Seismic isolation device
The seismic isolation device with a buckling prevention mechanism stabilizes coil springs against excessive seismic motion by engaging to bear vertical loads, addressing instability and simplifying design, while maintaining effective seismic load reduction.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- HITACHI GE NUCLEAR ENERGY LTD
- Filing Date
- 2025-12-26
- Publication Date
- 2026-07-16
AI Technical Summary
Conventional seismic isolation devices using coil springs or disc springs face instability and buckling issues when subjected to seismic motion exceeding the design level, leading to loss of support and restoring functions, and existing devices with multiple damping mechanisms complicate design considerations.
A seismic isolation device incorporating a coil spring and a buckling prevention mechanism with a support mechanism and sliding surface, where the sliding member does not contact the sliding surface in a stationary state but engages to bear vertical load during excessive seismic motion, preventing coil spring buckling and ensuring stability.
The device effectively prevents coil spring buckling and maintains stable performance even under seismic loads exceeding the design level, simplifying design complexity and enhancing maintainability by allowing independent adjustment of seismic isolation members.
Smart Images
Figure JP2025045955_16072026_PF_FP_ABST
Abstract
Description
Seismic isolation device
[0001] The present invention relates to a seismic isolation device for reducing the seismic load acting on structures such as equipment and buildings during an earthquake.
[0002] As one of the means to enhance the seismic performance of structures such as equipment and buildings, the application of a seismic isolation structure can be cited. In a seismic isolation structure, the target structure is supported by a seismic isolation device, and during an earthquake, the seismic isolation device is deformed to absorb the energy of vibration, thereby reducing the seismic load acting on the structure. The seismic isolation device is composed of seismic isolation members having a support function for supporting the upper structure, a damping function for absorbing energy during an earthquake, and a restoring function for attempting to return to the original position with respect to the displacement caused by the earthquake. Representative seismic isolation members include laminated rubber, coil springs, sliding bearings, linear rolling bearings, oil dampers, steel dampers, and viscous dampers. There are various types of seismic isolation devices devised for the seismic isolation device, including those equipped with seismic isolation members other than these and those combining various seismic isolation members, and some of these are actually in use.
[0003] A coil spring is a seismic isolation member having a support function and a restoring function, and is used by being arranged in a seismic isolation layer in parallel with a viscous damper having a damping function. It has a structure in which a helical spring member is fixed to the upper structure and the lower foundation via flanges, respectively. The coil spring supports the upper structure by the elastic force in the axial direction of the spring member. When seismic motion acts, it exhibits a horizontal restoring force due to the shear deformation of the spring member and a vertical restoring force due to the deformation in the axial direction of the spring member. [[ID=II]]
[0004] When an excessive seismic motion exceeding the seismic motion considered in the design acts on this coil spring, there is a concern that the vertical load fluctuation increases and the deformation of the spring member becomes excessive, resulting in buckling of the spring member and loss of the support function and instability of the restoring function. The loss of the support function and instability of the restoring function may also cause damage to the upper structure that is the target of seismic isolation. Therefore, even when a seismic motion exceeding the design level acts, a seismic isolation device that operates stably is desired.
[0005] An example of a conventional seismic isolation device is described in Patent Document 1. The seismic isolation device described in Patent Document 1 is capable of preventing buckling of laminated rubber bearings and adjusting the amount of sinking, and comprises a laminated rubber bearing and a friction disc spring bearing installed alongside the laminated rubber bearing. The friction disc spring bearing has a friction damping force generating unit as a damper mechanism, which consists of a sliding plate provided on the foundation and a friction material placed on the sliding plate, and a disc spring unit provided directly above the sliding plate and equipped with a flexing member for pressing the friction material against the sliding plate, with a disc spring used as the flexing member.
[0006] Japanese Patent Publication No. 2017-172733
[0007] Conventional seismic isolation devices using coil springs or disc springs have a problem in that if excessive seismic motion exceeding the seismic motion considered in the design (seismic motion at the design-exceeding level) acts on the device, the coil springs or disc springs buckle, making the support and restorative functions of the seismic isolation device unstable. Furthermore, in seismic isolation devices that always obtain damping resistance from both mechanisms placed side by side (for example, coil springs and viscous dampers, or laminated rubber bearings and friction disc spring bearings as described in Patent Document 1), the design must take into account the characteristics of both mechanisms, which presents a challenge in terms of design complexity.
[0008] The objective of the present invention is to provide a seismic isolation device that can prevent coil spring buckling and provide a stable response even when seismic motion exceeds the design level.
[0009] The seismic isolation device according to the present invention comprises a coil spring fixed to the superstructure and the lower foundation, and a buckling prevention mechanism comprising a support mechanism and a sliding surface. The support mechanism has one end fixed to the superstructure or the lower foundation and has a sliding member at the other end. The sliding surface is fixed to the lower foundation or the superstructure and is provided at a position opposite to the sliding member. The sliding member does not contact the sliding surface in a stationary state.
[0010] According to the present invention, it is possible to provide a seismic isolation device that can prevent buckling of the coil spring and obtain a stable response even when seismic motion exceeding the design level is applied.
[0011] This is an elevation view showing an example of a seismic isolation device according to Embodiment 1 of the present invention in a stationary state. This is an elevation view showing an example of a seismic isolation device according to Embodiment 1 when seismic motion at the design level is applied. This is an elevation view showing an example of a seismic isolation device according to Embodiment 1 when seismic motion exceeding the design level is applied. This is an elevation view showing an example of a seismic isolation device according to Embodiment 1 in a critical deformation state. This is an elevation view showing an example of a stationary state of a structure equipped with a base isolation type seismic isolation structure that includes the seismic isolation device according to Embodiment 1. This is a plan view showing an example of a seismic isolation layer in Embodiment 1. This is an elevation view showing an example of a seismic isolation device according to Embodiment 2 of the present invention in a stationary state. This is an elevation view showing an example of a stationary state of a structure equipped with a base isolation type seismic isolation structure that includes the seismic isolation device according to Embodiment 2. This is a plan view showing an example of a seismic isolation layer in Embodiment 2.
[0012] The seismic isolation device according to the present invention can stably reduce the seismic load acting on the superstructure even when seismic motion at a level exceeding the design level, which would cause the coil spring to buckle.
[0013] The seismic isolation device according to the present invention includes a support mechanism positioned alongside the coil spring and fixed to the superstructure. In a stationary state, the support mechanism does not contact the sliding surface fixed to the lower foundation. When seismic motion exceeding the design level acts, it contacts the sliding surface and bears a portion of the vertical load acting on the seismic isolation layer. This reduces the vertical load applied to the coil spring, prevents buckling of the coil spring, and allows for a stable response.
[0014] Hereinafter, an embodiment of the seismic isolation device according to the present invention will be described with reference to the drawings. In the drawings referred to herein, the same or corresponding components are denoted by the same reference numerals, and repeated descriptions of these components may be omitted.
[0015] The seismic isolation device according to Embodiment 1 of the present invention will be described using Figures 2 and 3, and Figures 1A to 1D.
[0016] Figure 2 is an elevation view showing an example of a static state (a state in which no earthquake is occurring) of a structure equipped with a base isolation type seismic isolation structure, which includes the seismic isolation device 1 according to this embodiment. The seismic isolation device 1 according to this embodiment is installed in the seismic isolation layer 4 between the superstructure 2 and the lower foundation 3.
[0017] The superstructure 2 is the structure to which the seismic isolation device 1 according to this embodiment reduces seismic loads, and is installed on the lower foundation 3. Seismic motion is input to the lower foundation 3. The seismic isolation layer 4 is equipped with the seismic isolation device 1 according to this embodiment and a viscous damper 7 having a damping function.
[0018] The seismic isolation device 1 according to this embodiment is arranged in parallel with the viscous damper 7 and includes a buckling prevention mechanism 5 and a coil spring 6. The buckling prevention mechanism 5 will be explained with reference to Figure 1A.
[0019] The coil spring 6 is fixed at one end to the superstructure 2 and at the other end to the lower foundation 3, and supports the superstructure 2. The coil spring 6 has a supporting function and a restoring function and is designed to respond at a desired seismic isolation period. If the coil spring 6 buckles, its supporting function and restoring function become unstable.
[0020] The viscous damper 7 is a seismic isolation device with damping function, and comprises a housing 16 and a piston 15. The housing 16 is a cylindrical container fixed to the lower foundation 3 and filled with a viscous material 17. The piston 15 is fixed to the superstructure 2 and is located inside the housing 16. During an earthquake, the piston 15 moves within the viscous material 17 in accordance with the relative displacement between the superstructure 2 and the lower foundation 3, and the vibration energy is damped by the resistance generated when the piston 15 moves.
[0021] Figure 3 is a plan view showing an example of a seismic isolation layer 4. As an example, Figure 3 shows a seismic isolation layer 4 in which four coil springs 6, four buckling prevention mechanisms 5, and four viscous dampers 7 are arranged. The buckling prevention mechanism 5 includes a support mechanism 10 and a stopper 9, as will be described later.
[0022] Figure 1A is an elevation view showing an example of a seismic isolation device 1 according to this embodiment in a stationary state (a state in which no earthquake is occurring). As described above, the seismic isolation device 1 is equipped with a buckling prevention mechanism 5 and a coil spring 6 and is installed in the seismic isolation layer 4. The buckling prevention mechanism 5 and the coil spring 6 are arranged in parallel with each other.
[0023] The buckling prevention mechanism 5 comprises a support mechanism 10, a sliding surface 13, and a stopper 9.
[0024] The support mechanism 10 comprises a column member 8, an elastic member 11, and a sliding member 12. One end of the support mechanism 10 is fixed to the superstructure 2, and the other end is equipped with the elastic member 11 and the sliding member 12.
[0025] The column member 8 is a member that extends vertically, with one end fixed to the superstructure 2 via a fixing member (for example, a flange), and the other end, which is the end on the lower foundation 3 side, is equipped with an elastic member 11. The elastic member 11 is provided at the other end of the column member 8 and is made of, for example, rubber or a coil spring. The sliding member 12 is provided on the elastic member 11 and is made of, for example, fluororesin or metal. That is, the elastic member 11 is provided between the column member 8 and the sliding member 12, and the sliding member 12 is provided at the other end of the support mechanism 10.
[0026] The sliding surface 13 is fixed to the lower foundation 3 and is positioned opposite the sliding member 12. The sliding surface 13 is made of, for example, fluororesin or metal.
[0027] The stopper 9 is fixed to the sliding surface 13 and is a protruding member that extends from the sliding surface 13 and surrounds the support mechanism 10 (see Figure 3). For example, the stopper 9 is an annular member, and the support mechanism 10 is located inside the annulus. In a stationary state, the stopper 9 does not contact the support mechanism 10. The stopper 9 may also be fixed to the lower foundation 3 and be a protruding member that extends from the lower foundation 3.
[0028] In the seismic isolation device 1 according to this embodiment, the sliding member 12 of the buckling prevention mechanism 5 is separated from the sliding surface 13 and does not contact the sliding surface 13 when stationary. The sliding member 12 can contact the sliding surface 13 when seismic motion is applied. When the sliding member 12 contacts the sliding surface 13, it can slide horizontally along the sliding surface 13. The elastic member 11 adjusts the vertical vibration characteristics of the seismic isolation device 1 when the sliding member 12 contacts the sliding surface 13.
[0029] Next, the operation of the seismic isolation device 1 according to this embodiment will be described.
[0030] As shown in Figure 1A, in a stationary state (when no earthquake is occurring), the seismic isolation device 1 according to this embodiment has the sliding member 12 of the buckling prevention mechanism 5 not in contact with the sliding surface 13, and the superstructure 2 is supported by the axial elastic force of the coil spring 6. The support mechanism 10 of the buckling prevention mechanism 5 is not in contact with the stopper 9.
[0031] Figure 1B is an elevation view showing an example of a seismic isolation device 1 according to this embodiment under conditions where design-level seismic motion is applied. Design-level seismic motion refers to seismic motion of a strength that allows the coil spring 6 to stably perform its support and restoring functions.
[0032] When seismic motion at the design level is applied, the coil spring 6 undergoes shear deformation in response to the horizontal seismic load and axial deformation in response to the vertical seismic load transmitted between the superstructure 2 and the lower foundation 3. As a result, the superstructure 2 responds with a longer period than if it were directly fixed to the lower foundation 3. Furthermore, the viscous damper 7 (Figure 2) attenuates the vibration energy. In this embodiment, the seismic load transmitted to the superstructure 2 can be reduced in this way.
[0033] In the seismic isolation device 1 according to this embodiment, when an earthquake motion of the design level is applied, the sliding member 12 of the buckling prevention mechanism 5 changes its distance from the sliding surface 13 due to the deformation of the coil spring 6, but it does not come into contact with the sliding surface 13. Therefore, the earthquake load is not transmitted to the buckling prevention mechanism 5.
[0034] Thus, in the seismic isolation device 1 according to this embodiment, the buckling prevention mechanism 5 does not operate in a stationary state (Figure 1A) or when seismic motion at the design level is applied (Figure 1B), and only the coil spring 6 operates. For this reason, in the seismic isolation device 1 according to this embodiment, the seismic isolation layer 4 can be designed without including the mechanical characteristics of the buckling prevention mechanism 5 within the range of seismic motion at the design level, thus simplifying the design of the seismic isolation layer 4. Furthermore, a seismic isolation device that has a coil spring 6 but does not have a buckling prevention mechanism 5 can be easily converted to the seismic isolation device 1 according to this embodiment by adding the buckling prevention mechanism 5.
[0035] Figure 1C is an elevation view showing an example of a seismic isolation device 1 according to this embodiment under conditions where seismic motion exceeding the design level is applied. Seismic motion exceeding the design level refers to excessive seismic motion that exceeds the seismic motion considered in the design, and is of a strength that would cause the coil spring 6 to buckle and not function properly without the buckling prevention mechanism 5, preventing it from stably performing its support and restorative functions.
[0036] When seismic motion exceeding the design level acts, the horizontal and vertical deformation of the coil spring 6 increases, and the sliding member 12 of the buckling prevention mechanism 5 comes into contact with the sliding surface 13. When the sliding member 12 and the sliding surface 13 come into contact with each other, the support mechanism 10 bears a portion of the vertical seismic load, and the vibration energy is attenuated by the sliding resistance caused by the contact between the sliding member 12 and the sliding surface 13.
[0037] In this embodiment, the buckling prevention mechanism 5 bears a portion of the vertical seismic load in this manner, thereby reducing the vertical seismic load acting on the coil spring 6 and preventing buckling of the coil spring 6.
[0038] As the horizontal displacement of the coil spring 6 increases, the vertical load before buckling decreases. In the seismic isolation device 1 according to this embodiment, as the horizontal displacement of the coil spring 6 increases, it undergoes shear deformation and its vertical length shortens, which increases the vertical seismic load borne by the buckling prevention mechanism 5. For this reason, the seismic isolation device 1 according to this embodiment, which is equipped with the buckling prevention mechanism 5, can respond more stably to stronger seismic motions compared to a seismic isolation device equipped only with a coil spring 6 and without the buckling prevention mechanism 5.
[0039] Furthermore, in the seismic isolation device 1 according to this embodiment, an elastic member 11 is provided between the column member 8 and the sliding member 12 at the other end of the column member 8 of the support mechanism 10 of the buckling prevention mechanism 5. By adjusting the rigidity of this elastic member 11, the vertical vibration characteristics of the seismic isolation device 1 can be adjusted, and the seismic response of the superstructure 2 to earthquake motion exceeding the design level can be effectively reduced.
[0040] Figure 1D is an elevation view showing an example of the seismic isolation device 1 according to this embodiment in the limit deformation state. The limit deformation state is the state in which the seismic isolation device 1 can no longer deform.
[0041] If the horizontal and vertical deformation of the coil spring 6 increases further from the state shown in Figure 1C, the seismic isolation device 1 will reach its limit deformation state. In the limit deformation state, the support mechanism 10 of the buckling prevention mechanism 5 will come into contact with the stopper 9 protruding from the sliding surface 13. The coil spring 6 is in a state where it is prone to buckling due to increased horizontal deformation, but since the support mechanism 10 is in contact with the stopper 9, further horizontal deformation is prevented.
[0042] In the seismic isolation device 1 according to this embodiment, the stopper 9 restricts the horizontal movement of the support mechanism 10, thereby preventing buckling of the coil spring 6 and suppressing unstable behavior and loss of support function of the seismic isolation device 1.
[0043] Thus, in the seismic isolation device 1 according to this embodiment, when ground motion at the design level acts (FIG. 1B), only the coil spring 6 acts, and when ground motion exceeding the design level acts (FIG. 1C), the buckling prevention mechanism 5 arranged in parallel with the coil spring 6 acts. The buckling prevention mechanism 5 bears the seismic load in the vertical direction and suppresses the buckling of the coil spring 6. Therefore, the seismic isolation device 1 according to this embodiment can operate stably and can effectively reduce the seismic load acting on the superstructure 2 even against stronger ground motion.
[0044] Furthermore, for ground motion of such a magnitude that the coil spring 6 is displaced excessively in the horizontal direction, the support mechanism 10 of the buckling prevention mechanism 5 abuts against the stopper 9 (FIG. 1D), thereby inhibiting further deformation of the coil spring 6 in the horizontal direction and suppressing unstable behavior of the seismic isolation device 1.
[0045] As described above, the seismic isolation device 1 according to this embodiment can prevent the buckling of the coil spring 6 even when strong ground motion exceeding the design level acts, and can respond stably even to such strong ground motion.
[0046] Also, in the seismic isolation device 1 according to this embodiment, the coil spring 6, the buckling prevention mechanism 5, and the viscous damper 7 are each arranged independently (for example, FIG. 3). Therefore, when the ground motion that needs to be considered for the superstructure 2 is changed, it is easy to change or adjust the configuration of the seismic isolation members (for example, the coil spring 6, the buckling prevention mechanism 5, and the viscous damper 7), and the seismic isolation device 1 according to this embodiment is excellent in maintainability.
[0047] The separation distance between the sliding member 12 and the sliding surface 13 of the buckling prevention mechanism 5 in the stationary state can be determined based on, for example, the mechanical characteristics of the coil spring 6. For example, the buckling limit of the coil spring 6 can be obtained from the support load and the fluctuating load of the coil spring 6, and the separation distance between the sliding member 12 and the sliding surface 13 in the stationary state can be determined from this buckling limit.
[0048] Incidentally, in this embodiment, an example where the support mechanism 10 of the buckling prevention mechanism 5 is fixed to the upper structure 2 has been described. The support mechanism 10 may be fixed to the lower foundation 3. In this case, the sliding surface 13 is fixed to the upper structure 2, the sliding member 12 of the support mechanism 10 is separated from the sliding surface 13 in the stationary state, and the stopper 9 is fixed to the sliding surface 13 or the upper structure 2. That is, the buckling prevention mechanism 5 may have a configuration that is vertically inverted with respect to the buckling prevention mechanism 5 shown in this embodiment.
[0049] The seismic isolation device 1 according to Embodiment 2 of the present invention will be described with reference to FIGS. 5 and 6, and FIG. 4. Hereinafter, the seismic isolation device 1 according to this embodiment will be mainly described with respect to the differences from the seismic isolation device 1 according to Embodiment 1. The seismic isolation device 1 according to this embodiment has a configuration in which the buckling prevention mechanism 5 and the viscous damper 7 included in the seismic isolation device 1 according to Embodiment 1 are integrated.
[0050] FIG. 5 is an elevation view showing an example of a stationary state (a state in which an earthquake has not occurred) of a structure having a base-isolated seismic isolation structure including the seismic isolation device 1 according to this embodiment. The seismic isolation device 1 according to this embodiment is installed in the seismic isolation layer 4 between the upper structure 2 and the lower foundation 3.
[0051] The seismic isolation device 1 according to this embodiment includes a viscous damper integrated buckling prevention mechanism 14 and a coil spring 6. The viscous damper integrated buckling prevention mechanism 14 will be described with reference to FIG. 4.
[0052] FIG. 6 is a plan view showing an example of the seismic isolation layer 4. FIG. 6 shows, as an example, the seismic isolation layer 4 in which four coil springs 6 and four viscous damper integrated buckling prevention mechanisms 14 are arranged. As will be described later, the viscous damper integrated buckling prevention mechanism 14 includes a support mechanism 10 and a housing 18.
[0053] FIG. 4 is an elevation view showing an example of the seismic isolation device 1 according to this embodiment in a stationary state (a state in which an earthquake has not occurred). As described above, the seismic isolation device 1 includes a viscous damper integrated buckling prevention mechanism 14 and a coil spring 6. The viscous damper integrated buckling prevention mechanism 14 and the coil spring 6 are arranged in parallel with each other.
[0054] The viscous damper-integrated buckling prevention mechanism 14 combines the functions of the buckling prevention mechanism 5 and the viscous damper 7 described in Example 1, and includes the support mechanism 10 and housing 18 described in Example 1. The support mechanism 10 further includes the function of the piston 15 (Figure 2) of the viscous damper 7 described in Example 1.
[0055] The housing 18 is a cylindrical container fixed to the lower foundation 3, having a bottom and sides, and filled with a viscous substance 17. The support mechanism 10 is located inside the housing 18 (see Figure 6). During an earthquake, the support mechanism 10 moves within the viscous substance 17 in accordance with the relative displacement between the superstructure 2 and the lower foundation 3, and the vibration energy is attenuated by the resistance generated when the support mechanism 10 moves. The bottom surface of the housing 18 is the sliding surface 13 described in Embodiment 1. The sides of the housing 18 are the stoppers 9 described in Embodiment 1, surrounding the support mechanism 10.
[0056] In the seismic isolation device 1 according to this embodiment, when a seismic motion at the design level acts, the coil spring 6 deforms in the same manner as shown in Figure 1B, and the viscous damper-integrated buckling prevention mechanism 14 causes the support mechanism 10 to move within the viscous body 17 in accordance with the relative displacement between the superstructure 2 and the lower foundation 3, and the vibration energy is attenuated by the resistance generated when the support mechanism 10 moves. In this embodiment, the seismic load transmitted to the superstructure 2 can be reduced in this way.
[0057] Due to the deformation of the coil spring 6, the sliding member 12 of the viscous damper-integrated buckling prevention mechanism 14 experiences a change in its separation distance from the sliding surface 13, but it does not come into contact with the sliding surface 13. Therefore, seismic loads are not transmitted to the viscous damper-integrated buckling prevention mechanism 14.
[0058] In the seismic isolation device 1 according to this embodiment, when an earthquake motion exceeding the design level acts, the coil spring 6 deforms in the same manner as shown in Figure 1C, and the sliding member 12 of the viscous damper-integrated buckling prevention mechanism 14 comes into contact with the sliding surface 13. When the sliding member 12 and the sliding surface 13 come into contact with each other, the support mechanism 10 bears a portion of the vertical earthquake load, and the vibration energy is attenuated by the sliding resistance associated with the contact between the sliding member 12 and the sliding surface 13, and the resistance generated when the support mechanism 10 moves within the viscous body 17.
[0059] In the seismic isolation device 1 according to this embodiment, in the limit deformation state, the support mechanism 10 of the viscous damper-integrated buckling prevention mechanism 14 contacts the stopper 9 (side surface of the housing 18) protruding from the sliding surface 13, similar to the state shown in Figure 1D.
[0060] In the limit deformation state, the support mechanism 10 contacts the inner surface of the housing 18, and the inner side surface of the housing 18 is subjected to an outward force. However, thanks to the stopper 9 on the side surface of the housing 18, the side surface of the housing 18 is prevented from breaking due to the horizontal force. In other words, the stopper 9 improves the horizontal strength of the housing 18, allowing it to withstand horizontal forces that would cause the side surface of a conventional housing 18 to break.
[0061] Furthermore, the seismic isolation device 1 according to this embodiment may be configured with only a support mechanism 10 added to a conventional viscous damper, or with only a stopper 9 added to a conventional viscous damper. The support mechanism 10 has the function of supporting vertical forces and partially suppressing horizontal forces through sliding resistance with the bottom surface of the housing 18. The stopper 9 has the function of preventing the side surface of the housing 18 from breaking due to excessive horizontal forces.
[0062] Although the coil spring 6 is prone to buckling due to increased horizontal deformation, the support mechanism 10 is in contact with the stopper 9, preventing further horizontal deformation. In this way, buckling of the coil spring 6 can be prevented, and unstable behavior and loss of support function of the seismic isolation device 1 can be suppressed.
[0063] As described above, the seismic isolation device 1 according to this embodiment comprises a viscous damper-integrated buckling prevention mechanism 14 and a coil spring 6, and the viscous damper-integrated buckling prevention mechanism 14 has the functions of the buckling prevention mechanism 5 and viscous damper 7 described in Embodiment 1. Therefore, the seismic isolation device 1 according to this embodiment, like the seismic isolation device 1 according to Embodiment 1, can prevent buckling of the coil spring 6 even when seismic motion exceeds the design level, and can respond stably even to strong seismic motion.
[0064] Furthermore, in the seismic isolation device 1 according to this embodiment, the viscous damper-integrated buckling prevention mechanism 14 combines the functions of both the buckling prevention mechanism 5 and the viscous damper 7 described in Embodiment 1, thus reducing the number of seismic isolation members and providing excellent arrangement flexibility in the seismic isolation layer 4.
[0065] Examples 1 and 2 describe a case where the superstructure 2 is a structure equipped with a base isolation type seismic isolation structure. The present invention is also applicable when the superstructure 2 is a structure equipped with a partial seismic isolation structure or a tuned mass damper.
[0066] Furthermore, Figure 3 shows an example where the number of buckling prevention mechanisms 5, coil springs 6, and viscous dampers 7 are equal, and Figure 6 shows an example where the number of coil springs 6 and viscous damper-integrated buckling prevention mechanisms 14 are equal. The number of these seismic isolation members may differ from one another. In addition, the positions of these seismic isolation members in the seismic isolation layer 4 can be arbitrarily determined. For this reason, the present invention can be expected to reduce the number of seismic isolation members and improve their arrangement flexibility.
[0067] Furthermore, in this invention, instead of the coil spring 6, a seismic isolation member such as an air spring, which behaves in three dimensions and has both a support function and a restoring function, may be used. In this case, the seismic load acting on the superstructure 2 can be reduced by setting the separation distance between the sliding member 12 and the sliding surface 13 of the buckling prevention mechanism 5, or by setting the rigidity of the elastic member 11, according to the mechanical properties of the seismic isolation member to be combined.
[0068] Furthermore, the seismic isolation device according to the present invention can be used in combination with other seismic isolation components such as sliding bearings and oil dampers. By using it in combination with other seismic isolation components, the seismic isolation device can be given desired characteristics, and it is possible to prevent the response from becoming unstable when excessive seismic motion is applied.
[0069] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible. For example, the embodiments described above are explained in detail to make the present invention easier to understand, and the present invention is not necessarily limited to embodiments having all of the described configurations. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to delete parts of the configuration of each embodiment, or to add or replace other configurations.
[0070] 1... Seismic isolation device, 2... Superstructure, 3... Lower foundation, 4... Seismic isolation layer, 5... Buckling prevention mechanism, 6... Coil spring, 7... Viscous damper, 8... Column member, 9... Stopper, 10... Support mechanism, 11... Elastic member, 12... Sliding member, 13... Sliding surface, 14... Viscous damper integrated buckling prevention mechanism, 15... Piston, 16... Housing, 17... Viscous body, 18... Housing.
Claims
1. A seismic isolation device comprising: a coil spring fixed to a superstructure and a lower foundation; a buckling prevention mechanism comprising a support mechanism and a sliding surface, wherein one end of the support mechanism is fixed to the superstructure or the lower foundation and the other end is provided with a sliding member; the sliding surface is fixed to the lower foundation or the superstructure and is provided at a position opposite to the sliding member; and the sliding member does not contact the sliding surface in a stationary state.
2. The seismic isolation device according to claim 1, wherein the buckling prevention mechanism comprises a stopper fixed to the sliding surface, and the stopper is a member that protrudes from the sliding surface and surrounds the support mechanism.
3. The seismic isolation device according to claim 1, wherein the sliding member is capable of contacting the sliding surface when seismic motion is applied.
4. The seismic isolation device according to claim 1, wherein the support mechanism comprises a column member with one end fixed to the superstructure and an elastic member provided at the other end of the column member, the elastic member being provided between the column member and the sliding member.
5. The seismic isolation device according to claim 1, wherein the buckling prevention mechanism comprises a housing fixed to the lower foundation, the housing is filled with a viscous material, the support mechanism is located inside the housing, and the sliding surface is the bottom surface of the housing.