JPH06212835A - Fluidal vibration damper - Google Patents

Abstract

PURPOSE:To obtain a large vibration-damping effect with a small mass ratio by horizontally balancing and holding a storage tank, in which water vibrated with the vibrations of a building and required phase difference is stored, at all times. CONSTITUTION:A storage tank 14, which has the period of vibrations coinciding with the period of intrinsic vibrations of a building and in which water 16 vibrated with the vibrations of the building and required phase difference is stored, is installed onto the floor 10 of the building. In the vibration damper, the storage tank 14 is borne in a rockable manner at a level lower than the center of gravity of the tank 14, and balanced and held horizontally at all times by a tank horizontal holding means. The supporting point of the tank 14 and the tank horizontal holding means are composed of a tank base 14a formed in a downward projected arcuate surface and a pedestal 12 receiving the tank base 14a, the arcuate surface of the pedestal 12 is projected downward, and the curvature of the arcuate surface of the pedestal 12 is made smaller than that of the tank base 14a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid damping system for a passive fluid system, which has a large mass damping effect with a small mass ratio (fluid weight / structure weight). .

[0002]

2. Description of the Related Art A passive fluid type vibration damping device is provided with a storage tank at a predetermined position of a structure such as a rooftop of a high-rise building, and the vibration cycle peculiar to the structure is provided inside the storage tank. A liquid such as water that vibrates with a required phase difference from the vibration of the structure in the vibration cycle is stored, and when the structure is in a stationary state, as shown by an imaginary line in FIG. The liquid 2 in the storage tank 1 fixed on the floor 3 is stationary. When the structure vibrates, the tank 1
The liquid 1 inside oscillates with a delay of 90 ° from the vibration phase of the building, the liquid moves in that direction, and the oscillating displacement ± x1 acts on the wall surface of the tank 1 as an inertial force F1 and is transmitted to the building. This swing energy acts as a damping force for the structure,
Prevents structures from swaying indefinitely due to wind or earthquakes.

The storage tank constituting this passive fluid type vibration damping device is conventionally either fixed to the upper portion of the structure as shown in the figure or suspended from above. However, there were technical drawbacks described below.

[0004]

First, in the case of the fixed system, the movement of the center of gravity of the fluid in the storage tank is slow, the inertial force is small, and the vibration damping effect is small. Conversely, a large capacity tank and fluid are required to provide a large damping force.

On the other hand, in the method of hanging from above, the inertial force is large because the structure itself sways due to the swaying of the structure.
Since the tank is supported like a pendulum, the space occupied by the entire device becomes large, and the natural period due to the pendulum and the natural period due to the movement of the liquid intersect and the analysis is complicated. There was a possibility that sloshing would be diminished due to less relative movement with the tank.

The present invention solves the above problems, and an object thereof is to make it possible to cause a large inertial force by allowing the tank to slightly tilt as the liquid rocks. The present invention provides a fluid type vibration damping device.

[0007]

In order to achieve the above-mentioned object, the present invention provides a storage tank at a predetermined position of a structure, and the inside of the tank has a vibration which matches a vibration cycle peculiar to the structure. In a vibration damping device in which a liquid is stored that is periodic and vibrates with a required phase difference from the vibration of the structure, the tank can be rocked on the installation surface of the structure at a level lower than the center of gravity of the tank. In addition to being supported, the swing of the tank is always kept in horizontal balance by the tank horizontal holding means.

Further, the supporting portion of the tank and the horizontal holding means are composed of a bottom surface of the tank formed in a downwardly convex arc surface and a pedestal for receiving the same. The arc surface of the pedestal is convex downward and its curvature is small. It is smaller than the curvature of the circular arc surface of the bottom surface of the tank.

Further, the supporting portion of the tank is a pin attached to the side surface or the lower surface of the central portion of the tank, and the tank horizontal holding means is a damper member having a spring or the like.

[0010]

According to the above construction, when the structure is in a stationary state, the fulcrum of the storage tank and the center of gravity of the fluid coincide with each other and are stationary. When the structure vibrates from this state, the liquid is oscillated and displaced according to the intensity of the vibration, and at the same time, the position of the center of gravity is changed and the storage tank is tilted so that the displacement direction side becomes lower around the fulcrum, Further, the fluid flow is accelerated, and a larger inertial force is transmitted to the structure through the wall surface of the tank. Since the cycle of the tank tilt always matches the rocking cycle of water, the analysis is simple. Moreover, since the tank itself hardly moves horizontally, there is no fear of reducing sloshing.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention. In the figure, for example, a rooftop floor 1 such as a high-rise building
A pedestal 12 which is a concave arc surface having a predetermined curvature is fixedly arranged on the 0, a U-shaped storage tank 14 is installed on the pedestal 12, and control water 16 is stored therein. ing. The water 16 has a vibration cycle that matches the unique vibration cycle of the building, and vibrates with a required phase difference from the vibration of the structure, and a damping force is applied by this phase difference.

The bottom surface 14a of the storage tank 14 is formed as a convex arcuate surface having a curvature higher than that of the pedestal, and is swingably supported on the pedestal 12 with the center of the bottom surface 14a as a fulcrum portion. .

In the above structure, when the building is in a stationary state, the center of gravity G0 of the water 16 and the fulcrum O of the bottom surface 14a coincide with each other, and the balance is maintained in a horizontal state as shown by an imaginary line in the figure and the stationary state is maintained. There is.

When vibration is transmitted to the building from this state due to strong wind or earthquake, the swing displacement ± x1 acts on the wall surface of the tank 14 as an inertial force F1 and is transmitted to the building (see FIG. 5).
However, in the present invention, at the same time, its center of gravity G0 moves in the displacement directions G1 and G2. As a result, the tank 14 has a fulcrum O
Around the center of gravity in the direction of movement of the center of gravity, and this inclination accelerates the flow of water x2 (> x1: see Fig. 5), resulting in a larger inertial force F2 (> F1: see Fig. 5). It effectively contributes as a damping force against.

Although not shown, if a means for restricting the maximum inclination of the tank 14 is provided, it is possible to prevent the water tank 16 from falling or the water 16 falling down. Further, the tank 14 can be tilted not only in the left-right direction but also in all directions according to the movement of the water 16 such as the front-back direction orthogonal to the paper surface.

FIG. 2 shows an experimental example of the time history of the amplitude when a certain structure model is vibrated.
When an input wave of a certain specific amplitude is given to the structure model as shown in (a), when the control for damping is not performed, the structure model is sequentially changed as shown in (b). Vibration continues while being damped.

On the other hand, when the system in which the tank is tilted only by moving the center of gravity of water is adopted, the amplitude is sharply attenuated as shown in (c), which is extremely effective for damping vibration. confirmed.

FIG. 3 shows a second embodiment of the present invention. The same parts as those of the above-mentioned embodiment are designated by the same reference numerals, and only different points will be described by using different reference numerals.

In the figure, the center of the bottom surface of a U-shaped storage tank 20 in which water 16 is stored is supported like a seesaw by a fulcrum portion 22 arranged on the floor 10, and a pair of left and right bottom surfaces are provided. A damper member 24 having a compression spring or the like is interposed.

The damper member 24 horizontally supports the tank 20 while the tank 20 is stationary as shown by the imaginary line in the figure, and both corners of the bottom surface of the tank 20 at the time of rocking as shown by the solid line in the figure are on the floor 10. It has a function as a cushion to prevent the collision with.

Also in this structure, when the structure is in a stationary state, the center of gravity G0 of the water 16 and the fulcrum O of the fulcrum portion 22 coincide with each other, and as shown by the imaginary line in the figure, the balance is maintained in the horizontal state and the stationary state is achieved. ing. When the vibration is transmitted to the structure from this state, the swing displacement ± x1 is applied to the wall surface of the tank 20 by the inertial force F1.
Acts as a and is transmitted to the building, and at the same time, its center of gravity G
0 moves in the displacement direction, and as a result, the tank 20 tilts in the moving direction of the center of gravity around the fulcrum O, and this tilt accelerates the water flow x2 to generate a larger inertial force F2.

Although a U-shaped storage tank is used as the storage tank in each of the above-mentioned embodiments, it is needless to say that a rectangular tank or other shape may be used for vibration damping.

[0024]

As described above in detail with reference to the respective embodiments, in the fluid damping device according to the present invention, when the structure vibrates, the liquid swings and displaces in accordance with the strength of the vibration, At the same time, by changing the position of the center of gravity and tilting the storage tank so that the displacement direction becomes lower around its fulcrum, the fluid flow is further accelerated and a larger inertial force is transmitted to the structure through the tank wall surface. A large mass damping effect can be obtained with a smaller mass ratio than that of, and it is suitable for downsizing and cost reduction of the device. Since the cycle of the tilt of the tank always matches the rocking cycle of water, the analysis is simple and the design can be done easily. Moreover, since the tank itself hardly moves horizontally, there is no fear of reducing sloshing.

[Brief description of drawings]

FIG. 1 is a principle explanatory view of a fluid damping device according to a first embodiment of the present invention.

2A to 2C are graphs showing an experimental example of a time history of amplitude when vibration is applied to a structure model.

FIG. 3 is a principle explanatory view of a fluid type vibration damping device according to a second embodiment of the present invention.

FIG. 4 is a principle explanatory diagram of a conventional passive fluid type vibration damping device.

[Explanation of symbols]

 10 floors 14, 20 storage tank 16 water (liquid) 14a, 22 fulcrum part (14a bottom surface, 22 fulcrum part)

Claims (3)

[Claims] 1. A storage tank is provided at a predetermined position of a structure, and inside the tank, a vibration cycle that matches a vibration cycle specific to the structure and has a required phase difference from the vibration of the structure. In a vibration damping device in which a liquid vibrating with a liquid is stored, the tank is swingably supported on the installation surface of the structure at a level lower than the center of gravity of the tank, and the swinging of the tank is performed by a tank horizontal holding means. A fluid type vibration damping device characterized by maintaining a horizontal balance at all times. 2. The fulcrum portion of the tank and the horizontal holding means are
It is characterized in that it comprises a tank bottom formed in a downwardly convex arc surface and a pedestal for receiving it, and the arc surface of the pedestal is downwardly convex and its curvature is smaller than the curvature of the arc surface of the tank bottom. The fluid type vibration damping device according to claim 1. 3. The fluid damping device according to claim 1, wherein the fulcrum portion of the tank is a pin attached to a side surface or a lower surface of the central portion of the tank, and the tank horizontal holding means is a damper member having a spring or the like. .