper end fixed to the mounting plate 14B. That is, the elastic body 30 is interposed between the mounting plate 14B and the second laminated rubber body 20, and the second laminated rubber body 20 is coupled to the mounting plate 14B via the elastic body 30.

  The mounting plates 14A and 14B are fixed to a base 54 and a water tank 56 installed on the ground, respectively. In this state, when the ground (and the foundation) and the water storage tank 56 are relatively moved in the horizontal direction, the vibration energy of the relative movement is generated by the first laminated rubber body 12, the second laminated rubber body 20, and the elastic body 30. Part of it is absorbed by shear deformation.

  Next, the operation of the seismic isolation structure 10 will be described.

  When a vertical load is not acting on the seismic isolation structure 10 (when the water storage tank 56 is not supported), as shown in FIG. 3, the first laminated rubber body 12 and the elastic body 30. And the 2nd lamination | stacking rubber body 20 is in the state which is not compressively deformed.

  In FIG. 4, the displacement of the elastic body 30 in the stacking direction B and the shearing force acting on the second laminated rubber body 20 (Smin when the elastic body 30 is not deformed and Smax when the compression deformation is maximum) are shown. The relationship is shown.

  When the weight of the water storage tank 56 is light, that is, when the amount of water stored in the water storage tank 56 is small, the seismic isolation structure 10 is first laminated by the load M1 from the water storage tank 56 as shown in FIG. The rubber body 12 is compressed, and the elastic body 30 is elastically deformed by α1 (see FIG. 4) due to the compression.

  In this state, when the base 54 and the water tank 56 are relatively moved in the horizontal direction by vibration input such as an earthquake, the first laminated rubber body 12 undergoes shear deformation as shown in FIG. On the other hand, due to the elastic deformation of the elastic body 30, the action of the shear force is small at S <b> 1 (see FIG. 4) for the second laminated rubber body 20. Therefore, mainly when the first laminated rubber body 12 undergoes shear deformation, a part of vibration energy is absorbed, and a seismic isolation effect can be obtained.

  When the weight of the water storage tank 56 is medium, that is, when the amount of water stored in the water storage tank 56 is about half of the full water, as shown in FIG. The first laminated rubber body 12 is compressed by M2, and the elastic body 30 is elastically deformed by α2 (see FIG. 4) due to the compression.

  In this state, when the base 54 and the water tank 56 are relatively moved in the horizontal direction by vibration input such as an earthquake, the first laminated rubber body 12 undergoes shear deformation as shown in FIG. On the other hand, due to the elastic deformation of the elastic body 30, the shearing force acts on the second laminated rubber body 20 at S2 (see FIG. 4). Therefore, mainly the first laminated rubber body 12 undergoes shear deformation and the second laminated rubber body 20 supplementarily undergoes shear deformation, so that part of the vibration energy is absorbed, and a seismic isolation effect can be obtained.

  When the weight of the water storage tank 56 is heavy, that is, when the amount of water stored in the water storage tank 56 is full, as shown in FIG. The laminated rubber body 12 is compressed, and the elastic body 30 is compressed to the maximum and elastically deformed by α3 (see FIG. 4).

  In this state, when the base 54 and the water storage tank 56 are relatively moved in the horizontal direction by vibration input such as an earthquake, the first laminated rubber body 12 is sheared and deformed as shown in FIG. In addition, when the shear force of S3 (see FIG. 4) acts and the second laminated rubber body 20 undergoes shear deformation, a part of vibration energy is absorbed, and a seismic isolation effect can be obtained.

Here, considering the seismic isolation characteristics of the seismic isolation structure 10, the relationship between the seismic isolation period T, the load m from the supported body, and the horizontal spring constant k _h of the entire seismic isolation structure 10 is expressed by the equation: It becomes like (1).

According to the seismic isolation structure 10 of the present embodiment, as described above, when the load m from the water storage tank 56 increases, the shear force acting on the second laminated rubber body 20 increases, and the seismic isolation structure 10 as a whole. It increases the horizontal direction of the spring constant k _h of. Thus, the horizontal direction of the spring constant k _h of the seismic isolation structure as compared with the case of the constant, it is possible to maintain the seismic isolation characteristics can exert seismic isolation effect.

  In the present embodiment, the shape of the elastic body 30 is described in the case where the lower end portion is wider than the upper end portion and the inner peripheral wall 30A is concave. However, the shape is not limited to this shape. For example, as shown in FIG. 11A, the inner peripheral wall 30A may have a notch shape 30B instead of the concave shape of R. Further, as shown in FIG. 11-1 (B), two concave grooves 30C may be formed on the mounting plate 14B side (upper side in the drawing), or as shown in FIG. 11-1 (C). As described above, the concave groove 30D is formed at the center in the width direction on the mounting plate 14B side (the upper side in the drawing), and the radially inner and outer radial ridges 31 constituting the concave groove 30D are cross-sectioned on the mounting plate 14B side. You may form so that it may become a mountain shape toward. Furthermore, as an elastic body, as shown to FIG. 11-2 (D), it is good also as the square elastic body 30H from which an upper end part and a lower end part become the same width.

  As an elastic body, a plurality of coil springs 30S may be arranged as shown in FIG.

  In the present embodiment, the first laminated rubber body 12 has a columnar shape and the second laminated rubber body 20 has a cylindrical shape. However, the first laminated rubber body 12 has a prismatic shape (such as a 3-8 octagonal column). The two-layer rubber body 20 and the elastic body 30 may have a rectangular tube shape along the outer periphery thereof.

  Further, the second laminated rubber body need not be cylindrical, and a plurality of columnar second laminated rubber bodies 21 are arranged so as to surround the outer periphery of the first laminated rubber 12 as shown in FIG. Also good. In this case, the elastic body 31 may be formed at the upper end of each second laminated rubber body 21.

  In the present embodiment, the first laminated rubber body 12 has a columnar shape, and the cylindrical second laminated rubber body 20 and the elastic body 30 are arranged on the outer periphery thereof. The body 20 and the elastic body 30 may be columnar, and the cylindrical first laminated rubber body 12 may be disposed on the outer periphery thereof. By disposing the first laminated rubber body 12 radially inward as in this embodiment, a stable seismic isolation effect can be exhibited particularly when the load from the water storage tank 56 is small.

  In the present embodiment, the elastic body 30 is disposed on the upper side of the second laminated rubber body 20, that is, on the water storage tank 56 side, but the elastic body 30 is disposed on the lower side of the second laminated rubber body 20, that is, the base 54. It may be arranged on the side.

DESCRIPTION OF SYMBOLS 10 Base isolation structure 12 1st laminated rubber body 16 Elastic plate 18 Metal plate 20 2nd laminated rubber body 26 Elastic plate 28 Metal plate 30 Elastic body 54 Base 56 Water storage tank (supported body)
R space

Claims (3)

A first laminated rubber body in which elastic plates and metal plates are alternately laminated, one end in a laminating direction is fixed to a base, and the other end in the laminating direction is fixed to a supported body;
Separated from the first laminated rubber body and arranged in parallel, elastic plates and metal plates are alternately laminated in the same direction as the laminating direction, and one end of the laminating direction is fixed to one of the base or the supported body. A second laminated rubber body having the other end spaced apart from the base or the other of the supported body;
An elastic body disposed between the other of the base or the supported body and the other end of the second laminated rubber body, in contact with both, and having a lower spring constant than the first laminated rubber body and the second laminated rubber body; ,
Seismic isolation structure with   2. The seismic isolation structure according to claim 1, wherein the second laminated rubber body is disposed so as to surround an outer periphery of the first laminated rubber body.   The seismic isolation structure according to claim 2, wherein the first laminated rubber body has a columnar shape, and the second laminated rubber body has a cylindrical shape surrounding the first laminated rubber body.

Images