JPH0520543B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to 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. .

[Conventional technology]

Figure 2 shows a model of a conventional general dynamic vibration absorber, in which the additional mass (mass m) is connected to a structure (mass M, spring constant K ), and the vibrations of the structure can be reduced by having the added mass absorb the vibrations.

When designing a dynamic vibration absorber, it is said that in order to minimize the maximum value of the amplitude multiplier of the main vibration system, the dynamic vibration absorber and the main vibration system should have the following relationship (``Dynamic vibration absorber ``Practical (1)'', Kazuto Seto, Machine Research Vol. 36, No. 4, 1984, pp. 477-478).

ω _o /Ω _o = 1/1 + μ ζ = √38 (1+) Here, Ω _o = √: Natural frequency of the main vibration system ω _o =√: Natural frequency of the vibration absorber system μ = m/M: Vibration absorption Mass ratio of the main vibration system to the main vibration system ζ=c/2√: Damping rate of the vibration absorber system On the other hand, the applicant has proposed that the spring We have proposed a pendulum-type dynamic vibration absorber whose vibration period is easier to adjust than the formula. In a conventional dynamic vibration absorber, the vibration period of the weight as an additional mass is T = 2π√1, which is the difference between the natural period (or natural frequency) of the building and the vibration period (or frequency) of the additional mass of the dynamic vibration absorber. )
When damping is performed by adjusting the spring constant k or additional mass m. On the other hand, the vibration period of a pendulum type dynamic vibration absorber is T = 2π√ l is the length of the pendulum g is the gravitational acceleration, and the vibration period (or vibration frequency) can be adjusted.

Regarding pendulum-type dynamic vibration absorbers, there is one that uses the ice heat storage tank of the air-conditioning equipment unit installed on the top floor of a building as a pendulum weight to control the sway of the building in response to the wind. “Introducing a pendulum vibration damping device”, Architectural Technology, October 1988 issue, No. 58
(see page).

In addition, there is a dynamic vibration absorber called a sloshing damper that suppresses the vibration of a structure by utilizing the vibration of liquid (usually water) in a water tank.
Publication No. 63-181868 discloses a double dynamic vibration absorber that combines a conventional dynamic vibration absorber using an additional mass such as steel and a water tank installed on the steel as the additional mass. In addition, regarding a double dynamic vibration absorber, there is an invention disclosed in Japanese Patent Application No. 132917/1983 by the applicant.

[Problem to be solved by the invention]

Incidentally, in structures such as pencil buildings, which have low horizontal rigidity, therefore have a long natural period, and are likely to resonate with the dominant period of wind pressure fluctuations, vibration disturbances (mainly problems with livability) due to wind sway are likely to occur. However, when considering comfort, it is said that the level of acceleration that people begin to feel is around 1.0 Gal, and it has traditionally been considered extremely difficult to reduce minute vibrations such as those caused by wind vibrations. .

Furthermore, since the sloshing damper uses a liquid such as water, it requires a very large water tank in order to obtain a sufficient vibration suppression effect, and there are problems with the installation location and installation method.

Furthermore, in the vibration suppression device described in Japanese Patent Application Laid-Open No. 63-181868, the natural period of the structure, the vibration period of the first vibration system, and the second vibration period are set to be the same, so that vibration suppression is not necessarily optimal. It has not become effective.

The present invention aims to solve the problems in the prior art as described above.

[Means to solve the problem]

The present invention includes a first vibration system that uses a pendulum type dynamic vibration absorber that has little friction and can sensitively respond to minute vibrations, and a second vibration system that mainly damps the vibrations of the first vibration system. The main vibration system is combined with the sloshing damper to configure the double dynamic vibration absorber by setting the natural frequencies of the first vibration system and the second vibration system near the natural frequency of the structure. It is possible to effectively suppress the shaking of the structure.

That is, the pendulum-type sloshing damper of the present invention comprises 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. , by hanging material,
The support stand and water tank vibrate as weights, 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.

The total mass m ₁ of the support stand and water tank as additional mass of the first vibration system and the mass m ₂ of the liquid in the water tank are:
It is desirable to set the mass of each structure to be as follows: 1/200M≦m ₁ ≦1/50M 1/100m ₁ ≦m ₂ ≦1/10m ₁ (1). If the added mass is too small, the damping effect will be small, and if it is too large, it will be uneconomical and will also affect the design of the structure body.

The response magnification when a structure installed with the pendulum type sloshing damper of the present invention receives an external force such as wind is derived from the following vibration equation with reference to FIG.

For the mass M, spring constant K, damping constant C, etc. of the structure, the mass m ₁ of the first vibration system, the length l of the pendulum,
By appropriately selecting the mass m ₂ and damping constant c ₂ of the second vibration system, the natural frequency ω ₁ of the first vibration system and the natural frequency ω ₂ of the second vibration system are given. The acceleration X, velocity X, and displacement X of the main vibration system with respect to the vibration external force F are determined, and in this way, the response magnification of the main vibration system with respect to the vibration external force F can be calculated.

[ω ₁ =√, ω ₂ =√ _{2 2} ] Then, within the range of (1) above, the mass m ₁ of the first vibration system,
Setting the mass m ₂ of the second vibration system and finding the response magnification for various values, the following conditions (3) and (4) are obtained.
It can be seen that the response magnification can be kept sufficiently low under

ω ₁ > Ω > ω ₂ or ω ₁ < Ω < ω ₂ …(3) and, Therefore, by making adjustments under the conditions (1), (3), and (4) above, a large vibration damping effect can be obtained.

Note that the vibration equation (2) above is expressed as the second vibration system as an additional mass, and a spring and damper that connect this to the additional mass of the first vibration system, as shown in Fig. 15. In order to replace it with a sloshing damper, it is necessary to calculate and design equivalent values using equations (5) and (6) below.

Referring to FIG. 16, the natural frequency ω ₂ of sloshing liquid in a water tank with a rectangular plane can be obtained from the Hausner theory using the following equation.

The mass of free water (mass of the second vibration system) m ₂ during liquid sloshing can be determined from the Hausner theory using the following equation.

m ₂ = m _w ×0.527l/Htanh [1.58H/l] …(6) (m _w is the total mass of the liquid in the water tank) The stiffness of the second vibration system is k ₂ = m ₂ ω ₂ ² = m _w ×0.833g/Htanh ² [1.58H/l].

[Effect]

FIG. 1 shows a model of the pendulum type sloshing damper 7 of the present invention.
The hanging type weight 11 absorbs the vibration, and then the vibration transmitted to the weight 11 is absorbed by the liquid such as water 22 in the water tank 20 as it violently agitates, and the vibration energy is absorbed by wave breaking (slotzing). It can be eliminated by the contact friction of the aquarium or water tank.

It uses a suspension system with low friction and a liquid that is easily shaken, so it can respond sensitively to even small shakes.

Furthermore, by adjusting the pendulum type sloshing damper of the present invention under the conditions (1), (3), and (4) above, it is possible to sufficiently reduce the response magnification of the structure to external vibrational forces. can.

〔Example〕

3 to 11 schematically show an experimental apparatus for a pendulum type sloshing damper according to the present invention.

Figures 3 and 4 show the test specimen frame 1, and the excitation direction is column 2 (C-channel,
100 x 50 x 5 x 7.5) in the weak axis direction, and has one layer and one span (height 3.0 m, span 0.54 m).
The structure perpendicular to the excitation direction has three layers and one span (height
1.0m x 3, span 1.1m) (beam 3 is H
By reinforcing it with shaped steel (100 x 100 x 6 x 8) and braces 4, the effects of torsion are suppressed.

At the top of the frame 1, a weight 5 of approximately 3.0t that gives the mass of the structure, a vibration device 6, and a pendulum type sloshing damper 7 of the present invention are attached (weight
By inputting standing waves and random waves to the vibration device 6, the frame 1
Excite. The primary natural period of this test frame according to undamped eigenvalue analysis was 1.1 seconds.

Figure 5 shows the overall structure of the pendulum type sloshing damper 7 installed on the top of the frame, Figures 6 to 8 show the structure of the pendulum 10 that constitutes the first vibration system, and Figures 9 to 11 The figure shows the structure of a water tank 20 that constitutes the second vibration system.

The weight 11 of the pendulum 10 is plate-shaped, and the outer peripheral frame 8 of the device is connected by a wire rope 12.
It is suspended at four points. Also, 9 in the figure
is a mounting plate for mounting the device. An acrylic water tank 20 is attached on top of the weight 11. One section of the divided aquarium has an inner length L.
590mm, width B 45mm, height H ₀ 190mm, aquarium 2
0 has a triangular rib 2 with a protruding length h of 10 mm on the inside.
1 were installed at equal intervals to improve the damping effect.

Figure 12 shows an example of the experimental results when an unsteady wave is input from the vibration excitation device in the above-mentioned experimental apparatus. When a type sloshing damper is installed (solid line),
The response acceleration at the top of the frame has been significantly reduced.

Compared to conventional sloshing dampers, the pendulum type sloshing damper of the present invention requires about 1/30th the amount of water and about 1/7th the volume when trying to obtain the same wind sway suppressing effect. When applied to an actual building, for example, in a building of about 1000 tons, a large vibration reduction effect can be obtained with a pendulum weight of 10 to 20 tons and a water volume of about 200 to 500 tons.

13 and 14 show examples of application to the structure 30, such as the installation method in which the wire rope 12 is hung around the ceiling beam 32 of the tower building 31 as shown in FIG. 13, and the method shown in FIG. One possible method is to hang the wire rope 12 around the ceiling beam 33 on the top floor of the building.

[Effects of the invention] It responds sensitively to even small wind vibrations and earthquake motions,
Since shaking is effectively suppressed and attenuated quickly, discomfort caused by shaking can be eliminated.

By combining a pendulum type dynamic vibration absorber and a sloshing damper as a double dynamic vibration absorber,
Compared to conventional sloshing dampers, a large vibration damping effect can be obtained by filling a small volume of water tank with a small amount of liquid.

By appropriately setting the mass, natural frequency, etc. of the first vibration system and the second vibration system, an optimal vibration suppression effect can be obtained.

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

It can effectively suppress wind sway in high-rise residential buildings, high-rise buildings, and high-rise towers.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram showing the device of this invention as a model, Figure 2 is a conceptual diagram showing a conventional general dynamic vibration absorber as a model, and Figure 3 is an outline of the frame used in the experiment. 4 is a surface diagram of the same, FIG. 5 is an elevational view showing a cross section of a part of the experimental apparatus of the present invention attached to a frame, and FIG. 6 shows the structure of the pendulum type dynamic vibration absorber. Plan views shown in Figures 7 and 8.
The figures are respectively a front view and a side view, Figure 9 is a plan view showing the structure of the aquarium, Figures 10 and 11 are
The figures are respectively a front view (partial sectional view) and a side view, Fig. 12 is a graph showing the experimental results, and Fig. 13 is a graph showing the experimental results.
Figure 14 is a schematic diagram showing an example of the installation position of the device, Figure 15 is a model diagram corresponding to the vibration equation, and Figure 16 is an explanatory diagram for explaining the relationship between the dimensions of the water tank and the natural frequency. It is. 1... Test specimen frame, 6... Vibration device, 7... Pendulum type sloshing damper, 8... Outer periphery frame,
10... Pendulum, 11... Weight, 12... Wire rope, 20... Water tank, 21... Rib, 22... Water.

Claims (1)

[Scope of Claims] 1. Consists of a support stand suspended from a structure via a plurality of hanging members, and a water tank installed on the support stand, wherein the support stand and liquid are suspended by the hanging members. a first vibration system that forms a pendulum type dynamic vibration absorber that vibrates using a water tank as a weight and damps the vibration of the structure; and a slot that damps the vibration of the first vibration system by the vibration of the liquid in the water tank. and a second vibration system forming a Tsusing damper, and the natural frequency of the first vibration system and the natural frequency of the second vibration system are set to predetermined values near the natural frequency of the structure. A pendulum-type sloshing damper with a structure characterized by the following: 2 The total mass m ₁ of the support stand and the water tank and the mass m ₂ of the liquid in the water tank, respectively, where the mass of the structure is M, 1/200M≦m ₁ ≦1/50M 1/100m ₁ ≦ m ₂ ≦1/10m ₁ , and the natural frequency ω ₁ of the first vibration system and the natural frequency ω ₂ of the second vibration system are ω ₁ where the natural frequency of the structure is Ω. ＞Ω＞ω ₂ or ω ₁ <Ω＜ω ₂ , and adjustment is made within the range where |Ω−ω ₁ | and |Ω−ω ₂ | are 1/20 or less of Ω. A pendulum type sloshing damper of a structure according to claim 1.