JPH0756185B2 - Vibration suppression device for structures - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to vibration of structures installed in these structures in order to suppress vibrations excited in buildings and civil engineering structures due to earthquakes and winds. The present invention relates to a suppression device.

"Conventional technology" Due to factors such as the development of high-strength materials, the progress of machining technology, and the development of structural analysis technology using computers, the construction and civil engineering structures of recent years have become larger, diversified in form, and lighter in weight. In addition to being done, it has a structure that is highly flexible against external forces. In such a lightweight and flexible structure, its natural frequency is low and its internal vibration damping tends to be small, so that various unexpected vibrations may occur due to the influence of external forces such as earthquakes and winds. Can occur.

In particular, as described above, as the size of the structure increases, the amplitude of the vibration excited by the external force also increases, and this vibration gives an uncomfortable feeling to the person living inside the structure, and There was even a fear of applying a stress exceeding the permissible range to the frame.

In recent years, by attaching a vibration suppression device that vibrates at a cycle equal to the natural vibration cycle of the structure to this structure, the vibration energy of the structure near the natural vibration cycle is absorbed by the vibration suppression device, and thus the vibration of the structure A method that suppresses is proposed and implemented.

FIG. 7 is a diagram showing the conventional vibration suppressing device. In FIG. 7, reference symbol S is a structure S such as a super high-rise building, and the vibration suppressing device 1 is installed on the roof of this structure S. The vibration suppressing device 1 includes a weight block 2 made of concrete having a mass of about several% of the mass of the structure S.
Is supported slidably in the horizontal direction of the structure S by sliding mechanisms 3 and 3 such as rollers, and the sliding direction about the center of the roof of the structure S by elastic and repellency mechanisms 4 and 4 such as springs. It is configured to vibrate along. Then, in the vibration suppressing device 1, the mass of the weight block 2 and the elasticity of the repulsion mechanisms 4 and 4 are set so that the vibration cycle along the sliding direction of the weight block 2 becomes the same as the natural vibration cycle of the structure S. The rate is adjusted.

When the structure S in which the vibration suppressing device 1 having the above configuration is installed starts to vibrate due to an external force such as an earthquake or wind, the vibration suppressing device 1 vibrates at the same vibration cycle as the natural vibration cycle of the structure S. To start. Therefore, by exchanging the vibration energy between the structure S and the vibration suppressing device 1, the vibration suppressing device 1 absorbs the vibration energy of the structure S, and thus the vibration of the structure S is suppressed. It

“Problems to be Solved by the Invention” By the way, in the conventional vibration suppressing device 1, since the vibration suppressing device 1 vibrates in the same vibration cycle as the structure S,
Since the vibration of the structure S is suppressed, when the vibration of the structure S is suppressed as a result of the vibration of the structure S becoming smaller than the amplitude of the vibration suppressing device 1, the vibration suppressing device 1 reverses the vibration. To act as a vibration exciter on the structure S and apply a vibration force to the structure S. Therefore, it is necessary to attach a damper such as a dashpot to the vibration suppressing device 1 in order to damp its own vibration. However, as described above, the weight block 2 vibrating in the vibration suppressing device 1
Is a large-weight member having a mass of about several percent of the structure S, and therefore, a damper for damping the vibration of the weight block 2 is large-scaled and the damping force is not easily adjusted. .

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vibration suppressing device for a structure capable of damping the vibration of the vibration suppressing device itself with a simple configuration.

"Means for Solving Problems" In order to solve the problems, the present invention provides a structure that is installed in a structure and suppresses vibrations excited in the structure due to an external force such as an earthquake or wind. A vibration suppressing device, comprising: a first vibration system and a second vibration system installed on the first vibration system, wherein the first vibration system is the same as the natural vibration period of the structure. The second vibrating system is configured to vibrate at a natural vibration period of, and the second vibrating system is placed on the first vibrating system and is stored in the tank. And a liquid that vibrates in the same natural vibration period, and the tank has a space above the liquid surface of the liquid in a stationary state to allow the vibration of the liquid.

[Operation] In the present invention, when the first vibrating system vibrates so as to suppress the vibration excited in the structure by an external force such as an earthquake or wind, the liquid stored in the storage tank of the second vibrating system becomes the first It has the same vibration cycle as the 1st vibration system and is 1/4 of the 1st vibration system.
The first vibration system vibrates with a phase delay of the cycle, and the vibration of the first vibration system is suppressed.

[Examples] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 to FIG. 3 are views showing a structure vibration suppressing apparatus which is an embodiment of the present invention. 1 to 3, reference symbol S is a structure such as a super high-rise building, and it is assumed that the structure S has the most effect on the vibration excited by an external force such as an earthquake or wind. A vibration suppressing device 10 for suppressing the vibration of the structure S is installed on the rooftop where the structure can be formed. The vibration suppressing device 10 is roughly composed of a first vibrating system 11 installed on the roof of the structure S and a second vibrating system 20 installed on the first vibrating system 11. .

The first vibration system 11 is configured similarly to the conventional vibration suppression device 1. That is, the first vibrating system 11 is provided with a weight block 12 made of concrete having a mass of about several percent of the mass of the structure S, and a rail 14 extending in both the vertical and horizontal directions of the structure S. , 14, ... Are crossed each other. On the lower surface of the weight block 12, bearings 15, 15, ... Slidable along these rails 14, 14 ,. Further, stoppers 16, 16 extending in the height direction of the structure S are provided at both ends of the rails 14, 14 so as to project from the roof of the structure S, and the stoppers 16, 16 ,. And the weight block
Cylinder-type elastic repelling mechanisms 13, 13, ... Therefore, this weight block 12 is
The structure S is configured to vibrate in both vertical and horizontal directions around the intersection of 14, 14 ,. The natural vibration cycle of the weight block 12 in both the vertical and horizontal directions is determined by adjusting the mass of the weight block 12 and the elastic moduli of the repulsion mechanisms 13, 13 ,. It corresponds to the vibration period.

On the other hand, the second vibrating system 20 is installed on the upper surface of the weight block 12 of the first vibrating system 11 and has a flexible structure supporting base 21 made of a laminated structure of an elastic body such as rubber and a steel plate. A bottomed cylindrical storage tank 22 installed on the table 21, and a weight block 12 of the first vibration system 11 stored in the storage tank 22.
Liquid that vibrates with the same natural vibration period as that of the liquid 23
The storage tank 22 is configured to have a space above the liquid surface of the liquid 23 in a stationary state for allowing the vibration of the liquid 23. The mass of the liquid 23 in the storage tank 22 is 1/50 of the mass of the weight block 12.
It is preferably within the range of to 1/100.

Next, the operation of the vibration suppressing device 10 having the above configuration will be described.

The vibration system including the structure S and the vibration suppressing device 10 has a sixth
The vibration model can be approximated and simplified as shown in the figure. This vibration model includes a vibration system A (a vibration model of a structure S) in which an object 8A having a mass M ₀ is supported via a spring 7A having a spring constant K ₀ and a dashpot 9A having a damping rate h ₀ , and a spring A vibration system B (a vibration model of the first vibration system 11) in which an object 8B having a mass M ₁ is supported via a spring 7B having a constant K _{1 and} a dashpot 9B having a damping rate h ₁ and a spring constant K ₂ Via a spring 7C and a dashpot 9C having a damping rate h ₂ of a vibration system C (a vibration model of the second vibration system 20) in which an object 8C having a mass of M ₂ is supported. It is a model.

Then, in such a vibration model, the vibration system A / B
If the natural vibration periods of are matched, when the vibration system A starts to vibrate due to an external force such as an earthquake or wind applied to the object 8A,
The vibrating system B vibrates with a phase delay of 1/4 cycle with respect to the vibrating system A, whereby the vibration of the vibrating system A can be suppressed. Similarly, if the natural vibration periods of the vibrating systems B and C are matched, the vibrating system C starts vibrating with a phase delay of 1/4 with respect to the vibrating system B, thereby suppressing the vibration of the vibrating system B. can do.

Here, since the object 8B has a mass of about several percent of that of the object 8A, the natural vibration period T ₀ of the structure S is almost unique by the mass M ₀ and the spring constant K ₀ determined from the structural design point of view. Is decided. Further, since the object 8C has a mass of about 2% of the object 8B, the same applies to the natural vibration period T ₁ of the first vibration system 11. Therefore, the mass of the weight block 12 and the elastic moduli of the repulsion mechanisms 13, 13, ... Are adjusted so that the natural vibration cycle T ₁ of the first vibration system 11 matches the natural vibration cycle T ₀ of the structure S. In addition, the storage tank may be so arranged that the natural vibration period T ₂ of the second vibration system 20 matches the T _1.
The size and capacity of 22 and the storage amount of liquid 23 may be set.

Here, the natural vibration period of each vibration system A, B, C is given by the following formula.

Therefore, for the vibration systems A and B, the natural vibration period can be obtained by substituting each variable into the above equation. However, for the vibration system C, the mass M of the liquid 23 in the storage tank 22 does not become the mass M ₂ that acts as a vibration body as it is, and therefore some theoretical analysis is required.

According to the Hausner theory that holds for the behavior of the stored liquid in the storage tank, the free water effective mass (mass acting as a vibrating body) M that can move in the storage tank 22
₂ is given by the following equation.

However, H ... the distance from the bottom of the storage tank 22 to the water surface R ... the radius of the storage tank M ... the mass of the liquid 23 actually stored in the storage tank 22 and the liquid in the storage tank 22 The 23 natural frequencies ω (so-called sloshing natural frequencies) are given by the following equation.

Further, from the natural frequency ω obtained by the equation (3), the natural vibration period T ₂ of the liquid 23 in the storage tank 22 is obtained by the following equation.

Then, the natural vibration cycle T ₂ of the liquid 23 in the storage tank 22 and the natural vibration cycle of the first vibration system 11 obtained by the equation (4)
Between _{T 1, T 1 = T 2} ...... (5) so as to hold the aforementioned variables H, R, M, i.e. it so be set storage amount of the dimensions and the liquid 23 in the reservoir tank 22 is there.

Therefore, the vibration suppressing device 10 of this embodiment is the first vibration system.
A storage tank 22 that stores a liquid 23 that vibrates in the same natural vibration period as that of the first vibration system 11 is installed on top of 11, and is a simple structure, but surely The vibration of the first vibration system 11 can be suppressed. Moreover, after the vibration suppressing device 10 is installed, the liquid 23 in the storage tank 22 is
By adjusting the storage amount, the vibration suppressing effect can be easily adjusted to the optimum state. Furthermore, the storage tank
A viscous liquid is generally used as the liquid 23 stored in the liquid 22.However, by mixing with a liquid 23 having a different viscosity coefficient such as oil, or by appropriately using a partition plate or the like in the storage tank 22. The vibration damping rate due to the viscous resistance can be easily adjusted by arranging them to provide a wave-dissipating effect.

Next, FIG. 4 to FIG. 5 are views showing a structure vibration suppressing apparatus which is another embodiment of the present invention. In this embodiment, the difference from the above-mentioned embodiment is that the first vibrating system 11 is configured similarly to the second vibrating system 20. That is, the first vibration system 11 is the same as the storage tank 22 of the second vibration system 20.
The storage tank 32 has a larger diameter, and the liquid 33 is stored in the storage tank 32 and vibrates in the same natural vibration cycle as the natural vibration cycle of the structure S. On the surface of the liquid 33, a saucer-shaped support plate 34 is suspended with its bottom portion facing upward, and the second vibrating system 20 is supported by the support plate 34.
It is installed on top. The configuration of the second vibration system 20 is
Since it is almost the same as the above-mentioned embodiment, its explanation is omitted. Therefore, the vibration suppressing device 10 having the above configuration
Also in, it is possible to obtain the same effect as that of the above embodiment.

The results of the simulation experiment conducted by the inventor of the present application will be shown below to verify the damping effect of the vibration suppressing device 10 of the present invention. As an experimental system, a 5-layer model simulated structure S (mass M ₀ = 400 kg × 5 layers, first-order natural period T ₀ =
The experimental system is such that the second vibrating system 20 of the present invention (total mass of liquid 23, M ₁ = 52 kg, first-order natural period T ₁ = 0.41 sec) is directly installed on the roof of 0.41 sec). Fig. 8 shows the displacement of the fourth layer of the simulated structure S when the second vibration system 20 is not provided when a random wave (EL-CENTRO-NS wave) is applied to such an experimental system. FIG. 9 shows the displacement of the fourth layer of the simulated structure S when the vibration system 20 of FIG. As you can see in the results shown,
It can be understood that the vibration system 20 suppresses the vibration of the simulated structure S.

Furthermore, as a result of the simulation, the effective mass M _{2 of the} liquid 23 is
It has been found that an effective vibration suppressing effect can be achieved by setting the ratio of the mass of the structure to be damped to the mass M of the structure to be M ₂ / M = 1/50 to 1/100 (6) . That is, the effective mass M ₂ is equal to the mass M of the structure.
If it is less than 1/100, sufficient damping effect cannot be obtained, and
When it is 0 or more, the influence of the liquid mass on the structure design of the structure becomes large, and it may be necessary to redesign the structure of the structure. Therefore, it is necessary to set the ratio as shown in the above formula (6). Occurs.

The structure vibration suppression device 10 according to the present invention is not limited to the above-described embodiment. As an example, the storage tank 22
The shape may be changed to various shapes such as a rectangular parallelepiped shape, a spherical shape, and a plane ellipse shape depending on the shape of the structure S and the installation conditions. In this case, the theory may be appropriately changed, and the dimensions of the tank, the storage depth of the liquid, and the like may be set based on the formula corresponding to the shape. When the storage tank 22 is made of a steel plate, the durability of the storage tank 22 itself can be increased by mixing a rust preventive agent in the liquid 23.

[Effect of the Invention] As described in detail above, according to the present invention, when vibration is excited in a structure by an external force such as an earthquake or wind, the first vibration system has the same natural vibration period as the structure. With a natural vibration period of 1/4 and with a phase delay of 1/4 cycle with respect to the structure, thereby suppressing the vibration of the structure, and further, the second vibration system causes the first vibration. The system vibrates in the same natural vibration period as the system and with a phase delay of 1/4 period with respect to the first vibration system, whereby the vibration of the first vibration system is suppressed. Therefore, the first vibrating system having a simple configuration including the storage tank and the liquid stored in the storage tank and vibrating in the same natural vibration cycle as the first vibrating system
It is possible to reliably suppress the vibration of the first vibration system by attaching it to the vibration system. Therefore, according to the present invention, it is possible to realize a vibration suppressing device for a structure capable of damping the vibration of the vibration suppressing device itself with a simple configuration.

[Brief description of drawings]

FIG. 1 is a front view showing a state where a structure vibration suppressor according to an embodiment of the present invention is installed on the roof of a structure, FIG. 2 is a plan view of the same, and FIG. 3 is a front view of the same. FIG. 4 is a front view showing another embodiment of the present invention, FIG. 5 is a plan view of the same, and FIG. 6 is a schematic view showing a vibration model of a structure and a vibration suppressing device.
FIG. 7 is a schematic view showing a conventional vibration suppression device, FIG. 8 is a view showing a vibration state of a simulated structure without a vibration suppression device, and FIG. 9 is a simulated structure provided with a vibration suppression device. It is a figure which shows the vibration condition of. S ... Structure, 10 ... Vibration suppressor, 11 ... First vibration system, 20 ... Second vibration system, 22 ... Storage tank, 23 ... Liquid.

Claims (1)

[Claims] 1. A vibration suppressing device for a structure, which is installed in a structure and suppresses vibration excited in the structure by an external force such as an earthquake or wind, comprising a first vibration system and the first vibration. A second vibrating system installed on the system, wherein the first vibrating system is configured to vibrate in a natural vibration cycle that is the same as the natural vibration cycle of the structure. Is composed of a tank placed on the first vibrating system and a liquid stored in the tank and vibrating in the same natural vibration period as the first vibrating system. A vibration suppressing device for a structure, which has a space above the liquid surface of the liquid in a stationary state to allow vibration of the liquid.