Base isolation structure

Abstract

To provide a base isolation structure capable of damping vibration by a bearing member having small deformation with respect to the displacement of a structure.SOLUTION: A base isolation structure is provided with a column 16 for supporting a structural body (upper structural body 14), a rotary support part 16A which is provided at one end of the column 16 and is a pin joint in structural design, and an elastic or viscoelastic bearing member 24 which is symmetrically arranged on the other end face of the column 16 around the center line CL of the column 16 and has a compressive rigidity greater than a tensile rigidity.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a seismic isolation structure. [Background technology]

[0002] Patent Document 1 below shows a building in which a seismic isolation device and a damper are installed in a seismic isolation layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-137309 Summary of the Invention [Problem to be solved by the invention]

[0004] As shown in the above-mentioned Patent Document 1, in a building with a seismic isolation structure, displacement is sometimes concentrated in the seismic isolation layer to suppress relative displacement between other layers. Furthermore, in order to attenuate vibrations, dampers or other damping materials may be provided in the seismic isolation layer. In this case, the bearing members that make up the seismic isolation device must be able to shear by an amount equal to the displacement of the structure while supporting the load of the structure, such as a building. Similarly, the damping material must also deform by an amount equal to the displacement of the structure. For this reason, seismic isolation devices and damping materials are required to have a large deformation capacity that corresponds to the displacement of the structure.

[0005] In consideration of the above, an object of the present invention is to provide a seismic isolation structure that can attenuate vibrations using support members that undergo small deformation in response to displacement of the structure. [Means for solving the problem]

[0006] The seismic isolation structure of claim 1 comprises a pillar that supports a structure, a rotational support part that is provided at one end of the pillar and is a pin joint in structural design, and an elastic or viscoelastic bearing member that is arranged symmetrically around the center line of the pillar on the other end face of the pillar and has compressive rigidity greater than tensile rigidity.

[0007] In the seismic isolation structure of claim 1, when a horizontal force acts to the right during an earthquake on a structure supported by columns, if the force is small, the support member undergoes shear deformation to the right and generates a restoring force that tries to return the structure to the left. On the other hand, if the horizontal force becomes large, the rotating support member at one end begins to rotate, causing the column to tilt to the right.

[0008] As a result, the support member attached to the other end of the column is compressed on either the left or right side of the center line of the column by the load of the structure, and a restoring force acts on the column to return it to its original position, tilted to the right. At this time, the support member undergoes shear deformation to the right, and a shear force of the same magnitude as the restoring force acting on the column is generated in the support member.

[0009] In this way, by configuring the structure so that the restoring force of the support members is used until the columns tilt, and then the gravity that accompanies the tilt of the columns restores the structure's posture, the horizontal displacement of the structure due to seismic forces can be absorbed by the tilt of the columns. This makes it possible to build a seismic isolation structure using support members with small shear deformation (high shear rigidity). In other words, vibrations can be damped using support members that deform little relative to the displacement of the structure.

[0010] The seismic isolation structure of claim 2 is the seismic isolation structure of claim 1, wherein the end of the column on the side where the support member is installed is formed wider than the rotation support portion.

[0011] In the seismic isolation structure of claim 2, the end where the support member is located is wider than the end where the pin is connected, so the support member can be located further outward from the center of the column than in a case where the support member is not widened. This makes it easier for compressive forces to act on the support member.

[0012] The seismic isolation structure of claim 3 is the seismic isolation structure of claim 1 or 2, further comprising a restoring member that imparts a restoring force when the structure is displaced.

[0013] In the seismic isolation structure of claim 3, the restoring force can be made larger than in the case where there is no restoring material.

[0014] A seismic isolation structure according to a fourth aspect of the present invention is the seismic isolation structure according to the third aspect, wherein the restoring member is a cable that is pulled when the structure is displaced upward to provide a restoring force.

[0015] In the seismic isolation structure of claim 4, a restoring force can be obtained to return a structure that has been lifted up by an inclined column to its original position.

[0016] The seismic isolation structure of claim 5 is the seismic isolation structure of claim 3, wherein the restoring material is an elastic or viscoelastic restoring material that undergoes shear deformation and imparts a restoring force when the structure is displaced laterally.

[0017] In the seismic isolation structure of claim 5, a restoring force can be obtained to return a structure displaced in the lateral direction to its original state.

[0018] A seismic isolation structure according to claim 6 is the seismic isolation structure according to claim 1, wherein the support members are arranged to incline downward in a direction from the center of the pillar toward the outside.

[0019] In the seismic isolation structure of claim 6, the initial rigidity at the beginning of deformation is high, and a large rigidity effect can be obtained with a support member having a small rigidity.

[0020] In addition, the seismic isolation structure of claim 6 may be a seismic isolation structure described in any one of claims 1 to 5, in which the support member is arranged at an incline downward in a direction from the center of the column toward the outside. [Effects of the Invention]

[0021] According to the present invention, vibration can be damped by a support member that undergoes small deformation relative to the displacement of the structure. [Brief explanation of the drawings]

[0022] [Figure 1] 1A is an elevation view showing a building to which a seismic isolation structure according to an embodiment of the present invention is applied, and FIG. 1B is an elevation view showing a state in which the upper structure has been displaced. [Figure 2]FIG. 1A is a plan view showing an example of the arrangement of seismic isolation devices in a seismic isolation structure according to an embodiment of the present invention, and FIG. 1B is a plan view showing another example. [Figure 3] 1 is a cross-sectional view showing an example of a seismic isolation device in a seismic isolation structure according to an embodiment of the present invention. [Figure 4] (A) is a partially enlarged cross-sectional view showing an example of a method for fixing a seismic isolation device in a seismic isolation structure according to an embodiment of the present invention, and (B) is a partially enlarged cross-sectional view showing the state in which a tensile force is applied to the seismic isolation device. [Figure 5] (A) is a cross-sectional view showing an example in which the rotation support part in a seismic isolation structure according to an embodiment of the present invention is formed using a spherical bearing, (B) is a cross-sectional view showing an example in which the rotation support part is formed using a pivot bearing, and (C) is a cross-sectional view showing an example in which the rotation support part is formed using a bearing consisting of a piston with an elastomer sealed inside. [Figure 6] (A) is a cross-sectional view showing an example in which the rotation support part in a seismic isolation structure according to an embodiment of the present invention is formed as a low-rigidity part, and (B) is an elevation view showing an example in which the rotation support part is formed as a low-rigidity part and the column is formed of steel. [Figure 7] FIG. 2 is an elevational view showing various dimensions of columns and support members in a seismic isolation structure according to an embodiment of the present invention. [Figure 8] FIG. 2 is an elevation view conceptually showing the stress state according to the deformation of the support member in the seismic isolation structure according to the embodiment of the present invention. [Figure 9] FIG. 2 is an elevation view conceptually showing the stress state at the lower end of a column in a seismic isolation structure according to an embodiment of the present invention. [Figure 10] 1A is a graph showing the relationship between the displacement of the upper structure relative to the lower structure and the restoring force against seismic force in a seismic isolation structure according to an embodiment of the present invention, and FIG. 1B is a graph showing specific numerical values. [Figure 11](A) is a graph showing an example of the change in acceleration over time on the top floor of a building to which a seismic isolation structure according to an embodiment of the present invention is applied, (B) is a graph showing an example of the change in acceleration over time on the top floor of a comparative building, and (C) is a graph showing an example of the change in displacement over time on the top floor of a building to which a seismic isolation structure according to an embodiment of the present invention is applied. [Figure 12] FIG. 1 is an elevation view showing an example in which a restoring material is added to a seismic isolation structure according to an embodiment of the present invention. [Figure 13] 10 is a graph showing the restoring force of an added restoring material in a seismic isolation structure according to an embodiment of the present invention. [Figure 14] FIG. 10 is an elevation view showing another example of a seismic isolation structure according to an embodiment of the present invention in which a restoring material is added. [Figure 15] (A) is an elevation view showing an example of a seismic isolation structure according to an embodiment of the present invention in which the support members are arranged at an incline, and (B) is a graph showing the restoring force when the support members are arranged at an incline. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, a seismic isolation structure according to an embodiment of the present invention will be described with reference to the drawings. Components indicated by the same reference numerals in the various drawings are the same components. However, unless otherwise specified in the specification, each component is not limited to one, and multiple components may be present.

[0024] Furthermore, descriptions of overlapping configurations and symbols in each drawing may be omitted. Note that the present disclosure is not limited to the following embodiments, and may be implemented by making appropriate modifications, such as omitting configurations, replacing them with different configurations, or combining one embodiment with various modified examples, within the scope of the purpose of the present disclosure.

[0025] <Building> 1(A) shows a building 10 to which a seismic isolation structure according to an embodiment of the present invention is applied. The building 10 is, as an example, a building with a column capital seismic isolation structure, and is configured with a substructure 12, an upper structure 14, and columns 16 between the substructure 12 and the upper structure 14.

[0026] The lower structure 12 may be, for example, a structure below the seismic isolation layer in a building with mid-story seismic isolation, or may be a foundation supporting the upper structure 14. The number of columns 16 is not particularly limited, and they may be appropriately arranged at the corners, periphery, inside, etc. of the upper structure 14 in a plan view.

[0027] The lower end of the pillar 16 forms a rotation support portion 16A that is pin-joined to the lower structure 12. A seismic isolation device 20 is fixed to the upper end surface 16B of the pillar 16. The upper structure 14 is then fixed to the seismic isolation device 20. In this way, the pillar 16 supports the upper structure 14 via the seismic isolation device 20.

[0028] The end (upper end) of the pillar 16 on which the seismic isolation device 20 is installed is wider than the rotation support part 16A. Specifically, the pillar 16 has a shape in which the cross-sectional area gradually increases from the lower end to the upper end.

[0029] 1, the pillar 16 is made of reinforced concrete, but the embodiment of the present invention is not limited to this. For example, the pillar 16 may be made of steel, as in the case of pillar 18 shown in FIG. 6(B).

[0030] This column 18 comprises a main body 18A with a constant cross-sectional area from the bottom to the top, and a capital part 18B to which the seismic isolation device 20 is fixed at the top end of the main body 18A. The capital part 18B is wider than the main body 18A and is formed to protrude outward from the main body 18A. The wider part of the capital part 18B relative to the main body 18A can be reinforced with a rib 18C.

[0031] (Seismic isolation device) The seismic isolation devices 20 are arranged symmetrically around the center line CL of the column 16. The seismic isolation devices 20 may be cylindrical bearings arranged in plurality on the upper end surface 16B of the column 16, as in the seismic isolation device 20A shown in Fig. 2(A). Alternatively, the seismic isolation device 20 may be an annular bearing arranged in single form on the upper end surface 16B of the column 16, as in the seismic isolation device 20B shown in Fig. 2(B).

[0032] The seismic isolation device 20 is a general term for the seismic isolation devices 20A and 20B. In the following description, they will be referred to as the seismic isolation device 20 unless there is a particular need to distinguish between them.

[0033] 3, the seismic isolation device 20 is configured to include an upper flange 22A, a lower flange 22B, and a support member 24. The upper flange 22A is a steel plate and is fixed to the upper structure 14. Similarly, the lower flange 22B is a steel plate and is fixed to the column 16.

[0034] A steel plate 14L is fixed to the upper structure 14, and the upper flange 22A is bolted to the steel plate 14L. Similarly, a steel plate 16L is fixed to the column 16, and the lower flange 22B is bolted to the steel plate 16L. The steel plates 14L and 16L may be omitted.

[0035] The bearing member 24 is a laminated rubber bearing, and is fixed to the upper flange 22A and the lower flange 22B. The rubber forming the bearing member 24 is a laminated rubber of a natural rubber type having elasticity or viscoelasticity. The number of laminated rubber layers is not particularly limited, and may be the same as the number of laminated rubber layers used in bearing members of general seismically isolated buildings.

[0036] However, it is preferable that the number of layers of the laminated rubber be about one-third of the number of layers used in a general bearing member. For example, it is recommended to use about 10 layers. This gives the bearing member 24 greater shear rigidity than a general bearing member.

[0037] 4(A) and 4(B), the lower flange 22B is fixed so as to be movable toward and away from the column 16 (steel plate 16L). Specifically, a through hole H1 is formed in the lower flange 22B, and a bushing BR is fitted into this through hole H1.

[0038] The bushing BR is composed of annular metal parts B1, B2, and B3, and rubber parts R1 and R2. Rubber part R1 is disposed between metal parts B1 and B2, and rubber part R2 is disposed between metal parts B2 and B3. Rubber part R1 is fixed to metal parts B1 and B2, and rubber part R2 is fixed to metal parts B2 and B3.

[0039] A flange is formed at the upper end of the outermost metal part B1, and this flange protrudes outward from the through-hole H1 and is engaged with the lower flange 22B of the seismic isolation device 20. In addition, the innermost metal part B3 is pressed by the bolt BL via the stopper S1.

[0040] 4(B), when an upward tensile force acts on the lower flange 22B, the metal part B1 engaged with the lower flange 22B is lifted, and the rubber parts R1 and R2 elastically deform, allowing the displacement of the lower flange 22B. Meanwhile, the metal part B1 comes into contact with the stopper S1, restricting the amount of displacement of the lower flange 22B.

[0041] As a result, even if a tensile force acts on the seismic isolation device 20, the tensile force is not input to the support member 24 until the lift of the lower flange 22B reaches a predetermined displacement.

[0042] In addition to (or instead of) fixing the lower flange 22B to the column 16 (steel plate 16L) so that it can be moved toward or away from the column 16, the upper flange 22A shown in Fig. 3 may be fixed to the upper structure 14 (steel plate 14L) so that it can be moved toward or away from the column 16. Alternatively, the bushing BR does not necessarily need to be provided, and it is sufficient that the tensile rigidity of the support member 24 is formed to be smaller than the compressive rigidity.

[0043] (Rotation support part) 5(A) is used for the rotation support part 16A. The spherical bearing 30 is used by combining a recessed member 30A and a protruding member 30B. For example, the recessed member 30A is embedded in the lower structure 12, and the protruding member 30B is fixed to the lower end of the pillar 16.

[0044] The curved surface formed on the recessed member 30A and the curved surface formed on the protruding member 30B have the same curvature, and the protruding member 30B can rotate and displace while in contact with the recessed member 30A.

[0045] As the rotation support portion 16A, for example, a pivot bearing 32 shown in FIG. 5(B) may be used.

[0046] The pivot bearing 32 is used in combination with a lower shoe 32A having a convex portion and an upper shoe 32B having a concave portion, and for example, the lower shoe 32A is fixed to the lower structure 12 and the upper shoe 32B is fixed to the lower end of the column 16.

[0047] The curved surface formed on the lower shoe 32A and the curved surface formed on the upper shoe 32B have the same curvature, and the upper shoe 32B can rotate and displace while in contact with the lower shoe 32A.

[0048] Furthermore, as the rotation support portion 16A, for example, a bearing 34 shown in FIG. 5(C) may be used, which is configured as a piston filled with elastomer.

[0049] This bearing 34 is a sliding bearing with a pin function (for example, a Uniton bearing (registered trademark)). It is used in combination with a base member 34A with a recess and a bearing body 34B with a protrusion. For example, the base member 34A is fixed to the lower structure 12, and the bearing body 34B is fixed to the lower end of the column 16.

[0050] An elastomer 34C is disposed in the recess of the base member 34A and the protrusion of the support body 34B. The support body 34B can rotate and displace while squeezing the elastomer 34C.

[0051] Furthermore, the rotation support portion 16A may be, for example, a low-rigidity portion 36 shown in FIGS. 6(A) and 6(B).

[0052] The low rigidity portion 36 is formed by combining a steel lower plate 36A, an upper plate 36B, and a main body portion 36C, and for example, the lower plate 36A is fixed to the lower structure 12 and the upper plate 36B is fixed to the lower end of the column 16.

[0053] The main body 36C is a steel material fixed to the lower plate 36A and the upper plate 36B, and is formed using a solid square column or cylinder, a hollow square tube or cylinder, an H-shaped steel, etc. The low rigidity portion 36 has a low bending rigidity compared to other portions of the column 16, and forms a plastic hinge against bending forces input to the column 16, for example.

[0054] As described above, in the present invention, various aspects of the rotation support portion can be adopted. The rotation support portion may be any portion of the column 16 (or column 18) that can be regarded as a pin joint in terms of structural design. In other words, the rotation support portion may be any portion of the column 16 (or column 18) that has lower rigidity than other portions and that serves as the center of rotation when an external force is applied.

[0055] <Action and effect> In the seismic isolation structure according to the embodiment of the present invention, when a horizontal force acts on the building 10, the upper structure 14 is displaced. For example, as shown in Figure 1(B), when a horizontal force acts to the right during an earthquake on the upper structure 14 supported by the column 16, if the force is small, the support member 24 of the seismic isolation device 20 undergoes shear deformation to the right and generates a restoring force that tries to return the upper structure 14 to the left. On the other hand, if the horizontal force becomes large, the rotation support part 16A provided at the lower end of the column 16 begins to rotate, causing the column 16 to tilt to the right.

[0056] As a result, the support member 24 of the seismic isolation device 20 provided on the upper end surface of the column 16 is compressed to the left of the center line CL of the column 16 by the load of the upper structure 14, and a restoring force acts on the column 16 to return it to its original position, which has been tilted to the right.

[0057] At this time, the support member 24 undergoes shear deformation to the right, and a shear force of the same magnitude as the restoring force acting on the column 16 is generated in the support member 24 .

[0058] In this way, the horizontal displacement of the upper structure 14 due to seismic forces can be absorbed by the tilt of the columns 16, by using the restoring force of the support members 24 until the columns 16 tilt, and then using the gravitational restoration that accompanies the tilt of the columns 16 to restore their posture after the columns 16 tilt.

[0059] This allows the base isolation structure to be constructed using bearing members 24 with small shear deformation (large shear rigidity). In other words, vibrations can be damped with bearing members 24 that undergo small deformation relative to the displacement of the upper structure 14.

[0060] Specifically, the shear force acting on the column 16 is Q, the weight of the upper structure 14 acting on the column 16 is M, the gravitational acceleration is g, as shown in Figure 7, the total vertical length of the column 16 and the seismic isolation device 20 is h, the length of the lower end of the column 16 is D1, and the center-to-center distance of the support members 24 arranged symmetrically about the center line CL of the column 16 is D2.

[0061] Furthermore, the displacement of the upper structure 14 relative to the lower structure 12 is x, and the shear deformation of the elastic body forming the support member 24 is x r Let's say.

[0062] If the shear stiffness of the elastic body forming the support member 24 is k and the degree of fixation of the lower part of the column 16 is sufficiently hard compared to the stiffness of the elastic body, the following equation (1-1) holds until the column 16 begins to tilt.

[0063] Q=kx r =kx (1-1) formula

[0064] The shear force when column 16 begins to tilt is Q0, and the shear deformation of the elastic body is x r0 Then, by transforming the above equation (1-1), the following equation (1-2) holds.

[0065] Q0=kx r0 ···(1-2) formula

[0066] As shown in Figure 8, when the column 16 starts to tilt to the right, a compressive force Mg acts on the left support member 24, sandwiched between the upper structure 14 and the column 16. On the other hand, as mentioned above, no tensile force is input to the left support member 24. This compressive force Mg is applied from the center position of the left support member 24, i.e., from the center line CL of the column 16, to [(D2 / 2)-x r ] acts on a position away.

[0067] A compressive force Mg also acts on the lower end of the column 16. It is assumed that this compressive force Mg acts so that the stress distribution becomes a triangular distribution, as shown in Figure 9. In this case, the compressive force Mg acts at a position that divides the lower end length D1 of the column 16, which is the support width, into 2:1, that is, at a position (D1 / 6) away from the center line CL of the column 16.

[0068] The balance between the shear force couple Q0 and the compressive force couple Mg gives the following equation (2).

[0069] Q0h = Mg[(D2 / 2)-x r0 ]+Mg(D1 / 6) That is, Q0h=Mg[(D2 / 2)+(D1 / 6)-x r0 ]...Equation (2)

[0070] Here, if (D2 / 2) + (D1 / 6) = D, then from equations (1-2) and (2), the following equation (3-1) can be obtained, that is, the shear force Q0 when the column 16 begins to tilt.

[0071] Q0=MgD / [h+(Mg / k)] (3-1) formula

[0072] When the column 16 starts to tilt, the shear force is Q0. If the column 16 is pushed further to the right, the column 16 starts to tilt and the shear force falls below Q0. Regarding the shear force Q at this time, the following equation (4) can be obtained from equations (1-1) and (2).

[0073] Q = Mg(Dx) / h (4)

[0074] From these characteristics, the relationship between the displacement of the upper structure 14 relative to the lower structure 12 and the restoring force against the seismic force can be obtained as shown by the lines N1 and N2 in Figure 10(A). Equation (4) represents the line N2 in Figure 10.

[0075] Also, Figure 10(B) shows the relationship between the displacement of the upper structure 14 relative to the lower structure 12 and the restoring force against seismic force when M = 1000 [t], D1 = 0.8 [m], D2 = 1.0 [m], h = 5.0 [m], and the initial period (the period calculated under conditions before the column 16 begins to tilt, with the upper structure 14 being a rigid body) which depends only on the rigidity of the support member 24 is 1.5 [s].

[0076] Here, the upper structure 14 is treated as a five-mass model, and an earthquake response analysis is performed on the seismic isolation layer (layer formed by the columns 16 and seismic isolation devices 20) with the above characteristics. In this case, the upper structure 14 is treated as a rigid body, and damping is applied to the vibration system with a natural period of 1.5 seconds so that the damping constant is 10%.

[0077] In this case, as shown in Figure 11(A), the maximum acceleration on the fifth floor (top floor) is 2.28 m / s 2 On the other hand, the maximum acceleration of the conventional building shown in Figure 11(B) (a non-base-isolated structure fixed to the foundation, which is a comparative example) is 14.54 [m / s 2 ], and according to the present invention, the maximum acceleration is reduced to about 1 / 6 of that of the conventional example.

[0078] Furthermore, Figure 11(C) shows the displacement of the upper structure 14 relative to the lower structure 12. According to this figure, the maximum displacement of the upper structure 14 is approximately 0.219 [m]. In contrast, the maximum displacement of the support members 24 is the displacement when the columns 16 begin to tilt, which is a displacement of 0.064 [m] at the break point in Figure 10(B). As such, the displacement of the support members 24 is small relative to the displacement of the upper structure 14, and most of the displacement of the upper structure 14 is caused by the tilt of the columns 16. In other words, according to the present invention, even if the displacement of the support members 24 is small relative to the displacement of the upper structure 14, it is possible to obtain an acceleration reduction effect.

[0079] Furthermore, in the seismic isolation structure according to the embodiment of the present invention, the upper end of the pillar 16 is formed wider than the portion where the rotation support portion 16A is provided. This allows the seismic isolation device 20 (bearing member 24) to be positioned further outward from the center of the pillar 16 compared to when the upper end of the pillar 16 is not widened. This makes it easier for compressive force to act on the bearing member 24.

[0080] <Modification> The seismic isolation structure of the present invention may be provided with a restoring member that applies a restoring force when the upper structure 14 is displaced relative to the lower structure 12.

[0081] An example of a restoring material is a cable 40 shown in Fig. 12. The cable 40 is made of, for example, steel, connects the upper end of the column 16 to the lower structure 12, and is pulled to provide a restoring force when the upper structure 14 is displaced upward or laterally. The restoring force of the cable 40 increases as the displacement of the upper structure 14 increases, as shown by the line N3 in Fig. 13.

[0082] On the other hand, the restoring force due to the inclination of the columns 16 and the deformation of the support members 24 decreases as the displacement of the upper structure 14 increases, as shown by the line N2. In this modified example, by combining cables 40 whose restoring force increases as the displacement of the upper structure 14 increases, it is possible to obtain structural characteristics in which the restoring force increases as the displacement of the upper structure 14 increases, as shown by the line N4 (the sum of the restoring force shown by the line N2 and the restoring force shown by the line N3).

[0083] In addition, an elastic body such as a spring may be arranged at the end of the cable 40 to reduce the tensile force input to the cable 40 at the initial stage of displacement of the upper structure 14.

[0084] Another example of the restoring material is an elastic or viscoelastic restoring material, such as high-damping rubber 42 shown in Fig. 14. The high-damping rubber 42 is fixed to the upper surface of a footing 44A fixed to the lower structure 12. A footing 44B is fixed on top of the high-damping rubber 42.

[0085] A downwardly protruding stress transmission member 46 is fixed to the upper structure 14. The stress transmission member 46 is displaced in accordance with the displacement of the upper structure 14, and deforms the high-damping rubber 42 via the footing 44B. Even when such a restoring material is used, the structural characteristics shown in Figure 13 can be obtained.

[0086] In the seismic isolation structure of the present invention, the upper end surface 16B of the pillar 16 is formed so as to follow a horizontal plane, but the embodiment of the present invention is not limited to this. For example, as shown in Fig. 15(A), the upper end surface 16B of the pillar 16 may be formed so as to be inclined, and the seismic isolation device 20 may be arranged so that the outer side is inclined downward.

[0087] In this embodiment, if the inclination angle of the center line CL2 of the support member 24 of the seismic isolation device 20 relative to the vertical direction is θ, then the above equation (3-1) can be rewritten as the following equation (3-2).

[0088] Q0=Mg(D+Mgθ) / [h+(Mg / k)]···(3-2) formula

[0089] In this formula (3-2), the shear force Q0 when the column 16 begins to tilt is larger than in formula (3-1). According to this embodiment, the initial rigidity is larger as shown by the line N5 in Figure 15(B), and a large rigidity effect can be obtained using the same support member 24.

[0090] It is preferable to determine the inclination angle θ so that the intersection O of the center lines CL2 of the support members 24 arranged on both sides of the center line CL of the column 16 is below the rotation support part 16A. This makes it easier to obtain the gravity restoration effect.

[0091] In addition, in the above embodiment, the rotation support portion 16A is formed at the lower end of the pillar 16, and the seismic isolation device 20 is arranged on the upper end surface of the pillar 16, but the embodiment of the present invention is not limited to this. For example, the rotation support portion 16A may be formed at the upper end of the pillar 16, and the seismic isolation device 20 may be arranged on the lower end surface of the pillar 16. In other words, the present invention may be configured by inverting the top and bottom of the structure shown in Fig. 1. As such, the present invention can be implemented in various modes. [Explanation of symbols]

[0092] 14 Upper structure (structure) 16 pillars 16A Rotation support part 18 pillars 24 Support member 30 Spherical bearing (rotation support part) 32 Pivot bearing (rotation support part) 34 Bearing (rotation support part) 36 Low rigidity section (rotation support section) 40 Cable (Restored Material) 42 High damping rubber (restoring material)

Claims

1. A column supporting the structure; a rotation support portion provided at one end of the column and having a pin joint in structural design; an elastic or viscoelastic support member disposed symmetrically around the center line of the column on the other end surface of the column, the support member having a compressive stiffness greater than a tensile stiffness; It has a seismic isolation structure.

2. The end of the column on which the support member is installed is formed wider than the rotation support portion. The seismic isolation structure according to claim 1.

3. A restoring material is provided that imparts a restoring force when the structure is displaced. The seismic isolation structure according to claim 1 or 2.

4. The restoring member is a cable that is pulled and imparts a restoring force when the structure is displaced upward. The seismic isolation structure according to claim 3.

5. The restoring material is an elastic or viscoelastic restoring material that undergoes shear deformation and imparts a restoring force when the structure is displaced laterally. The seismic isolation structure according to claim 3.

6. The support member is disposed so as to be inclined downward in a direction from the center of the column toward the outside. The seismic isolation structure according to claim 1.

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