JPH02282582A - Double pendulum water tank damper - Google Patents

Abstract

PURPOSE:To improve the damping property by suspending and holding the first water tank from a structure, and suspending and supporting the second water tank filled with a liquid inside from the structure so as to be immersed in a liquid of the first water tank. CONSTITUTION:A water tank 20 filled with a liquid 21 inside and fitted with a weight 11 on the bottom is suspended and supported at four points by wire ropes 12 from a frame 4 at the top section of a structure 3 to form the first pendulum water tank damper 1. A water tank 20a filled with a liquid 21a inside is supported by a weight 11a to form the second pendulum water tank damper 1a. The water tank 20a is suspended and supported by wire ropes 12a from the frame 4 so that the lower section of the weight 11a supporting the water tank 20a is immersed in the liquid 21 of the water tank 20.

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, Japanese Patent Application Laid-Open No. 63-114
Examples include the invention described in Publication No. 773.

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, OGa1, and it has traditionally been considered extremely difficult to reduce minute vibrations such as those caused by wind vibrations. It's here.

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 contrast, the applicant has developed a first system using a pendulum-type dynamic vibration absorber that has low 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. We have developed a pendulum-type sloshing damper (hereinafter referred to as a pendulum water tank damper) that effectively suppresses wind sloshing ("Vibration experiment of side wind structure targeting wind sway", Kobori et al., Proceedings of the Academic Conference of the Architectural Institute of Japan, (Refer to 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.

Furthermore, in the case of small vibrations, the rigidity of non-structural members increases, and conversely, the natural period becomes shorter. As described above, it is difficult to accurately estimate the natural period of a structure in that state.

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, 1982, etc.).

The present invention solves the above problem by configuring a double pendulum water tank damper to widen the tuning range, and furthermore, by introducing a damping mechanism between both pendulum water tank dampers, the damping performance as a dynamic vibration absorber is improved. This is an attempt to improve the results.

[Means to solve the problem]

The double pendulum aquarium damper of the present invention suspends and supports a first aquarium of a predetermined mass with a predetermined amount of liquid injected into the interior by a plurality of hanging members from a structure, and further injects a predetermined amount of liquid into the interior. The second water tank having a predetermined mass is suspended from a structure using a plurality of hanging members so that at least the lower part thereof is immersed in the liquid in the first water tank.

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.

The first water tank constituting the first pendulum is such that the second water tank (including the weight) as a pendulum can swing inside, and the first water tank can swing inside.
The dimensions are designed so that the vibrations of the liquid in the tank can be synchronized with the vibrations of the structure and the first pendulum.

If a weight as an additional mass is attached to the second water tank, part or all of this weight portion may be immersed in the liquid in the water tank.

Further, by providing a lip on the bottom or side surface of the water tank or the weight, it is possible to adjust the viscous resistance when the water tank or the weight swings in the liquid of the first water tank.

[For production]

FIG. 4 is a model diagram of only the first vibration system of the double pendulum water tank damper of the present invention, and the equation of motion is as follows.

That is, the liquid in the first water tank not only dampens the vibrations of the first pendulum itself, but also
It also functions as an attenuator to attenuate the pendulums. However, for this purpose, the mass ml of the first pendulum and the mass ml of the second
The condition is that the mass ratio of the mass m2 of the pendulum is close to 1.

In this way, the vibrational energy of the structure is converted into the vibrational energy of the pendulum, and the oscillation energy of the structure is converted into the vibrational energy of the pendulum and the
The vibration is attenuated by the viscous resistance between the heavy pendulums and by being converted from the pendulum into thermal energy due to friction and crushing of the liquid in the tank.

〔Example〕

1 to 3 schematically show an example of the double pendulum aquarium damper of the present invention, which is composed of a first pendulum aquarium damper 1 and a second pendulum aquarium damper 1a.
The lower side of the weight 11a attached to the water tank 20a of the second pendulum tank damper 1a is immersed in the liquid 21 of the water tank 20 constituting the pendulum tank damper, and when the pendulum swings, it receives the viscous resistance of the liquid 21. , designed to attenuate the swing of both pendulums.

Regarding the first pendulum water tank damper 1, the water tank 20
is suspended from a frame 4 at the top of the structure 3 by wire ropes 12 at four points. A weight 11 as an additional mass is attached to the bottom side of the water tank 20. In this embodiment, the water tank 20 is directly suspended and supported by a wire rope 12, and has a mass ml, a hanging length ll, and a natural frequency ω. This constitutes the first vibration system of the hanging allowance. In addition,
As the weight 11, steel or the like is used.

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.

The weight lla of the second pendulum aquarium damper 1a is the aquarium 20.
It also serves as a support stand for a, and suspends and supports a weight lla with a wire rope 12a, and has a first vibration system with a swing suspension with a mass m2, a suspension length 12, and a natural frequency ω2, and a second vibration system using sloshing. It consists of

Further, a plurality of ribs 5 are provided on the bottom and side surfaces of the weight lla to adjust viscous resistance when the weight lla swings within the liquid 20 of the first pendulum aquarium damper 1.

These pendulum aquarium dampers 1 and 1a are configured as double dynamic vibration absorbers having a first vibration system and a second vibration system, respectively, for the main vibration system, so compared to conventional sloshing dampers, they have the same wind vibration. When trying to obtain a suppressive effect, only about 1/30th of the amount of water and about 1/7th of the volume are sufficient. When applied to an actual building, for example, in a building of about 1,000 kg, the weight of the pendulum is 10 to 20 tons, and the amount of water is 2
A large vibration reduction effect can be obtained with a value of about 00 to 5001.

Regarding stability when the optimal synchronization is broken, the natural frequencies of the first vibration system of the swing suspension of the two pendulum water tank dampers 1 and 1a are set to ω1, ω2, and the natural frequency of the structure 3 (first-order natural frequency). 2 in the response magnification that appears in the case of a single pendulum aquarium damper, by setting the magnitude relationship as (131<Ω×ω2) and adjusting within a range where the difference between ω1 and ω2 is not too large. The two peaks are smoothed out, the maximum response magnification is reduced, and even when optimum tuning is lost, there is less influence, and the stability of the dynamic vibration absorber can be improved.

To give concrete numerical values, in the magnitude relationship ω1 × Ω × ω2, Ω−ω and ω2−Ω are 1710 for Ω.
It is desirable to adjust within the following range. The mass m+, mg of each weight of the first vibration system is 1/100 to l/4 of the mass M of the structure that is the main vibration system, considering the damping effect.
For example, in the case of 1/200, the natural frequency ω1 of the first pendulum aquarium damper 1 is set to be about 4% smaller than the natural frequency Ω of the structure, and the natural frequency ω1 of the second pendulum aquarium damper 1a is The frequency ω2 is set approximately 4% larger than the natural frequency Ω of the structure.

The double 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 building tower, 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〕

■ The first vibration system and the second vibration system of the two swing tank dampers.
By appropriately setting the mass and natural frequency of the vibration system, the vibration suppression effect is greater than that of a single swinging aquarium damper with the same added mass ratio, and stability is achieved when optimal synchronization is lost. Excellent in sex. This is particularly noticeable when the added mass ratio to the structure is small.

■ 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.

■ The liquid in the water tank of the first swing tank damper not only damps the vibrations of the first pendulum itself, but also functions as a damper that dampens the mutual vibrations of the first and second pendulums. , damping performance can be improved.

■ By combining the pendulum double-motion vibration absorber and the sloshing damper as a double-dynamic vibration absorber, compared to the conventional sloshing damper, a large vibration damping effect can be obtained by putting a small amount of liquid into a small-capacity 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 showing the outline of the double swing aquarium damper of the present invention as a model, Fig. 2 is its I■ sectional view, Fig. 3 is its nn sectional view, and Fig. 4 is the present invention. FIG. 2 is a model diagram for analysis of the first vibration system in the double swinging water tank damper. 1... swinging water tank damper 3... structure, 4...
・Outer frame, 5... Lip, 11... Weight, 12
... wire rope, 20 ... water tank, 21 ... liquid -1 -force LLφ

Claims (3)

[Claims] (1) A first tube of a predetermined mass with a predetermined amount of liquid injected inside.
A second aquarium having a predetermined mass and having a predetermined amount of liquid injected therein is suspended and supported from a structure by a plurality of hanging materials, and at least the lower part of the second aquarium is immersed in the liquid in the first aquarium. A double pendulum aquarium damper is characterized in that it is suspended and supported from a structure by a plurality of hanging members. (2) The second water tank according to claim 1, wherein a weight is attached to the first water tank and the second water tank to maintain a predetermined mass.
Heavy pendulum aquarium damper. (3) Only the weight portion of the second water tank is immersed in the liquid in the first water tank, and the weight has ribs on the surface to adjust viscous resistance due to the liquid in the first water tank. 3. A double pendulum aquarium damper as claimed in claim 2.