JPH083288B2 - Articulated 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. On the other hand, in order to change the natural period of each pendulum tank damper, it is necessary to change the pendulum length,
Adjusting after installation is not always easy.

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

The present invention is intended to solve the above-mentioned problems in a pendulum water tank damper.

[Means for solving the problem]

The connection type pendulum water tank damper of the present invention comprises a plurality of pendulum water tank dampers arranged in parallel, and these pendulum water tank dampers are connected by springs.

Each pendulum water tank damper has a water tank in which a liquid is injected as a weight, and a first vibration system as a pendulum type dynamic vibration absorber that is suspended and supported by a plurality of suspension members from a structure, and this water tank and its inside. A double dynamic vibration absorber is configured by combining the injected liquid and a second vibration system as a sloshing damper, and the weights of the first vibration systems of the plurality of pendulum water tank dampers are set to be substantially equal. In addition, the tuning frequencies of the plurality of pendulum water tank dampers with respect to the natural frequency of the structure are slightly shifted in the vicinity of the natural frequency of the structure.

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.

[Action]

When the weights of two pendulums are connected by a spring, as shown in FIGS. 3 (a) and 3 (b), the two pendulums both vibrate in the same direction (primary vibration type) and the opposite direction. Occurs (secondary vibration type).

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

From the above equation of motion, different pendulum slightly mass equal frequency, natural frequency when connected by the spring of spring constant k _D is first-order natural frequency, ₁ omega and secondary natural frequency ₂ ω is Becomes

Therefore, the secondary natural frequency is the value of the spring constant k _D of the spring,
It can be freely adjusted by moving it closer to or closer to the primary natural frequency ₁ ω.

Therefore, in order to damp the vibration of the structure that occurs during strong winds or earthquakes, by adjusting the secondary natural frequency ₂ ω, the spring-coupled pendulum water tank damper is tuned to the natural frequency Ω of the structure. When the natural frequency (or the natural period) of is changed over time, the tuning period can be adjusted by changing the spring constant k _D.

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 the heat energy associated with the friction and crushing of the liquid in the water tank, whereby the vibration is attenuated.

〔Example〕

FIG. 1 and FIG. 2 show the outline of the connection type pendulum damper of the present invention, in which two pendulum water tank dampers 1, 1a arranged in parallel are connected by a coil spring 2 having a spring constant k _D.

In the figure, the water tank 20 of the pendulum water tank damper 1 on the left side is suspended at four points by a wire rope 12 from the frame 4 at the top of the structure 3. The water tank 20 is provided with an additional weight 11 that also serves as a support for mass adjustment,
In this embodiment, the additional weight 11 on which the water tank 20 is placed is suspended and supported by the wire rope 12, and the mass m ₁ (the mass of the water tank 20 and the liquid 21 plus the mass of the additional weight 1) and the suspension length l ₁ ,
It constitutes a pendulum-type first vibration system having a natural frequency ω ₁ . A steel material or the like is used as the additional weight 11.

The water tank 20 has a predetermined amount of liquid 21 such as water whose vibration cycle 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. The frequency is adjusted according to the size of the water tank 20 and the water depth.

The pendulum aquarium damper 1a on the right side is the same, and the mass m ₂ ,
A pendulum type first vibrating system having a suspension length l ₂ and a natural frequency ω ₂ and a second vibrating system by sloshing are configured.

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, the amount of water is about 1/30 when trying to obtain the same wind sway suppressing effect as compared with a conventional sloshing damper. The volume is about 1/7. When applied to an actual building, for example, in a building of about 1000t, the weight of the pendulum (total of the aquarium, water and additional weight) is 10 to 20t, and the amount of water is 200 to 200t.
A large vibration reduction effect can be obtained at about 500 liters.

Then, by connecting the two pendulum water tank dampers 1 and 1a with the spring 2, the primary natural frequency ₁ ω and the secondary natural frequency ₂ ω expressed by the above equations (1) and (2) are A connected pendulum aquarium damper is constructed. As described above, the secondary natural frequency ₂ ω can be adjusted by changing the spring constant of the spring 2. For example, ₁ ω <Ω for the natural frequency Ω of the structure.
By setting the magnitude relationship to be < ₂ ω and adjusting within the range where the difference between ₁ ω and ₂ ω is not so large, the two peaks in the response magnification appearing in the case of a single pendulum tank damper are equalized, and the maximum response is obtained. The 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.

Regarding the stability when the optimum tuning is broken down, concrete values are as follows: Ω in the magnitude relation of ₁ ω <Ω < ₂ ω.
It is desirable to adjust _-1 ω and ₂ ω-Ω to within 1/10 of Ω. Mass of each weight of the first vibration system m ₁ , m
Considering the damping effect, ₂ is preferably about 1/100 to 1/400 of the mass M of the structure that is the main vibration system, for example, 1/200.
In the case of 1, the primary natural frequency ₁ ω is set to be about 4% smaller than the natural frequency Ω of the structure, and the secondary natural frequency ₂ ω is set to be about 4% larger than the natural frequency Ω of the structure.

Further, the above is the case where two pendulum water tank dampers 1 and 1a are connected by the spring 2, but it is also possible to connect three or more pendulum water tank dampers by springs.

In addition, as a method of installing the connection type pendulum tank damper of the present invention to the structure, a method of installing a wire rope to the ceiling beam of the tower of the building or a wire rope to the ceiling beam of the top floor of the building It is possible to install it.

[Advantages of the Invention] By appropriately setting the masses and natural frequencies of the first vibration system and the second vibration system of the pendulum water tank dampers arranged in parallel and connected by springs, the additional mass of the two is added. Compared to a single pendulum tank damper with the same ratio, it has a greater effect of suppressing vibration, and also has excellent stability when optimal tuning is broken. This is particularly remarkable when the added mass ratio to the structure is small.

Even if the natural frequency of the structure changes over time, by changing the spring constant of the connecting spring, such as by replacing the spring, it is possible to easily cope with the pendulum water tank damper body without adjusting it.

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.

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 view showing a model of the outline of the connection type pendulum water tank damper of the present invention, FIG. 2 is a plan view showing the connection of the pendulum water tank damper by a spring, FIG. 3 (a),
(B) is an explanatory view showing the first and second vibration modes of the connected pendulum, and FIG. 4 is a model diagram for analyzing the first vibration system in the connected pendulum water tank damper of the present invention. 1 ... Pendulum water tank damper, 2 ... Spring, 3 ... Structure, 4 ... Outer frame, 11 ... Weight, 12 ... Wire rope, 20 ... Water tank, 21 ... Liquid

Claims (2)

[Claims] 1. A weight of a water tank filled with a liquid,
A combination of a first vibrating system as a pendulum type dynamic vibration absorber suspended and supported by a plurality of suspending materials from a structure and a second vibrating system as a sloshing damper consisting of the water tank and a liquid injected therein. The multiple pendulum water tank dampers that make up the double dynamic vibration absorber are connected by springs,
The weights of the first vibration systems of the plurality of pendulum water tank dampers are set to be substantially equal to each other, and the respective tuning frequencies of the plurality of pendulum water tank dampers with respect to the natural frequency of the structure are set to the natural vibrations of the structure. Coupling type pendulum aquarium damper characterized in that it is set slightly displaced in the vicinity of the number. 2. The connection type pendulum water tank damper according to claim 1, wherein an additional weight for mass adjustment is attached to the water tank.