JP7465702B2 - Seismic isolation device and design method - Google Patents

Description

The present invention relates to a seismic isolation device.

A seismic isolation building, which has a seismic isolation layer made of laminated rubber or the like formed on the foundation of the building, prevents earthquake motion from propagating from the foundation to the building. Vibrations caused by earthquake motion are attenuated by arranging seismic isolation devices such as viscous dampers or oil dampers in the seismic isolation layer. In this configuration, the shaking of the building is suppressed within the range of motion of the seismic isolation layer, avoiding collisions with retaining walls and preventing the acceleration of the upper floors of the building from increasing excessively.

Until now, the structure of the seismic isolation layer has been designed assuming a level 2 earthquake motion (hereafter referred to as L2 earthquake motion), which is assumed to be a major earthquake, but there is a demand for seismic isolation buildings that can withstand extremely large level 3 earthquake motion (hereafter referred to as L3 earthquake motion), which significantly exceeds level 2 earthquake motion. In order to avoid collisions with retaining walls, it is possible to design the damper to increase its viscous damping coefficient. However, with this method, even in small to medium-sized earthquakes, the increased response acceleration of the upper floors of the building may make furniture and other items more likely to fall over, or the force generated by the damper may be transmitted to the main body of the building, causing damage to the building itself, which may undermine the effectiveness of seismic isolation buildings.

For example, Patent Document 1 discloses a configuration for increasing the viscous damping coefficient of the damper when a large earthquake occurs. According to this, since the viscous damping coefficient is small during small to medium-sized earthquakes, it is possible to suppress the increase in the response acceleration of the upper stories of the building, and by increasing the viscous damping coefficient during a large earthquake, it is possible to avoid collision with the retaining wall.

JP 2018-91034 A

However, the damper disclosed in Patent Document 1 has a complex structure, and the damping force changes discontinuously due to a sudden change in the viscous damping coefficient, so it was necessary to take this into account in the seismic design.

One of the objectives of the present invention is to provide a seismic isolation device that can respond to various earthquake motions with a simple structure.

According to one embodiment of the present invention, there is provided a seismic isolation device connected to a building, the seismic isolation device comprising: a first damper whose damping force increases with an increase in response speed, and a first increase rate of the damping force at the first speed is greater than a second increase rate of the damping force at a second speed greater than the first speed; and a second damper arranged in parallel to the first damper whose damping force increases with an increase in response speed, and a third increase rate of the damping force at the first speed is smaller than a fourth increase rate of the damping force at the second speed, and a fifth increase rate of the damping force at a third speed greater than the second speed is smaller than the fourth increase rate.

The damping force of the second damper between the first speed and the second speed may be proportional to the square of the response speed.

The damping force of the first damper between the first speed and the second speed may be proportional to the α power of the response speed (α is 0.1 or more and 0.9 or less).

The change in the rate of increase of the total damping force of the first damper and the second damper may gradually decrease as the response speed increases, then gradually increase, and then further decrease discontinuously at a predetermined speed at which the response speed increases.

The first damper may have a first increase rate of damping force at a predetermined speed between the first speed and the second speed.

The damping force of the second damper at the second speed may be smaller than the damping force of the first damper at the second speed.

The second speed may be half the maximum design speed of the first damper or the second damper.

The second speed may be 0.5 m/s.

The second speed may be 0.75 m/s.

The damping force of the second damper at the second speed may be greater than or equal to 0.2 and less than or equal to 0.8 of the damping force of the first damper at the second speed.

The second damper may be arranged parallel to the first damper.

Furthermore, according to one embodiment of the present invention, a design method is provided that includes determining the viscous damping coefficients of the first damper and the second damper so as to achieve the first to fifth increase rates in the seismic isolation device.

The present invention provides a seismic isolation device that can respond to various earthquake motions with a simple structure.

2 is a diagram showing an example of an arrangement of a seismic isolation device in the first embodiment of the present invention. FIG. 4 is a diagram showing the response speed dependency of the damping force of the seismic isolation device in the first embodiment of the present invention. FIG. 4 is a diagram showing an increase rate of the damping force of the seismic isolation device in the first embodiment of the present invention. FIG. FIG. 11 is a diagram showing a simulation result showing the relationship between the top acceleration and the seismic isolation layer displacement in the first embodiment of the present invention. FIG. 11 is a diagram showing a simulation result showing the relationship between the damper speed and the seismic isolation layer displacement in the first embodiment of the present invention. A diagram showing the response speed dependency of the damping force of the seismic isolation device in the second embodiment of the present invention. 13 is a diagram showing an increase rate of the damping force of a seismic isolation device in a second embodiment of the present invention. FIG. A diagram showing the response speed dependency of the damping force of the seismic isolation device in the third embodiment of the present invention. FIG. 13 is a diagram showing an increase rate of the damping force of a seismic isolation device according to the third embodiment of the present invention. A diagram showing the response speed dependency of the damping force of a seismic isolation device in the fourth embodiment of the present invention. FIG. 13 is a diagram showing an increase rate of the damping force of a seismic isolation device in the fourth embodiment of the present invention. 13 is a diagram showing an example of the arrangement of a seismic isolation device in a fifth embodiment of the present invention. FIG. 13 is a diagram showing an example of the arrangement of a seismic isolation device in a sixth embodiment of the present invention. FIG. FIG. 13 is a diagram for explaining a model used in a simulation.

One embodiment of the present invention will be described in detail below with reference to the drawings. The embodiment described below is merely an example of the present invention, and the present invention should not be interpreted as being limited to these embodiments. In the drawings referred to in this embodiment, identical parts or parts having similar functions are given the same or similar symbols (symbols consisting of only a number followed by A, B, etc.), and repeated explanations may be omitted.

First Embodiment
1 is a diagram showing an example of the arrangement of a seismic isolation device in a first embodiment of the present invention. A seismic isolation device 1 and seismic isolation rubber 50 in the first embodiment are provided between a building 80 and a foundation 60 to form a seismic isolation layer. The building 80 is designed to have a clearance d between it and a retaining wall 90. Displacement of the building 80 due to earthquake motion is suppressed by the seismic isolation layer, but each structure constituting the seismic isolation layer is designed so that this displacement is smaller than the clearance d and the building 80 does not collide with the retaining wall 90.

The seismic isolation device 1 includes two types of dampers arranged in parallel. In this example, the two types of dampers include a viscous damper 10 (first damper) and a velocity-squared damper 20 (second damper), which are arranged vertically in parallel to each other. Both ends of the viscous damper 10 and the velocity-squared damper 20 are supported by a foundation-side support section 64 fixed to the foundation 60 and a building-side support section 84 fixed to the building 80. In this example, a pair of one viscous damper 10 and one velocity-squared damper 20 is arranged between one foundation-side support section 64 and one building-side support section 84. The positional relationship between the viscous damper 10 and the velocity-squared damper 20 is not limited to the relationship shown in FIG. 1. For example, either one may be installed on top, and the positional relationship between them may differ depending on the installation location.

The seismic isolation device 1, which uses two types of dampers each with the characteristics described below, can prevent the building 80 from colliding with the retaining wall 90 even in the event of a major earthquake, while suppressing an increase in response acceleration in the upper floors of the building 80 in small to medium-sized earthquakes.

The viscous damper 10 generates a damping force on the piston rod by moving the piston head inside a cylinder that contains a viscous material. The damping force F (kN) generated by the viscous damper 10 is expressed as F = CVα (α is 0.1 to 0.9) using the viscous damping coefficient C and the piston moving speed V (m/s). In this example, the entire viscous damper 10 (the sum of the two viscous dampers 10 shown in FIG. 1) is designed to have the characteristics of a viscous damping coefficient C = 1800 (kN/(m/s)α) and α = 0.3, and the maximum design speed (hereinafter referred to as the maximum design speed) is determined to be 1.0 (m/s). In FIG. 1, two viscous dampers 10 are used, but one viscous damper 10 or more viscous dampers 10 may be used. In addition, the viscous damper 10 may be arranged in a direction other than that shown in FIG. 1, for example, in a horizontal plane, in a direction perpendicular to this direction (the depth direction in FIG. 1).

The velocity-squared damper 20 is an orifice damper, which generates a damping force in a piston rod by moving a piston head with an orifice formed in it inside a cylinder filled with oil. The damping force F (kN) generated by the velocity-squared damper 20 is expressed as F= ^CV2 using the viscous damping coefficient C and the piston moving speed V (m/s). This viscous damping coefficient C is expressed as (ρ· ^A3 )/(Cf· ^a2 ), where ρ is the density of the oil, A is the area of the piston head (cross-sectional area inside the cylinder), Cf is the flow coefficient, and a is the orifice area.

In this example, the velocity squared damper 20 as a whole (the sum of the two velocity squared dampers 20 shown in FIG. 1 ) is designed to have a characteristic of a viscous damping coefficient C=4000 (kN/(m/s) ² ), and the maximum design speed (design maximum speed) is determined to be 1.0 (m/s). The velocity squared damper 20 has a relief mechanism that reduces the damping force F at a relief speed VSr (m/s) or higher (VSr=0.65 (m/s) in this example) so that the damping force F becomes 2000 (kN) at this design maximum speed. In FIG. 1 , two velocity squared dampers 20 are used, but one velocity squared damper 20 may be used, or more velocity squared dampers 20 may be used. The velocity squared dampers 20 may also be arranged in a direction other than that shown in FIG. 1 , for example, in a direction perpendicular to the horizontal plane (depth direction in FIG. 1 ).

Next, we will explain the dependency of the damping force F on the response speed V for the viscous damper 10, the velocity-squared damper 20, and the seismic isolation device 1 that combines these. Here, we will also explain the increase rate R of the damping force F with an increase in the response speed V, that is, the differential value of the damping force F with respect to the response speed V.

Figure 2 is a diagram showing the response speed dependency of the damping force of the seismic isolation device in the first embodiment of the present invention. Figure 3 is a diagram showing the increase rate of the damping force of the seismic isolation device in the first embodiment of the present invention. Figure 2 shows the response speed V on the horizontal axis and the damping force F on the vertical axis, and shows the relationship between the damping force FV of the viscous damper 10 (dashed line), the damping force FS of the velocity squared damper 20 (two-dot chain line), and the damping force FF of the seismic isolation device 1 (solid line). As described above, the seismic isolation device 1 has the viscous damper 10 and the velocity squared damper 20 arranged in parallel. Therefore, the damping force FF of the seismic isolation device 1 is the sum of the damping force FV of the viscous damper 10 and the damping force FS of the velocity squared damper. Figure 3 shows the increase rate RV of the damping force FV (dashed line), the increase rate RS of the damping force FS (two-dot chain line), and the increase rate RF of the damping force FF (solid line).

The rate of increase RF of the damping force FF of the seismic isolation device 1 gradually decreases as the response speed V increases from 0 to speed VFm (region RA), gradually increases as it increases to the relief speed VSr after reaching a minimum value at speed VFm (region RB), decreases discontinuously at the relief speed VSr, and then maintains the lowest value as it increases to the maximum design speed (region RC).

The damping force FV of the viscous damper 10 changes in proportion to the 0.3 power of the response speed V, as described above. Therefore, the larger the response speed V, the smaller the increase rate RV. In other words, the increase rate (first increase rate) at a certain first speed (e.g., speed in region RA) is greater than the increase rate (second increase rate) at a second speed (e.g., speed in region RB) that is greater than the first speed.

The damping force FS of the velocity-squared damper 20 varies in proportion to the square of the response speed V as described above, and also has a relief mechanism. Therefore, as the response speed V increases, the increase rate RS increases, decreases discontinuously at the relief speed VSr, and then maintains its lowest value up to the maximum design speed. In other words, the increase rate at the first speed (third increase rate) is smaller than the increase rate at the second speed (fourth increase rate). Also, the increase rate at the third speed (speed in region RC) that is greater than the second speed (fifth increase rate) is smaller than the fourth increase rate.

In this example, the viscous damping coefficients C of the viscous damper 10 and the velocity-squared damper 20 are determined so that the damping force FS of the velocity-squared damper 20 is approximately 2/3 times the damping force FV of the viscous damper 10 at ^{0.5 (m/s), which is half the maximum design speed. As a result, as described above, the viscous damper 10 is designed to have a viscous damping coefficient C = 1800 (kN/(m/s) 0.3} ), and the velocity-squared damper 20 is designed to have a viscous damping coefficient C = 4000 (kN/(m/s) ² ).

The viscous damping coefficient C of the viscous damper 10 and the velocity-squared damper 20 may be determined so that the damping force FS of the velocity-squared damper 20 is not limited to 2/3 times the damping force FV of the viscous damper 10 at this response speed, but is more preferably 0.2 times or more and 0.8 times or less, more preferably 0.5 times or more and 0.7 times or less, depending on the usage situation, target specifications, etc. It is preferable that the damping force FS of the velocity-squared damper 20 is smaller than the damping force FV of the viscous damper 10. In addition, the response speed when determining such a relationship does not have to be determined as half the design maximum speed. For example, even if the design maximum speed is larger, it may be 0.5 (m/s) corresponding to the L2 earthquake motion, and may be at least a speed smaller than the relief speed VSr. In addition, half of the design maximum speed may correspond to the above-mentioned second speed.

In this way, by setting each parameter (e.g., the viscous damping coefficient C and the relief speed VSr) of the viscous damper 10 and the velocity-squared damper 20, it is possible to design the characteristics of the seismic isolation device 1, such as the first amplification rate to the fifth amplification rate described above. In this way, the present invention can be seen as a method for designing the characteristics of the seismic isolation device 1 to accommodate earthquake motions ranging from small to medium-sized to large-scale earthquake motions.

Next, the results of the earthquake response analysis using the seismic isolation device 1 will be explained by comparing it with an example in which only the viscous damper 10 is used as in the conventional case (conventional example) and an example in which the viscous damping coefficient C of the viscous damper 10 is doubled (comparative example). Here, a simulation of the earthquake response was performed under the following conditions:

Figure 14 is a diagram for explaining the model used in the simulation. Model 1000 includes seismic isolation layer 1M and building 80M. The seismic isolation layer 1M is a part that can be replaced with the seismic isolation device 1 and the conventional example and comparative example described above for comparison. The building 80M is assumed to be seven stories tall. The height of each story is 4.0 (m), and the weight of each story is 750 tons. The vibration period of the upper part of the building 80M is 0.8 (s) (2% damping relative to the primary natural period of the upper structure), and the vibration period of the seismic isolation layer 1M is 4 (s). The earthquake motion used is based on the BCJ-L2 simulated earthquake motion of the Japan Construction Center, with 0.5 times the level 1 earthquake motion (L1 earthquake motion), 1.0 times the level L2 earthquake motion, and 1.5 times the level L3 earthquake motion.

Figure 4 is a diagram showing the simulation results showing the relationship between the top acceleration and the seismic isolation layer displacement in the first embodiment of the present invention. Figure 5 is a diagram showing the simulation results showing the relationship between the damper speed and the seismic isolation layer displacement in the first embodiment of the present invention. Figures 4 and 5 show the analysis results FP (solid line) of the seismic isolation device 1, the analysis results VP1 (two-dot chain line) of the conventional example, and the analysis results VP2 (dashed line) of the comparative example. The damper speed corresponds to the response speed described above, and is equivalent to the piston movement speed.

According to the analysis result VP1, when only the viscous damper 10 is used, the damping force does not increase even if the damper speed increases, so the displacement of the seismic isolation layer exceeds 0.6 (m) in the case of L3 earthquake motion, which is larger than the other results.

On the other hand, according to the analysis result VP2, as a result of doubling the viscous damping coefficient C of the viscous damper 10 compared to the conventional example, the damping force becomes large even if the damper speed is low, and while the displacement of the seismic isolation layer is kept to about 0.4 (m) to 0.5 (m) in the case of L3 earthquake motion, the top acceleration exceeds 0.3 (m/ ^s2 ), and even in the case of L2 earthquake motion, the top acceleration is close to 0.3 (m/ ^s2 ), which is larger than the other results. When such a large acceleration occurs, it is possible that furniture etc. will fall over or the building itself will be damaged.

According to the analysis results FP, in the case of L2 earthquake motion, the top acceleration is suppressed to approximately 1.5 (m/ ^s2 ), which is almost the same as the conventional example using only viscous damper 10, but in the case of L3 earthquake motion, the displacement of the seismic isolation layer is suppressed to approximately 0.5 (m) and the top acceleration is also suppressed to approximately 2.3 (m/ ^s2 ).

In this way, the seismic isolation device 1 keeps the rate of increase of the damping force mainly due to the viscous damper 10 low up to a response speed of about 0.5 (m/s) for L2 earthquake motion, and as the earthquake motion becomes larger, the rate of increase of the damping force mainly due to the velocity-squared damper 20 increases, allowing the damping force to increase rapidly overall. In this way, by using the seismic isolation device 1, which combines two types of dampers, in the seismic isolation layer, it is possible to reduce the displacement of the seismic isolation layer and reduce the clearance d shown in Figure 1, and it is also possible to keep the top acceleration low.

Second Embodiment
In the seismic isolation device 1 in the first embodiment, the designed maximum speed is 1.0 (m/s), but in the second embodiment, an example in which the designed maximum speed is 1.50 (m/s) will be described.

FIG. 6 is a diagram showing the response speed dependency of the damping force of the seismic isolation device in the second embodiment of the present invention. FIG. 7 is a diagram showing the increase rate of the damping force of the seismic isolation device in the second embodiment of the present invention. The viscous damping coefficients C of the viscous damper 10 and the velocity squared damper 20 are determined so that the damping force FS of the velocity squared damper 20 is approximately 0.6 times the damping force FV of the viscous damper 10 at 0.75 (m/s), which is half the design maximum speed. In this example, the viscous damper 10 is set to the same viscous damping coefficient C=1800 (kN/(m/s) ^0.3 ) as in the first embodiment. The velocity squared damper 20 is set to a viscous damping coefficient C=1800 (kN/(m/s) ² ) smaller than in the first embodiment. Therefore, the relief speed VSr of the velocity squared damper 20 is set to be larger than that in the first embodiment.

Even if the design maximum velocity is set to a value different from that in the first embodiment, by appropriately setting the viscous damping coefficient C and the relief speed VSr, the characteristics of the seismic isolation device 1 can be controlled so that for small to medium-sized earthquake motions, the influence of the damping force due to the viscous damper 10 is mainly kept at a low rate of increase, and as the earthquake motion becomes larger, the influence of the damping force due to the velocity-squared damper 20 is mainly increased at a higher rate, resulting in a rapid increase in the overall damping force.

Third Embodiment
In a building where only the viscous damper 10 is installed, a velocity-squared damper 20 may be added through seismic reinforcement work or the like to enable the building to handle large earthquake motions. Adding the velocity-squared damper 20 increases the damping force of the entire seismic isolation device, but depending on the strength of the base-side support part 64 and the building-side support part 84, the velocity-squared damper 20 having the characteristics of the first embodiment may not be able to withstand the damping force. In that case, it is necessary to reduce the damping force at the design maximum velocity compared to the first embodiment.

FIG. 8 is a diagram showing the response speed dependency of the damping force of the seismic isolation device in the third embodiment of the present invention. FIG. 9 is a diagram showing the increase rate of the damping force of the seismic isolation device in the third embodiment of the present invention. The viscous damping coefficients C of the viscous damper 10 and the velocity squared damper 20 are determined so that the damping force FS of the velocity squared damper 20 is approximately 1/3 times the damping force FV of the viscous damper 10 at 0.5 (m/s), which is half the design maximum speed. In this example, the viscous damper 10 is set to the viscous damping coefficient C=1800 (kN/(m/s) ^0.3 ), which is the same as in the first embodiment. The velocity squared damper 20 is set to the viscous damping coefficient C=1000 (kN/(m/s) ² ), which is smaller than in the first embodiment. The relief speed VSr of the velocity squared damper 20 is the same as in the first embodiment. The damping force at the design maximum speed may be reduced by setting the viscous damping coefficient C larger than this and the relief speed VSr smaller than that in the first embodiment.

Thus, even if it is necessary to make the damping force at the maximum design velocity smaller than in the first embodiment, by appropriately setting the viscous damping coefficient C and the relief speed VSr, it is possible to control the characteristics of the seismic isolation device 1 so that for small to medium-sized earthquake motions, the influence of the damping force due to the viscous damper 10 is mainly kept at a low rate of increase, and as the earthquake motion becomes larger, the influence of the damping force due to the velocity-squared damper 20 is mainly increased at a higher rate, and the overall damping force increases rapidly.

Fourth Embodiment
In the first embodiment, the seismic isolation device 1 has a configuration in which the viscous damper 10 and the velocity-squared damper 20 are combined, but an oil damper (first damper) may be used instead of the viscous damper 10. The oil damper generates a damping force in a piston rod by moving a piston head, in which an adjustment valve is arranged, inside a cylinder that contains oil. The damping force F (kN) generated by the oil damper is expressed as F=CV, using the viscous damping coefficient C and the piston moving speed V (m/s).

Figure 10 is a diagram showing the response speed dependency of the damping force of the seismic isolation device in the fourth embodiment of the present invention. Figure 11 is a diagram showing the increase rate of the damping force of the seismic isolation device in the fourth embodiment of the present invention. In Figure 10, the damping force of the oil damper is indicated by FL (dashed line). In Figure 11, the increase rate of the oil damper is indicated by RL (dashed line). The oil damper is designed to have a characteristic of viscous damping coefficient C = 2000 (kN/(m/s)), and has a relief mechanism that reduces the damping force F at a relief speed VLr (m/s) or higher (VLr = 0.3 in this example) so that the damping force F becomes 2000 (kN) at the maximum design speed. The characteristics of the velocity squared damper 20 are the same as those of the first embodiment. The damping force FF of the entire seismic isolation device is the sum of the damping force FL of the oil damper and the damping force FS of the velocity squared damper.

The damping force FL of the oil damper changes in proportion to the response speed V as described above, and also has a relief mechanism. Therefore, even if the response speed V increases, the increase rate RL remains constant, decreases discontinuously at the relief speed VSr, and then maintains a low value up to the maximum design speed. In other words, the increase rate (first increase rate) at a certain first speed (e.g., a speed in region RA) is greater than the increase rate (second increase rate) at a second speed (e.g., a speed in region RB) that is greater than the first speed. In addition, the increase rate at a specified speed (any speed in region RA) between the first and second speeds is the same increase rate (first increase rate) as the first speed.

The rate of increase RF gradually increases as the response speed V increases from 0 to speed VLr (region RA), then decreases discontinuously at speed VLr, then gradually increases as the response speed V increases to the relief speed VSr (region RB), then decreases discontinuously at the relief speed VSr, and then maintains a low value as the response speed V increases to the maximum design speed (region RC).

Even if an oil damper is used instead of the viscous damper 10 in this way, by appropriately setting the viscous damping coefficient C and the relief speeds VLr and VSr, the characteristics of the seismic isolation device 1 can be controlled so that for small to medium-sized earthquake motions, the rate of increase in the damping force due to the oil damper is mainly kept low, and as the earthquake motion becomes larger, the rate of increase in the damping force due to the velocity-squared damper 20 is mainly increased, causing the overall damping force to increase rapidly.

Fifth Embodiment
In the first embodiment, the viscous damper 10 and the velocity-squared damper 20 are arranged side by side in the vertical direction, but in the fifth embodiment, a seismic isolation device 1A in which the viscous damper 10 and the velocity-squared damper 20 are arranged side by side in the horizontal direction will be described.

Figure 12 is a diagram showing an example of the arrangement of a seismic isolation device in the fifth embodiment of the present invention. Figure 12 is a diagram showing the positional relationship between the viscous damper 10 and the velocity-squared damper 20 when the seismic isolation layer is viewed from the building 80 side toward the foundation 60. By using the foundation side support part 64A and the building side support part 84A, which have a shape that is wider in the horizontal direction than in the first embodiment, a seismic isolation device 1A is realized in which the viscous damper 10 and the velocity-squared damper 20 are arranged side by side in the horizontal direction. The positional relationship between the viscous damper 10 and the velocity-squared damper 20 is not limited to the relationship shown in Figure 12; for example, either one may be installed on the outside, or the positional relationship between them may differ depending on the installation location.

Sixth Embodiment
In the first embodiment, one viscous damper 10 and one velocity-squared damper 20 were supported by one foundation-side support portion 64 and one building-side support portion 84, but they may each be supported by a separate configuration.

Figure 13 is a diagram showing an example of the arrangement of a seismic isolation device in the sixth embodiment of the present invention. In the seismic isolation device 1B in the sixth embodiment, the viscous damper 10 is supported by the foundation side support part 64B-1 and the building side support part 84B-1, and the velocity squared damper 20 is supported by the foundation side support part 64B-2 and the building side support part 84B-2. The foundation side support part 64B-1 and the foundation side support part 64B-2 are both fixed to the foundation 60, but are separate structures in other parts. The building side support part 84B-1 and the building side support part 84B-2 are both fixed to the building 80, but are separate structures in other parts. In this way, the viscous damper 10 and the velocity squared damper 20 are not limited to being supported together by the same structure, and may each be supported by a separate structure.

Note that by being supported by separate structures, the viscous damper 10 and the velocity-squared damper 20 may be installed at positions separated from each other, and do not have to be arranged in parallel. If the viscous damper 10 and the velocity-squared damper 20 are not arranged in parallel, the value of the viscous damping coefficient C can be adjusted according to the angle formed by the viscous damper 10 and the velocity-squared damper 20, etc.

1, 1A, 1B... Seismic isolation device, 10... Viscous damper, 20... Velocity-squared damper, 50... Seismic isolation rubber, 60... Foundation, 64, 64A, 64B-1, 64B-2... Foundation side support part, 80... Building, 84, 84A, 84B-1, 84B-2... Building side support part, 90... Retaining wall

Claims (10)

A seismic isolation device connected to a building , the seismic isolation device having a predetermined speed at which an increase rate of a damping force with respect to a response speed becomes a minimum value and a relief speed that discontinuously decreases ,
a first damper in which a damping force increases with an increase in a response speed, and a first increase rate of the damping force at a first speed is greater than a second increase rate of the damping force at a second speed that is greater than the first speed;
a second damper arranged in parallel to the first damper, the second damper having a damping force that increases with an increase in response speed, a third increase rate of the damping force at the first speed being smaller than a fourth increase rate of the damping force at the second speed, and a fifth increase rate of the damping force at a third speed that is larger than the second speed being smaller than the fourth increase rate;
Equipped with
the first speed is a speed in a range of response speed from 0 to the predetermined speed,
the second speed is a speed in which the response speed is in a range from the predetermined speed to the relief speed,
A seismic isolation device , wherein the third speed is a response speed that falls within a range from the relief speed to a design maximum speed . The seismic isolation device according to claim 1, wherein the damping force of the second damper between the first speed and the second speed is proportional to the square of the response speed. The seismic isolation device according to claim 1 or 2, wherein the damping force of the first damper between the first speed and the second speed is proportional to the α power of the response speed (α is 0.1 or more and 0.9 or less). The seismic isolation device according to claim 1 , wherein the damping force of the second damper at the second speed is smaller than the damping force of the first damper at the second speed. The seismic isolation device according to claim 4 , wherein the second speed is half a maximum design speed of the first damper or the second damper. The seismic isolation device according to claim 4 or claim 5 , wherein the second speed is 0.5 m/s. The seismic isolation device according to claim 4 or claim 5 , wherein the second speed is 0.75 m/s. The seismic isolation device according to claim 5 , wherein the damping force of the second damper at the second speed is greater than or equal to 0.2 and less than or equal to 0.8 of the damping force of the first damper at the second speed. The seismic isolation device according to claim 1 , wherein the second damper is disposed in parallel to the first damper. A design method comprising determining the viscous damping coefficients of the first damper and the second damper so as to achieve the first increase rate to the fifth increase rate in a seismic isolation device described in any one of claims 1 to 9 .

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