JP7543022B2 - Seismic Isolation System - Google Patents

Description

The present invention relates to a seismic isolation system for a seismically isolated building that uses a velocity-dependent damper as a damping material. In particular, the present invention relates to a seismic isolation system that can reduce vibrations by applying a large damping force when a storm or strong wind hits the seismically isolated building.

Seismic isolated buildings (there is no limit to the height of a seismically isolated building, but the present invention is particularly effective for high-rise buildings that are 60m or taller) are prone to vibration when exposed to wind. Therefore, it is important to consider how to reduce wind-induced vibrations using the seismic isolation layer.

In general, seismically isolated buildings are constructed by placing a seismic isolation layer on top of excavated ground, and then constructing the building on top of that seismic isolation layer. However, if the seismically isolated building is a building that is taller than a certain height (e.g. a high-rise building), the seismic isolation layer may be placed on the middle floors of the building.

There are many different types of wind that hit a seismically isolated building, ranging from everyday winds (such as the first spring wind), to strong winds that blow once every few decades, and even windstorms that blow once every few hundred years. Taking measures against everyday winds makes the building more comfortable to live in (ensuring "livability"), taking measures against strong winds allows the building to continue to be used (ensuring "usability"), and taking measures against windstorms ensures the safety of the building's residents (ensuring "safety"). In particular, as shown in Figure 1, the wind load that a seismically isolated building receives during a windstorm can sometimes be comparable to the seismic load during a major earthquake. Thus, taking measures against winds of various strengths is extremely important for the residents of seismically isolated buildings.

Generally, seismically isolated buildings (especially ultra-high-rise seismically isolated buildings) reduce wind-induced vibrations by increasing the strength and rigidity of the seismic isolation layer. A seismically isolated building designed in this way can be called a "rigid resistance type." To create a rigid resistance type seismically isolated building, it is necessary to increase the number of hysteretic dampers installed and increase the elastic limit strength of the seismic isolation layer. A hysteretic damper is a damper that absorbs vibrations by utilizing the ductility and frictional resistance of metal, such as steel dampers and lead dampers.

By the way, prior art related to the present invention is disclosed in Patent Document 1 below. This document discloses an invention related to a cooling device for a sliding seismic isolation device that can effectively cool the sliding plate whose temperature rises during an earthquake. The cooling device is installed so that the support part of the sliding seismic isolation device fits into the opening, and has a base plate with a circular opening in the center, multiple fins standing upright from the base plate, and a riding part on the outer periphery of the base plate. Note that the invention in Patent Document 1 relates to a device that cools a sliding seismic isolation device, and does not cool an oil damper like the present invention described below.

JP 2018-146076 A

In the aforementioned rigid resistance type seismically isolated building, if multiple hysteretic dampers are installed to suppress deformation due to wind loads, the number of hysteretic dampers installed will be excessive for earthquakes. Therefore, there is a risk that the response reduction effect of the seismically isolated building will be reduced when an earthquake occurs.

The present invention has been made to solve the above problems, and aims to provide a seismic isolation system that can ensure the habitability, usability, and safety of a seismically isolated building even when it is hit by winds of various strengths.

Another goal is to provide a seismic isolation system that can sufficiently reduce the response of seismically isolated buildings even in the event of an earthquake.

The aspects of the means for solving the above problems are as follows.
[First aspect]
A seismic isolation system that suppresses wind-induced vibrations in a seismic isolation building,
The seismic isolation building is provided with a seismic isolation layer,
A seismic isolation system characterized in that a velocity-dependent damper is provided in the seismic isolation layer.

[Second aspect]
A blower that blows air to the velocity-dependent damper to cool the velocity-dependent damper;
A wind energy detection means provided in the seismically isolated building or in the vicinity of the seismically isolated building;
The seismic isolation system of the first aspect, further comprising a control means for starting and stopping air blowing to the velocity-dependent damper based on information detected by the wind energy detection means.

[Third aspect]
The second aspect of the seismic isolation system, wherein the wind energy detection means is an anemometer, the detected information is wind speed, and the control means operates to start blowing air to the velocity-dependent damper when the wind speed exceeds a predetermined wind speed value, and to stop blowing air to the velocity-dependent damper when the wind speed is below the predetermined wind speed value.

[Fourth aspect]
The seismic isolation system of the second aspect, wherein the conditions for blowing and stopping air to the velocity-dependent damper by the control means are set based on heat generated by operation of the velocity-dependent damper.

[Fifth aspect]
The seismic isolation building is provided with an elevator,
The seismic isolation layer is provided on an intermediate floor of the seismic isolation building,
The elevator shaft is structured to be integrated with the upper floor above the seismic isolation layer of the seismic isolated building,
The seismic isolation system of the first aspect, wherein when the seismic isolated building shakes, the elevator shaft moves together with the upper floors of the seismic isolated building.

As described above, the present invention ensures the habitability, usability, and safety of a seismically isolated building even when it is exposed to winds of various strengths.

This is a graph comparing the horizontal forces acting on a building during a windstorm and a major earthquake. 1 is a schematic diagram of a seismic isolation system according to a first embodiment of the present invention. 1 is a graph showing an example of the relationship between a horizontal force acting on a building and a damping force. FIG. 11 is a schematic diagram of a seismic isolation system according to a second embodiment of the present invention, showing a state before a horizontal force is applied. 4 is a schematic diagram of a seismic isolation system according to a second embodiment of the present invention, after a horizontal force is applied, and for reference, the state of FIG.

Below, an embodiment of the seismic isolation system according to the present invention will be described with reference to the attached drawings.

First Embodiment
Fig. 2 shows a seismic isolation system 1 according to the first embodiment. This seismic isolation system 1 has a seismic isolation layer 4 between the first floor and the top floor (middle floor) of a seismic isolated building 2. In the seismic isolated building 2, the portion located above the seismic isolation layer 4 is referred to as the upper floor 2A, and the portion located below the seismic isolation layer 4 is referred to as the lower floor 2B.

The location of the seismic isolation layer 4 is not particularly limited, but it is preferable to place it at a height of approximately half the height of the seismic isolated building 2 (the distance from the ground to the roof). This is because it is possible to ensure a wide range of seismic isolation effects.

The seismic isolation layer 4 is equipped with an isolator 6 for blocking the transmission of shaking in the vertical direction, and a velocity-dependent damper 7 for absorbing the energy of shaking generated in the seismic isolated building 2. In this way, it is preferable to use both the isolator 6 and the velocity-dependent damper 7 as seismic isolation members for the seismic isolation layer 4.

When an earthquake occurs, the isolator 6 blocks earthquake vibrations and prevents them from being transmitted from the ground to the seismically isolated building 2 (or from the lower floor 2B of the seismically isolated building 2 to the upper floor 2A). It also has the effect of blocking wind vibrations, for example, preventing earthquake vibrations from being transmitted from the upper floor 2A to the lower floor 2B of the seismically isolated building 2. There are no particular limitations on the type of isolator 6, and for example, in addition to laminated rubber, sliding bearings and rolling bearings can be used.

The velocity-dependent damper 7 is installed inside the seismically isolated building 2 and absorbs vibrations that occur in the seismically isolated building 2 due to earthquakes, etc. There are two main types of dampers: hysteretic dampers such as steel dampers and lead dampers, and velocity-dependent dampers such as oil dampers. As mentioned above, hysteretic dampers are used in the seismically isolated building 2 with the aim of preventing vibrations by increasing the strength and rigidity of the seismic isolation layer 4.

However, if a hysteretic damper is used, there is a concern that the response reduction effect of the base-isolated building 2 will decrease when an earthquake occurs. Therefore, in this embodiment, a velocity-dependent damper 7 is used as the damper. When a velocity-dependent damper 7 is used as the damping material, the high damping performance of the velocity-dependent damper 7 can ensure a sufficient response reduction effect of the base-isolated building 2 when an earthquake occurs. At the same time, it is also possible to control vibrations caused by winds of various strengths, such as everyday winds, strong winds, and storms.

Figure 3 shows a graph of an example of the results of a study on the relationship between damping force and horizontal force acting on a building. In this way, by using a velocity-dependent damper 7 as a damping material, the large damping force of the seismic isolation layer 4 can be exerted, reducing the wind load (horizontal force). The simulation shown in Figure 3 shows that when a velocity-dependent damper 7 is used, the wind load can be reduced by approximately 30% compared to when a stiffness resistance damper is used.

In the drawings, for ease of understanding, the isolator 6 and velocity-dependent tamper 7 are shown enlarged and schematic, and one isolator 6 and one velocity-dependent tamper 7 are shown on the seismic isolation layer 4. However, in reality, multiple isolators 6 and multiple velocity-dependent tampers 7 are provided on the seismic isolation layer 4.

Here, it has been discovered that new problems may arise when using a velocity-dependent damper 7 as a damper. For example, when an oil damper 7, which is a type of velocity-dependent damper 7, is used, there is no problem when absorbing temporary vibrations such as those caused by an earthquake, but if the base-isolated building 2 is exposed to wind for a long period of time (e.g., more than two hours) and wind load continues to be applied, the following problems may occur.

In other words, the oil in the multiple oil dampers 2 (referred to as the "oil damper group") heats up and gradually rises in temperature, and if the heat temperature exceeds a critical temperature, the performance of the oil dampers may deteriorate. As a result, the seismic isolation function may deteriorate and the seismic isolated building 2 may continue to shake excessively due to the wind. This possibility is particularly noticeable when the seismic isolated building 2 is a building with one long side and a short intersecting side.

Therefore, the seismic isolation system 1 according to this embodiment is provided with a blower 11 for cooling the oil damper 7. The blower 11 is provided to blow air to the oil damper 7 to cool the oil in the oil damper 7. The type of the blower 11 is not particularly limited. For example, as shown in the figure, a blower equipped with a propeller fan in which a propeller rotates by the power of a motor and air flows along the axial direction of the motor can be used. In addition, a blower equipped with a multi-blade fan or turbo fan in which air flows in a centrifugal direction perpendicular to the axial direction of the motor may be used, or a blower equipped with a diagonal flow fan in which the rotor is attached diagonally to the axial direction of the motor and air flows diagonally to the axial direction of the motor may be used. In addition, a louver may be provided in the seismic isolation layer to allow air to flow in and out, thereby circulating the air in the seismic isolation layer and suppressing heat generation in the oil damper.

The illustrated blower 11 is attached to the seismic isolation layer 4, but it does not necessarily have to be attached to the seismic isolation layer 4. For example, the blower 11 may be installed on the upper floor 2A or lower floor 2B outside the seismic isolation layer 4, and blow air from there to the oil damper 7. However, considering the cooling effect and piping arrangement, it is preferable to install it as close to the oil damper 7 as possible. There is no particular limit to the number of blowers 11 to be installed, but for example, a simulation is used to find the amount of heat generated by the oil damper 7 based on the amplitude and frequency generated by the wind hitting the seismic isolated building 2, and the number of blowers required to suppress the heat generated by the oil damper 7 is determined.

In addition, an anemometer 3 is provided on the roof of the seismically isolated building 2 as a wind energy detection means 3. This anemometer 3 measures the wind speed of the wind hitting the seismically isolated building 2, and although only one is provided in the drawing, multiple anemometers may be provided. The installation position of the anemometer 3 is not particularly limited, but since the higher the floor of the seismically isolated building 2, the more likely it is to shake, and it is necessary to suppress the shaking of the upper floors as a priority, it is preferable to install it on the upper floor of the seismically isolated building 2. For example, it is preferable to install it on the roof of the seismically isolated building 2 as shown in the drawing, or on the side wall of the upper floor 2A of the seismically isolated building 2. The wind energy detection means 3 may also be provided in the vicinity of the seismically isolated building 2. For example, the wind energy detection means 3 may be provided in a building next to the seismically isolated building 2 or in another structure, and the detection results may be transmitted from there to the control device 5 of the seismically isolated building 2.

The type of anemometer 3 is not particularly limited. For example, a vane anemometer that determines the wind speed from the rotation speed of an impeller, an anemometer that has a propeller and a tail and determines the wind speed from the rotation speed of the propeller and the wind direction from the direction of the tail, an ultrasonic anemometer that propagates ultrasonic waves in three directions and determines the wind speed from the delay time of the ultrasonic waves, a cup anemometer that has a cup and measures the wind speed from the rotation of the cup, etc. can be used.

The seismic isolation system 1 according to this embodiment is equipped with a control device 5 that determines the amount of air sent to the oil damper 7. In the illustrated embodiment, the control device 5 is provided in the lower part of the lower floor 2B, but it may also be provided on the upper floor 2A or in a structure other than the seismic isolated building 2, for example, in a structure in the vicinity of the seismic isolated building 2.

This control device 5 can operate each device, for example, as follows. For example, based on the wind speed detected by the anemometer 3, the control device 5 starts blowing air to the oil damper 7 when the wind speed exceeds a predetermined wind speed value (e.g., 40 m/s). Also, after the wind speed falls below the predetermined wind speed value (e.g., 40 m/s) and a certain amount of time has passed, the control device 5 stops blowing air to the oil damper 7.

In addition, the decision as to whether or not to blow air may be made based on the heat generated by the operation of the oil damper 7. For example, when the heat generation temperature of the oil damper 7 exceeds a predetermined value (e.g., 50°C), blowing air to the oil damper 7 begins, and when the heat generation temperature falls below the predetermined value (e.g., 50°C), blowing air to the oil damper 7 stops. This heat generation temperature can be detected, for example, by attaching a thermometer (not shown) to the oil damper 7.

The limit temperature of the oil damper 7 is generally considered to be around 85°C, so it is preferable to set the timing of the air blowing so that this limit temperature is not exceeded.

In addition, the control means 5 may increase or decrease the amount of air sent to the oil damper 7 based on the information detected by the wind energy detection means 3.

For example, when the anemometer 3 detects that a weak wind is blowing against the seismically isolated building 2, the amount of air blown to the oil damper 7 can be controlled to be reduced, and conversely, when it detects that a strong wind is blowing against the seismically isolated building 2, the amount of air blown to the oil damper 7 can be controlled to be increased.

As described above, by blowing air from the blower 11, heat generation from the oil in the oil damper 2 can be suppressed, and a decrease in the performance of the oil damper 7 can be prevented. As a result, a decrease in the seismic isolation function can be prevented, and the seismic isolated building 2 can be prevented from continuing to shake excessively due to the wind.

To prevent the oil damper 7 from generating heat, it is preferable to provide the blower 11 and wind energy detection means 3, but the installation of these devices to prevent heat generation is not essential.

Second Embodiment
The seismic isolation system 1 according to the second embodiment is shown in Fig. 4 and Fig. 5. The same parts as those in the first embodiment will not be described, and only the different parts will be described. For ease of viewing, Fig. 4 and Fig. 5 do not show the wind energy detection means 3, the control device 5, the isolator 6, the speed-dependent damper 7, and the blower 11, but they are provided in the same manner as in Fig. 2.

In the second embodiment, an elevator 9 is installed in the seismically isolated building 2, extending vertically across the seismic isolation layer 4. This elevator 9 is integrated with the floor above the seismic isolation layer 4 (upper floor 4A). In Figures 4 and 5, the integrated parts are shown with diagonal shading. As shown by the diagonal shading, in the second embodiment, the elevator 9 is suspended from above.

In a seismically isolated building 2 equipped with an elevator 9, when strong winds hit the seismically isolated building 2, the seismic isolation layer 4 is significantly deformed, which can cause the elevator 9 passage (shaft) to be significantly deformed, potentially making it impossible to operate. Therefore, in this embodiment, the upper floor 2A and the elevator 9 are integrated together. In other words, the elevator 9 shaft is suspended from the upper floor 2A. With this structure, as shown in Figure 5, even if the seismic isolation layer 4 is displaced by strong winds, the displacement does not affect the elevator shaft, and as a result, the elevator 9 can continue to operate.

Third Embodiment
Although not shown, a seismic isolation system 1 according to a third embodiment will be described. Since the third embodiment is almost the same as the second embodiment, differences from the second embodiment will be described with reference to FIG. 4 (description of the same parts as the second embodiment will be omitted).

The third embodiment differs from the second embodiment in that the upper floor 2A and the elevator 9 are not integrated. Also, unlike the second embodiment, the number of velocity-dependent dampers 7 installed is increased to increase the damping force, thereby reducing the deformation of the seismic isolation layer during strong winds to less than 30 mm. It is more preferable that the deformation be 35 mm or less, and even more preferable that it be 30 mm or less. Even if the upper floor 4A and the elevator 9 are not integrated, as long as the deformation is 30 mm or less, the elevator 9 can continue to operate even when strong winds blow.

(others)
The damping force of the velocity-dependent damper 7 can reduce the wind load (horizontal force) even against winds that blow daily, such as the first spring wind. Compared to storms and strong winds, the amplitude of the seismic isolation layer caused by winds that blow daily is small, so the damping effect of the velocity-dependent damper 7 is reduced to about 20 to 30%. However, for amplitudes that cause problems in habitability, the internal viscous damping of the building is small, so about 20 to 30% is sufficient to improve habitability. Recently, there have been cases where a tuned mass damper (hereinafter referred to as "TMD") is installed on the top of the seismic isolated building 2 to improve habitability by the damping force of the TMD, but by providing the velocity-dependent damper 7 as in the present invention, it is possible to omit the installation of the TMD.

In the explanation so far, an oil damper 7 has been used as an example of a velocity-dependent damper 7, but the velocity-dependent damper 7 is not limited to an oil damper 7, and other velocity-dependent dampers such as a viscous damper may also be used.

(effect)
By providing the velocity-dependent damper 7 in the seismically isolated building 2, it is possible to effectively reduce the deformation and wind load of the building 2 due to various winds (everyday wind, strong wind, storm wind) while ensuring the effect of reducing the response of the seismically isolated building 2 when an earthquake occurs. Furthermore, by providing a cooling mechanism for the velocity-dependent damper 7, it is possible to maintain the performance of the damper 7 even when the seismically isolated building 2 is exposed to wind for a long period of time. Furthermore, by making the elevator 9 a suspended type, it is possible to continue operating the elevator 9 even in strong winds.

1...seismic isolation system, 2...seismic isolated building, 2A...upper floor, 2B...lower floor, 3...wind energy detection means, 4...seismic isolation layer, 5...control device (control means), 6...isolator, 7...velocity-dependent damper (e.g. oil damper), 8...ground, 9...elevator, 11...fan

Claims (4)

A seismic isolation system that suppresses wind-induced vibrations in a seismic isolation building,
The seismic isolation building is provided with a seismic isolation layer,
A velocity-dependent damper is provided in the seismic isolation layer,
A blower that blows air to the velocity-dependent damper to cool the velocity-dependent damper;
A wind energy detection means provided in the seismically isolated building or in the vicinity of the seismically isolated building;
and a control means for controlling the speed-dependent damper to start and stop blowing air based on the information detected by the wind energy detection means.
A seismic isolation system comprising: 2. The seismic isolation system of claim 1, wherein the wind energy detection means is an anemometer, the detected information is wind speed, and the control means operates to start blowing air to the velocity-dependent damper when the wind speed exceeds a predetermined wind speed value and to stop blowing air to the velocity-dependent damper when the wind speed is below the predetermined wind speed value. 2. The seismic isolation system according to claim 1 , wherein the conditions for starting and stopping the airflow to the velocity-dependent damper by the control means are set based on heat generated by the operation of the velocity-dependent damper. The seismic isolation building is provided with an elevator,
The seismic isolation layer is provided on an intermediate floor of the seismic isolation building,
The elevator shaft is structured to be integrated with the upper floors above the seismic isolation layer of the seismic isolated building,
The seismic isolation system according to claim 1 , wherein when the seismic isolated building shakes, the elevator shaft moves together with the upper floors of the seismic isolated building.

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