JPH02282583A - Connection type pendulum water tank damper - Google Patents

Abstract

PURPOSE:To improve the damping effect by connecting multiple pendulum water tank dampers suspending and supporting water tanks each filled with a preset quantity of a liquid inside and having the preset mass with multiple suspending materials from a structure with springs having the preset spring constant. CONSTITUTION:A water tank 20 filled with a preset quantity of a liquid 21 inside, fitted with a weight 11 concurrently serving as a support bed, and having the preset mass is suspended from a frame 4 at the top section at four points by wire ropes 12 to form a pendulum water tank damper 1. A water tank 20a is likewise suspended from the frame 4 by wire ropes 12a to form a pendulum water tank damper 1a. Two pendulum water tank dampers 1 and 1a are connected by a coil spring 2 with the spring constant KD.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applied to a pendulum water tank as a dynamic vibration absorber for reducing the influence of vibrational external forces acting on structures, such as wind and earthquakes, in the fields of civil engineering and architecture. This concerns dampers.

[Conventional technology]

As a dynamic vibration absorber for structures, JP-A No. 631) 47
Examples include the invention described in Publication No. 73.

By the way, for example, a building like the Pencil Building has low horizontal rigidity and therefore has a long natural period (small natural frequency).
Structures that tend to resonate with the prevailing period of wind pressure fluctuations are likely to suffer from vibration disturbances (mainly problems with livability) due to wind shaking. However, when considering livability, it is said that the level of acceleration that people begin to feel is around 1, Q Ga1.
Conventionally, it has been considered extremely difficult to reduce minute vibrations such as those caused by wind vibrations.

In addition, conventional sloshing dampers that store liquid in a water tank (such as Japanese Patent Application Laid-open No. 101764/1982) use liquid such as water, so in order to obtain sufficient vibration suppression effects, a very large water tank is required. There are problems with the installation location and installation method.

In response, the applicant proposed a first method using a pendulum-type dynamic vibration absorber, which has less friction and can respond sensitively to minute vibrations.
By combining the vibration system and a sloshing damper, which constitutes the second vibration system mainly for damping the vibrations of the first vibration system, to form a double dynamic vibration absorber, the shaking of the structure, which is the main vibration system, can be suppressed. A sloshing damper that effectively suppresses swinging suspension (hereinafter referred to as a pendulum water tank damper)
(Refer to "Vibration Experiment of Side Wind Structure Subject to Wind Shaking", Kobori et al., Abstracts of Academic Lectures at the Architectural Institute of Japan Conference, October 1988, and Patent Application No. 1983-323061).

The pendulum water tank damper consists of a support base that is suspended and supported via a plurality of hanging members, and a water tank installed on the support base, with respect to the structure that constitutes the main vibration system. The water tank vibrates as a weight, damping the vibrations of the structure. Furthermore, the vibrations of the liquid in the water tank constituting the second vibration system provide a damping force to the vibrations of the first vibration system.

[Problem to be solved by the invention]

However, with a single dynamic vibration absorber, there are problems with stability when optimal tuning is lost, such as the damping effect being impaired by slight variations in parameters.

Furthermore, a problem unique to civil engineering and architectural structures is the difficulty in estimating the natural period of the structure. Dynamic vibration absorbers that damp the vibrations of structures must be designed by accurately estimating the natural period of the structure, but the natural period of the structure is not always constant during its service life. For example, after experiencing a large earthquake, a structure becomes less rigid and has a longer natural period.

On the other hand, in order to change the natural period of each pendulum aquarium damper, it is necessary to change the length of the pendulum, which is not necessarily easy to adjust after installation.

As a means of solving the former problem, a method of using two dynamic vibration absorbers in parallel has been proposed (for example, "Optimum design method of two composite dynamic vibration absorbers and their effects"). ” Seto et al., Proceedings of the Japan Society of Mechanical Engineers, 1984, etc.).

The present invention aims to solve the above-mentioned problems in pendulum aquarium dampers.

[Means to solve the problem]

The connected pendulum aquarium damper of the present invention has a plurality of pendulum aquarium dampers arranged in parallel, in which a predetermined mass of an aquarium injected with a predetermined amount of liquid is suspended and supported from a structure by a plurality of hanging members. However, these pendulum aquarium dampers are connected to each other by a spring having a predetermined spring constant.

Although it is possible to use the weight of the aquarium itself as a weight, a weight is usually attached to the aquarium as an additional mass.

[For production]

When two pendulum weights are connected by a spring, Figure 3 (a)
, (as shown in bl), a phenomenon occurs in which the two pendulums both vibrate in the same direction (primary vibration type), and a phenomenon in which they vibrate in the opposite direction (secondary vibration type).

The equation of motion at this time is as follows with reference to FIG.

From the above equation of motion, when pendulums with the same mass and slightly different periods are connected by a spring with a spring constant, the natural frequency is the first-order natural frequency, ω, and the second-order natural frequency, 2ω, are respectively.

Therefore, the second natural frequency is the spring constant of the spring with a value of 0,
It can be freely adjusted by moving it closer to or farther away from the first natural frequency, ω.

Therefore, in order to damp the vibrations of structures that occur during strong winds or earthquakes, the spring-connected pendulum water tank damper is tuned to the structure's natural frequency Ω by adjusting the secondary natural frequency 2ω, and the structure's natural frequency Ω is tuned. If the natural frequency (or natural period) changes over time, the tuning period can be adjusted by eight rounds by changing the spring constant kD.

In this way, the vibration energy of the structure is converted into the vibration energy of the pendulum, and further converted from the pendulum into thermal energy due to friction and crushing of the liquid in the water tank, thereby damping the vibration.

〔Example〕

FIGS. 1 and 2 schematically show the connected pendulum damper of the present invention, in which two pendulum water tank dampers 1 and 1a arranged in parallel are connected by a coil spring 2 having a spring constant kD.

In the figure, the water tank 20 of the pendulum water tank damper 1 on the left is connected to the wire rope 1 against the frame 4 at the top of the structure 3.
2, it is suspended at four points. In the water tank 20,
A weight 1) that also serves as a support base is attached as an additional mass. In this embodiment, the weight 1) on which the aquarium 20 is mounted is suspended and supported by wire rows 1) 2. It constitutes a first vibration system with a pre-oscillation having a natural frequency ω1. Note that a steel material or the like is used as the weight 1).

A predetermined amount of liquid 21 such as water with a synchronized vibration period is injected into the water tank 20, and the sloshing action of the liquid 21 as a second vibration system provides damping properties to the first vibration system and the structure 3. There is. Note that the vibration period is adjusted by 8 depending on the dimensions and water depth of the water tank 20.

The same applies to the pendulum water tank damper 1a on the right side, and the mass m2
, a first vibration system with pre-swinging and a natural frequency ω2, and a second vibration system with sloshing.

These pendulum aquarium dampers 1 and 1a are configured as double dynamic vibration absorbers having a first vibration system and a second vibration system for the main vibration system, so compared to conventional sloshing dampers, they achieve the same wind vibration suppression. When trying to obtain the effect, the amount of water is about 1/30 and the volume is about 1/7. When applied to an actual building, for example, in a building of about 1,000 yen, the weight of the pendulum is 10~20 tons, and the amount of water is about 1/30. is 200-50
A large vibration reduction effect can be obtained at a value of about 01.

And two pendulum aquarium dampers 1. By connecting la with the spring 2, a connected pendulum aquarium damper having a first natural frequency, ω, and a second natural frequency, 2ω, expressed by the above-mentioned equations (1) and (2) is constructed. As mentioned above, 2
The next natural frequency 2ω can be adjusted by changing the spring constant of the spring 2. For example, the natural frequency 2ω of the structure can be adjusted by 1. ω
By setting the magnitude relationship as 〈Ω × 2ω and adjusting within a range where the difference between ω and 2ω is not too large, the two peaks in the response magnification that appear in the case of a single pendulum tank damper are equalized, and the maximum response is In addition to reducing the magnification, there is less influence even when optimum tuning is lost, and the stability as a dynamic vibration absorber can be improved.

Concerning stability when optimal synchronization is disrupted, specific numerical values are as follows: 1. In the magnitude relationship ω〈Ω×2ω,
It is desirable to adjust Ω-1ω and ω-Ω to Ω within a range of about 1710 or less. Considering the damping effect, the masses mI and mz of each weight of the first vibration system are preferably about 1/100 to 1/400 of the mass M of the structure that is the main vibration system, for example, 1/200 of the mass M of the structure that is the main vibration system. In this case, the first natural frequency, ω, is set to be approximately 4% smaller than the natural frequency Ω of the structure, and the second natural frequency 8ω is set to be 4% smaller than the natural frequency Ω of the structure.
Set it approximately % higher.

Moreover, although the above is a case in which two pendulum aquarium dampers are connected at 1° 1a with spring 2, it is also possible to connect three or more pendulum aquarium dampers with respective springs.

The interlocking pendulum water tank damper of the present invention can be installed in a structure by hanging a wire rope around a beam on the ceiling of a tower of a building, or by hanging a wire rope around a beam on the ceiling of the top floor of a building. One possible method is to install it.

〔Effect of the invention〕

■ By appropriately setting the mass and natural frequency of the first vibration system and second vibration system of each pendulum aquarium damper arranged in parallel and connected by a spring, the total added mass ratio of the two dampers is the same. It has a greater vibration suppression effect than the pendulum aquarium damper, and also has excellent stability when optimal synchronization is lost. This is particularly noticeable when the added mass ratio to the structure is small.

■ Even if the natural frequency of the structure changes over time, this can be easily addressed by changing the spring constant of the connected springs, such as by replacing the springs, without having to adjust the pendulum aquarium damper itself.

■ Because it uses a suspension system with low friction and a liquid that easily shakes, it responds sensitively to even small wind shakes and earthquake motions, effectively suppressing shaking and attenuating it quickly, eliminating discomfort caused by shaking. can be removed.

■ By combining a pendulum type dynamic vibration absorber and a sloshing damper as a double dynamic vibration absorber, compared to a conventional sloshing damper, a large vibration damping effect can be obtained by putting a small amount of liquid into a small volume water tank. be able to.

■ The device is compact and easy to install, so
Can be installed in a small space.

■ Wind sway in high-rise residential buildings, high-rise buildings, and high-rise towers can be effectively suppressed.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram schematically showing the outline of the connected pendulum aquarium damper of the present invention, Fig. 2 is a plan view showing how the pendulum aquarium damper is connected by a spring, Fig. 3 (a),
(bl is an explanatory diagram showing the primary and secondary vibration modes of the connected pendulums, and FIG. 4 is a model diagram for analysis of the first vibration system in the connected pendulum water tank damper of the present invention. 1.・Pendulum aquarium damper, 2... spring, 3...
Structure, 4... Peripheral frame, 1)... Weight, 12
...Wire rope, 20...Water tank, 21...Liquid (Figure 4, Figure 1, Figure 2, Figure 3 axis) (b)

Claims (2)

[Claims] (1) A plurality of pendulum aquarium dampers, each made by suspending and supporting an aquarium of a predetermined mass with a predetermined amount of liquid injected into the interior from a structure using a plurality of hanging materials, are connected to each other by a spring having a predetermined spring constant. This is a connected pendulum aquarium damper. (2) The connected pendulum water tank damper according to claim 1, wherein a weight is attached to the water tank to maintain a predetermined mass of the water tank.