JPH0756184B2 - Vibration suppression device for structures - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vibration suppressing device that suppresses vibration caused in a structure by an earthquake, wind, or the like.

"Conventional technology and its problems" 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, recent structures have become larger, diversified in form, and lightweight. As it becomes more and more popular, the structure is becoming more flexible. And
In such a lightweight and flexible structure, the natural frequency is low and the vibration damping tends to be small.
Various unpredictable vibrations may occur due to the effects of aerodynamic external forces caused by wind.

For this reason, aerodynamic measures may be taken on the outer shape of the structure for the purpose of cutting off this type of vibration source. However, the outer shape of the structure has various restrictions in terms of function or design. It is difficult to rely on this aerodynamic measure alone.

Therefore, the inventor of the present application has filed Japanese Patent Application No. 60-241045
-101764), in the required position of the structure,
Proposal of a vibration suppression device capable of suppressing the vibration of a structure by providing a storage tank for storing a liquid that vibrates in the same cycle as the structure's unique vibration cycle and with a phase difference However, the above-mentioned problem is solved.

One example of the vibration suppression device shown in the above-mentioned specification has a structure in which a cylindrical storage tank is provided on the roof of a structure and liquid is stored in this storage tank. By the way, the liquid stored in this storage tank has the same vibration period as the natural vibration period of the structure, and it is necessary to secure a predetermined amount that causes a predetermined phase shift. It is possible that the amount will change due to water reduction due to evaporation and increase in rainwater, and countermeasures are necessary.

In view of the above problems, the present invention has been made by developing the vibration suppressing device proposed by the inventor of the present application, and makes it possible to always secure a predetermined amount of liquid in the vibration suppressing storage tank. Therefore, it is an object of the present invention to provide a vibration suppressing device that always exhibits a reliable vibration suppressing effect.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a structure with a storage tank for storing a liquid, and the liquid in the storage tank has the structure between the side walls of the storage tank. It is assumed that the storage tank vibrates at the same natural vibration cycle as the natural vibration cycle, and the storage tank is a structure vibration suppressing device having a space above the liquid level of the liquid in a stationary state and allowing the vibration of the liquid. Then, an auxiliary tank for storing the liquid is provided in the vicinity of the storage tank, and a supply / drainage device for moving the liquid between the auxiliary tank and the storage tank is additionally provided between the auxiliary tank and the storage tank. The liquid supply / drainage device is configured to be controlled by the detection signal of the liquid level detector that detects the liquid level in the storage tank.

"Operation" When vibration acts on the structure due to wind, etc., the liquid stored in the storage tank vibrates in the same cycle as the structure's vibration cycle with a required phase shift Suppress the vibration. Further, the liquid in the storage tank is constantly maintained at a predetermined amount by operating the liquid supply device and the liquid discharge device in response to the increase in water caused by rain and the decrease in water caused by evaporation.

"Embodiment" FIGS. 1 to 5 show a structure such as a high-rise structure provided with a vibration suppressing device according to an embodiment of the present invention. The storage tank 3 that suppresses vibration is installed on the rooftop that can be expected to be most effective against the vibration caused by the vibration. When the storage tank 3 is installed, the storage tank 3 may be provided on the rooftop via a flexible support base having a laminated structure of an elastic body such as rubber and a steel plate.

The storage tank 3 is a cylindrical storage tank used for the purpose of storing drinking water of the structure 1 or fire prevention water, or a cylindrical storage tank installed separately from these purposes. The storage tank 3 has a space above the liquid surface of the liquid W in a stationary state to allow the vibration of the liquid W, and the liquid W is provided under the condition that the natural vibration period is the same as the natural vibration period of the structure 1. By storing the water, the vibration of the structure caused by the wind or the like is suppressed. In addition,
The storage tank 3 may be divided into a plurality of parts as necessary.

Further, auxiliary tanks 10, 10 are provided on the roof of the structure 1 on both sides of the storage tank 3. Then, on the side wall of the storage tank 3 adjacent to the auxiliary tanks 10, 10, a suction / drainage pipe 12 is formed at a position slightly higher than a required liquid level of the liquid W. This suction / drain pipe 12 is
A liquid W in the storage tank 3 communicates with the auxiliary tank 10, and a pump 16 is incorporated in each of the suction and discharge pipes 12, 12.
Further, inside the storage tank 3, a liquid surface detector 17 for detecting a required liquid surface level is installed. The liquid level detector 17 is connected to the operation control section of the pump 16, and the pump is driven by a signal output from the liquid level detector 17.
16 operates so that the liquid W in the auxiliary tank 10 can be supplied to the storage tank 3 via the supply / drainage pipe 12. That is,
The supply / drainage pipe 12, the pump 16, and the liquid detector 17 constitute a supply / drainage device 20.

Next, the operation of the vibration suppressing device configured as described above will be described.

The liquid W in the storage tank 3 is stored at a depth such that the vibration cycle of the structure 1 is the same as the vibration cycle of the structure 1, thereby causing a phase shift of 1/4 cycle with the vibration of the structure 1 caused by wind. Vibration of the structure 1 is suppressed.

Further, when the liquid in the storage tank 3 increases due to rain or the like, or when the liquid in the storage tank 3 decreases due to vaporization or the like, the liquid level detector 17 detects this and operates the pump 16. The liquid W in the auxiliary tank 10 is supplied to a required height. As described above, the liquid level detector 17 operates and the inside of the storage tank 3
The amount of liquid W is adjusted to the required depth. As a result, a fixed amount of liquid W can always be stored in the storage tank 3,
The vibration suppressing device always exerts a predetermined vibration suppressing effect. While the liquid W is vibrating, the troughs of the waves formed by the liquid W may temporarily reach below the liquid level detector 17, but the liquid level detector 17 continuously continues for a predetermined time. If the pump 16 is operated only when the drop in the liquid level of the liquid W is detected, this problem can be solved.

By the way, the amount of the liquid W stored in the auxiliary tank 10 provided on the roof of the structure 1 is set so as not to impede the vibration suppressing effect of the liquid W stored in the storage tank 3.

In the following, Japanese Patent Application No. 60-241045 (JP-A-62-101764)
No.) Describes the vibration analysis of the structure 1 and the storage tank performed in the specification.

First, the storage tank 3 and the structure 1 exhibit vibration characteristics similar to the vibration model shown in FIG.

In the vibration model shown in Fig. 3, the spring 4A with a spring constant K ₀
A vibration system A (a vibration model of a structure) that supports an object 5A of M ₀ and adds a dashpot 6A with a damping rate h ₀ , and an object of mass M ₁ to a spring 4B having a spring constant K ₁ 5B
And a vibration system B (vibration model in the storage tank) configured to add a dashpot 6B having a damping rate h ₁ .

Then, in such a vibration model, when the vibration system A starts to vibrate due to an external force applied to the object 4A, the vibration system B
Starts to vibrate with a phase difference of 1/4 cycle, so that the vibration of the vibration system A can be suppressed by matching the natural vibration cycles of the vibration systems A and B.

Here, the natural vibration period of the vibration system is And the natural vibration period T ₀ of the construct 1 is
Since it is uniquely determined by the mass M ₀ and the spring constant K ₀ determined from the structural design point of view, the natural vibration period T ₁ of the liquid W stored in the storage tank 3 should be equal to the above T ₀ . The size and the capacity of the storage tank 3 are set so that they are matched with each other.

That is, 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 ₁ movable in the storage tank 3 as shown in the figure is It is given by the following equation (2).

However, H ... the distance from the bottom of the storage tank 3 to the water surface R ... the radius of the storage tank M ... the mass of the liquid actually stored in the storage tank 3 and the natural frequency of the storage liquid W ω (so-called sloshing natural frequency) is given by the following equation (3).

Further, from the natural frequency ω, the natural vibration period T is obtained as shown in the following equation (4).

If, for example, R = 15 m H = 2 m M = 1414 t (subsequently, M = 812 t) is substituted for the above parameters, T = 11.7 seconds.

Then, between the natural vibration period T ₁ of the liquid in the storage tank and the natural vibration period T ₀ of the structure obtained by the above formula, T ₀ = T ₁ ……………… (5) Formula is established. As described above, each dimension and storage amount of the storage tank 3 are set.

As a result of the simulation of the change in the vibration suppression effect with respect to the change in the frequency, the characteristics shown in FIGS. 4 and 5 were obtained. FIG. 4 shows the result of the simulation performed with the liquid (water) stored in the storage tank, and FIG. 5 shows the result of the simulation performed with the storage tank empty.

That is, the vibration can be suppressed as shown in FIG. 5 by providing the storage tank in the structure having a large amplitude at the frequency close to the natural frequency and storing the liquid as shown in FIG.

Furthermore, as a result of the simulation, it is effective when the ratio of the effective mass M ₁ of the liquid W and the mass M of the structure ₁ is set to M ₁ / M = 1/50 to 1/100 (6) It was possible to exert the vibration suppression effect. Here, when the effective mass is 1/100 or less, a sufficient damping effect cannot be obtained, and when it is 1/50 or more, the mass of the liquid has a large influence on the structure design of the structure, and the structure of the structure is re-established. Since it is necessary to design, it is necessary to set the ratio of M to M ₁ as in the above equation (6).

It should be noted that the shape of the storage tank 3 is not limited to the cylindrical shape as shown in the above embodiment, and may be changed into various shapes such as a flat quadrangular shape, a spherical shape, and a flat elliptical shape according to the installation conditions.
In this case, the Hausner's theory may be applied to set the vibration period and the mass based on an equation corresponding to the shape.

"Effects of the Invention" As described above, the present invention has a configuration in which a liquid that vibrates with a phase difference in the same cycle as the structure is stored in a storage tank provided at a required position of the structure. Since the vibration suppresses the vibration of the structure, it is possible to obtain the vibration suppressing effect on the wind that causes the vibration different from the frequency of the earthquake, mainly in the structure in which the strength against the earthquake is increased.

Further, by using the suction / drainage device, the liquid in the storage tank can be discharged to the auxiliary tank, or the liquid in the auxiliary tank can be supplied to the storage tank to maintain the liquid in the storage tank at a predetermined amount.
There is an effect that the vibration of the structure can be suppressed by always exerting a predetermined vibration suppressing effect. Furthermore, if the liquid supply storage tank or the fire protection water tank provided in the structure is used as the vibration suppression storage tank, it is not necessary to install a special storage tank, and there is an advantageous effect in terms of equipment cost.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a front view of a structure equipped with a vibration suppressing device, FIG. 2 is a sectional view of a storage tank, and FIG. FIG. 4 is a front view of a vibration model of a structure, FIG. 4 is a sectional view showing a vibration damping state provided with the vibration damping device of the present invention, and FIG. 5 is a sectional view showing a vibration state of a structure provided with an empty storage tank. Is. W ... Liquid, 1 ... Structure, 2 ... Support stand, 3 ... Storage tank, 10 ... Auxiliary tank, 12 ... Supply / drain pipe, 16 ... Pump, 17 ... Liquid detector.

Claims (1)

[Claims] 1. A structure is provided with a storage tank for storing a liquid, wherein the liquid in the storage tank vibrates between the side walls of the storage tank at a natural vibration cycle that is the same as the vibration cycle unique to the structure. The storage tank is a vibration suppression device for a structure having a space for allowing the vibration of the liquid above the liquid surface of the liquid in a stationary state, and an auxiliary device for storing the liquid near the storage tank. A tank is provided,
A liquid supply / drainage device for moving liquid between them is provided between the auxiliary tank and the storage tank, and the liquid supply / drainage device is configured to detect a liquid level in the storage tank. A vibration suppressing device for a structure, which is controlled by a detection signal of a detector.