Base isolation device

Abstract

To provide a base isolation device that is easy to place and can reduce earthquake motion efficiently.SOLUTION: A base isolation device 11 is arranged between an upper structure 14 (base isolation part) in which earthquake vibration is reduced, and a lower foundation 15 (non-base isolation part) in which earthquake vibration is not reduced, and reduces earthquake response of the upper structure. The base isolation device has a metamaterial layer 13 that inhibits transmission of vibration in a specific frequency range, and a base isolation layer 12 in which an arbitrary resonant frequency range is set. The metamaterial layer and the base isolation layer are arranged in series, and the base isolation layer is arranged closer to the upper structure than the metamaterial layer. The specific frequency range of the metamaterial layer and the resonant frequency range of the base isolation layer are set to be equivalent.SELECTED DRAWING: Figure 1A

Description

[Technical field]

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

[0002] One method for improving the earthquake resistance of buildings, equipment, and other structures is the application of seismic isolation structures. In seismic isolation structures, structures that require reduced seismic force during an earthquake are placed on seismic isolation devices, which deform during an earthquake to absorb the seismic energy, thereby reducing the seismic load acting on the structure.

[0003] A seismic isolation device has some or all of the following: a support function to support a structure, a damping function to absorb the energy of seismic forces during an earthquake, and a restoring function to return to the original position in response to displacement caused by an earthquake. Typical seismic isolation devices include those using laminated rubber, laminated rubber with lead plugs, elastic sliding bearings, linear rolling bearings, oil dampers, steel dampers, and coil springs. Many other seismic isolation devices have also been proposed. Various seismic isolation structures that combine these seismic isolation devices have also been proposed.

[0004] One example of this type of technology is described in Patent Document 1. Patent Document 1 describes a technology in which a hardening device is provided with a tension member that connects the upper structure of the seismic isolation section and the side wall of the non-seismic isolation section at an angle from the vertical direction, and tension is applied to the hardening device during an earthquake to suppress relative displacement between the seismic isolation section and the non-seismic isolation section.

[0005] Also, Patent Document 2 describes a structure having a resonator that emits a wave that weakens the amplitude of an incident wave, the structure including a plurality of voids and resonators disposed inside some or all of the voids, the voids being unevenly disposed. This structure is a mechanical metamaterial. Here, "metamaterial" refers to an artificial material that behaves in a way that is not found in natural materials. Among metamaterials, those that have the property of blocking vibration propagation in a specific frequency range are called "mechanical metamaterials," and are being considered for use as a means for reducing vibration and noise. And, the structure described in Patent Document 2 is being considered for use as a damping device that reduces earthquake vibrations (earthquake motion) input to a building. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2022-95388 A [Patent Document 2] JP 2019-45789 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the technology described in Patent Document 1 is configured to receive earthquake motion with a seismic isolation device and a hardening type device arranged in parallel. The technology described in Patent Document 1 requires the response characteristics of the seismic isolation layer to be set taking into account the mechanical characteristics of the seismic isolation device and the hardening type device, which makes the design complicated. In addition, the technology described in Patent Document 1 is configured to connect the tension members of the hardening type device to the upper structure of the seismic isolation section and the side wall of the non-seismic isolation section at an angle from the vertical, which restricts the placement position. Therefore, the technology described in Patent Document 1 has the problem of poor placement.

[0008] Furthermore, in the technology described in Patent Document 2, the amount of energy absorbed by the mechanical metamaterial is less than that of a seismic isolation device using laminated rubber, laminated rubber containing lead plugs, elastic sliding bearings, linear motion rolling bearings, oil dampers, steel dampers, coil springs, etc. Therefore, the technology described in Patent Document 2 has the problem that if only the mechanical metamaterial is used, the amount of energy absorbed is small and there is a limit to the effect of reducing earthquake motion.

[0009] The present invention has been made to solve the above-mentioned problems, and has as its main object to provide a seismic isolation device that is easy to arrange and efficiently reduces earthquake motion. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, the present invention provides a seismic isolation device that is arranged between a seismic isolation section in which earthquake vibrations are reduced and a non-seismic isolation section in which earthquake vibrations are not reduced, and reduces the seismic response of the seismic isolation section, the device having a metamaterial layer that inhibits the transmission of vibrations in a specific frequency range, and a seismic isolation layer in which an arbitrary resonant frequency range is set, the specific frequency range of the metamaterial layer is equivalent to the resonant frequency range of the seismic isolation layer, the seismic isolation layer and the metamaterial layer are arranged in series, and the seismic isolation layer is arranged closer to the seismic isolation section than the metamaterial layer. Other means will be described later. Effect of the Invention

[0011] According to the present invention, it is possible to provide a seismic isolation device which is excellent in terms of placement and which efficiently reduces earthquake motion. [Brief description of the drawings]

[0012] [Figure 1A] 1 is a schematic diagram of a seismic isolation structure using a seismic isolation device according to an embodiment of the present invention. [Figure 1B] 1 is an explanatory diagram of the operation of a seismic isolation structure using a seismic isolation device according to an embodiment during an earthquake. FIG. [Diagram 2] FIG. 2 is a plan view of the seismic isolation device according to the embodiment. [Figure 3A] 1 is a schematic diagram of a seismic isolation structure using a seismic isolation device of a comparative example. [Figure 3B] 1 is an explanatory diagram of the operation of a seismic isolation structure using a seismic isolation device of a comparative example during an earthquake. [Figure 4A] FIG. 2 is a plan view showing unit components constituting the periodic structure of a metamaterial layer. [Figure 4B] 13 is a plan view showing another unit component that constitutes the periodic structure of the metamaterial layer. FIG. [Figure 4C] FIG. 13 is a plan view showing yet another unit component that constitutes the periodic structure of the metamaterial layer. [Diagram 5] FIG. 2 is a plan view of a metamaterial layer. [Figure 6] FIG. 1 is a perspective view of a metamaterial layer. [Figure 7] FIG. 13 is a schematic diagram of a modified seismic isolation structure using a seismic isolation device. [Figure 8] FIG. 2 is a graph showing a resonance curve of a linear damping system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings. Note that each drawing is merely a schematic illustration to allow a sufficient understanding of the present invention. Therefore, the present invention is not limited to only the illustrated examples. In addition, in each drawing, common or similar components are given the same reference numerals, and duplicated explanations thereof will be omitted.

[0014] <Configuration of seismic isolation device> Hereinafter, the configuration of the seismic isolation device 11 according to this embodiment will be described with reference to Fig. 1A, Fig. 1B, and Fig. 2. Fig. 1A is a schematic configuration diagram of a seismic isolation structure 10 using the seismic isolation device 11 according to this embodiment. Fig. 1A shows the configuration of the seismic isolation structure 10 using the seismic isolation device 11 according to this embodiment at rest. Fig. 1B is an explanatory diagram of the operation of the seismic isolation structure 10 using the seismic isolation device 11 during an earthquake. Fig. 2 is a plan view of the seismic isolation device 11.

[0015] As shown in FIG. 1A, the seismic isolation device 11 according to this embodiment is a device disposed between an upper structure 14 (seismic isolation section) in which earthquake vibrations are reduced, and a lower base 15 (non-seismic isolation section) in which earthquake vibrations are not reduced. The seismic isolation device 11 has a function of reducing the earthquake response of the upper structure 14 (seismic isolation section). The seismic isolation device 11 is configured by arranging in series a seismic isolation layer 12 in which an arbitrary resonant frequency range is set, and a metamaterial layer 13 that inhibits the transmission of vibrations in a specific frequency range. In addition, the seismic isolation layer 12 is disposed closer to the upper structure 14 (seismic isolation section) than the metamaterial layer 13.

[0016] Here, the metamaterial layer 13 is an artificial material that has been artificially endowed with vibration characteristics of a material. The metamaterial layer 13 is configured as a so-called mechanical metamaterial that has the property of blocking vibration propagation in a specific frequency range. The metamaterial layer 13 has a periodic structure inside the member with respect to vibration. Due to the periodic structure, the metamaterial layer 13 can obtain a phenomenon called a band gap in which waves in a specific frequency range are scattered and cannot pass through the inside of the member. The metamaterial layer 13 can reduce vibration and noise by blocking waves in a specific frequency range.

[0017] In the configuration shown in FIG. 1A, the seismic isolation devices 11 are arranged in the vertical direction, so "arranged in series" means that the seismic isolation layer 12 and the metamaterial layer 13 are arranged in a vertically overlapping manner. However, in the seismic isolation structure 10, the seismic isolation devices 11 can be arranged not only in the vertical direction but also in the horizontal direction or in an oblique direction. In this case, "arranged in series" means that the seismic isolation layer 12 and the metamaterial layer 13 are arranged in a horizontal direction or in an oblique direction and overlapped. In addition, the seismic isolation structure 10 can use the seismic isolation devices 11 as a means for suspending equipment. In this case, the seismic isolation structure 10 has a configuration in which the seismic isolation devices 11 are arranged in the vertical direction, but since the suspended equipment becomes the seismic isolation part, "arranged in series" means that the metamaterial layer 13 is arranged on the upper side and the seismic isolation layer 12 is arranged on the lower side, and overlapped, unlike the example shown in FIG. 1A.

[0018] The upper part of the seismic isolation device 11 is fixed to the lower part of a superstructure 14, such as a building or equipment, for which response during an earthquake is to be reduced, and supports the superstructure 14. The lower part of the seismic isolation device 11 is fixed to a lower foundation 15 that is not seismically isolated, and is installed so that the seismic isolation layer 12 faces the superstructure 14. In this embodiment, the seismic isolation structure 10 will be described as supporting the superstructure 14 with four seismic isolation devices 11, as shown in FIG. 2.

[0019] The seismic isolation layer 12 is composed of laminated rubber, laminated rubber with lead plugs, elastic sliding bearings, linear motion rolling bearings, oil dampers, steel dampers, coil springs, etc. The seismic isolation layer 12 has some or all of the following: supporting performance to support the structure, damping performance to absorb energy during an earthquake, and restoring performance to return to the original position in response to displacement caused by an earthquake.

[0020] In this embodiment, the specific frequency range of the metamaterial layer 13 is equivalent to the resonant frequency range of the seismic isolation layer 12. Therefore, when seismic motion propagates inside the metamaterial layer 13 during an earthquake, the seismic isolation device 11 can inhibit the vibration propagation in the resonant frequency range of the seismic isolation layer 12 by the metamaterial layer 13. As a result, the seismic isolation device 11 can input seismic motion from which vibration components in the resonant frequency range of the seismic isolation layer 12 have been removed to the seismic isolation layer 12. Therefore, the seismic isolation device 11 can make it difficult to excite the resonance of the seismic isolation layer 12 during an earthquake, and can reduce the response (displacement) of the seismic isolation layer 12. As a result, as shown in FIG. 1B, the seismic isolation device 11 can suppress the relative displacement between the upper structure 14 (seismic isolation portion) and the lower base 15 (non-seismic isolation portion).

[0021] In addition, in the seismic isolation device 11 of this embodiment, the rigidity of the seismic isolation device 11 (i.e., the seismic isolation layer 12 and the metamaterial layer 13) is set so that the resonant frequency range of the vibration system composed of the upper structure 14 (seismic isolation section) and the seismic isolation device 11 (i.e., the seismic isolation layer 12 and the metamaterial layer 13) is within the low vibration frequency range of 2 to 4 Hz, where the excitation component of seismic motion is relatively small.

[0022] Here, in order to easily explain the operation of the seismic isolation device 11 according to this embodiment, the configuration and operation of a comparative seismic isolation device 110 will be explained with reference to Figs. 3A and 3B. Fig. 3A is a schematic configuration diagram of a seismic isolation structure 100 using the comparative seismic isolation device 110. Fig. 3A shows the configuration of the seismic isolation structure 100 using the comparative seismic isolation device 110 when at rest. Fig. 3B is a diagram explaining the operation of the seismic isolation structure 100 using the comparative seismic isolation device 110 during an earthquake.

[0023] As shown in FIG. 3A, the seismic isolation device 110 of the comparative example differs from the seismic isolation device 11 of this embodiment (FIG. 1A) in that it does not have a metamaterial layer 13 and only has a seismic isolation layer 12.

[0024] In a seismic isolation structure 100 using such a comparative example seismic isolation device 110, the seismic isolation device 110 is fixed onto a lower foundation 15 (non-seismically isolated portion), and an upper structure 14 (seismically isolated portion) is fixed to the top of the seismic isolation device 110 for support.

[0025] In addition, in the comparative example of the seismic isolation device 110, the rigidity of the seismic isolation device 110 (i.e., the seismic isolation layer 12) is set so that the resonant frequency range of the vibration system composed of the upper structure 14 (seismic isolation section) and the seismic isolation device 110 (i.e., the seismic isolation layer 12) is in the low frequency range of 2 to 4 Hz, where the excitation component of seismic motion is relatively small.

[0026] As shown in FIG. 3B, in the seismic isolation structure 100 using the seismic isolation device 110 of the comparative example, the lower foundation 15 (non-seismically isolated portion) vibrates due to seismic motion during an earthquake, and the vibration is transmitted to the upper structure 14 (seismically isolated portion) via the seismic isolation device 110. At that time, the seismic isolation layer 12 of the seismic isolation device 110 deforms to absorb the energy of the seismic force. As a result, the seismic isolation device 110 of the comparative example reduces the energy of the seismic force transmitted to the upper structure 14. The deformation of the seismic isolation layer 12 of the seismic isolation device 110 during the earthquake causes a relative displacement between the upper structure 14 and the lower foundation 15.

[0027] Unlike the seismic isolation device 11 according to this embodiment, the seismic isolation device 110 of the comparative example only has the seismic isolation layer 12. Therefore, in the seismic isolation device 110 of the comparative example, resonance of the seismic isolation layer 12 is easily excited during an earthquake, and the response (amount of displacement) of the seismic isolation layer 12 is easily increased. Therefore, in the seismic isolation device 110 of the comparative example, the relative displacement between the upper structure 14 (seismic isolation portion) and the lower foundation 15 (non-seismic isolation portion) is easily increased.

[0028] In contrast, the seismic isolation device 11 according to this embodiment has a seismic isolation layer 12 and a metamaterial layer 13. As described above, in the seismic isolation device 11 according to this embodiment, when seismic motion propagates inside the metamaterial layer 13 during an earthquake, the metamaterial layer 13 can inhibit vibration propagation in the resonance frequency range of the seismic isolation layer 12. Therefore, the seismic isolation device 11 according to this embodiment can make it difficult to excite the resonance of the seismic isolation layer 12 during an earthquake, and can reduce the response (displacement) of the seismic isolation layer 12. As a result, as shown in FIG. 1B, the seismic isolation device 11 can suppress the relative displacement between the upper structure 14 (seismic isolation portion) and the lower base 15 (non-seismic isolation portion).

[0029] Moreover, the seismic isolation device 11 according to this embodiment has a configuration in which the seismic isolation layer 12 and the metamaterial layer 13 are fixed in series between the upper structure 14 (seismic isolation portion) and the lower foundation 15 (non-seismic isolation portion). Therefore, the seismic isolation device 11 according to this embodiment has excellent arrangability and is effective when a seismic isolation structure is applied to a structure that is heavy relative to its installation area.

[0030] Moreover, the seismic isolation device 11 according to this embodiment can be configured to have a resonant frequency range in the low frequency range of 2 to 4 Hz by fixing a plurality of seismic isolation layers 12 to the metamaterial layer 13.

[0031] <Metamaterial layer configuration> The configuration of the metamaterial layer 13 will be described below with reference to Figs. 4A to 6. Fig. 4A is a plan view showing a unitary component 13A constituting the periodic structure of the metamaterial layer 13 of the seismic isolation device 11. Fig. 4B is a plan view showing another unitary component 13B constituting the periodic structure of the metamaterial layer 13 of the seismic isolation device 11. Fig. 4C is a plan view showing yet another unitary component 13C constituting the periodic structure of the metamaterial layer 13 of the seismic isolation device 11. Fig. 5 is a plan view of the metamaterial layer 13 composed of the unitary component 13A (Fig. 4A) of the seismic isolation device 11. Fig. 6 is a perspective view of the metamaterial layer 13 composed of the unitary component 13A (Fig. 4A) of the seismic isolation device 11. In the example shown in Figs. 5 and 6, the metamaterial layer 13 of the seismic isolation device 11 is configured such that the unitary components 13A (Fig. 4A) are arranged in five rows in two horizontal directions and three rows in the vertical direction.

[0032] In the examples shown in Figures 4A, 5, and 6, the unit component 13A that constitutes the periodic structure of the metamaterial layer 13 of the seismic isolation device 11 is configured such that a spherical central portion 16A is arranged inside a cubic peripheral portion 17A.

[0033] In addition, in the example shown in Figure 4B, the unit component 13B that constitutes the periodic structure of the metamaterial layer 13 of the seismic isolation device 11 is configured in such a way that a prolate spheroidal central portion 16B is arranged inside a cubic shaped peripheral portion 17B.

[0034] In the example shown in Figure 4C, the unit component 13C that constitutes the periodic structure of the metamaterial layer 13 of the seismic isolation device 11 is configured in such a way that a columnar central portion 16C that is cross-shaped when viewed from above is arranged inside a cubic peripheral portion 17C.

[0035] Unit constituent members 13B shown in Fig. 4B and unit constituent members 13C shown in Fig. 4C are arranged periodically, such as "row a in one horizontal direction, row b in the other horizontal direction, and row c in the vertical direction," in place of unit constituent members 13A (Fig. 6), to form metamaterial layer 13 (Fig. 6) of seismic isolation device 11. Metamaterial layer 13 (Fig. 6) configured in this manner is a mechanical metamaterial that can block the propagation of vibrations within a specific frequency range within the member due to its periodic structure.

[0036] The metamaterial layer 13 (FIG. 6) can set a frequency range in which vibration propagation is inhibited by appropriately selecting the dimensions, shapes, and materials of the peripheral parts 17A, 17B, and 17C and the central parts 16A, 16B, and 16C of the unit components 13A, 13B, and 13C shown in FIG. 4A to FIG. 4C. In this embodiment, the metamaterial layer 13 sets the resonant frequency range of the seismic isolation layer 12 as the frequency range in which vibration propagation is inhibited.

[0037] In this embodiment, the peripheral parts 17A, 17B, and 17C of the metamaterial layer 13 are made of, for example, metal or concrete in order to ensure the rigidity required to support the upper structure 14 (seismic isolation part). The central parts 16A, 16B, and 16C of the metamaterial layer 13 are made of a material different from that of the peripheral parts 17A, 17B, and 17C, or are made as voids.

[0038] However, the unit components 13A, 13B, and 13C shown in Figures 4A to 4C are merely examples, and the configuration and shape of the unit components can be changed as desired. Also, the metamaterial layer 13 of the seismic isolation device 11 shown in Figures 5 and 6 is merely an example, and the configuration and shape of the metamaterial layer 13 can be changed as desired, for example, to "row a in one horizontal direction, row b in the other horizontal direction, and row c in the vertical direction."

[0039] <Modifications of seismic isolation structures> In the seismic isolation structure 10 shown in FIG. 1A, the seismic isolation device 11 deforms and absorbs the energy of the seismic force during an earthquake, causing a relative displacement between the upper structure 14 (seismic isolation section) where seismic motion is reduced and the lower base 15 (non-seismic isolation section) where seismic motion is not reduced. Equipment and devices installed in facilities such as factories, power generation plants, and hospitals are equipped with pipes for connecting to other devices and cables for supplying power. Therefore, in the seismic isolation structure 10, it is required that the pipes and cables connecting the upper structure 14 (seismic isolation section) and the lower base 15 (non-seismic isolation section) reduce the load caused by the relative displacement between the upper structure 14 (seismic isolation section) and the lower base 15 (non-seismic isolation section) during an earthquake. In addition, if a new structure for absorbing the relative displacement is provided to reduce the load, design costs and material costs for the absorbing structure are incurred, so it is required that the seismic isolation device 11 reduces the relative displacement between the upper structure 14 (seismic isolation section) and the lower base 15 (non-seismic isolation section) during an earthquake as much as possible. In order to meet these demands, a modified seismic isolation structure 10A shown in FIG. 7 is provided here.

[0040] Hereinafter, the configuration of a modified seismic isolation structure 10A using the seismic isolation device 11 will be described with reference to Fig. 7. Fig. 7 is a schematic configuration diagram of a modified seismic isolation structure 10A using the seismic isolation device 11.

[0041] In the modified seismic isolation structure 10A shown in Fig. 7, the configuration of the seismic isolation device 11 itself is the same as that of the seismic isolation structure 10 shown in Fig. 1A. However, the modified seismic isolation structure 10A differs from the seismic isolation structure 10 shown in Fig. 1A in that the metamaterial layer 13 of the seismic isolation device 11 is disposed within the lower foundation 15, and the metamaterial layer 13 fixes the multiple seismic isolation layers 12.

[0042] Such a modified seismic isolation structure 10A can be realized by replacing a part of the lower base 15 with the metamaterial layer 13 or by forming the lower base 15 itself from the metamaterial layer 13.

[0043] The modified seismic isolation structure 10A can reduce the relative displacement between the upper structure 14 (seismic isolation portion) and the lower foundation 15 (non-seismic isolation portion) during an earthquake using the same principle as the seismic isolation structure shown in Fig. 1A. Furthermore, in the modified seismic isolation structure 10A, the metamaterial layer 13 is disposed in the lower foundation 15, thereby reducing the height dimension of the seismic isolation device 11 and improving its ease of placement. Such a modified seismic isolation structure 10A is effective in cases where there is a height restriction, such as when installing equipment in a building or when applying a seismic isolation structure to existing equipment connected to other equipment, piping, cables, etc.

[0044] In addition, the metamaterial layer 13, which is a mechanical metamaterial for blocking the propagation of low-frequency vibrations, has a relatively large size for the unit components of the periodic structure. For this reason, the metamaterial layer 13 tends to become large. If the metamaterial layer 13 becomes large, the arrangement of the structure may be restricted. The modified seismic isolation structure 10A is effective because it can reduce the height dimension of the seismic isolation device 11 and improve the arrangement even when the arrangement of the structure is restricted.

[0045] The seismic isolation device 11 can use not only commonly used low-rigidity seismic isolation members such as laminated rubber, laminated rubber with lead plugs, elastic sliding bearings, linear rolling bearings, oil dampers, steel dampers, and coil springs, but also seismic isolation members having any rigidity for the seismic isolation layer 12. In particular, when a seismic isolation member having a ratio of the resonant frequency range (lower limit value of the resonant frequency range) of the seismic isolation layer 12 to the natural frequency of the upper structure 14 (seismic isolation section) of 1.4 or more is used for the seismic isolation layer 12, the seismic isolation device 11 can efficiently suppress the response displacement, although the effect of reducing the response acceleration is low, compared to the comparative seismic isolation device 110 (FIG. 3A).

[0046] The reason why the ratio of the resonant frequency range (the lower limit of the resonant frequency range) of the seismic isolation layer 12 to the natural frequency of the upper structure 14 is set to 1.4 or more is as follows. Here, the reason will be explained with reference to FIG. 8.

[0047] Fig. 8 is a graph showing the resonance curve of a linear damping system. Fig. 8 shows the absolute acceleration response magnification (the ratio of the maximum acceleration of the seismic isolated structure 10 (seismic isolated building) to the acceleration of the seismic motion) for each damping constant h when a sinusoidal seismic motion is input to the seismic isolated structure 10 (seismic isolated building). The horizontal axis of Fig. 8 represents the ratio (P / ω0) between the circular frequency ω0 of the seismic isolated structure 10 (seismic isolated building) and the frequency P of the sinusoidal seismic motion. The vertical axis of Fig. 8 represents the ratio of the maximum acceleration of the seismic isolated structure 10 (seismic isolated building).

[0048] In the example shown in FIG. 8, line L10 represents the absolute acceleration response magnification when the damping constant h is 0. Line L11 represents the absolute acceleration response magnification when the damping constant h is 0.1. Line L12 represents the absolute acceleration response magnification when the damping constant h is 0.2. Line L13 represents the absolute acceleration response magnification when the damping constant h is 0.4. Line L14 represents the absolute acceleration response magnification when the damping constant h is 0.707. Line L15 represents the absolute acceleration response magnification when the damping constant h is 1.0.

[0049] As shown in Fig. 8, regardless of the damping constant h, when the ratio (P / ω0) between the circular frequency ω0 of the seismic isolation structure 10 (seismic isolation building) and the frequency P of the sinusoidal earthquake motion is 1.4 or more, the absolute acceleration response magnification becomes 1 or less. Therefore, when the ratio (P / ω0) between the circular frequency ω0 of the seismic isolation structure 10 (seismic isolation building) and the frequency P of the sinusoidal earthquake motion is 1.4 or more, vibration is suppressed. Therefore, when the ratio of the resonant frequency range (lower limit value of the resonant frequency range) of the seismic isolation layer 12 to the natural frequency of the upper structure 14 (seismic isolation section) is set to 1.4 or more, the seismic isolation device 11 can suppress the response displacement of the seismic isolation layer 12 during an earthquake and efficiently reduce the displacement of the seismic isolation structure 10 (seismic isolation building).

[0050] In addition, the seismic isolation device 11 can expand the design range of the metamaterial layer 13 designed to inhibit the same vibration frequency component by using a seismic isolation material having any rigidity in the seismic isolation layer 12. Therefore, the seismic isolation device 11 can be applied to the upper structure 14 (seismic isolation part) with various natural frequencies.

[0051] <Main features of the seismic isolation device> (1) As shown in FIG. 1A, the seismic isolation device 11 according to this embodiment is disposed between an upper structure 14 (seismic isolation section) in which earthquake vibrations are reduced and a lower base 15 (non-seismic isolation section) in which earthquake vibrations are not reduced, and is a device that reduces the earthquake response of the upper structure 14 (seismic isolation section). The seismic isolation device 11 according to this embodiment has a metamaterial layer 13 that inhibits the transmission of vibrations in a specific frequency range, and a seismic isolation layer 12 in which an arbitrary resonant frequency range is set. The specific frequency range of the metamaterial layer 13 is equal to the resonant frequency range of the seismic isolation layer 12. The metamaterial layer 13 and the seismic isolation layer 12 are disposed in series, and the seismic isolation layer 12 is disposed closer to the upper structure 14 (seismic isolation section) than the metamaterial layer 13.

[0052] In the seismic isolation device 11 according to the present embodiment, when seismic motion propagates through the inside of the metamaterial layer 13 during an earthquake, the metamaterial layer 13 can inhibit vibration propagation in the resonance frequency range of the seismic isolation layer 12. As a result, the seismic isolation device 11 according to the present embodiment can input seismic motion from which vibration components in the resonance frequency range of the seismic isolation layer 12 have been removed to the seismic isolation layer 12. Therefore, the seismic isolation device 11 according to the present embodiment can make it difficult to excite the resonance of the seismic isolation layer 12 during an earthquake, and can reduce the response (displacement) of the seismic isolation layer 12. As a result, the seismic isolation device 11 according to the present embodiment can suppress the relative displacement between the upper structure 14 (seismic isolation section) and the lower foundation 15 (non-seismic isolation section). In addition, the seismic isolation device 11 according to the present embodiment has a configuration in which the seismic isolation layer 12 and the metamaterial layer 13 are fixedly arranged in series between the upper structure 14 (seismic isolation section) and the lower foundation 15 (non-seismic isolation section). The seismic isolation device 11 according to the present embodiment has excellent arrangement properties and can efficiently reduce seismic motion.

[0053] (2) As shown in FIG. 7, in the seismic isolation device 11 according to this embodiment, the metamaterial layer 13 may be configured as a part of the lower base 15 (non-seismically isolated portion).

[0054] The seismic isolation device 11 according to this embodiment can reduce the relative displacement between the upper structure 14 (seismic isolation section) and the lower foundation 15 (non-seismic isolation section) during an earthquake. Moreover, the seismic isolation device 11 according to this embodiment can improve the arrangement by suppressing the height dimension of the seismic isolation device 11. Moreover, the seismic isolation device 11 according to this embodiment can reduce the load generated by the relative displacement between the upper structure 14 (seismic isolation section) and the lower foundation 15 (non-seismic isolation section) during an earthquake on the pipes, cables, etc. connecting the upper structure 14 (seismic isolation section) and the lower foundation 15 (non-seismic isolation section). Moreover, the seismic isolation device 11 according to this embodiment can efficiently reduce the relative displacement between the upper structure 14 (seismic isolation section) and the lower foundation 15 (non-seismic isolation section) during an earthquake.

[0055] (3) In the seismic isolation device 11 according to this embodiment, the resonant frequency range (lower limit of the resonant frequency range) of the seismic isolation layer 12 is preferably 1.4 times or more the natural frequency of the upper structure 14 (seismic isolation section) (FIG. 8). The specific frequency range of the metamaterial layer 13 is equivalent to the resonant frequency range of the seismic isolation layer 12. Therefore, the specific frequency range of the metamaterial layer 13 is also preferably 1.4 times or more the natural frequency of the upper structure 14 (seismic isolation section).

[0056] The seismic isolation device 11 according to this embodiment suppresses the response displacement of the seismic isolation layer 12 during an earthquake, and can efficiently reduce the amount of displacement of the seismic isolation structure 10 (seismic isolated building).

[0057] As described above, according to this embodiment, it is possible to provide a seismic isolation device 11 that is excellent in terms of placement and efficiently reduces earthquake motion.

[0058] The present invention is not limited to the above-described embodiment, and includes various modified examples. For example, the above-described embodiment has been described in detail to easily explain the present invention, and is not necessarily limited to having all of the configurations described. In addition, it is possible to replace a part of the configuration of the embodiment with another configuration, and it is also possible to add another configuration to the configuration of the embodiment. In addition, it is possible to add, delete, or replace a part of each configuration with another configuration.

[0059] For example, the seismic isolation layer 12 shown in the above embodiment may be a seismic isolation member having seismic isolation performance in three directions, composed of laminated rubber and coil springs, and the metamaterial layer 13 may be configured to have a frequency that inhibits vibration transmission in each direction so as to match the resonant frequency range of the seismic isolation member in each direction. In this case, it is possible to reduce the relative displacement during an earthquake in all three directional components of seismic motion. Furthermore, it is also possible to effectively reduce earthquake response by combining the seismic isolation device 11 according to this embodiment with another seismic isolation device in parallel or in series.

[0060] For the sake of simplicity, Figures 1 to 7 show an embodiment in which the seismic isolation device 11 is placed under the superstructure 14 whose seismic response is to be reduced. However, the seismic isolation device 11 is not limited to being placed under the superstructure 14, and can also be applied to equipment that is fixed in a suspended state, for example.

[0061] In addition, for the sake of simplicity of explanation, Figures 1 and 2 show an embodiment in which the upper structure 14 for reducing earthquake response is supported by four seismic isolation devices 11. However, the number of seismic isolation devices 11 in this embodiment that can be arranged is not limited, and it is also effective to arrange any number of seismic isolation devices 11.

[0062] In addition, for the sake of simplicity, Figures 4A to 6 show an embodiment of metamaterial layer 13 in which central parts 16A, 16B, and 16C of the periodic structure have symmetry. However, the configuration of the periodic structure of metamaterial layer 13 of seismic isolation device 11 is not limited, and any periodic structure for inhibiting desired frequency components can be adopted.

[0063] In the above embodiment, the lower foundation 15 is described as a non-seismic isolation part in which earthquake vibrations are not reduced. However, the non-seismic isolation part includes not only parts in which earthquake vibrations are not reduced, but also parts in which earthquake vibrations are reduced but to a lesser extent than the seismic isolation part (parts that do not actively contribute to seismic isolation). [Explanation of symbols]

[0064] 10, 10A, 100 Seismic isolation structure 11,110 Seismic isolation device 12 Seismic isolation layer 13 Metamaterial layer 13A, 13B, 13C Unit components 14. Upper structure (earthquake-proof section) 15 Lower foundation (non-earthquake-proof part) 16A,16B,16C Center 17A, 17B, 17C Periphery L10,L11,L12,L13,L14,L15 line

Claims

1. A seismic isolation device that is disposed between a seismic isolation section in which earthquake vibrations are reduced and a non-seismic isolation section in which earthquake vibrations are not reduced, and reduces the seismic response of the seismic isolation section, A seismic isolation layer in which an arbitrary resonance frequency range is set; A metamaterial layer that blocks transmission of vibrations in a specific frequency range; The specific frequency range of the metamaterial layer is equal to the resonant frequency range of the seismic isolation layer, The seismic isolation layer and the metamaterial layer are arranged in series, The seismic isolation layer is disposed closer to the seismic isolation section than the metamaterial layer. A seismic isolation device characterized by the above.

2. The seismic isolation device according to claim 1, The metamaterial layer is configured as a part of the non-seismic isolation portion. A seismic isolation device characterized by the above.

3. The seismic isolation device according to claim 1, The resonant frequency range of the seismic isolation layer is 1.4 times or more the natural frequency of the seismic isolation section. A seismic isolation device characterized by the above.

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