JPH083289B2 - Connectable double pendulum water tank 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 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 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 which constitutes a double dynamic vibration absorber by combining with a second vibrating system as a sloshing damper made of liquid.

First, the masses of the weights of the first vibration system of the first pendulum water tank damper and the second pendulum water tank damper are set to be substantially equal to each other to form the second pendulum water tank damper.
At least the lower part of the water tank is soaked in the liquid in the first water tank that constitutes the first pendulum water tank damper.

Further, the tuning frequency of the first pendulum water tank damper and the second pendulum water tank 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, and the first pendulum is also set. The tank damper and the second pendulum tank damper are connected by a spring.

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.

[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). In the connection type double pendulum water tank damper of the present invention, the viscous resistance of the liquid in the first water tank is added thereto. 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 frequencies (natural circular frequencies) when the masses of the two pendulums are almost equal and the periods are slightly different, are the 1st natural frequency, ₁ ω, and the 2nd natural frequency ₂ ω But each 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 structural vibrations that occur during strong winds or earthquakes, by adjusting the secondary natural frequency ₂ ω, the linked double pendulum water tank damper is tuned to the natural frequency Ω of the structure. When the natural frequency (or natural period) of an object changes over time, the first pendulum tank damper and the second
The tuning period can be adjusted by changing the spring constant k _D of the spring that connects the pendulum water tank damper.

Further, the liquid in the water tank of the first pendulum water tank damper is not limited to the attenuator for damping the vibration of the first pendulum itself,
It also functions as an attenuator that attenuates the first pendulum and the second pendulum.

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

〔Example〕

FIG. 1 and FIG. 2 schematically show an example of the connection type 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. The lower side of the additional weight 11a attached to the water tank 20a of the second pendulum water tank damper 1a is immersed in the liquid 21 of the water tank 20 constituting the first pendulum water tank damper, and the viscous resistance of the liquid 21 when the pendulum swings. In response to this, the swing of both pendulums is damped. In addition, the spring constant of the first pendulum water tank damper 1 and the second pendulum water tank damper 1a
They are connected by a coil spring 2 of k _D , and in this embodiment, the inner upper part of the water tank 20 of the first pendulum water tank damper 1 and the second
The upper part of the additional weight 11a of the pendulum water tank damper 1a is connected.

Looking at the first pendulum aquarium damper 1, the aquarium 20
Is suspended at four points by the wire rope 12 from the outer peripheral frame 4 at the top of the structure 3. The weight 20 for weight adjustment is attached to the bottom of the water tank 20. In this embodiment, the water tank 20 is directly attached to the wire rope.
Suspended and supported by 12 and constructs a pendulum type first vibration system with mass m ₁ (mass of water tank 20 and liquid 21 plus mass of additional weight 11), suspension length l ₁ , and natural frequency ω _1. are doing. A steel material or the like is used as the additional weight 11.

The water tank 20 has a predetermined amount of liquid such as water whose vibration cycle is synchronized.
21 is injected, and the sloshing action of the liquid 21 serving as the second vibrating system imparts damping properties to the first vibrating 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, by connecting the two pendulum water tank dampers 1 and 1a with the spring 2,
A coupled double pendulum water tank damper having a primary natural frequency of ₁ ω and a secondary natural frequency of ₂ ω expressed by the above equations (1) and (2) is configured. As described above, the secondary natural frequency ₂ ω can be adjusted by changing the spring constant of the spring 2. For example, the natural frequency Ω of the structure is ₁ ω <Ω < ₂ ω, and ₁ By adjusting within a range where the difference between ω and ₂ ω is not too large, the two peaks in the response magnification that appear in the case of a single pendulum tank damper are leveled, the maximum response magnification is reduced, and optimal tuning is disrupted. Even when it does, there is little influence, and the stability as a dynamic vibration absorber can be improved.

To give specific numerical values, in the magnitude relation of ₁ ω <Ω < ₂ ω, it is desirable to adjust Ω− ₁ ω and ₂ ω−Ω 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. In the case of 200, 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.

In addition, as a method of installing the connection type double pendulum aquarium damper of the present invention to a structure, a method of installing a wire rope on a ceiling beam of a building tower or a wire rope for a ceiling beam of a top floor of a building It is possible to think of a way 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.

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.

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 view showing a model of an outline of a connection type double pendulum water tank damper of the present invention, FIG. 2 is a sectional view taken along the line I-I, and FIGS. And FIG. 4 is a model diagram for analyzing the first vibration system in the coupled double pendulum water tank damper of the present invention. 1 ... Pendulum water tank damper, 2 ... Spring, 3 ... Structure, 4 ... Outer frame, 5 ... Rib, 11 ... 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 to be 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. The water tank damper is connected by a spring, and the tuning frequency of the first pendulum water tank damper and the second pendulum water tank damper with respect to the natural frequency of the structure is slightly increased in the vicinity of the natural frequency of the structure. Coupling type double pendulum aquarium damper characterized by being staggered. 2. The connection type double pendulum water tank damper according to claim 1, wherein an additional weight for mass adjustment is attached to the water tank. 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.