Seismic isolation structure

Abstract

To provide a base isolation structure capable of lengthening a natural period while reducing a vertical space between a lower structure and an upper structure.SOLUTION: A base isolation structure 1 provided between a lower structure 2 and an upper structure 3 includes a fixed structure 10 fixed to one of the lower structure 2 and the upper structure 3, a movable structure 20 supported by the other of the lower structure 2 and the upper structure 3 movably in a horizontal direction, a tension member 30 having one end fixed to the other of the lower structure 2 and the upper structure 3, and a conversion mechanism 40 supported by the fixed structure 10, connected to the tension member 30 and the movable structure 20 and configured to convert a vertical load applied from the movable structure 20 into a tensile force of the tension member 30 so as to reduce a horizontal restoring force applied from the tension member 30 to either of the lower structure 2 and the upper structure 3.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 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 upper structure supported by the tension members in a simple pendulum manner relative to the lower structure (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 while reducing the vertical space between the lower structure and the upper structure. [Means for solving the problem]

[0008] The seismic isolation structure of the present invention according to the configuration (1) is a seismic isolation structure provided between a lower structure and an upper structure, and includes a fixed structure fixed to one of the lower structure and the upper structure, and a fixed structure fixed to the other of the lower structure and the upper structure. was established between The present invention is characterized by comprising a movable structure supported by a support mechanism on either the lower structure or the upper structure so as to be freely movable in the horizontal direction, a tension member having one end fixed to the other of the lower structure or the upper structure, and a conversion mechanism supported by the fixed structure and connected to the tension member and the movable structure, which converts the vertical load applied from the movable structure into a tensile force of the tension member so that the horizontal restoring force applied from the tension member to the other of the lower structure or the upper structure is reduced.

[0009] The seismic isolation structure of configuration (2) of the present invention may be configured such that, in the above configuration (1), the conversion mechanism has a fixed pulley rotatably supported on the fixed structure and a movable pulley rotatably supported on the movable structure, and the tension member is fixed at the other end to either the fixed structure or the movable structure and wound around the fixed pulley and the movable pulley.

[0010] The seismic isolation structure of configuration (3) of the present invention may be configured such that, in the above configuration (1), the conversion mechanism is supported at one end on the fixed structure so as to be able to tilt freely in the vertical direction, and is connected at the other end to either the other end of the tension member or one of the movable structures, and has a lever member connected to the other end of the tension member or the other of the movable structures between the one end and the other end.

[0011] The seismic isolation structure of configuration (4) of the present invention may be configured such that, in the above configuration (1), the conversion mechanism is connected to the movable structure at one end and to the other end of the tension member at the other end, and has a lever member supported on the fixed structure between the connection part with the movable structure and the connection part with the tension member so as to be freely tiltable in the vertical direction, and a direction conversion pulley supported on the fixed structure so as to be freely rotatable, and around which the tension member is wound.

[0012] The seismic isolation structure of configuration (5) of the present invention may be configured such that, in the above configuration (1), the conversion mechanism is configured by a gear mechanism including a first gear rotatably supported on the fixed structure and meshing with a first tooth rod material connected to the movable structure, and a second gear rotatably supported on the fixed structure and meshing with a second tooth rod material connected to the other end of the tension member.

[0013] The seismic isolation structure of configuration (6) of the present invention may be configured as follows: in the above configuration (1), the conversion mechanism has a first diameter portion and a second diameter portion of a different diameter or the same diameter as the first diameter portion, and the conversion mechanism has a cylinder supported by the fixed structure, a first piston attached to the first diameter portion and connected to the movable structure, a second piston attached to the second diameter portion and connected to the other end of the tension member, and a fluid filled inside the cylinder between the first piston and the second piston.

[0014] The seismic isolation structure of the present invention having the configuration (7) in the above configurations (1) to (6) preferably has a support material fixed to either the lower structure or the upper structure, the fixed structure or the movable structure, and a plurality of rollers rotatably supported on the support material and arranged to surround the middle portion of the tension member. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a seismic isolation structure that can lengthen the natural period while reducing the vertical space between the lower structure and the upper structure. [Brief explanation of the drawings]

[0016] [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] FIG. 2 is a front view schematically showing the configuration of a modified example of the seismic isolation structure shown in FIG. 1, in which support members for supporting a plurality of rollers are provided on a movable 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. 2 is a front view schematically showing the configuration of a modified example of the base isolation structure shown in FIG. 1, in which the structure is turned upside down. [Figure 5] FIG. 2 is a front view showing an example of a conversion mechanism. [Figure 6] FIG. 6 is a front view showing the conversion mechanism shown in FIG. 5 in a state where it is performing a seismic isolation operation. [Figure 7] FIG. 10 is a front view showing another example of the conversion mechanism. [Figure 8] FIG. 8 is a front view showing the conversion mechanism shown in FIG. 7 in a state where it is performing a seismic isolation operation. [Figure 9] FIG. 10 is a front view showing yet another example of the conversion mechanism. [Figure 10] FIG. 10 is a front view showing the conversion mechanism shown in FIG. 9 in a state where it is performing a seismic isolation operation. [Figure 11] FIG. 10 is a front view showing yet another example of the conversion mechanism. [Figure 12] FIG. 12 is a front view showing the conversion mechanism shown in FIG. 11 in a state where it is performing a seismic isolation operation. [Figure 13] FIG. 12 is a front view showing a modified example of the conversion mechanism shown in FIG. [Figure 14] FIG. 10 is a front view showing yet another example of the conversion mechanism. [Figure 15] FIG. 15 is a front view showing the conversion mechanism shown in FIG. 14 in a state where it is performing a seismic isolation operation. [Figure 16] FIG. 6 is a front view showing a more specific configuration of the seismic isolation structure shown in FIG. 5. [Figure 17] FIG. 17 is a side view of the seismic isolation structure shown in FIG. [Figure 18] FIG. 17 is a cross-sectional view taken along the line AA in FIG. [Figure 19] FIG. 17 is a front view showing the seismic isolation structure shown in FIG. 16 in a state where the seismic isolation operation is being performed. DETAILED DESCRIPTION OF THE INVENTION

[0017] 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.

[0018] As shown in Figure 1, a seismic isolation structure 1 according to a first embodiment of the present invention is installed between a substructure 2 and an upper structure 3. The seismic isolation structure 1 can reduce horizontal vibrations transmitted from the ground to the upper structure 3 via the substructure 2.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The seismic isolation structure 1 includes a fixed structure 10, a movable structure 20, a tension member 30, and a conversion mechanism 40.

[0023] The fixed structure 10 is fixed to either the lower structure 2 or the upper structure 3. In this embodiment, the fixed structure 10 is fixed to the lower structure 2.

[0024] In this embodiment, the fixed structure 10 is shown schematically as a rectangular shape, but its shape, etc. can be modified in various ways as long as it is constructed, for example, from steel or the like, so as to have a predetermined rigidity that can support a combination of loads transmitted to the fixed structure 10, including the weight of the upper structure 3, live load, earthquake load, wind load, etc.

[0025] The movable structure 20 is supported by either the lower structure 2 or the upper structure 3 (the other to which the fixed structure 10 is not fixed) so as to be movable horizontally. In this embodiment, the movable structure 20 is supported by the upper structure 3 so as to be movable horizontally. The movable structure 20 is movable in any horizontal direction relative to the upper structure 3, and supports the vertical force applied from the upper structure 3.

[0026] The movable structure 20 can be configured to include, for example, a column section 20a configured as a column extending in the vertical direction, a base section 20b provided at the upper end of the column section 20a, and movable structure end sections 20c provided at the lower end of the column section 20a so as to protrude like beams on both sides in the horizontal direction, and be supported by the base section 20b on the underside of the upper structure 3 so as to be freely movable in the horizontal direction. In this case, in order to support the movable structure 20 so as to be freely movable in any horizontal direction relative to the upper structure 3, a support mechanism 21 such as a linear rolling bearing (CLB) or a roller mechanism can be provided between the base section 20b and the underside of the upper structure 3. The support mechanism 21 that supports the movable structure 20 on the underside of the upper structure 3 so as to be freely movable in the horizontal direction is not limited to the linear rolling bearing (CLB) or roller mechanism described above, and various other mechanisms can be used as long as they can support the movable structure 20 so as to be freely movable in any horizontal direction relative to the upper structure 3.

[0027] The movable structure 20 is configured, for example, using steel material, etc., so as to have a predetermined rigidity capable of supporting a combination of loads transmitted to the movable structure 20, including the weight of the upper structure 3 and the seismic isolation structure 1, live load, earthquake load, wind load, etc.

[0028] The movable structure 20 has a movable structure end portion 20c and is supported on either the lower structure 2 or the upper structure 3 so that it can be freely moved horizontally, and its shape or configuration can be modified in various ways, such as a truss structure or a portal structure.

[0029] The tension member 30 is disposed in a vertical position, and its upper end (one end) is fixed to the underside of the superstructure 3. The tension member 30 can be, for example, a string-like member such as a rope, wire, or chain that has a tensile strength sufficient to support a combination of loads transmitted to the tension member 30, including the weight of the superstructure 3 and the movable structure 20, the live load, earthquake load, wind load, etc., of the superstructure 3 and the seismic isolation structure 1, the live load, earthquake load, wind load, etc. However, it may also be a rod-like member made of steel or the like. In this embodiment, the tension member 30 is a rope. When the substructure 2 vibrates horizontally relative to the superstructure 3 due to an earthquake or the like, the tension member 30 can tilt in the vibration direction due to the vibration.

[0030] The seismic isolation structure 1 may also be configured to include a support member 50 fixed to either the lower structure 2 or the upper structure 3 or the movable structure 20, and a plurality of rollers 51 rotatably supported by the support member 50 and arranged to surround the middle portion of the tension member 30. In this embodiment, the support member 50 is fixed to the lower structure 2, and two rollers 51 are rotatably supported on the support member 50 and arranged horizontally opposite each other with the tension member 30 sandwiched between them. More specifically, the support member 50 may be configured to include, for example, a columnar portion 50a extending vertically, a beam portion 50b protruding horizontally like a beam from the upper end of the column portion 50a, and two support protrusions 50c extending upward from the upper surface of the beam portion 50b and arranged horizontally spaced apart, and the two rollers 51 are rotatably supported by the corresponding support protrusions 50c. In this case, when the lower structure 2 vibrates horizontally relative to the upper structure 3 due to an earthquake or the like, the tension member 30 tilts in the vibration direction like a pendulum between the upper structure 3 and the two rollers 51, and is maintained in a vertical position on the side of the lower structure 2 closer to the two rollers 51.

[0031] As shown as a modified example in Fig. 2, the seismic isolation structure 1 can also be configured such that the support members 50 are fixed to the movable structure 20. In this case, the support members 50 do not have column portions 50a, and can be configured such that the beam portions 50b are integrally connected to the column portions 20a of the movable structure 20.

[0032] The conversion mechanism 40 is supported by the fixed structure 10 and connected to the tension member 30 and the movable structure 20, and is configured to convert a vertical load applied from the movable structure 20 into a tensile force of the tension member 30 so that the horizontal restoring force applied from the tension member 30 to the upper structure 3 is reduced. In this embodiment, the conversion mechanism 40 is configured to reduce the vertical load applied from the movable structure 20 and convert it into a tensile force of the tension member 30. That is, the conversion mechanism 40 has a so-called booster configuration and has a first connecting part 41 that is connected to the movable structure 20 and is movable in the vertical direction relative to the fixed structure 10, and a second connecting part 42 that is connected to the lower end (the other end) of the tension member 30 and is movable in the vertical direction relative to the fixed structure 10, and is configured to reduce the vertical displacement of the second connecting part 42 and convert it into a vertical displacement of the first connecting part 41, thereby reducing the vertical load applied from the movable structure 20 and converting it into a tensile force of the tension member 30. In this embodiment, the movable structure end 20c of the movable structure 20 constitutes the first connecting portion 41, but these may be configured separately, with the movable structure end 20c being connected to the first connecting portion 41. Furthermore, the first connecting portion 41 is not limited to being connected to the movable structure 20 at the movable structure end 20c, and may also be configured to be connected to another portion of the movable structure 20, such as the pillar portion 20a or another protruding portion provided on the pillar portion 20a.

[0033] In order to prevent the upper structure 3 from tilting relative to the lower structure 2, an appropriate configuration is provided, such as arranging multiple seismic isolation structures 1 between the lower structure 2 and the upper structure 3, with the horizontal arrangement of the fixed structure 10 and the movable structure 20 reversed.

[0034] As shown in Figure 3, in the seismic isolation structure 1 of this embodiment having the above configuration, when the lower structure 2 vibrates horizontally relative to the upper structure 3 due to an earthquake or the like, the tension member 30 tilts in the vibration direction between the upper structure 3 and the two rollers 51 due to the vibration, and the movable structure 20 moves horizontally relative to the upper structure 3, thereby performing seismic isolation operation and preventing the vibration of the lower structure 2 from being transmitted to the upper structure 3.

[0035] In addition, in the seismic isolation structure 1 of this embodiment having the above configuration, when the tension member 30 tilts in the vibration direction between the upper structure 3 and the two rollers 51 due to the vibration, the second connecting part 42 connected to the lower end of the tension member 30 is pulled upward by the tension member 30 and displaces upward relative to the lower structure 2, and the upward displacement of the second connecting part 42 is reduced by the conversion mechanism 40 and converted into an upward displacement of the first connecting part 41, and the movable structure 20 connected to the first connecting part 41 is displaced upward relative to the lower structure 2. In this case, the conversion mechanism 40 is configured to convert displacement at a conversion magnification α (α>1) such that when the upward displacement of the movable structure 20 relative to the lower structure 2 is y, the upward displacement of the second connecting part 42 relative to the lower structure 2 is αy, and if the amplitude of the horizontal vibration of the lower structure 2 relative to the upper structure 3 is x, the vertical distance between the roller 51 and the upper structure 3 is h, the angle that the tension member 30 makes with respect to the vertical direction is θ, the weight of the upper structure 3 is mg, and the vertical load (compression force) supported by the movable structure 20 is F, the tensile force applied to the tension member 30 is F / α, and therefore, due to the balance of the vertical forces, mg + (F / α) × cosθ - F = 0, and F is given by the following (Equation 1).

[0036] Formula F = {α / (α-cosθ)} × mg (Equation 1)

[0037] In addition, the horizontal restoring force F h is F h = (F / α) × sinθ, so substituting (Equation 1) into this gives the restoring force F h is expressed as follows (Equation 2).

[0038] Formula F h =mgsinθ / (α-cosθ) (Equation 2)

[0039] sinθ=x / (x 2 +h 2 ) 1 / 2 , cosθ=h / (x 2 +h 2 ) 1 / 2 By rearranging (Equation 2) using h is expressed as follows (Equation 3).

[0040] Formula F h =mg / {α(1+(h / x) 2 ) 1 / 2 -(h / x)} (Formula 3)

[0041] When x>>h, h / x→0, so in (Equation 3), the restoring force F h At this time, the horizontal stiffness k of the substructure 2 relative to the superstructure 3 is k=F h / x=mg / αx, so the horizontal natural period T of the substructure 2 relative to the superstructure 3 is T=2π(m / k) 1 / 2 =2π(αx / g) 1 / 2 Therefore, the natural period T of the base isolation structure 1 for horizontal vibration is α 1 / 2 The magnification of the natural period T can be variously changed by changing the conversion magnification α of the conversion mechanism 40.

[0042] As described above, the seismic isolation structure 1 of this embodiment is configured to include a fixed structure 10 fixed to the lower structure 2, a movable structure 20 supported on the upper structure 3 so as to be freely movable horizontally, a tension member 30 having one end fixed to the upper structure 3, and a conversion mechanism 40 supported on the fixed structure 10 and connected to the tension member 30 and the movable structure 20, and configured to convert the vertical load applied from the movable structure 20 into a tensile force of the tension member 30 so that the horizontal restoring force applied from the tension member 30 to the upper structure 3 is reduced, thereby making it possible to lengthen the natural period of the seismic isolation structure 1 during seismic isolation operation.

[0043] Furthermore, in the seismic isolation structure 1 of this embodiment having the above-mentioned configuration, the natural period of the seismic isolation structure 1 during seismic isolation operation can be lengthened, so that it is not necessary to increase the first floor height of the building or to make the base of the foundation deeper 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.

[0044] 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.

[0045] As shown in Figure 4, the seismic isolation structure 1 can be configured in a way that is upside down compared to that shown in Figure 1, i.e., the fixed structure 10 is fixed to the underside of the upper structure 3, the movable structure 20 is supported on the upper surface of the lower structure 2 so as to be freely movable in the horizontal direction, and one end of the tension member 30 is fixed to the upper surface of the lower structure 2. In this case too, the conversion mechanism 40 is supported by the fixed structure 10 and is configured to reduce the vertical displacement of the second connecting part 42 and convert it into a vertical displacement of the first connecting part 41, thereby reducing the vertical load applied from the movable structure 20 and converting it into a tensile force of the tension member 30. In this upside-down configuration shown in Figure 4, as in the case of the configuration shown in Figure 1, the natural period of the seismic isolation structure 1 can be set to α without using the conversion mechanism 40 for a structure in which the displacement of the movable structure 20 and the displacement of the second connecting part 42 are the same. 1 / 2 It can be multiplied by α>1.

[0046] 4, the support member 50 can also be fixed to the movable structure 20, as in the modified example shown in FIG.

[0047] The conversion mechanism 40 can have various configurations as long as it is supported by the fixed structure 10, connected to the tension member 30 and the movable structure 20, and configured to reduce the vertical load applied from the movable structure 20 and convert it into a tensile force of the tension member 30. The specific configuration of the conversion mechanism 40 will be described below.

[0048] As shown in FIG. 5 as an example, the conversion mechanism 40 can have a fixed pulley 60 rotatably supported on the fixed structure 10 and a movable pulley 61 rotatably supported on the movable structure 20, with the other end of the tension member 30 fixed to either the fixed structure 10 or the movable structure 20 and wound around the fixed pulley 60 and the movable pulley 61. In the case shown in FIG. 5, the tension member 30 is wound around the movable pulley 61, fixed pulley 60, and movable pulley 61 in that order, and then the other end is fixed to the fixed structure 10. As a result, the conversion factor α of the conversion mechanism 40 is 3. The conversion factor α of the conversion mechanism 40 can be changed in various ways by changing the number of times the tension member 30 is wound around the fixed pulley 60 and the movable pulley 61.

[0049] The fixed structure 10 may include, for example, a columnar portion 10a extending vertically, a fixed structure end portion 10b provided at the upper end of the column portion 10a so as to protrude horizontally like a beam, and a pulley support portion 10c extending downward from the fixed structure end portion 10b. The fixed structure 10 may be configured such that the lower end of the column portion 10a is fixed to the upper surface of the substructure 2, the pulley support portion 10c rotatably supports a fixed pulley 60, and the other end of the tension member 30 is fixed to the pulley support portion 10c. The movable structure 20 may be configured such that the first connecting portion 41 is fixed to the movable structure end portion 20c in a position where it protrudes upward, and the first connecting portion 41 rotatably supports a movable pulley 61. In this case, the second connecting portion 42 is the boundary portion between the portion of the tension member 30 between the roller 51 and the movable pulley 61 and the portion wound around the movable pulley 61.

[0050] In the conversion mechanism 40 configured as described above, when the lower structure 2 vibrates horizontally relative to the upper structure 3 due to an earthquake or the like and the tension member 30 tilts in the vibration direction between the upper structure 3 and the two rollers 51 due to the vibration, the tension member 30 is pulled upward and the movable pulley 61 moves closer to the fixed pulley 60, as shown in FIG. 6, and the movable structure 20 is pulled up by the movable pulley 61 together with the first connecting part 41 and displaced upward relative to the lower structure 2. At this time, if the upward displacement of the first connecting part 41 or the movable structure 20 relative to the lower structure 2 is y, the upward displacement of the second connecting part 42, i.e., the upward displacement of the part between the two rollers of the tension member 30 and the movable pulley 61, is αy (α>1), which is y multiplied by the conversion magnification α of the conversion mechanism 40. Therefore, the natural period for horizontal vibration of the seismic isolation structure 1 using the conversion mechanism 40 shown in FIG. 5 is α compared to a structure not using the conversion mechanism 40, as explained in the configuration shown in FIG. 1. 1 / 2 multiplied by (α>1). Therefore, with a seismic isolation structure 1 equipped with a conversion mechanism 40 having such a configuration, the natural period of the seismic isolation structure 1 during seismic isolation operation can be lengthened. Furthermore, the magnification of the natural period of the seismic isolation structure 1 can be changed by changing the number of times that the tension member 30 of the conversion mechanism 40 is wound around the fixed pulley 60 and the movable pulley 61.

[0051] 5, the conversion mechanism 40 can be made small and have a large conversion ratio. This makes it possible to make the conversion mechanism 40 less expensive, and to further reduce the installation space of the seismic isolation structure 1, thereby further reducing the cost of installing the seismic isolation structure 1.

[0052] As another example shown in FIG. 7 , the conversion mechanism 40 may be configured such that one end is supported by the fixed structure 10 so as to be tiltable in the vertical direction, the other end is connected to either the other end of the tension member 30 or the movable structure 20, and a lever member 62 is connected between the one end and the other end to either the other end of the tension member 30 or the movable structure 20. In this embodiment, the other end of the tension member 30 is connected to the other end of the lever member 62, and the other end of the movable structure 20 is connected to a position closer to the one end of the lever member 62 than the center between the one end and the other end. In this case, if the horizontal distance between the portion of the lever member 62 supported by the fixed structure 10 and the portion connected to the movable structure 20 is 1, and the horizontal distance between the portion of the lever member 62 supported by the fixed structure 10 and the portion connected to the tension member 30 is α (α>1), the conversion magnification of the conversion mechanism 40 is α. The conversion magnification α of the conversion mechanism 40 can be changed by changing the connection positions of the movable structure 20 and the tension member 30 with respect to the lever member 62.

[0053] The lever member 62 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 lever member 62, including the weight of the upper structure 3 and the seismic isolation structure 1, the live load, the earthquake load, the wind load, etc. The fixed structure 10 is configured to support the lever member 62 so that it can tilt in the vertical direction. The movable structure 20 is connected to the lever member 62 so that it can tilt freely, using a connecting mechanism 63 such as a universal joint. In this case, the connecting portion of the lever member 62 with the movable structure 20 becomes the first connecting portion 41, and the connecting portion of the lever member 62 with the tension member 30 becomes the second connecting portion 42.

[0054] In the conversion mechanism 40 configured as shown in Fig. 7, when the lower structure 2 vibrates horizontally relative to the upper structure 3 due to an earthquake or the like and the tension member 30 tilts in the vibration direction between the upper structure 3 and the two rollers 51 due to the vibration, the portion of the lever member 62 connected to the tension member 30 is pulled upward by the tension member 30, and the lever member 62 tilts so that the connected portion with the tension member 30 moves upward, with the fixed structure 10 as the fulcrum. At this time, if the amount of upward displacement of the first connecting portion 41 of the lever member 62 connected to the movable structure 20 relative to the lower structure 2, i.e., the amount of upward displacement of the movable structure 20, is y, the amount of upward displacement of the second connecting portion 42 of the lever member 62 connected to the tension member 30 is αy (α>1), which is y multiplied by the conversion magnification α of the conversion mechanism 40. Therefore, the natural period of the base isolation structure 1 using the conversion mechanism 40 shown in FIG. 7 for horizontal vibration is α 1 / 2 multiplied by (α>1). Therefore, with a seismic isolation structure 1 equipped with a conversion mechanism 40 having such a configuration, the natural period of the seismic isolation structure 1 during seismic isolation operation can be lengthened. Furthermore, the magnification of the natural period of the seismic isolation structure 1 can be changed in various ways by changing the connection positions of the movable structure 20 and the tension member 30 with respect to the lever member 62.

[0055] 7, the conversion mechanism 40 can be made simple in configuration, which allows the conversion mechanism 40 to be made more inexpensively.

[0056] 9, the conversion mechanism 40 can also be configured such that a lever member 62 is connected at one end to the movable structure 20 and at the other end to the other end of the tension member 30, and is supported by the fixed structure 10 between the connection portion with the movable structure 20 and the connection portion with the tension member 30 so as to be tiltable in the vertical direction, and has a direction-changing pulley 64 supported rotatably by the fixed structure 10 and around which the tension member 30 is wound. In this embodiment, the lever member 62 is supported by the fixed structure 10 so as to be tiltable in the vertical direction on the side of the connection portion with the movable structure 20 rather than the center position between the connection portion with the movable structure 20 and the connection portion with the tension member 30, and the direction-changing pulley 64 is arranged closer to the lower structure 2 than the lever member 62. Even in this case, if the horizontal distance between the portion of the lever member 62 supported by the fixed structure 10 and the portion connected to the movable structure 20 is 1, and the horizontal distance between the portion of the lever member 62 connected to the fixed structure 10 and the portion connected to the tension member 30 is α (α>1), the conversion magnification α of the conversion mechanism 40 will be α. The conversion magnification α of the conversion mechanism 40 can be changed in various ways by changing the connection positions of the movable structure 20 and the tension member 30 to the lever member 62.

[0057] Even in this case, the lever member 62 is configured, for example, using steel or the like, to have a predetermined rigidity capable of supporting a combination of loads transmitted to the lever member 62, including the weight of the upper structure 3 and the seismic isolation structure 1, the live load, the earthquake load, the wind load, etc. The fixed structure 10 can be configured such that a connecting mechanism 65, such as a universal joint, is provided at the upper end of the column portion 10a, and this connecting mechanism 65 supports the lever member 62 so that it can tilt up and down. As in the case shown in FIG. 7 , the movable structure 20 is connected to the lever member 62 so that it can tilt using a connecting mechanism 63, such as a universal joint. The direction-changing pulley 64 can be configured to be rotatably supported by a pulley support member 66 fixed to the lower structure 2, for example. The tension member 30 is wound around the pulley support member 66, and its extension direction is reversed up and down, and it is connected to the lever member 62 from the side of the lower structure 2. In this case as well, the connecting portion of the lever member 62 with the movable structure 20 becomes the first connecting portion 41, and the connecting portion of the lever member 62 with the tension member 30 becomes the second connecting portion .

[0058] In the conversion mechanism 40 configured as shown in Fig. 9, when the lower structure 2 vibrates horizontally relative to the upper structure 3 due to an earthquake or the like and the tension member 30 tilts in the vibration direction between the upper structure 3 and the two rollers 51 due to the vibration, the portion of the lever member 62 connected to the tension member 30 is pulled downward by the tension member 30, whose moving direction has been reversed by the direction-changing pulley 64, and the lever member 62 tilts so that the connected portion with the tension member 30 moves downward and the connected portion with the movable structure 20 moves upward, with the fixed structure 10 as the fulcrum. At this time, if the amount of upward displacement of the first connecting portion 41 of the lever member 62 connected to the movable structure 20 relative to the lower structure 2 is y, i.e., the amount of upward displacement of the movable structure 20, the amount of downward displacement of the second connecting portion 42 of the lever member 62 connected to the tension member 30 is αy (α>1), which is obtained by multiplying y by the conversion magnification α of the conversion mechanism 40. Therefore, the natural period of the base isolation structure 1 using the conversion mechanism 40 shown in FIG. 9 for horizontal vibration is α 1 / 2 multiplied by (α>1). Therefore, with a seismic isolation structure 1 equipped with a conversion mechanism 40 configured in this way, the natural period of the seismic isolation structure 1 during seismic isolation operation can be lengthened. Furthermore, the magnification of the natural period of the seismic isolation structure 1 can be changed in various ways by changing the horizontal position of the fixed structure 10 that supports the lever member 62, or the connection positions of the movable structure 20 and the tension member 30 relative to the lever member 62.

[0059] 9, the conversion mechanism 40 can be made simple in configuration, which allows the conversion mechanism 40 to be made more inexpensively.

[0060] As shown in Figure 11 as another example, the conversion mechanism 40 can also be configured with a gear mechanism including a first gear 67 rotatably supported by the fixed structure 10 and meshing with a first gear rod member 69 connected to the movable structure 20, and a second gear 68 rotatably supported by the fixed structure 10 and meshing with a second gear rod member 70 connected to the other end of the tension member 30. The first gear rod member 69 is a rod-shaped member having a plurality of teeth 69a arranged in a line on its side surface that mesh with the first gear 67, and the second gear rod member 70 is a rod-shaped member having a plurality of teeth 70a arranged in a line on its side surface that mesh with the second gear 68. In this embodiment, the first gear 67 and the second gear 68 are configured to rotate coaxially and integrally with each other, and the second gear 68 has a greater number of teeth than the first gear 67. In this case, the reduction ratio of the meshing between the first gear 67 and the first tooth rod material 69 is set to 1, and the reduction ratio of the meshing between the second gear 68 and the second tooth rod material 70 is set to α (α>1), so that the conversion magnification of the conversion mechanism 40 is set to α. The conversion magnification α of the conversion mechanism 40 can be changed in various ways by changing at least one of the reduction ratio of the meshing between the first gear 67 and the first tooth rod material 69 and the reduction ratio of the meshing between the second gear 68 and the second tooth rod material 70.

[0061] The first gear 67, the second gear 68, the first gear rod member 69, and the second gear rod member 70 are each made of, for example, steel or the like, so as to have a predetermined rigidity capable of supporting a combination of loads transmitted to the conversion mechanism 40, including the weight of the upper structure 3 and the seismic isolation structure 1, live load, earthquake load, wind load, etc. The fixed structure 10 can be configured to rotatably support the first gear 67 and the second gear 68 at the upper end portion of the column portion 10a. The movable structure 20 can be configured to be connected to the first gear rod member 69 at the movable structure end portion 20c, or can be configured to be connected to the first gear rod member 69 at another portion of the movable structure 20. In this case, the movable structure end portion 20c connected to the first gear rod member 69 of the movable structure 20 also serves as the first connecting portion 41, and the connecting portion of the second gear rod member 70 with the tension member 30 serves as the second connecting portion 42.

[0062] In the conversion mechanism 40 configured as shown in Fig. 11, when the lower structure 2 vibrates horizontally relative to the upper structure 3 due to an earthquake or the like and the tension member 30 tilts in the vibration direction between the upper structure 3 and the two rollers 51 due to the vibration, the second tooth rod member 70 connected to the tension member 30 is pulled upward by the tension member 30, causing the second gear 68 to rotate, and the first gear 67 rotates integrally with the second gear 68, causing the first tooth rod member 69 to move upward and displacing the movable structure 20 upward, as shown in Fig. 12. At this time, if the amount of upward displacement of the first connecting part 41 connected to the first tooth rod member 69 relative to the lower structure 2, i.e., the amount of upward displacement of the movable structure 20, is y, the amount of upward displacement of the second connecting part 42 of the second tooth rod member 70 connected to the tension member 30 is αy (α>1), which is y multiplied by the conversion magnification α of the conversion mechanism 40. Therefore, the natural period of the base isolation structure 1 using the conversion mechanism 40 shown in FIG. 11 for horizontal vibration is α 1 / 2 multiplied by (α>1). Therefore, according to the seismic isolation structure 1 equipped with the conversion mechanism 40 having such a configuration, the natural period of the seismic isolation structure 1 during seismic isolation operation can be lengthened. Furthermore, the magnification of the natural period of the seismic isolation structure 1 can be changed in various ways by changing at least one of the reduction ratio of the meshing between the first gear 67 and the first gear rod member 69 and the reduction ratio of the meshing between the second gear 68 and the second gear rod member 70.

[0063] 11, the conversion mechanism 40 can be made small and have a large conversion ratio. This makes it possible to make the conversion mechanism 40 less expensive, and to further reduce the installation space of the seismic isolation structure 1, thereby further reducing the cost of installing the seismic isolation structure 1.

[0064] 13, the gear mechanism constituting the conversion mechanism 40 may be configured such that a first gear 67 and a second gear 68 are rotatably supported by the fixed structure 10 on separate axes parallel to each other and are meshed with each other. Also, the gear mechanism constituting the conversion mechanism 40 may be configured such that another gear is provided between the first gear 67 and the second gear 68, so that three or more gears mesh with each other.

[0065] 14, the conversion mechanism 40 may include a cylinder 71 having a first diameter portion 71a and a second diameter portion 71b having the same or different diameter as the first diameter portion 71a and supported by the fixed structure 10, a first piston 72 attached to the first diameter portion 71a and connected to the movable structure 20, a second piston 73 attached to the second diameter portion 71b and connected to the other end of the tension member 30, and a fluid 74 filled inside the cylinder 71 between the first piston 72 and the second piston 73. In this embodiment, the first diameter portion 71a has a larger diameter than the second diameter portion 71b. In this case, the inner diameter of the second diameter portion 71b or the outer diameter of the second piston 73 is set to 1, and the inner diameter of the first diameter portion 71a or the outer diameter of the first piston 72 is set to α (α>1), thereby providing a conversion magnification of the conversion mechanism 40 as α. The conversion ratio α of the conversion mechanism 40 can be varied by changing at least one of the inner diameter of the second diameter portion 71b or the outer diameter of the second piston 73 and the inner diameter of the first diameter portion 71a or the outer diameter of the first piston 72.

[0066] The cylinder 71, the first piston 72, and the second piston 73 are each configured, for example, using steel or the like, to have a predetermined rigidity capable of supporting a combination of loads transmitted to the conversion mechanism 40, including the weight of the upper structure 3 and the seismic isolation structure 1, live load, earthquake load, wind load, etc. The fixed structure 10 can be configured to support the cylinder 71 at a fixed structure end 10b provided at the upper end of the column 10a, but can also be configured to support the cylinder 71 at another portion of the fixed structure 10. The movable structure 20 can be configured to be integrally connected to the first piston 72 at the lower end of the column 20a. In this case, the column 10a connected to the first piston 72 of the movable structure 20 also serves as the first connecting portion 41. The movable structure 20 can also be configured to be connected to the first piston 72 at another portion of the movable structure 20. The second piston 73 can be configured such that the second connecting portion 42 is integrally formed and the tension member 30 is connected at the second connecting portion 42, but the second piston 73 may have another shape that has a portion for connecting the tension member 30. In addition, various fluids can be used as the fluid 74, including liquids such as oil and water, and gases such as air.

[0067] In the conversion mechanism 40 configured as shown in Fig. 14, when the lower structure 2 vibrates horizontally relative to the upper structure 3 due to an earthquake or the like and the tension member 30 tilts in the vibration direction between the upper structure 3 and the two rollers 51 due to the vibration, the second piston 73 connected to the tension member 30 is pulled upward by the tension member 30 and displaces upward, as shown in Fig. 15, and the upward displacement of the second piston 73 is transmitted via the fluid 74, causing the first piston 72 to move upward and displacing the movable structure 20 upward. At this time, if the amount of upward displacement of the first connecting part 41 or the first piston 72 relative to the lower structure 2, i.e., the amount of upward displacement of the movable structure 20, is y, the amount of upward displacement of the second connecting part 42 or the second piston 73 connected to the tension member 30 is αy (α>1), which is y multiplied by the conversion magnification α of the conversion mechanism 40. Therefore, the natural period of the base isolation structure 1 using the conversion mechanism 40 shown in FIG. 14 for horizontal vibration is α 1 / 2multiplied by (α>1). Therefore, with a seismic isolation structure 1 equipped with a conversion mechanism 40 configured in this way, the natural period of the seismic isolation structure 1 during seismic isolation operation can be lengthened. Furthermore, the magnification of the natural period of the seismic isolation structure 1 can be changed in various ways by changing at least one of the inner diameter of the second diameter portion 71b or the outer diameter of the second piston 73 and the inner diameter of the first diameter portion 71a or the outer diameter of the first piston 72.

[0068] 14, the conversion mechanism 40 can be made small and have a large conversion ratio. This makes it possible to make the conversion mechanism 40 less expensive, and to further reduce the installation space of the seismic isolation structure 1, thereby further reducing the cost of installing the seismic isolation structure 1.

[0069] Figures 16, 17, and 18 show an example of a configuration for stably supporting an upper structure 3 relative to a lower structure 2 so that the upper structure 3 is movable horizontally. Figure 16 is a front view showing a more specific configuration of the seismic isolation structure 1 shown in Figure 5, Figure 17 is a side view of the seismic isolation structure 1 shown in Figure 16, and Figure 18 is a cross-sectional view taken along line AA in Figure 16. Figure 19 is a front view showing the seismic isolation structure 1 shown in Figure 16 in a state where the seismic isolation operation is being performed. In Figures 16 to 19, the same reference numerals are used to designate members corresponding to those previously described.

[0070] The seismic isolation structure 1 shown in Figure 1 is the minimum configuration that produces the seismic isolation effect, and is unstable as a configuration that supports the upper structure 3 so that it can move freely horizontally relative to the lower structure 2 without tilting it. Therefore, a configuration is required that can stably support the upper structure 3 so that it can move freely horizontally relative to the lower structure 2.

[0071] 16, 17, and 18 uses a fixed structure 10 having a pedestal-like configuration in which the upper ends of four pillars 10a are connected by four fixed structure end portions 10b, and a movable structure 20 having a configuration in which the lower ends of four pillars 20a are connected by four movable structure end portions 20c and two movable structure end portions 20c arranged in a cross shape, and the upper ends of the four pillars 20a are connected by four base portions 20b. The fixed structure 10 and the movable structure 20 are each square-shaped in a plan view, and the movable structure 20 is arranged coaxially inside the fixed structure 10.

[0072] Two guide rollers 76, rotatably supported by support members 75, are attached to the four pillars 10a of the fixed structure 10, spaced apart from one another and facing inward. These guide rollers 76 are in contact with the outer circumferential surfaces of the pillars 20a of the movable structure 20. This restricts horizontal movement of the movable pulley 61 relative to the fixed pulley 60 (described later), and allows the movable structure 20 to be guided by the guide rollers 76 and move vertically relative to the fixed structure 10 without tilting.

[0073] The support member 50 has four beams 50b arranged in a cross shape, and these beams 50b are connected to the fixed structure end portion 10b and fixed to the upper end portion of the fixed structure 10. A support protrusion 50c is fixed to each beam 50b, and four rollers 51 are rotatably supported by these support protrusions 50c and are arranged two by two facing each other with the tension member 30 in between. Therefore, even if the upper structure 3 moves relative to the lower structure 2 in any horizontal direction, the tension member 30 is supported by any of the rollers 51, and the portion of the tension member 30 between the upper structure 3 and the roller 51 can tilt relative to the upper structure 3.

[0074] 16, 17, and 18, a linear roller bearing (CLB) is used as a support mechanism 21 that supports a movable structure 20 on an upper structure 3 so that the movable structure 20 is movable in the horizontal direction. In this case, the support mechanism 21 has two lower guide rails 21a fixed parallel to each other on the upper surface of the base 20b, two upper guide rails 21b fixed to the lower surface of the upper structure 3 in an orientation perpendicular to the lower guide rails 21a, and two sliders 21c slidably attached to the corresponding lower guide rails 21a and upper guide rails 21b, and the sliders 21c move along the lower guide rails 21a and upper guide rails 21b, allowing the movable structure 20 to move in either direction in the horizontal direction relative to the upper structure 3.

[0075] 16, 17, and 18, the conversion mechanism 40 has a configuration including a fixed pulley 60 and a movable pulley 61, similar to the conversion mechanism 40 shown in FIG. 5. More specifically, the conversion mechanism 40 includes a pulley support unit 10c suspended from a support member 50 by a hanging member 77 formed of a wire or a pillar, and three fixed pulleys 60 are rotatably supported by the pulley support unit 10c. The conversion mechanism 40 also includes a first connecting unit 41 connected to the movable structure end 20c by a connecting member 78 formed of a wire or a pillar. In this case, the first connecting unit 41 functions as a pulley support unit and rotatably supports the three movable pulleys 61. The tension member 30 is wound alternately around fixed pulleys 60 and movable pulleys 61, and after being wound around three fixed pulleys 60 and movable pulleys 61, the other end is fixed to a fixed portion 79 provided on the pulley support portion 10c.

[0076] 16, 17, and 18, when the lower structure 2 vibrates horizontally relative to the upper structure 3 due to an earthquake or the like, the tension members 30 tilt in the vibration direction between the upper structure 3 and the four rollers 51 due to the vibration, and the movable structure 20 moves horizontally relative to the upper structure 3, thereby performing seismic isolation operation and suppressing the transmission of vibrations of the lower structure 2 to the upper structure 3. Furthermore, when the lower structure 2 vibrates horizontally relative to the upper structure 3 due to an earthquake or the like, the tension members 30 are pulled upward, and the movable pulley 61 moves closer to the fixed pulley 60, as shown in FIG. 19, and the movable structure 20 is pulled up by the movable pulley 61 and displaced upward relative to the lower structure 2. At this time, the upward displacement of the movable structure 20 relative to the substructure 2 is y, whereas the upward displacement of the portion between the four rollers 51 of the tension member 30 and the movable pulley 61 is αy (α>1), which is y multiplied by the conversion magnification α of the conversion mechanism 40. Therefore, the natural period of the seismic isolation structure 1 with respect to horizontal vibration is α with respect to a structure that does not use the conversion mechanism 40, as explained in the configuration shown in FIG. 1 / 2 Therefore, even in the seismic isolation structure 1 equipped with the conversion mechanism 40 having such a configuration, the natural period of the seismic isolation structure 1 during seismic isolation operation can be lengthened.

[0077] 16, 17, and 18, the fixed structure 10 and the movable structure 20 are reliably supported by the lower structure 2 and the upper structure 3, respectively, and tilting of the movable structure 20 relative to the fixed structure 10 is restricted, so that the upper structure 3 can be stably supported and freely moved in the horizontal direction without tilting relative to the lower structure 2. Furthermore, according to the configuration of the seismic isolation structure 1 shown in FIGS. 16, 17, and 18, the fixed structure 10 has a box-like configuration in which the upper ends of four pillars 10a are connected by four fixed structure ends 10b, so that the rigidity of the fixed structure 10 can be increased and the conversion mechanism 40 can be reliably supported.

[0078] 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]

[0079] 1. Seismic isolation structure 2 Substructure 3 Superstructure 10 Fixed structure 10a Pillar 10b Fixed structure end 10c Pulley support part 20 Movable structure 20a Pillar 20b base 20c Movable structure end 21 Support mechanism 21a Lower guide rail 21b Upper guide rail 21c slider 30 Tensile material 40 Conversion Mechanism 41 1st connection part 42 2nd connection part 50 Support material 50a Pillar 50b Beam section 50c Support protrusion 51 Roller 60 fixed pulley 61 Moving pulley 62 Lever 63 Connection mechanism 64 Direction change pulley 65 Connection mechanism 66 Pulley support material 67 First Gear 68 2nd Gear 69 1st tooth rod material 70 Second tooth rod material 71 cylinders 71a First diameter 71b 2nd diameter section 72 First piston 73 Second piston 74 Fluid 75 Support member 76 Guide roller 77 Hanging material 78 Connecting material 79 Fixed part

Claims

1. A seismic isolation structure provided between a lower structure and an upper structure, a fixed structure fixed to either the lower structure or the upper structure; a movable structure supported by either the lower structure or the upper structure so as to be movable in a horizontal direction by a support mechanism provided between the other of the lower structure and the upper structure; a tension member having one end fixed to the other of the lower structure and the upper structure; A seismic isolation structure characterized by having a conversion mechanism supported by the fixed structure and connected to the tension member and the movable structure, which converts the vertical load applied from the movable structure into a tensile force of the tension member so that the horizontal restoring force applied from the tension member to the other of the lower structure and the upper structure is reduced.

2. The conversion mechanism is a fixed pulley rotatably supported on the fixed structure; a movable pulley rotatably supported by the movable structure, The seismic isolation structure according to claim 1 , wherein the tension member is fixed at the other end to either the fixed structure or the movable structure and wound around the fixed pulley and the movable pulley.

3. The conversion mechanism is The seismic isolation structure described in claim 1, wherein one end is supported by the fixed structure so as to be freely tiltable in the vertical direction, the other end is connected to either the other end of the tension member or the movable structure, and a lever member is connected between the one end and the other end to either the other end of the tension member or the movable structure.

4. The conversion mechanism is a lever member connected at one end to the movable structure and at the other end to the other end of the tension member, and supported by the fixed structure between a connection portion with the movable structure and a connection portion with the tension member so as to be tiltable in the vertical direction; The seismic isolation structure according to claim 1, further comprising a direction-changing pulley that is rotatably supported by the fixed structure and has the tension member wound therearound.

5. The conversion mechanism is a first gear that is rotatably supported by the fixed structure and that meshes with a first gear rod member connected to the movable structure; The seismic isolation structure according to claim 1, which is configured by a gear mechanism including a second gear that is rotatably supported by the fixed structure and that meshes with a second toothed rod member connected to the other end of the tension member.

6. The conversion mechanism is a cylinder having a first diameter portion and a second diameter portion having a diameter equal to or different from that of the first diameter portion, the cylinder being supported by the fixed structure; a first piston attached to the first diameter portion and connected to the movable structure; a second piston attached to the second diameter portion and connected to the other end of the tension member; The seismic isolation structure according to claim 1 , further comprising a fluid filled inside the cylinder between the first piston and the second piston.

7. a support member fixed to either the lower structure or the upper structure, the fixed structure, or the movable structure; A seismic isolation structure as described in any one of claims 1 to 6, comprising a plurality of rollers, each of which is rotatably supported on the support material and arranged to surround the middle portion of the tension material.

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