Seismic isolation structure

Abstract

To provide a base-isolation structure capable of achieving a longer natural period without making tension members longer.SOLUTION: The present invention relates to base-isolation structures 1, 100 and 200 provided between a lower structural object 2 and an upper structural object 3, and comprising: an upper structure 10 fixed to the upper structural object 3; a lower joint material 21 fixed to the lower structural object 2; and a first intermediate structure 30 provided between the upper structure 10 and a lower structure 20, wherein the first intermediate structure 30 has: a first intermediate structure upper end part 30a of an upper end part; a first intermediate structure lower end part 30b of a lower end part; and a first intermediate structure connection part 30c connecting the first intermediate structure upper end part 30a and the first intermediate structure lower end part 30b. The base-isolation structures 1, 100 and 200 have: a first tension member 40 provided between an upper structure lower end part 10b of the upper structure 10 and the first intermediate structure upper end part 30a; and a second tension member 50 provided between a lower structure upper end part 20b of the lower structure 20 and the first intermediate structure lower end part 30b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a seismic isolation structure provided between a lower structure and a superstructure. [Background technology]

[0002] BACKGROUND ART In structures such as buildings, it is known to provide a seismic isolation structure between a substructure, such as a foundation, and an upper structure in order to reduce vibrations transmitted from the ground during an earthquake.

[0003] A known example of such a seismic isolation structure is one that has a plurality of diagonal bars fixed to the lower structure, a plurality of inverted diagonal bars fixed to the upper structure, and tension members (connecting members) connected to an upper casing attached to the upper ends of the diagonal bars and a lower casing attached to the lower ends of the inverted diagonal bars and positioned below the upper casing, with the tension members supporting the upper structure relative to the lower structure in a simple pendulum manner (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2-35141 Summary of the Invention [Problem to be solved by the invention]

[0005] In general, seismic isolation performance can be improved by lengthening the natural period of a seismic isolation structure. In the conventional seismic isolation structure described above, the natural period is determined by the length of the pendulum formed by the tension member, so in order to achieve higher seismic isolation performance, the tension member must be made longer.

[0006] However, in order to lengthen the tension members in the above-mentioned conventional seismic isolation structure, it is necessary to increase the vertical space between the substructure and the superstructure. This requires increasing the height of the first floor of the building or deepening the base of the foundation, which increases the cost of installing the seismic isolation structure.

[0007] An object of the present invention is to provide a seismic isolation structure that can lengthen the natural period without lengthening the tension members. [Means for solving the problem]

[0011] The seismic isolation structure of the present invention is A seismic isolation structure provided between a lower structure and a superstructure, comprising: an upper structure fixed to the upper structure; a lower structure fixed to the lower structure; and a first intermediate structure provided between the upper structure and the lower structure, wherein the first intermediate structure has a first intermediate structure upper end portion at the upper end of the first intermediate structure, a first intermediate structure lower end portion at the lower end of the first intermediate structure, and a first intermediate structure connecting portion connecting the first intermediate structure upper end portion and the first intermediate structure lower end portion, a first tension member provided between the upper structure lower end portion at the lower end of the upper structure and the first intermediate structure upper end portion, and a second tension member provided between the lower structure upper end portion at the upper end of the lower structure and the first intermediate structure lower end portion, a tilt prevention hanging member that hangs down from the upper structure and suspends and holds the first intermediate structure; and .

[0012] In the above-described configuration, the seismic isolation structure of the present invention preferably further comprises a damping device provided between the upper structure and the lower structure for damping vibrations of the upper structure. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a seismic isolation structure that can lengthen the natural period without lengthening the tension members. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a front view schematically showing the configuration of a seismic isolation structure according to one embodiment of the present invention. [Figure 2] 10(a) and 10(b) are diagrams showing modified examples of the lower structure. [Figure 3] FIG. 2 is a front view showing the seismic isolation structure shown in FIG. 1 in a state where the seismic isolation operation is being performed. [Figure 4] FIG. 10 is a front view schematically showing the configuration of a modified seismic isolation structure in which two intermediate structures are provided between the upper structure and the lower structure. [Figure 5]FIG. 10 is a perspective view schematically showing the configuration of a seismic isolation structure according to another embodiment of the present invention. [Figure 6] FIG. 10 is a front view schematically showing the configuration of a seismic isolation structure according to yet another embodiment of the present invention. [Figure 7] FIG. 7 is a plan view of the seismic isolation structure shown in FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A seismic isolation structure according to the present invention will be described in detail below with reference to the accompanying drawings.

[0016] As shown in Figure 1, a seismic isolation structure 1, which is one embodiment of the present invention, is installed between a substructure 2 and a superstructure 3. The seismic isolation structure 1 can reduce horizontal vibrations transmitted from the ground to the superstructure 3 via the substructure 2.

[0017] Multiple seismic isolation structures 1 can also be arranged between the substructure 2 and the superstructure 3. The arrangement pattern and number of multiple seismic isolation structures 1 arranged between the substructure 2 and the superstructure 3 can be changed as appropriate.

[0018] The substructure 2 is a structure directly or indirectly fixed to the ground. The superstructure 3 is a structure constructed above the substructure 2. In this embodiment, the substructure 2 is the foundation of a building, and the superstructure 3 is a building such as a building, a warehouse, or a wooden structure.

[0019] The substructure 2 is not limited to the foundation of a building, and may be any other structure, such as a part constituting the lower floor of a building, as long as it is a structure fixed to the ground. If the substructure 2 is a part constituting the lower floor of a building, the superstructure 3 is a part constituting the upper floor of the building.

[0020] The seismic isolation structure 1 comprises an upper structure 10, a lower structure 20, a first intermediate structure 30, a first tension member 40 and a second tension member 50.

[0021] The upper structure 10 is fixed to the superstructure 3. The upper structure 10 can be configured to include, for example, a columnar portion 10a extending in the vertical direction, and an upper structure lower end portion 10b provided at the lower end of the column portion 10a so as to protrude horizontally like a beam, and be fixed to the underside of the superstructure 3 at the upper end of the column portion 10a. The upper structure 10 is configured, for example, using steel or the like, so as to have a predetermined rigidity capable of supporting a combination of loads transmitted to the upper structure 10, including the weight of the superstructure 3, live load, earthquake load, wind load, etc.

[0022] As long as the upper structure 10 has an upper structure lower end 10b at its lower end and is fixed to the superstructure 3, it is not limited to an L-shape in which the upper structure lower end 10b is cantilevered from the lower end of a single column 10a, and similar to the lower structure 20, its shape or configuration can be modified in various ways, such as an inverted gate-type configuration as shown in Figure 2(a) or an inverted truss structure configuration as shown in Figure 2(b).

[0023] The lower structure 20 is fixed to the lower structure 2. The lower structure 20 can be configured to include, for example, a columnar portion 20a extending in the vertical direction, and a lower structure upper end portion 20b provided at the upper end of the column portion 20a so as to protrude horizontally like a beam, and be fixed to the upper surface of the lower structure 2 at the lower end of the column portion 20a. The lower structure 20 is configured, for example, using steel material or the like, so as to have a predetermined rigidity capable of supporting a combination of loads transmitted to the lower structure 20, including the weight of the upper structure 3 and the seismic isolation structure 1, live load, earthquake load, wind load, etc.

[0024] The lower structure upper end 20b is preferably positioned higher than the upper structure lower end 10b.

[0025] As long as the lower structure 20 has a lower structure upper end 20b at its upper end and is fixed to the substructure 2, it is not limited to an inverted L-shape in which the lower structure upper end 20b is cantilevered from the upper end of a single column 20a. For example, as shown in Figure 2(a), it may have a gate-like configuration in which the upper ends of a pair of parallel columns 20a are connected by the lower structure upper end 20b, or as shown in Figure 2(b), it may have a truss structure in which the upper ends of three inclined columns 20a are joined by the lower structure upper end 20b. The shape and configuration can be modified in various ways.

[0026] The first intermediate structure 30 is provided between the upper structure 10 and the lower structure 20. The first intermediate structure 30 may have, for example, a first intermediate structure upper end portion 30a provided at the upper end of the first intermediate structure 30 so as to protrude horizontally like a beam, a first intermediate structure lower end portion 30b provided at the lower end of the first intermediate structure 30 so as to protrude horizontally like a beam in a direction different from that of the first intermediate structure upper end portion 30a, and a columnar first intermediate structure connecting portion 30c connecting the first intermediate structure upper end portion 30a and the first intermediate structure lower end portion 30b. The first intermediate structure 30 is configured, for example, using steel or the like, so as to have a predetermined rigidity capable of supporting a combination of loads transmitted to the first intermediate structure 30, including the weight of the upper structure 3 and the upper structure 10, live load, earthquake load, wind load, etc.

[0027] The shape or configuration of the first intermediate structure 30 can be modified in various ways as long as it has a first intermediate structure upper end portion 30a at the upper end portion, a first intermediate structure lower end portion 30b at the lower end portion, and a first intermediate structure connecting portion 30c that connects the first intermediate structure upper end portion 30a and the first intermediate structure lower end portion 30b.

[0028] The first tension member 40 is provided between the upper structure lower end 10b at the lower end of the upper structure 10 and the first intermediate structure upper end 30a of the first intermediate structure 30. The first tension member 40 is configured to have a tensile strength capable of supporting a combination of loads transmitted to the first tension member 40, including the weight of the upper structure 3 and the upper structure 10, live load, earthquake load, wind load, etc. More specifically, the first tension member 40 is formed, for example, from a steel material or the like, into a rod shape extending in the up-down direction (along the vertical direction), and is connected at its lower end to the upper structure lower end 10b by a pin joint and at its upper end to the first intermediate structure upper end 30a by a pin joint. This allows the first tension member 40 to tilt (rotate) in any direction in the horizontal direction relative to the upper structure lower end 10b and the first intermediate structure upper end 30a, respectively.

[0029] The connection structure of the first tension member 40 to each of the upper structure lower end 10b and the first intermediate structure upper end 30a is not limited to pin joints, but may be other structures such as a connection structure using a universal joint or a connection structure using a ring member, as long as it can transmit tensile loads and allows the first tension member 40 to tilt (rotate) relative to each of the upper structure lower end 10b and the first intermediate structure upper end 30a. Furthermore, the first tension member 40 is not limited to a steel bar, but may also be a wire, chain, etc.

[0030] The second tension member 50 is provided between the lower structure upper end 20b at the upper end of the lower structure 20 and the first intermediate structure lower end 30b of the first intermediate structure 30. The second tension member 50 is configured to have a tensile strength sufficient to support a combination of loads transmitted to the second tension member 50, including the weights of the upper structure 3, the upper structure 10, the first tension member 40, and the first intermediate structure 30, as well as live loads, earthquake loads, wind loads, and the like. More specifically, the second tension member 50 is formed, for example, from a steel material or the like, into a rod shape extending in the up-down direction (along the vertical direction), and is connected at its upper end to the lower structure upper end 20b by a pin joint and at its lower end to the first intermediate structure lower end 30b by a pin joint. This allows the second tension member 50 to tilt (rotate) in any horizontal direction relative to the lower structure upper end 20b and the first intermediate structure lower end 30b, respectively.

[0031] The connection structure of the second tensile member 50 to each of the upper end portion 20b of the lower structure and the lower end portion 30b of the first intermediate structure is not limited to pin joints, but may be other structures such as a connection structure using a universal joint or a connection structure using a ring member, as long as it can transmit tensile loads and allows the second tensile member 50 to tilt (rotate) relative to each of the upper end portion 20b of the lower structure and the lower end portion 30b of the first intermediate structure. Furthermore, the second tensile member 50 is not limited to a steel bar, but may also be a wire, chain, etc.

[0032] The first intermediate structure 30 is provided with an anti-tilt structure as appropriate to prevent the first intermediate structure 30 from tilting relative to the lower structure 2 or the upper structure 3. The specific configuration of the anti-tilt structure will be described later.

[0033] In the seismic isolation structure 1 configured as described above, the upper structure 10 is suspended and held in a pendulum-like manner by a first tensioning member 40 provided between the upper structure lower end 10b of the upper structure 10 and the first intermediate structure upper end 30a of the first intermediate structure 30, and the first intermediate structure 30 is suspended and held in a pendulum-like manner by a second tensioning member 50 provided between the lower structure upper end 20b of the lower structure 20 and the first intermediate structure lower end 30b of the first intermediate structure 30. As a result, as shown in Figure 3, when the lower structure 2 vibrates horizontally relative to the upper structure 3 due to an earthquake or the like, the seismic isolation structure 1 configured as described above performs seismic isolation operation by causing the first tensioning member 40 and the second tensioning member 50 to tilt in the vibrating direction like a pendulum due to the vibration, thereby suppressing the transmission of the vibration to the upper structure 3.

[0034] In the seismic isolation structure 1 of this embodiment having the above configuration, both the first tensioning member 40 and the second tensioning member 50 are configured to tilt like pendulums during seismic isolation operation, so the natural period for horizontal vibration corresponds to the natural period of a simple pendulum having a length equal to the sum of the lengths of the first tensioning member 40 and the second tensioning member 50. Therefore, in the seismic isolation structure 1 of this embodiment, the natural period during seismic isolation operation can be lengthened without lengthening the tensioning members.

[0035] Furthermore, in the seismic isolation structure 1 of this embodiment having the above-mentioned configuration, the natural period during seismic isolation operation can be lengthened without lengthening the tension members, so there is no need to increase the first floor height of the building or deepen the position of the base plate of the foundation in order to expand the vertical space between the lower structure 2 and the upper structure 3, thereby reducing the cost of installing the seismic isolation structure 1.

[0036] In this way, according to the seismic isolation structure 1 of this embodiment, the natural period can be lengthened and the seismic isolation performance of the seismic isolation structure 1 can be improved without increasing installation costs.

[0037] As shown in FIG. 4, the seismic isolation structure 1 can be configured such that a second intermediate structure 31 is provided between a first intermediate structure 30 and a lower structure 20.

[0038] Similar to the first intermediate structure 30, the second intermediate structure 31 may have a configuration including, for example, a second intermediate structure upper end portion 31a provided in a beam-like manner protruding horizontally from the upper end portion of the second intermediate structure 31, a second intermediate structure lower end portion 31b provided in a beam-like manner protruding horizontally from the lower end portion of the second intermediate structure 31 in a direction different from the second intermediate structure upper end portion 31a, and a columnar second intermediate structure connecting portion 31c connecting the second intermediate structure upper end portion 31c and the second intermediate structure lower end portion 31b. The second intermediate structure 31 is configured, for example, using steel or the like, so as to have a predetermined rigidity capable of supporting a combination of loads transmitted to the second intermediate structure 31, including the weights of the superstructure 3, the superstructure 10, the first tension member 40, the first intermediate structure 30, and the third tension member 60, as well as live loads, earthquake loads, wind loads, and the like.

[0039] The shape or configuration of the second intermediate structure 31 can be modified in various ways as long as it has a second intermediate structure upper end portion 31a at the upper end, a second intermediate structure lower end portion 31b at the lower end, and a second intermediate structure connecting portion 31c that connects the second intermediate structure upper end portion 31c and the second intermediate structure lower end portion 31b.

[0040] The second intermediate structure lower end 31b at the lower end of the second intermediate structure 31 is connected to the lower structure upper end 20b by a second tension member 50. More specifically, the second tension member 50 is connected at its upper end to the lower structure upper end 20b of the lower structure 20 by a pin joint, and at its lower end to the second intermediate structure lower end 31b of the second intermediate structure 31 by a pin joint. This allows the second tension member 50 to tilt (rotate) in any horizontal direction relative to each of the lower structure upper end 20b and the second intermediate structure lower end 31b.

[0041] Meanwhile, the second intermediate structure upper end 31a at the upper end of the second intermediate structure 31 is connected to the first intermediate structure lower end 30b of the first intermediate structure 30 by a third tensioning member 60. The third tensioning member 60 is composed of a rod, wire, chain, or the like, having a tensile strength sufficient to support a combination of loads transmitted to the third tensioning member 60, including the weights of the superstructure 3, the superstructure 10, the first tensioning member 40, and the first intermediate structure 30, as well as live loads, earthquake loads, wind loads, and the like. The third tensioning member 60 is connected at its upper end to the second intermediate structure upper end 31c of the second intermediate structure 31 by a pin joint, and at its lower end to the first intermediate structure lower end 30b of the first intermediate structure 30 by a pin joint. This allows the third tensioning member 60 to tilt (rotate) in any horizontal direction relative to the second intermediate structure upper end 31c and the first intermediate structure lower end 30b, respectively. The third tension member 60 may have the same length as the second tension member 50 or may have a different length from the second tension member 50.

[0042] In this way, the seismic isolation structure 1 is configured to include the second intermediate structure 31 provided between the first intermediate structure 30 and the lower structure 20, with the second intermediate structure lower end 31b at the lower end of the second intermediate structure 31 connected to the lower structure upper end 20b by the second tension member 50, and the second intermediate structure upper end 31a at the upper end of the second intermediate structure 31 connected to the first intermediate structure lower end 30b by the third tension member 60. This increases the number of tension members that oscillate like a pendulum between the upper structure 10 and the lower structure 20 due to horizontal vibration of the lower structure 2 relative to the upper structure 3 due to an earthquake or the like, thereby making it possible to further lengthen the natural period during seismic isolation operation of the seismic isolation structure 1. This makes it possible to further lengthen the natural period during seismic isolation operation of the seismic isolation structure 1 without lengthening the tension members, thereby further improving the seismic isolation performance of the seismic isolation structure 1 without increasing installation costs.

[0043] The seismic isolation structure 1 can also be configured such that, in addition to the second intermediate structure 31 and the third tension member 60, multiple intermediate structures and tension members having the same configuration as the second intermediate structure 31 and the third tension member 60 are provided between the first intermediate structure 30 and the lower structure 20.

[0044] The natural period T1 of the seismic isolation structure 1 of this embodiment having the above configuration for horizontal vibration corresponds to the natural period of a simple pendulum having a length equal to the total length of the multiple tension members (e.g., first tension member 40, second tension member 50, and third tension member 60) provided between the upper structure 10 and the lower structure 20. For example, if the lengths of n (n=2, 3, 4, etc.) tension members provided between the upper structure 10 and the lower structure 20 are all the same length L, the natural period T1 can be calculated using the following (Equation 1).

[0045] Formula T1 = 2π × (nL / g) 1 / 2 =2π×(n) 1 / 2 ×(L / g) 1 / 2 (Formula 1)

[0046] In contrast, the natural period T2 for horizontal vibrations in the comparative example of a seismic isolation structure in which the lower structure 2 and the upper structure 3 are supported in a simple pendulum manner by a single tension member of length L can be calculated using the following equation (Equation 2).

[0047] Formula T2 = 2π × (L / g) 1 / 2 (Formula 2)

[0048] In this way, the base isolation structure 1 of this embodiment having the above configuration is configured to support the substructure 2 and the superstructure 3 in a pendulum manner with multiple tension members of length L, so the natural period T1 is set to (n) compared to the natural period T2 of the base isolation structure of the comparative example in which the substructure 2 and the superstructure 3 are supported in a simple pendulum manner with a single tension member of length L. 1 / 2For example, as shown in FIG. 1, if only the first intermediate structure 30 is provided between the upper structure 10 and the lower structure 20, resulting in two tension members (n=2), the effective pendulum suspension length can be doubled, and the natural period T1 can be approximately 1.414 times the natural period T2. Furthermore, as shown in FIG. 4, if the first intermediate structure 30 and the second intermediate structure 31 are provided between the upper structure 10 and the lower structure 20, resulting in three tension members (n=3), the effective pendulum suspension length can be tripled, and the natural period T1 can be approximately 1.732 times the natural period T2. Furthermore, if a similar intermediate structure is provided between the upper structure 10 and the lower structure 20 in addition to the first intermediate structure 30 and the second intermediate structure 31, resulting in four tension members (n=4), the effective pendulum suspension length can be quadrupled, and the natural period T1 can be doubled relative to the natural period T2. In this way, by increasing the number of intermediate structures provided between the upper structure 10 and the lower structure 20, the natural period T1 can be lengthened.

[0049] In the seismic isolation structure 1 of this embodiment having the above configuration, it is preferable that the upper end of the second tensile member 50 is positioned higher than the lower end of the first tensile member 40. With this configuration, the height dimension of the seismic isolation structure 1 can be made equivalent to that of the comparative example. As a result, the seismic isolation structure 1 has a longer natural period T1 than that of the comparative example, and can be placed in the same vertical space as that of the comparative example without increasing the first floor height of the building or deepening the position of the base of the foundation, thereby achieving high seismic isolation performance at low cost.

[0050] When the seismic isolation structure 1 of this embodiment having the above configuration is configured to have the same natural period as the seismic isolation structure of the comparative example described above, the suspension length of each tension member (e.g., first tension member 40, second tension member 50, and third tension member 60) provided between the upper structure 10 and the lower structure 20 can be made shorter than the suspension length of a single tension member in the seismic isolation structure of the comparative example described above. This makes it possible to make the height dimension of the seismic isolation structure 1 of this embodiment shorter than the height dimension of the seismic isolation structure of the comparative example having the same natural period, and to place the seismic isolation structure 1 in a space between the lower structure 2 and the upper structure 3 which has a smaller vertical dimension.

[0051] Fig. 5 is a perspective view that schematically shows the configuration of a seismic isolation structure 100 according to another embodiment of the present invention. In Fig. 5, the same reference numerals are used to designate members that correspond to the members described above.

[0052] As shown in another embodiment of the seismic isolation structure 100 in Figure 5, the seismic isolation structure 100 of the present invention can also be configured in such a way that three upper structures 10 and three lower structures 20 are provided, and the first intermediate structure 30 is suspended and held by three second tension members 50 provided between the upper end portion 20b of the lower structure and the lower end portion 30b of the first intermediate structure of each lower structure 20, and each upper structure 10 is suspended and held by three first tension members 40 provided between the upper end portions 30a of the three first intermediate structures of the first intermediate structure 30 and the lower end portion 10b of the upper structure.

[0053] In the illustrated example, in the seismic isolation structure 100, the lower end portion 30b of the first intermediate structure 30 is formed in the shape of a triangular plate, and the lower ends of the first intermediate structure connecting portions 30c extending upward are fixed to the upper surfaces of the portions near the three vertices.

[0054] The three upper structures 10 are each positioned adjacent to a corresponding first intermediate structure upper end portion 30a of the first intermediate structure 30. The first intermediate structure 30 has three first intermediate structure upper end portions 30a, and a first tension member 40 hangs down from each of the first intermediate structure upper end portions 30a. The lower ends of these three first tension members 40 are connected to the upper structure lower end portions 10b of the corresponding upper structures 10. All three first tension members 40 have the same length.

[0055] Alternatively, a through hole may be provided in the triangular plate-shaped lower end portion 30b of the first intermediate structure, and the lower end portion 10b of the upper structure 10 may be positioned below the lower end portion 30b of the first intermediate structure through the through hole.

[0056] The three lower structures 20 are each positioned near a corresponding vertex of the lower end 30b of the first intermediate structure. A second tension member 50 hangs down from the upper end 20b of each lower structure 20, and the lower ends of these second tension members 50 are connected to the lower end 30b of the first intermediate structure near the corresponding vertex. All three second tension members 50 have the same length.

[0057] With this configuration, the first intermediate structure 30 is suspended and held by three second tension members 50 of the same length at three points arranged to form a surface, and the upper structure 10 is suspended and held by three first tension members 40 of the same length at three points arranged to form a surface, thereby preventing the upper structure 10 and the first intermediate structure 30 from tilting relative to the lower structure 2 or the upper structure 3.

[0058] The tilt prevention configuration shown in FIG. 5 can also be applied to a configuration in which a second intermediate structure 31 is provided between a first intermediate structure 30 and a lower structure 20, as shown in FIG.

[0059] Fig. 6 is a front view schematically showing the configuration of a seismic isolation structure 200 according to still another embodiment of the present invention, and Fig. 7 is a plan view of the seismic isolation structure 200 shown in Fig. 6. In Fig. 6 and Fig. 7, the same reference numerals are used to designate members corresponding to the members described above.

[0060] As shown in Figures 6 and 7 as yet another embodiment, the seismic isolation structure 200 of the present invention can be configured to have a tilt prevention hanging member 40 that hangs down from the upper structure 3 and suspends and holds the first intermediate structure 30.

[0061] The seismic isolation structure 200 shown in Figures 6 and 7 has only a first intermediate structure 30 provided between the upper structure 10 and the lower structure 20, and is configured with one upper structure 10 and three lower structures 20.

[0062] The upper structure 10 has an inverted configuration of the truss structure shown in Fig. 2(b). That is, the upper structure 10 has three columns 10a joined together at their lower ends, and the upper ends of these columns 10a are fixed to the underside of the superstructure 3. The lower ends of the three columns 10a of the upper structure 10 joined together form the upper structure lower end portion 10b.

[0063] Three lower structures 20 are provided, each having a truss structure as shown in Fig. 2(b). That is, each lower structure 20 has three columns 20a joined to each other at their upper ends, and the lower ends of these columns 20a are fixed to the underside of the upper structure 3. The joined upper ends of the three columns 20a of each lower structure 20 form a lower structure upper end portion 20b, and a second tension member 50 hangs down from each of these lower structure upper end portions 20b.

[0064] The first intermediate structure 30 has three first intermediate structure connecting portions 30c joined together at their upper ends, and three beam-like first intermediate structure lower end portions 30b arranged in a truss shape, connecting the lower ends of adjacent first intermediate structure connecting portions 30c. The upper ends of the three first intermediate structure connecting portions 30c joined together form the first intermediate structure upper end portion 30a.

[0065] The lower ends of three second tension members 50 hanging down from the lower structure upper end 20b of the lower structure 20 are each connected to the connecting portion between the corresponding first intermediate structure lower end 30b and the first intermediate structure connecting portion 30c of the first intermediate structure 30. In addition, one first tension member 40 hangs down from the first intermediate structure upper end 30a of the first intermediate structure 30, and the lower end of the first tension member 40 is connected to the upper structure lower end 10b of the upper structure 10.

[0066] In the seismic isolation structure 200 configured as described above, three tilt prevention hangers 70 hang down from the superstructure 3. The lower ends of these tilt prevention hangers 70 are each connected to the corresponding first intermediate structure connecting portions 30c of the first intermediate structure 30. The lengths of these tilt prevention hangers 70 are the same.

[0067] With this configuration, the first intermediate structure 30 is suspended and held to the upper structure 3 by three anti-tilt hanging members 70 of the same length at three points arranged to form a plane, thereby preventing the first intermediate structure 30 from tilting relative to the lower structure 2 or the upper structure 3.

[0068] The seismic isolation structures 1, 100, and 200 can be configured to include a damping device 80 between the substructure 2 and the superstructure 3 for damping vibrations of the superstructure 3. For example, in the seismic isolation structure 200 shown in Figures 6 and 7, two oil dampers are provided as damping devices 80 between the lower end of the first tension member 40 and the substructure 2. These damping devices 80 are arranged so that their operating directions are parallel to the horizontal direction and perpendicular to each other, and can damp horizontal vibrations of the superstructure 3 relative to the substructure 2. Because the two damping devices 80 are arranged so that their operating directions are perpendicular to each other, the two damping devices 80 can cooperate to damp horizontal vibrations of the first intermediate structure 30, regardless of the direction of the vibration in any direction within 360 degrees, as long as the vibration is in the horizontal direction.

[0069] The damping device 80 is not limited to an oil damper, and various configurations can be used as long as it is capable of damping vibration. Furthermore, the damping device 80 is not limited to being installed between the lower end of the first tension member 40 and the lower structure 2, and can also be installed in other locations, such as between the upper structure 3 and the upper end of the second tension member 50, as long as it can damp horizontal vibration of the upper structure 3. Furthermore, by installing the damping device 80 so that it functions in the vertical direction, it is also possible to damp vertical vibration.

[0070] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0071] 1. Seismic isolation structure 2 Substructure 3 Superstructure 10 Upper structure 10a Pillar 10b Lower end of upper structure 20 Lower structure 20a Pillar 20b Upper end of lower structure 30 First intermediate structure 30a Upper end of first intermediate structure 30b Lower end of first intermediate structure 30c First intermediate structure connection part 31 Second intermediate structure 31a Upper end of second intermediate structure 31b Second intermediate structure lower end 31c Second intermediate structure connection part 40 First tension member 50 Second tension member 60 Third tensile member 70 Anti-tilt suspension material 80 Damping Device 100 Seismic isolation structure 200 Seismic isolation structure

Claims

1. A seismic isolation structure provided between a lower structure and an upper structure, an upper structure fixed to the superstructure; a lower structure fixed to the lower structure; a first intermediate structure provided between the upper structure and the lower structure, the first intermediate structure has a first intermediate structure upper end portion at an upper end portion of the first intermediate structure, a first intermediate structure lower end portion at a lower end portion of the first intermediate structure, and a first intermediate structure connecting portion connecting the first intermediate structure upper end portion and the first intermediate structure lower end portion, a first tension member provided between a lower end of the upper structure at the lower end of the upper structure and an upper end of the first intermediate structure; a second tension member provided between an upper end of the lower structure at the upper end of the lower structure and a lower end of the first intermediate structure; a tilt prevention hanger that hangs down from the upper structure and suspends and holds the first intermediate structure; A seismic isolation structure characterized by having:

2. The seismic isolation structure according to claim 1 , further comprising a damping device provided between the upper structure and the lower structure for damping vibrations of the upper structure.

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