JPH02282584A - Connection type double pendulum water tank damper - Google Patents

Abstract

PURPOSE:To improve the damping property by suspending end supporting the second water tank filled with a liquid inside in the liquid of the first water tank suspended and supported from a structure, and connecting both water tanks with springs. CONSTITUTION:A water tank 20 filled with a liquid 21 inside and fitted with a weight 11 on the bottom is suspended from an outer periphery frame 4 at the top section of a structure 3 by wire ropes 12 at four points 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 from the frame 4 by wire ropes 12a so that the lower section side of the weight 11a supporting the water tank 20a is immersed in the liquid 21 of the water tank 20. Both dampers 1 and 1a are connected by coil springs 12a 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, Japanese Patent Application Laid-Open No. 631147
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 habitability, it is said that the level of acceleration at which people begin to feel confused is around 1, OGa1, and conventionally it has been extremely difficult to reduce minute vibrations such as those caused by wind vibrations. It has been.

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 proposed a first method using a pendulum hole dynamic vibration absorber, which 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 preformed 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., Abstract 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.

In addition, in the case of small vibrations, the stiffness of non-structural members is added, and the natural period becomes short.As such, it is difficult to accurately estimate the natural period of the 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 connected double pendulum aquarium damper of the present invention has a first pendulum aquarium in which a first aquarium having a predetermined mass and a predetermined amount of liquid injected therein is suspended and supported from a structure by a plurality of hanging members. A damper and a second water tank having a predetermined mass and having a predetermined amount of liquid injected therein are suspended and supported from a structure using a plurality of hanging members so that at least the lower part is immersed in the liquid in the first water tank. The second pendulum aquarium damper is connected to a second pendulum aquarium damper 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.

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.

Furthermore, by providing ribs on the bottom or side surfaces of the water tank or the weight, it is possible to adjust the viscous resistance when the water tank or the weight swings within the liquid in the first water tank.

[For production]

When two pendulum weights are connected by a spring, Figure 3 (a)
, As shown in (b), a phenomenon occurs in which the two pendulums both vibrate in the same direction (primary vibration type) and in the opposite direction (secondary vibration type). In the connected double pendulum water tank damper of the present invention, viscous resistance of the liquid in the first water tank is added to this. FIG. 4 is a model diagram of only the first vibration system, and the equation of motion is as follows.

From the above equation of motion, the natural frequency (natural circular frequency) when the two pendulums have approximately the same mass and slightly different periods is the first-order natural frequency, ω, and the second-order natural frequency, 2ω. , respectively.

Therefore, the second natural frequency is the spring constant kDO value of the spring,
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 connected double pendulum water tank damper is tuned to the natural frequency Ω of the structure by adjusting the secondary natural frequency 2ω, and the structure If the natural frequency (or natural period) of the pendulum aquarium damper changes over time, the tuning period can be adjusted by changing the spring constant kD of the spring connecting the first pendulum aquarium damper and the second pendulum aquarium damper. I can do it.

Also, the liquid in the water tank of the first pendulum water tank damper is
It functions not only as a damper for damping the vibrations of the pendulum itself, but also as a damper for damping the first pendulum and the second pendulum each other.

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〕

FIG. 1 and FIG. 2 schematically show an example of the interlocking type 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. In the liquid 21 of the aquarium 20 constituting the first pendulum aquarium damper, the aquarium 2 of the second pendulum aquarium damper 1a is added.
The lower side of the weight lla attached to 0a is submerged, and when the pendulum swings, it receives viscous resistance from the liquid 21, thereby damping the swing of both pendulums. Further, the first pendulum aquarium damper 1 and the second pendulum aquarium damper 1a are connected by a coil spring 2 having a spring constant kl, and in this embodiment, the inner upper part of the aquarium 20 of the first pendulum aquarium damper 1 and , the weight of the second pendulum aquarium damper 1a
The upper part of a is connected.

Regarding the first pendulum water tank damper 1, the water tank 20
is suspended from the outer peripheral frame 4 at the top of the structure 3 by wire ropes 12 at four points. Water tank 20
A weight 11 as an additional mass is attached to the bottom side of the tank, and in this embodiment, the water tank 20 is directly suspended and supported by a wire rope 12, and a pendulum with a mass of ml, a hanging length of N+, and a natural frequency of ω1 is attached. It constitutes the first vibration system of the hole.

Note that the weight 11 is made of steel or the like.

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, suspends and supports a weight lla with a wire rope 12a, and constitutes a first vibration system of a pendulum hole with a mass m2, a hanging length I12, and a natural frequency ω2, and a second vibration system by sloshing. are doing.

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. Since the la is configured as a double dynamic vibration absorber with a first vibration system and a second vibration system for the main vibration system, it is compared with a conventional sloshing damper and aims to achieve the same wind vibration suppression effect. In this case, 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 to 20 tons, and the amount of water is 200 tons.
~500 I! A large vibration reduction effect can be obtained with a certain degree.

Regarding stability when the optimum synchronization is broken, by connecting the two pendulum water tank dampers 1 and 1a with the spring 2, the first natural frequency, ω, expressed by the above-mentioned equations (11 and (2)) , a connected double pendulum water tank damper with a secondary natural frequency tω is constructed.As mentioned above, the secondary natural frequency 2
ω can be adjusted by changing the spring constant of spring 2. For example, with respect to the natural frequency Ω of the structure, the magnitude relationship is 1ω < Ω × 2ω, and it can be adjusted within the range where the difference between ω and 2ω is not too large. By doing so, the two peaks in the response magnification that appear in the case of a single pendulum aquarium damper are smoothed out, the maximum response magnification is reduced, and even when optimal synchronization is lost, there is less influence, making it suitable for use as a dynamic vibration absorber. Stability can be improved.

To give specific numbers, 1. In the magnitude relationship ω〈Ω〈2ω, Ω-1ω and 2ω-Ω are 1710 with respect to Ω.
It is desirable to adjust within the following range. The quality itm+, m2 of each weight in the first vibration system is 1/100 to 1 of the quality iiM of the structure that is the main vibration system, considering the damping effect.
/400 is desirable.For example, in the case of 1/200, the first natural frequency, ω, is 4 from the natural frequency Ω of the structure.
%, and the secondary natural frequency 2ω is set to be about 4% larger than the natural frequency Ω of the structure.

The interlocking 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 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 by applying

〔Effect of the invention〕

■ The first vibration system and the second vibration system of two pendulum aquarium dampers.
By appropriately setting the mass and natural frequency of the vibration system, the vibration suppression effect is greater than that of a single pendulum water tank damper with the same added mass ratio, and stability is achieved even when optimal synchronization is lost. Excellent. 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.

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

■ 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 showing the outline of the connected double pendulum aquarium damper of the present invention as a model, Fig. 2 is its II sectional view, and Figs. 3 (a) and (b) are the connected pendulums. FIG. 4 is a model diagram for analysis of the first vibration system in the connected double pendulum water tank damper of the present invention. 1... Pendulum aquarium damper, 2... Spring, 3...
Structure, 4... Peripheral frame, 5... Rib, ■ l... Weight, 2... Wire rope, 20... Water tank, 1... Liquid diagram No. 1; Figures (a) (b)

Claims (3)

[Claims] (1) A first tube of a predetermined mass with a predetermined amount of liquid injected inside.
A first pendulum aquarium damper is formed by suspending and supporting an aquarium from a structure with a plurality of hanging members, and a second aquarium having a predetermined mass and having a predetermined amount of liquid injected therein are arranged such that at least the lower part of the damper is suspended from a structure. A connection characterized in that the second pendulum aquarium damper is suspended and supported from a structure by a plurality of hanging members so as to be immersed in the liquid in the first aquarium, and the second pendulum aquarium damper is connected by a spring having a predetermined spring constant. Type double pendulum aquarium damper. (2) The connected double pendulum water tank damper according to claim 1, wherein weights are attached to the first water tank and the second water tank to maintain a predetermined mass. (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. An interlocking double pendulum aquarium damper as claimed in claim 2.