JP2810892B2 - Vibration suppression device for structures - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration suppression device for a structure, which suppresses a vibration caused in the structure by an earthquake, wind, or the like.

`` Conventional technology and its problems '' In recent years, architectural and civil engineering structures have become larger, diversified in form due to factors such as the development of high-strength materials, advances in machining technology, and the development of structural analysis technology using computers. The structure is lightweight and flexible with respect to external forces. And, in such a lightweight and flexible structure, its natural frequency is low and the internal vibration damping tends to be small, so that various vibrations which cannot be expected due to the influence of an external force such as an earthquake or a wind are generated. 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 unnecessary unease to humans living inside the structure, There was even a risk of giving a stress exceeding the allowable range to the skeleton.

In view of this, the inventor of the present application disclosed in Japanese Patent Application No. 60-241045 that a predetermined position of a structure vibrates at the same period as the inherent vibration period of the structure and with a required phase difference. A tank for storing a liquid is provided, and a vibration suppressing device capable of suppressing the vibration of the structure by the vibration of the liquid is proposed to solve the above-described problem.

By the way, the acceleration response spectrum of a normal earthquake motion is
As shown in FIG. 4, the periodic component has an excellent periodic component in a specific range (about 0.2 to 1.0 second), but the periodic component in the other range is not small. In particular, as described above, since the vibration characteristics of the structure are becoming complicated along with the diversification of the types of the structure, it has been desired to realize a vibration suppression device that can flexibly cope with a wide range of vibration periods.

In view of the above circumstances, the present invention has been made by developing the vibration suppressing device proposed by the inventor of the present invention, and is capable of effectively attenuating the vibration of a structure having a wide natural vibration period. The purpose is to provide a suppression device.

"Means for solving the problem" Therefore, the present invention provides a structure in which a plurality of tanks are hung at predetermined positions of a structure and provided so as to freely vibrate, and each of the tanks is provided at one point of the structure. By being suspended so that the distance between the tank and the tank is always constant, it is possible to vibrate in the lateral direction, and inside these tanks,
A vibration suppression device for a structure in which liquids that vibrate with the same vibration period as the natural vibration period of each tank and that vibrate with the natural vibration of each of these tanks and a required phase difference are stored. The above-mentioned problem has been solved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 3 are views showing a vibration suppressing device according to a first embodiment of the present invention. In the figure, reference numeral 1 denotes a vibration suppression device, and the vibration suppression device 1 is a building (structure) 2.
A plurality of tanks 4, 4,
, And the liquid 5, stored in these tanks 4, 4, ...,
5, and so on.

The tank 4 is, as shown in FIGS. 1 and 2,
It is formed in the shape of a box with a rectangular shape in a plan view, and is suspended from the ceiling 3 of the building 2 via wires 6, 6,. Thereby, the tank 4 is installed so as to be able to freely vibrate in the horizontal direction with respect to the building 2 with a predetermined natural vibration period determined by the length 1 of the wire 6. In the vibration suppression device 1 as a whole, the lengths 1 of the wires 6 for suspending the tanks 4 are different so that there are a plurality of types of natural vibration periods of the tanks 4. Tank 4 is suspended. The natural vibration cycle of the tank 4 may be appropriately selected depending on the characteristics of the building 2, but it goes without saying that the proportion of the tank 4 having a vibration cycle near the natural vibration cycle of the building 2 should be excellent.

The tank 4 has an inner diameter a, and the liquid 5 is stored therein at a height H. The inner diameter a of the tank 4 and the storage height H of the liquid 5 are set in advance to values such that the vibration cycle of the liquid 5 stored in the tank 4 is the same as the natural vibration cycle of the tank 4. I have. Further, a and H are such that the total mass of the liquids 5, 5,... Stored in the tanks 4, 4,.
It is set to be in the range of 1/50 to 1/100.

The tank 4 is preferably formed of a material (for example, made of plastic) that does not corrode even during long-term use. Similarly, the liquid 5 is a viscous liquid (eg, oil) that does not easily evaporate even during long-term use. Is preferred. However, the materials of the tank 4 and the liquid 5 may be appropriately determined according to the construction conditions and the like, and are not limited to the above-described materials.

Next, the operation of the vibration suppressing device 1 having the above configuration will be described.

A vibration system including the building 2, the tank 4, and the liquid 5 includes:
It can be approximated and simplified to a vibration model as shown in FIG. In the following description, only the phenomenon regarding one tank 4 and the liquid 5 stored in this tank 4 will be discussed, but it goes without saying that the behavior of the vibration suppression device 1 as a whole can be described as a superposition of these. Nor.

The vibration model, the spring 7A and the damping factor h ₀ of the spring constant K ₀
Through the dashpot 9A, the mass M vibration system object 8A, which are supported in the ₀ A (vibration model of a building 2), via the spring 7B and dashpot 9B attenuation factor h ₁ of the spring constant K ₁ Te, the mass M ₁ of the object 8B is supported consisting vibration system B (the vibration model of the tank 4), springs 7C and decay rate of the spring constant K ₂ h ₂
Through the dashpot 9C, the mass M vibration system object 8C is formed by support ₂ C (vibration model of the liquid 5 in the tank 4)
Are connected in series.

In such a vibration model, when the vibration system A starts to vibrate at substantially the same vibration period as the natural vibration period of the vibration system B due to an external force such as an earthquake or wind applied to the object 8A, the vibration system B becomes 1/4. Since resonance occurs with a phase delay of the period, when the vibration periods of the vibration systems A and B coincide, the vibration of the vibration system A in the vibration period can be suppressed. Similarly, if the vibration periods of the vibration systems B and C coincide with each other, the vibration system C resonates with a 1/4 phase delay with respect to the vibration system B, whereby the vibration of the vibration system B and, consequently, the vibration system B A vibration can be suppressed.

Therefore, a vibration cycle in which vibration is to be suppressed by the tank 4 and the liquid 5, that is, a vibration cycle T ₂ of the liquid 5 stored in each tank 4 matches the natural vibration cycle T ₁ of the tank 4 itself. The size and capacity of the tank 4 and the storage amount of the liquid 5 may be set. The behavior of the liquid 5 stored in the tank 4 can be analyzed as follows.

The relationship between the j-th natural oscillation period T _j of sloshing and the j-th natural circular frequency ω _j is represented by the following equation.

T _j = 2π / ω _j (1) Then, in the above equation (1), if H is the storage depth of the liquid and g is the gravitational acceleration, ω _j is an amount given by the following equation.

Further, k _j in the above equation (2) is given by the following equation, where a is the width of the tank 4.

k _j = (2j−1) π / a (3) Accordingly, the natural oscillation period T _j of sloshing can be obtained from the above equations (1) to (3). In particular, in order to suppress the above-described vibration, the natural vibration period T in the first-order sloshing may be used. This is represented by the following equation.

As described above, according to the vibration suppression device 1 of this embodiment, it is possible to suppress the vibration excited in the building 2 due to an external force such as an earthquake or wind. In particular, in this embodiment, the plurality of tanks 4, 4,
Are held in a state where the lengths 1 of the wires 6 for suspending the tanks 4 are different so that a plurality of types of natural vibration periods exist. The tanks 4 selectively resonate in different vibration cycles of the tanks 4,..., Thereby effectively suppressing the vibration of the building 2 in a plurality of vibration cycles. In addition, the entire vibration suppression device 1 includes a plurality of tanks 4,
4, ... and the liquid 5, stored in these tanks 4, ...,
, The desired vibration suppression effect can be obtained for a wide range of vibration periods by appropriately selecting and determining the proportion of the tank 4 having various vibration periods. Therefore, according to this embodiment, it is possible to realize a vibration suppressing device capable of effectively attenuating the vibration of a structure having a wide natural vibration period.

"Modifications of the Invention" The details of the structure vibration suppressing device of the present invention are not limited to the above-described embodiments, and various modifications are possible. Hereinafter, a modified embodiment of the present invention will be described with reference to the drawings.

FIG. 6 is a view showing a structure vibration suppressing device according to a second embodiment of the present invention. In the following description,
The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. In this example,
The tank 4 of the vibration suppressing device 1 is formed in a spherical shape. The liquid 5 is stored in the tank 4 under such a condition that the vibration cycle is the same as the natural vibration cycle of the tank 4. Therefore, in this embodiment, similarly to the first embodiment, the vibration of the building 2 is effectively attenuated, and an effective vibration suppression effect can be obtained in a wide range of vibration periods.

It is needless to say that the shape and the number of the tanks 4 to be installed are arbitrary, and may be appropriately determined in consideration of the shape and the vibration properties of the building 2. The method of installing the tank 4 is also arbitrary. As an example, the tank 4 is installed so as to be movable in the horizontal direction by attaching a carriage to the tank 4 and the like.
It is needless to say that by fixing to the building 2 with a spring or the like, it is possible to freely vibrate at a specific vibration cycle.

[Effects of the Invention] As described above in detail, according to the present invention, a plurality of tanks are hung at predetermined positions of a structure and provided so as to be able to vibrate, and each tank is provided at one point of the structure. By suspending so that the distance between one point and the tank is always constant, it is possible to vibrate in the horizontal direction, and inside these tanks, at the same vibration cycle as the natural vibration cycle of each tank, and Since the vibration suppressing device of the structure is configured such that each of the natural vibrations and the liquid that vibrates with a required phase difference is stored, a plurality of types of natural vibration periods of a plurality of tanks exist as the vibration suppressing device as a whole. If these tanks are installed as described above, the tanks selectively resonate in each of the vibration cycles, whereby the vibration of the building can be effectively suppressed in a plurality of vibration cycles. Moreover, if the proportion of the tank having various vibration cycles is appropriately selected and determined, a desired vibration suppression effect can be obtained for a wide range of vibration cycles. Therefore, according to the present invention, it is possible to realize a vibration suppressing device capable of effectively attenuating the vibration of a structure having a wide range of natural vibration periods.

[Brief description of the drawings]

1 to 3 are views showing a structure vibration suppressing device according to a first embodiment of the present invention, wherein FIG. 1 is a front view,
Fig. 2 is a sectional view taken along the line II-II 'in Fig. 1, Fig. 3 is a schematic view showing a state of being installed on the roof of a building, and Fig. 4 is a view showing an acceleration response spectrum of earthquake motion. FIG. 5 is a schematic view showing a vibration model of a structure and a vibration suppressing device, and FIG.
FIG. 5 is a front view showing a structure vibration suppressing device according to a second embodiment of the present invention. 1 ... vibration suppression device, 2 ... building (structure), 4 ...
Tank, 5 ... liquid.

Claims (1)

(57) [Claims] A plurality of tanks are suspended at predetermined positions of a structure and are provided so as to be freely vibrated. Each of the tanks is provided at one point of the structure and a distance between the one point and the tank is always constant. By being suspended so as to be constant, it can freely vibrate in the horizontal direction, and the inside of these tanks has the same vibration cycle as the natural vibration cycle of each tank and the natural vibration of each of these tanks And a liquid that vibrates with a required phase difference.