JPH083287B2 - Double pendulum aquarium damper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to the fields of civil engineering and construction, such as wind and earthquake.
The present invention relates to a pendulum water tank damper as a dynamic vibration reducer for reducing the influence of a vibration external force acting on a structure.

[Conventional technology]

A dynamic vibration absorber for a structure is disclosed in JP-A-63-114773.
There are inventions described in the publication.

By the way, in a structure like Pencilville, which has low horizontal rigidity and therefore has a long natural period (small natural frequency) and is likely to resonate with the predominant cycle of wind pressure fluctuations, vibration disturbance due to wind sway (mainly habitability problem) Is likely to occur. However, when habitability is an issue, the level of acceleration at which a person begins to feel is said to be around 1.0 Gal, and conventionally,
It has been considered extremely difficult to reduce minute vibrations such as wind sway.

In addition, in the conventional sloshing damper (such as Japanese Patent Laid-Open No. 62-101764) in which a liquid is stored in a water tank, a liquid such as water is used. There is a problem with the installation position and installation method.

On the other hand, the Applicant has a first vibration system using a pendulum type dynamic vibration absorber that has little friction and can react sensitively to minute vibrations, and a second vibration system mainly for damping the vibrations of the first vibration system. A pendulum-type sloshing damper (hereinafter referred to as a pendulum tank damper) that effectively suppresses swaying of the structure that is the main vibration system by combining with a sloshing damper that forms the vibration system to form a double dynamic vibration absorber.
Has been developed (see "Vibration test of wind control structure for wind sway", Kobori et al., Summary of Academic Lectures at the Architectural Institute of Japan, October 1988 and Japanese Patent Application No. 63-323061).

The pendulum water tank damper is composed of a support base suspended and supported by a plurality of suspension members for a structure constituting the main vibration system, and a water tank installed on the support base. The water tank vibrates as a weight and damps the vibration of the structure. Furthermore, for the vibration of this first vibration system,
The vibration of the liquid in the water tank forming the second vibration system gives a damping force.

[Problems to be Solved by the Invention]

However, with a single dynamic vibration absorber, there is a problem in stability when optimal tuning is broken, such as the damping effect being impaired by a slight variation in the parameters.

Another problem peculiar to civil engineering and building structures is the difficulty in estimating the natural period of the structure. A dynamic vibration absorber that damps vibration of a structure needs to be designed by accurately estimating the natural period of the structure, but the natural period of the structure is not always constant during the service period. For example, a structure after undergoing a large earthquake has reduced stiffness and a longer natural period. Further, in the case of small vibration, the rigidity of the non-structural member is added, and conversely the natural period becomes shorter. Thus, it is difficult to accurately estimate the natural period of the structure in that state.

In addition, as a means for solving the former problem, there are two conventional methods.
A method of using individual dynamic vibration absorbers in parallel has been proposed (for example, "Optimal design method of two composite dynamic vibration absorbers and its effect", Backdoor et al., The Japan Society of Mechanical Engineers, Sho 59-1 etc. ).

The present invention solves the above-mentioned problem by constructing a double pendulum aquarium damper to widen the tuning range, and by introducing a damping mechanism between both pendulum aquarium dampers,
This is intended to improve the damping property as a dynamic vibration absorber.

[Means for solving the problem]

The double pendulum water tank damper of the present invention is a first pendulum type dynamic vibration absorber in which a first water tank in which a liquid is injected is used as a weight and is suspended and supported by a plurality of suspension members from a structure.
The first pendulum aquarium damper, which constitutes a double dynamic vibration absorber by combining a vibrating system and a second vibrating system as a sloshing damper composed of a first water tank and a liquid injected into the first water tank, as well as the internal The second vibration tank filled with the liquid was used as a weight, and the first vibration system as a pendulum type dynamic vibration absorber suspended and supported by a plurality of suspension members from the structure, and the second water tank and the inside thereof were injected. It has a second pendulum water tank damper that constitutes a double dynamic vibration absorber by combining with a second vibration system as a sloshing damper composed of a liquid, and the first pendulum water tank damper and the second pendulum water tank damper The weights of the first vibrating system are set to be substantially equal to each other, and the second water tank forming the second pendulum water tank damper, and at least the lower part forming the first pendulum water tank damper
Of the first pendulum water tank damper and the second pendulum water tank damper with respect to the natural frequency of the structure are slightly shifted in the vicinity of the natural frequency of the structure. It was set by.

As the weight of the pendulum of the first vibration system, it is possible to use only the water tank itself and the liquid in the water tank itself, but normally, an additional weight for adjusting the mass is attached to the water tank. That is, the mass of the weight of the first vibrating system in the present invention may be composed of the mass of the water tank and the liquid only, or may be composed of the mass of the water tank and the liquid and the mass of the additional weight when there is an additional weight.

In the first water tank that constitutes the first pendulum, the second water tank (including the additional weight) as a pendulum can swing inside, and the vibration of the liquid in the first water tank causes the structure and the first water tank to vibrate. It is designed to be tuned to the vibration of the pendulum.

When the additional weight is attached to the second water tank, part or all of the additional weight portion may be immersed in the liquid in the water tank.

Further, by providing ribs on the bottom and side surfaces of the water tank or the weight, the viscous resistance when the water tank or the weight swings in the liquid of the first water tank can be adjusted.

[Operation] 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 functions not only as a damper that damps the vibration of the first pendulum itself, but also as a damper that damps the first pendulum and the second pendulum.
However, for this purpose, the mass of the weight of the first pendulum m
_The condition is that the mass ratio of 1 to the mass m ₂ of the weight of the second pendulum is close to 1.

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

〔Example〕

1 to 3 schematically show an example of the double pendulum water tank damper of the present invention, which is composed of a first pendulum water tank damper 1 and a second pendulum water tank damper 1a.
In the liquid 21 of the water tank 20 that constitutes the pendulum water tank damper of
The lower side of the additional weight 11a incidental to the water tank 20a of the second pendulum water tank damper 1a is immersed, and when swinging the pendulum,
It receives the viscous resistance of the liquid 21 and damps the swing of both pendulums.

Looking at the first pendulum aquarium damper 1, the aquarium 20
Is a wire rope for the frame 4 at the top of the structure 3.
It is hung at 4 points by 12. An additional weight 11 is attached to the bottom surface side of the water tank 20, and in this embodiment, the water tank 20 is directly suspended and supported by the wire rope 12, and the mass m ₁ (the mass of the water tank 20 and the liquid 21 in the water tank 20 is And additional weight
11 plus mass), suspension length l ₁ , natural frequency ω ₁
The first pendulum type vibration system is constructed. In addition, weight 11
For example, a steel material or the like is used.

The water tank 20 has a predetermined amount of liquid 21 such as water whose frequency is synchronized.
Are injected, and the sloshing action of the liquid 21 as the second vibration system imparts damping properties to the first vibration system and the structure 3.

In the second pendulum water tank damper 1a, the additional weight 11a is the water tank 20a.
It also serves as a support stand for the additional weight 11a and the wire rope 1
Suspended and supported by 2a, mass m ₂ , suspension length l ₂ , natural frequency ω ₂
The first oscillating oscillating system and the second oscillating system by sloshing are constructed.

Further, a plurality of ribs 5 are provided on the bottom surface and the side surface of the additional weight 11a to adjust the viscous resistance when the additional weight 11a swings in the liquid 20 of the first pendulum water tank damper 1.

These pendulum aquarium dampers 1 and 1a are
Since it is configured as a double dynamic vibration absorber having a first vibration system and a second vibration system respectively, the amount of water is about 1/30 when compared with the conventional sloshing damper to obtain the same wind sway suppressing effect. , Volume is about 1/7. When applied to an actual building, for example, in a building of about 1000t, the pendulum weight (total of water tank, water and additional weight) is 10 to 20t, and the amount of water is about 200 to 500l, a large vibration reduction effect can be obtained.

Regarding the stability when the optimum tuning is broken, the natural frequencies of the pendulum type first vibration system of the two pendulum water tank dampers 1 and 1a are ω ₁ and ω ₂ , and the natural frequency of the structure 3 (first order Appears in the case of a single pendulum water tank damper by setting the magnitude relationship such that ω ₁ <Ω <ω ₂ and the difference between ω ₁ and ω ₂ is not too large The two peaks in the response magnification are equalized, the maximum response magnification is reduced, and even when the optimum tuning is broken, the influence is small, and the stability as a dynamic vibration absorber can be improved.

To give specific numerical values, in the magnitude relation of ω ₁ <Ω <ω ₂ , it is desirable to adjust Ω−ω ₁ and ω ₂ −Ω with respect to Ω within a range of about 1/10 or less. The masses m ₁ and m ₂ of the respective weights of the first vibration system are preferably about 1/100 to 1/400 of the mass M of the structure which is the main vibration system in consideration of the vibration damping effect. for 200 sets the first about 4% from the natural frequency Ω of natural frequency omega ₁ of the structure of the pendulum aquarium damper 1 small, natural frequency of the second pendulum aquarium damper 1a omega ₂
Is set to be about 4% larger than the natural frequency Ω of the structure.

As a method for installing the double pendulum tank damper of the present invention on a structure, a method of installing a wire rope on a ceiling beam of a tower of a building or a method of installing a wire rope on a ceiling beam of a top floor of a building It is possible to install it.

[Effects of the Invention] First vibration system and second vibration of two pendulum water tank dampers
By properly setting the mass and natural frequency of the vibration system, the vibration suppression effect is greater than that of a single pendulum tank damper with the same combined mass ratio of the two, and stability when optimal tuning is disrupted. Is excellent. This is particularly remarkable when the added mass ratio to the structure is small.

Since it uses a suspension system with low friction and a liquid that easily shakes, it reacts sensitively to small wind shakes and earthquake motions, effectively suppresses shakes, attenuates early and removes discomfort due to shakes be able to.

The liquid in the water tank of the first pendulum water tank damper not only attenuates the vibration of the first pendulum itself, but also functions as an attenuator that attenuates the vibration between the first pendulum and the second pendulum. The performance can be improved.

By combining a pendulum type dynamic vibration absorber and a sloshing damper as a double dynamic vibration absorber, a large amount of vibration damping effect can be obtained by putting a small amount of liquid in a small-capacity aquarium compared to a conventional sloshing damper. it can.

Since the device is compact and easy to install,
Can be installed in a small space.

Wind sway of high-rise houses, high-rise buildings, high-rise towers, etc. can be effectively suppressed.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a model of the outline of the connection type double pendulum water tank damper of the present invention, FIG. 2 is its I-I sectional view, FIG. 3 is II-II sectional view, and FIG. It is a model figure for analysis of the 1st vibration system in the double pendulum water tank damper of the present invention. 1 ... Pendulum water tank damper, 3 ... Structure, 4 ... Outer frame, 5 ... Rib, 11 ... Additional weight, 12 ... Wire rope, 20 ... Water tank, 21 ... Liquid

Claims (3)

[Claims] 1. A first oscillating system as a pendulum type dynamic vibration absorber in which a first water tank in which a liquid is injected is used as a weight and is suspended and supported by a plurality of suspension members from a structure, and the first vibration system. A first pendulum water tank damper that constitutes a double dynamic vibration absorber by combining a water tank and a second vibrating system as a sloshing damper that is composed of a liquid injected into the inside of the tank and a second water tank into which the liquid is injected As a weight, a first vibrating system as a pendulum type dynamic vibration absorber suspended and supported by a plurality of suspending members from a structure, and a second sloshing damper as a slender damper composed of the second water tank and a liquid injected into the second water tank. A second pendulum water tank damper that forms a double dynamic vibration absorber by combining two vibration systems, and a mass of a weight of the first vibration system of the first pendulum water tank damper and the second pendulum water tank. First vibration of damper The weights of the second water tanks are set substantially equal to each other, and the second water tank is suspended and supported so that at least a lower part thereof is immersed in the liquid in the first water tank, and the first pendulum water tank damper and the second pendulum water tank. A double pendulum water tank damper, wherein the tuning frequency of the damper with respect to the natural frequency of the structure is set to be slightly shifted in the vicinity of the natural frequency of the structure. 2. The natural frequency ω ₁ of the first vibration system of the first pendulum water tank damper and the natural frequency ω ₂ of the first vibration system of the second pendulum water tank damper are defined as The double pendulum water tank damper according to claim ₁ , wherein ω ₁ <Ω <ω ₂ is set for the following natural frequency Ω. 3. The double pendulum water tank damper according to claim 1, wherein a rib for adjusting viscous resistance due to the liquid in the first water tank is provided on a bottom surface or a side surface of the second water tank.