JP2004156750A - Base isolation structure and its arrangement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a base isolation structure surely capable of relieving local stress to a soft plate regardless of deformation directions, and an arrangement method for the base isolation structure. <P>SOLUTION: The corner of a hard plate 112 of the base isolation structure 102 is made to be a rounded part 126 which is curved with a specific radius of curvature R. The radius of curvature R is set so as to satisfy L/7≤R≤L/4 to a length L of one side of the hard plate 112. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a seismic isolation structure and a method of arranging the same.
[0002]
[Prior art]
FIG. 6 shows an example of a rubber bearing body 10 suitably used as a conventional seismic isolation structure for supporting a bridge or a pier (see Patent Document 1).
[0003]
The rubber support 10 has a structure in which a plurality of metal plates 14 (hard plates) are embedded in a rubber block 12, and the metal plates 14 and the intermediate rubber layer 16 are alternately laminated. As shown in FIG. 7, the radius of curvature r of the curved corner 24 of the metal plate 14 is in the range of 3 mm to L1 / 10 mm with respect to the length L1 of the longest side of the rubber block 12. Thereby, when the surface rubber layer 18 is tensile-deformed, a large tensile strain is not locally generated in the surface rubber layer 18.
[0004]
By the way, when seismic isolation is applied by applying a seismic isolation structure to a general building, unlike the bearings applied to bridges and piers, for example, the direction of vibration of the upper structure with respect to the ground during an earthquake cannot be specified. It is preferable that the direction of deformation of the seismic isolation structure (the direction in which vibration energy can be absorbed) is not biased in a specific direction. However, in the rubber bearing body 10 shown in FIG. 7, the range of the radius of curvature r is too small, and the thickness of the surface rubber layer 18 is not uniform. Directivity may occur in performance, and a large force may act locally on the surface rubber layer 18.
[0005]
In order to eliminate such inconvenience, the seismic isolation structure may be formed in a columnar shape. However, in the case of a columnar seismic isolation structure, for example, compared to a seismic isolation structure having a square horizontal cross section, the installation space for obtaining the same horizontal cross-sectional area to support the upper structure is larger. This is disadvantageous when there is not enough space for installing the seismic isolation structure (for example, in the case of seismic isolation renovation work on an existing superstructure).
[0006]
[Patent Document 1]
JP 2001-207412 A
[Problems to be solved by the invention]
In consideration of the above facts, the present invention can reliably alleviate local stress on a soft plate regardless of the direction of deformation while maintaining compactness as a seismic isolation structure, and also alleviates the occurrence of directionality in performance. It is an object to obtain a possible seismic isolation structure and a method of disposing the seismic isolation structure.
[0008]
[Means for Solving the Problems]
In the invention according to claim 1, the seismic isolation structure is provided between the support member and the upper structure, wherein the plurality of hard plates formed in a substantially square shape and the hard plates alternate with each other. Laminated and laminated, a soft plate that can be elastically sheared and deformed, and a covering member arranged to cover an outer end surface of the hard plate, wherein a radius of curvature R of a corner of the hard plate is The length L of the long side of the hard plate is set to satisfy L / 7 ≦ R ≦ L / 4.
[0009]
The “supporting member” here may be any member that supports a structure through a bearing, and includes, for example, a foundation, a foundation, and a ground of a general building. Examples of the "superstructure" include office buildings, hospitals, apartment houses, museums, public halls, schools, government buildings, shrines and temples, and seismic isolation structures for new construction or seismic isolation renovation. Is used.
[0010]
In the present invention, when the support member and the upper structure move relative to each other due to an earthquake or the like, the soft plate elastically shears and deforms, thereby absorbing energy and exerting a restoring force. Further, the hard plate and the soft plate are alternately laminated and laminated, so that even if a load on the upper structure acts, it is possible to suppress the compression deformation in the load direction. For this reason, when a shear force acts, energy can be reliably absorbed by shear deformation.
[0011]
The outer end surface of the hard plate is covered with a covering member, and the hard plate is protected. Here, the curvature radius R of the corner of the hard plate is set so as to satisfy L / 7 ≦ R ≦ L / 4 with respect to the length L of the long side of the hard plate. Therefore, when shear deformation occurs, regardless of the direction, the local stress concentration acting on the covering member from the hard plate can be reduced, and the occurrence of directionality in the seismic isolation performance can also be reduced.
[0012]
In addition, since the hard plate is formed in a substantially square shape, the soft plate is also formed in a square shape in accordance with this, and the water isolation section of the entire seismic isolation structure can be formed in a substantially square shape. As a result, a wide cross-sectional area can be ensured in a smaller installation space, space efficiency is improved, and the present invention can be easily applied to an upper structure where there is no room for installation space.
[0013]
According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a plastic deformation member that penetrates in a laminating direction of the hard plate and the soft plate and undergoes plastic deformation by receiving a shearing force. I do.
[0014]
Since the plastically deformable member is plastically deformed by the shearing force applied to the seismic isolation structure, the energy can be absorbed more reliably.
[0015]
When the hard plate is formed in a substantially square shape as described in claim 3, higher space efficiency can be obtained. In this case, by setting the length L of one side of the hard plate to be equal to or greater than 600 mm and equal to or less than 1400 mm, the present invention can be applied to more buildings.
[0016]
In the invention according to claim 5, in the invention according to any one of claims 1 to 4, on both end surfaces of the hard plate and the soft plate in the laminating direction, a support member and an upper structure are respectively provided. It has a mounting flange for mounting, and the height between the two mounting portion flanges is 200 mm or more and 700 mm or less.
[0017]
The seismic isolation structure can be easily attached to the support member and the upper structure using the attachment flange.
[0018]
In addition, particularly, the length L of one side of the hard plate is set to be 600 mm or more and 1400 mm or less as described in claim 4, and the height between the two mounting flanges is set to be 200 mm or more and 700 mm or less as described in claim 5. By doing so, application to even more buildings becomes possible.
[0019]
According to a sixth aspect of the present invention, there is provided a method of arranging the seismic isolation structure according to any one of the first to fifth aspects between the support member and the existing structure. There is provided an arrangement portion for arranging a seismic isolation structure on the ground, and after providing a support member in this arrangement portion, arranging the seismic isolation structure. And attached to existing structures.
[0020]
As a result, the seismic isolation structure can be easily applied to the existing structure, and the seismic isolation can be easily improved.
[0021]
In the invention according to claim 7, a seismic isolation structure disposed between the support member and the structure, wherein the plurality of hard plates formed in a substantially square shape and the hard plates are alternately attached. A soft plate that is laminated and elastically deformable by shearing, and a covering member disposed so as to cover an outer end surface of the hard plate, wherein a radius of curvature R of a corner of the hard plate is hard. The length L of the plate is set so as to satisfy L / 7 ≦ R ≦ l / 4.
[0022]
The “supporting member” here may be any member that supports a structure through a bearing, and includes, for example, a foundation, a foundation, and a ground of a general building. Examples of the "superstructure" include office buildings, hospitals, apartment houses, museums, public halls, schools, government buildings, shrines and temples, and seismic isolation structures for new construction or seismic isolation renovation. Is used.
[0023]
In the present invention, when the support member and the structure relatively move due to an earthquake or the like, the soft plate is elastically sheared and deformed, thereby absorbing energy and exerting a restoring force. Further, the hard plate and the soft plate are alternately laminated and laminated, so that even if a load is applied to the structure, the compression deformation in the load direction can be suppressed. For this reason, when a shear force acts, energy can be reliably absorbed by shear deformation.
[0024]
The outer end surface of the hard plate is covered with a covering member, and the hard plate is protected. Here, the curvature radius R of the corner of the hard plate is set so as to satisfy L / 7 ≦ R ≦ L / 4 with respect to the length L of the long side of the hard plate. Therefore, regardless of the direction of the shear deformation, local stress concentration acting on the covering member from the hard plate can be reduced, and the occurrence of directivity in the seismic isolation performance can also be reduced.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a seismic isolation structure 102 according to an embodiment of the present invention. FIG. 2 shows a building 104 to which the seismic isolation structure 102 is applied. The seismic isolation structure 102 is arranged between a building foundation 106 as an example of a support member and a bottom 108 (or PC board) of a building 104 as an example of an upper structure.
[0026]
As shown in FIG. 3, the seismic isolation structure 102 has a main body 110 formed by alternately stacking a plurality of hard plates 112 and soft plates 114 in the vertical direction. The hard plate 112 is formed in a plate shape from a material (for example, metal) having a predetermined rigidity. On the other hand, the soft plate 114 is formed of a material having viscoelasticity (for example, rubber), and is elastically sheared by receiving a horizontal shear force. The hard plate 112 and the soft plate 114 are firmly adhered to each other by vulcanization bonding (or with an adhesive) so that they are not inadvertently separated or displaced.
[0027]
When the building 104 relatively moves (vibrates) in the horizontal direction with respect to the building foundation 106 due to an earthquake or the like, the seismic isolation structure 102 is elastically sheared as a whole and absorbs the energy of the vibration. Here, as described above, since the hard plates 112 and the soft plates 114 are alternately stacked, even if a load acts in the stacking direction, the compression of the main body 110 (that is, the compression of the soft plate 114) is suppressed. ing. Therefore, the soft plate 114 can be sufficiently shear-deformed to absorb energy and exhibit a restoring force.
[0028]
The main body 110 further includes a covering material 116 for covering the outer end surfaces of the hard plate 112 and the soft plate 114 from the surroundings. The coating 116 prevents rain and light from acting on the hard plate 112 and the soft plate 114 from the outside, and prevents deterioration due to oxygen, ozone, ultraviolet rays, and the like. Further, the coating material 116 has a constant thickness so that its strength does not vary. Note that the covering material 116 can be formed of the same material as the soft plate 114. In this case, it is possible to form the soft plate 114 and the covering material 116 separately, and to integrate them by vulcanization bonding or the like in a later step. Alternatively, the covering material 116 and the soft plate 114 may be bonded with an adhesive or the like.
[0029]
At the upper end and the lower end of the main body 110, a mounting flange 118 that extends laterally beyond the main body 110 is fixed. The seismic isolation structure 102 can be attached to the building foundation 106 and the bottom 108 by inserting bolts 122 into bolt holes 120 formed in the attachment flange 118.
[0030]
At the center of the main body 110 and the upper and lower mounting flanges 118, a plug 124 is disposed so as to penetrate them (only one plug 124 is shown in the drawing, but two or more plugs 124 are provided). May be). The plug 124 is formed in a rod shape by a material (for example, metal, preferably lead) which undergoes composition deformation by receiving a shearing force. When the main body 110 is sheared, the plug 124 is also sheared and absorbs energy.
[0031]
As shown in detail in FIG. 3, the hard plate 112 and the soft plate 114 of the seismic isolation structure 102 of the present embodiment are formed so as to have a substantially square shape when viewed in a plan view. The horizontal cross section is formed in a substantially square block shape. This makes it possible to obtain the same effective area (or more) in a smaller installation space as compared to, for example, a disk-shaped hard plate 112 or soft plate 114 (horizontal cross section is circular). It has become.
[0032]
The corners of the hard plate 112 are rounded portions 126 that are curved with a constant radius of curvature R. This radius of curvature R is equal to the length L of one side of the hard plate 112.
L / 7 ≦ R ≦ L / 4 (1)
Is set to meet.
[0033]
When the seismic isolation structure 102 of this embodiment having such a structure is applied to an existing building 104, first, a part of the ground (a place where the seismic isolation structure 102 is disposed) is excavated. Then, the seismic isolation pit 128 for installation is formed, and the building foundation 106 is provided. Then, the seismic isolation structure 102 is installed between the building foundation 106 provided in the seismic isolation pit 128 of the building 104 and the bottom part 108 of the building 104, and the bolt 122 is inserted into the bolt hole 120 so as to be isolated. The seismic structure 102 is attached to the building foundation 106 and the bottom 108. Here, the seismic isolation structure 102 of the present embodiment is formed in a block shape having a substantially square horizontal section, so that, for example, both the horizontal sections of the flange 118 and the main body 110 are circular. Since the outer diameter of the flange becomes more compact, the building foundation 106 can naturally be made compact, and even a smaller seismic isolation pit 128 can be provided, which is excellent in workability. For example, on the side of the building 104, the clearance D generated between the building 104 and the seismic isolation pit 128 can be reduced. In the present embodiment, a cover plate 130 for closing the clearance D is attached to the building 104. The cover plate 130 preferably overlaps with the ground to such an extent that the clearance D can be closed even when the building 130 is relatively moved in the horizontal direction.
[0034]
When the building 104 to which the seismic isolation structure 102 is applied in this way is relatively moved (vibrated) in the horizontal direction with respect to the building foundation 106 due to an earthquake or the like, the main body 110 undergoes shear deformation (elastic deformation), It absorbs part of the energy of this vibration and exerts a restoring force. Further, the plug 124 undergoes shear deformation (plastic deformation) to absorb vibration energy.
[0035]
By the way, even when the main body 110 is sheared and deformed, the hard plate 112 itself is not deformed, so that a part of the four corners of the hard plate 112 presses the coating material 116 and Try to act on local stress. Here, in the seismic isolation structure 102 of the present embodiment, the corners are rounded portions 126 having a radius of curvature R in the range of the above equation (1). As described above, by setting L / 7 ≦ R, stress concentration on the coating material 116 is reduced, and damage to the coating material 116 can be prevented. In addition, by setting L / 7 ≦ R, the bias (direction) due to the direction when the main body 110 undergoes shear deformation is reduced, so that the vibration cannot be specified in advance such as an earthquake. A seismic effect can be exhibited.
[0036]
From this viewpoint, the larger the value of the radius of curvature R, the better. However, if it is too large, the hard plate 112 is substantially shaped like a circle, and the required effective cross-sectional area cannot be secured. Therefore, in order to eliminate such inconvenience, it is preferable to satisfy R ≦ L / 4.
[0037]
This will be described with reference to FIGS.
[0038]
FIGS. 4A and 4B show a hard plate 212 having a length L on one side and a rounded portion 214 having a radius of curvature R at a corner. R = L / 2 (that is, the hard plate 212 is circular), and FIG. 4B shows a case where R has an arbitrary value. FIG. 4C shows a hard plate 212 ′ (an octagon as a whole) provided with a straight chamfered portion 214 ′ at the corner as a reference.
[0039]
In general, the area of the hard plate 212 having a length L on one side provided with a radius portion 214 having a radius of curvature R = L / n (n is a real number of 2 or more) is a square having a length L on one side (the radius portion is (Not provided), the area S ′ = L ² (4-π) / n ² of the hatched region in FIGS.
Minus the value. Then, a value A = (4-π) / n ² obtained by dividing S ′ by the area S = L ² of the square.
Represents the degree of decrease in the effective cross-sectional area in the horizontal direction due to the provision of the radius portion 214 (here, this is referred to as “the reduction rate of the effective cross-sectional area”). This value is preferably small from the viewpoint of securing a wide effective area.
[0040]
For example, as shown in FIG. 4A, when n = 2, A ≒ 0.215. If n = 4, A ≒ 0.0537, n = 5, A ≒ 0.0343, n = 6, A ≒ 0.0238, and n = 7, 0.0175.
[0041]
FIG. 5 is a graph showing the relationship between the radius of curvature R and the above-described reduction rate (%) of the effective area. As can be seen from this graph, the radius of curvature R is set to L / 7 ≦ R ≦ L / 4 as in the present invention (1).
Within this range, the rate of decrease in the effective area can be kept low (that is, a wide effective area can be ensured), and the occurrence of directionality in the seismic isolation performance can be alleviated.
[0042]
Similarly, for the hard plate 212 ′ shown as a reference in FIG. 4 (C), when the reduction rate of the effective cross-sectional area is calculated in the same manner, when the length M of one side of the chamfered portion is M = L / 5, 0 .08 and 0.0225 in the case of M = 0.15L. However, in any case, depending on the direction and degree of deformation of the seismic isolation structure, a large force may locally act on the surface rubber layer in contact with both end positions 216 of the chamfered portion 214 '.
[0043]
Further, in the seismic isolation structure 102 of the present embodiment, the thickness of the covering material 116 is constant, and the strength thereof is also constant, so that damage to the covering material 116 is further prevented.
[0044]
In the present invention, the corner of the hard plate 112 only needs to be the radius 126 having a radius of curvature R that satisfies the above equation (1), and the specific configuration of the seismic isolation structure is limited to the above. Not done. For example, the hard plate 112 may have a rectangular shape instead of a square shape. In this case, the length of the long side of the rectangle may be taken as L in the above equation (1). Further, the angle formed by each side of the rectangle other than 90 degrees (parallelogram or trapezoid) may be used.
[0045]
Although the length L of the side of the hard plate is not particularly limited, it is preferably, for example, not less than 600 mm and not more than 1400 mm, since it can be applied to most buildings. From the same viewpoint, it is preferable that the height of the seismic isolation structure be 200 mm or more and 700 mm or less between the mounting flanges 118 (see FIG. 1).
[0046]
In the above description, an example in which the seismic isolation structure is applied to the existing building 104 has been described. However, the present invention is not limited to this. For example, it is also possible to apply the seismic isolation structure of the present invention when building a new building. It is possible.
[0047]
【The invention's effect】
Since the present invention is configured as described above, it is possible to reliably reduce the local stress on the soft plate regardless of the direction of deformation while maintaining the compactness of the seismic isolation structure, and to reduce the occurrence of directionality in performance. it can.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a seismic isolation structure according to an embodiment of the present invention.
FIG. 2 is a front view schematically showing a building to which the seismic isolation structure of one embodiment of the present invention is applied.
FIG. 3 is a sectional view taken along line III-III of FIG. 1 showing the seismic isolation structure of one embodiment of the present invention.
4A and 4B are explanatory diagrams for explaining a relationship between a shape of a hard plate and an effective cross-sectional area. FIG. 4A is a diagram illustrating a case where the hard plate is circular, and FIG. (C) shows the case where a straight chamfer is provided at the corner of the hard plate.
FIG. 5 is a graph showing a relationship between a radius of curvature of a radius portion provided on a hard plate and a reduction rate of an effective area.
FIG. 6 is a longitudinal sectional view showing a conventional rubber bearing.
FIG. 7 is a sectional view taken along line VV of FIG. 6 showing a conventional rubber bearing.
[Explanation of symbols]
102 Seismic isolation structure 104 Building (superstructure)
106 Building foundation (supporting members)
108 Steel frame 112 Hard plate 114 Soft plate 116 Coating material 124 Plug (plastic deformation member)
126 are (corner)
128 recess (arranged part)

Claims (7)

A seismic isolation structure provided between the support member and the upper structure,
A plurality of hard plates formed in a substantially square shape,
The hard plate is alternately laminated and laminated, and a soft plate that can be elastically sheared and deformed,
A covering member arranged to cover an outer end surface of the hard plate,
Has,
A seismic isolation structure wherein a radius of curvature R of a corner of the hard plate is set to satisfy L / 7 ≦ R ≦ L / 4 with respect to a length L of a long side of the hard plate. . A plastically deformable member that penetrates in the laminating direction of the hard plate and the soft plate and undergoes plastic deformation under shear.
The seismic isolation structure according to claim 1, comprising: The seismic isolation structure according to claim 1, wherein the hard plate is formed in a substantially square shape. The seismic isolation structure according to claim 3, wherein a length L of one side of the hard plate is not less than 600 mm and not more than 1400 mm. On both end surfaces in the laminating direction of the hard plate and the soft plate, each has a mounting flange for mounting to a support member and an upper structure,
The seismic isolation structure according to any one of claims 1 to 4, wherein a height between the two mounting flanges is 200 mm or more and 700 mm or less. A method of arranging a seismic isolation structure according to any one of claims 1 to 5, wherein the seismic isolation structure is arranged between a support member and an existing structure.
An installation part for arranging a seismic isolation structure is formed on the ground, a support member is provided in this arrangement part, and then the seismic isolation structure is provided. A method of arranging a seismic isolation structure characterized by being attached to an object. A seismic isolation structure provided between the support member and the structure,
A plurality of hard plates formed in a substantially square shape,
The hard plate is alternately laminated and laminated, and a soft plate that can be elastically sheared and deformed,
A covering member arranged to cover an outer end surface of the hard plate,
Has,
A seismic isolation structure wherein a radius of curvature R of a corner of the hard plate is set to satisfy L / 7 ≦ R ≦ l / 4 with respect to a length L of a long side of the hard plate. .

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