JP2760197B2 - Anti-vibration device with movable additional water for bridges - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping device using movable additional water for bridges, and more particularly, to a device for suppressing flutter vibration of a bridge girder by moving movable additional water and changing the position of the center of gravity of the bridge girder. It is about.

[0002]

2. Description of the Related Art Long span bridges such as suspension bridges, cable-stayed bridges, and large span continuous beams are more flexible than small and medium-sized bridges. The so-called flutter vibration occurs in which the bridge vibrates vertically or in a torsion direction due to the vortex generated in the bridge.

[0003] Such aerodynamic vibration is considered to be caused by unsteady aerodynamic force generated when an air flow separated from the leading edge corner portion of the spar from the windward side of the spar becomes a vortex and flows down the spar surface. FIG. 4 is an explanatory view showing the mechanism of the flutter vibration generation. In the figure, 41 is a bridge, 42 is a main girder, 43 is a deck, 44 is a railing, 45 is a side girder, 46
Is an arrow indicating the direction of the wind, 47 is a boundary layer, 48 is a vortex, 49
Is a line indicating the strength of the negative pressure. When such a bridge 41 receives wind from the horizontal direction 46, a strong boundary layer 47 is generated due to the influence of the column 44 and the side girder 45, and the boundary layer 47 and the deck 43.
A vortex 48 is formed between the upper surface and the lower surface of the main girder 42, and the vortex 48
Generates a negative pressure 49.

[0004] Then, the negative pressure due to the vortex of the air serves as an exciting force, which generates flutter vibration that vibrates the bridge girder vertically and in a torsional direction, thereby causing a risk of breakage of the bridge or, in the worst case, falling down of the bridge. For this reason, conventionally, as means for suppressing such aerodynamic vibration such as flutter vibration, FIG.
As shown in (a) to (i), straightening plates such as flaps 52, deflectors 53, and spoilers 54 are provided at both ends of the bridge 51 to prevent separation of air flow, or to make the cross section of the bridge girder closer to streamline. The fairing 55 on both ends of the bridge girder
Is provided.

[0005]

However, the effect of suppressing the aerodynamic vibration by such a conventional method is not always sufficient, and the flaps and fairings are made large and installed over the entire length of the bridge girder. Although the vibration suppression effect can be increased to some extent due to the above, the size and installation amount of the flaps and fairings are limited from the viewpoint of maintaining the appearance of the bridge and preventing danger.

The present invention makes use of the fact that the flutter vibration is suppressed by shifting the position of the center of gravity of the bridge girder to the windward side from the center of rotation, irrespective of the above-mentioned conventional method of changing the aerodynamic properties of the bridge. An object of the present invention is to provide a vibration isolator using movable additional water for bridges, which can effectively suppress and prevent the occurrence of flutter vibration of a bridge girder.

[0007]

According to a first aspect of the present invention, there is provided a vibration damping device using movable additional water for a bridge according to the present invention, wherein a liquid weight for changing the position of the center of gravity of a bridge girder is provided.
A storage tank provided at both edges of the bridge girder for storing the liquid weight, an injection means for injecting the liquid weight into the storage tank, and the liquid weight stored from the storage tank And a discharging means for discharging water.

According to a second aspect of the present invention, there is provided a vibration damping device using movable additional water for a bridge, wherein the liquid weight for changing the position of the center of gravity of the bridge girder and the liquid weight provided on both edges of the bridge girder are provided. A storage tank for storing the weight, a communication pipe communicating the storage tanks with each other, and a pump for moving the liquid weight between the storage tanks through the communication pipe.

Further, according to a third aspect of the present invention, there is provided a vibration isolator using movable additional water for a bridge according to the first aspect of the present invention, wherein the communication pipe connects the storage tanks with each other. And a pump for moving the liquid weight between the storage tanks through the communication pipe and pouring and discharging the liquid weight to and from the storage tank.

[0010]

In the vibration damping device using movable additional water for a bridge according to the present invention, an arbitrary amount of liquid weight is stored in storage tanks provided at both ends of the bridge girder by the injection means and the discharge means. Therefore, by changing the storage amounts in the storage tanks at both ends of the bridge girder, the position of the center of gravity of the bridge girder can be moved in the width direction of the bridge girder.

Therefore, when the bridge receives a strong wind from the side or the oblique direction, the position of the center of gravity of the bridge girder is adjusted by injecting a liquid weight into the storage tank on the windward side, that is, the center of rotation in the flutter vibration. Move it further upwind,
Thereby, flutter vibration can be suppressed.

In the vibration isolator using movable additional water for a bridge according to the second aspect of the present invention, the bridge is provided at both edges of the bridge girder when the bridge receives a strong wind from the side or obliquely. The liquid weight stored in the storage tank was moved from the leeward storage tank to the leeward storage tank through the communication pipe by the pump to move the center of gravity of the bridge girder to the leeward similarly to the above-described apparatus, Suppress flutter vibration.

[0013]

An embodiment of the present invention will be described with reference to the drawings. FIG.
FIG. 1 shows a schematic configuration of a first embodiment of the present invention, which is a cross-sectional view of the bridge girder viewed from the axial direction. As shown in the figure, in the vibration isolator using the movable additional water for a bridge according to the present embodiment, storage tanks 3 and 3a are provided on both edges of the bridge girder 1 and the storage tanks 3 and 3a are provided.
3a stores water as a liquid weight for changing the position of the center of gravity of the bridge girder 1. Further, the storage tanks 3 and 3a are provided with a water supply pipe 4 and a drain pipe 5 for supplying and discharging the water.

When the bridge girder 1 receives a strong wind 10 from the side or obliquely, water is poured into the storage tank 3 on the windward side to shift the center of gravity of the bridge girder 1 from the center of rotation 11 at the center of the bridge girder.
The flutter vibration of the bridge girder 1 is suppressed by moving the bridge girder 2. Further, if the need for vibration suppression is eliminated, the water in the storage tank 3 may be discharged from the drain pipe 5.

As described above, in the present embodiment, the storage tanks 3 and 3a are installed at the ends of the strength members 2 of the bridge girder, but the storage tanks 3 and 3a are installed in the fairings 9 and 9 provided on both edges of the bridge girder. 3, 3a may be arranged respectively, or may be installed at an end of the lower surface of the bridge girder.

The fairing 9 prevents separation of the air flow on the surface of the bridge girder and smoothes the air flow, so that the vibration damping effect of the bridge girder can be further improved. Further, the storage tanks 3 and 3a may be provided over the entire length of the bridge girder, or may be provided at a certain interval and provided in a part of the bridge girder.

FIG. 2 shows another embodiment of the present invention. FIG. 3 is a cross-sectional view of the vibration isolator according to the embodiment as viewed in the axial direction of the bridge girder, similarly to FIG. As shown in the drawing, the vibration isolator according to the present embodiment includes storage tanks 22 and 22a installed at both ends of a bridge girder 1, a water supply pipe 24 and a drain pipe 25 for supplying and draining water to and from the storage tanks. A pump 8 that communicates between the tanks 22 and 22a and can supply water in both forward and reverse directions along the way.
Are provided, and valves B1 to B9 are provided in each of the pipes.

In this apparatus, the pipes 24, 25, 2
6. With the valves B1 to B9 and the pump 8, it is possible to supply and drain water to and from the desired storage tanks 22 and 22a at both ends of the bridge girder and to move the stored water between the two storage tanks.

That is, when water is injected into the storage tank 22 on the left side of the figure, the water supply pipe 24 is opened with the valves B1, B4, B7 opened and the other valves B2, B3, B5, B6, B8, B9 closed. Perform water injection from. Conversely, when water is injected into the storage tank 22a on the right side of the figure, the valves B1 and B2 are opened, the other valves B3 to B9 are closed, and water is injected from the water supply pipe 24. When water is moved between the storage tanks 22 and 22a, the valves B3, B5, B6, and B7 are opened, and the other valves B1, B2, B4, B8, and B9 are closed to drive the pump 8. Send water in the desired direction.

On the other hand, only the valves B8 and B9 are opened to discharge the water stored in the storage tank 22 on the left side of the figure, and the valve B is discharged to discharge the water stored in the storage tank 22a on the right side of the figure.
When only 3, B4 and B9 are opened, the water stored in the storage tanks is discharged from the drain pipe 25 respectively. The storage tanks 22, 2
Above 2a, there are provided air release pipes 7, 7 for releasing air from the storage tank.

With the above operation, in the vibration isolator according to the present embodiment, as in the first embodiment, water is stored in the storage tank on the windward side against the wind from the side of the bridge girder, so that the bridge girder is maintained. Move the center of gravity to the windward side to prevent flutter vibration.

Next, the effect of suppressing flutter vibration by the vibration isolator according to the present invention will be described. The inventor of the present application has found that the following equation for flutter vibration of an aircraft wing in a two-dimensional flow can be applied to a bridge. That relates to flutter vibration unit span of the wing of an aircraft in a two-dimensional flow, the relationship between flutter expression wind U _F and the position of the center of gravity, the following equation has been proposed.

[0023]

(Equation 1)

Here, a is the rotation angle of the wing, and ωh is _h of the wing.
(Displacement) - frequency in the case where to perform the vibration only, omega _a wing of a (rotation angle) - a frequency in a case where to perform the vibration only, m is the mass of the wing unit span, It is expressed by the following equation.

[0025]

(Equation 2)

Further, [rho is the air density, b is the distance to the blade tip from the spanwise center, gamma _a is a symbol for dimensionless moment of inertia I _a of about x = bc point of the blade unit span , The moment of inertia _Ia is expressed by the following equation.

[0027]

(Equation 3)

[0028] x _a is a symbol for dimensionless static moment S _a of about x = bc point of the blade unit span, the static moment S _a is expressed by the following equation.

[0029]

(Equation 4)

Then, the above equation (1) indicates that ω _h ² / ω _a ² ≒
0 and is applied to a two-dimensional wing with a density ratio μ ≧ 10. In a bridge, the ω _h / ω _a is about 0.3, that is, ω _h ² / ω _a ² ≒ 0. 0.09.

The density ratio: μ = m / (πρb ² )
In the case of an aircraft, which represents the effect of altitude, in a bridge, the mass m per 1 m length of the bridge girder is m = 2.0
４4.0 tf · s ² / m (weight W = 20 to 40 tf). If the width 2b of the bridge girder is 30 m, b = 15.
m, and the air density ρ = 0.132 kgf · s ² / m, the density ratio μ is μ = {(2.0 to 4.0) × 10 ³ }.
/{Π×0.132×15 ² } = 21.4 to 42.8, which satisfies μ ≧ 10. Therefore, it is considered that Equation 1 can be applied to a bridge.

As shown in FIG. 4 (b), if the fluttering wind speed is U _{F 1} when the rotation center is considered to be the center of the bridge girder, c = 0 in this case. become.

[0033]

(Equation 5)

On the other hand, if the fluttering wind speed when the center of gravity is centered on the bridge girder is U _{F 2} , in this case, c = 0 and x _a =
Since it is 0, Equation 1 becomes as follows.

[0035]

(Equation 6)

Taking the ratio of these equations, the rate of increase of the fluttering wind speed U _{F 1} / U _{F 2} is as follows.

[0037]

(Equation 7)

Now, as an example, in the case of a bridge having a width of 30 m and a weight per unit length of the bridge girder of m = 20 tf / m, and moving the position of the center of gravity of the bridge to the windward side, the rise rate U _{F 1} of the flutter manifestation wind speed is increased. Table 1 is obtained by calculating / U _{F 2} .

[0039]

[Table 1]

As described above, by using the flutter vibration suppressing device according to the present invention, the wind speed at which the flutter vibration of the bridge girder occurs can be increased, and the flutter vibration in the bridge can be effectively suppressed.

[0041]

As described above, according to the present invention, by moving the center of gravity of the bridge girder to the windward side from the center of rotation, flutter vibration of the bridge girder can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a bridge girder showing the configuration of an embodiment of the present invention, viewed from the axial direction.

FIG. 2 is a cross-sectional view of a bridge girder showing the configuration of another embodiment of the present invention, as viewed from the axial direction.

3A and 3B are explanatory diagrams for analyzing flutter vibration, wherein FIG. 3A relates to flutter vibration of a unit wing width in a two-dimensional flow, and FIG. 3B relates to flutter vibration of a bridge.

FIG. 4 is an explanatory diagram showing a mechanism of flutter vibration generation.

FIG. 5 is an explanatory view showing means conventionally used for suppressing aerodynamic vibration such as flutter vibration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bridge girder 2 Strength member 3, 3a, 22, 22a Reservoir 4, 24 Water supply pipe 5, 25 Drain pipe 26 Communication pipe 7 Air release pipe 8 Pump 9, 55 Fairing 10, 46 Wind 11 Rotation center 12 Center of gravity position of bridge girder B1 to B9 Valve 41, 51 Bridge 42 Main girder 43 Deck 44 Railroad column 45 Side girder 47 Boundary layer 48 Vortex 49 Negative pressure strength line 52 Flap 53 Deflector 54 Spoiler In the drawings, the same reference numerals are the same or corresponding parts. Is shown.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G05D 19/00-19/02 E01D 1/00 E04H 9/02 341 E04H 9/14 F16F 15/02-15 / 03

Claims (3)

(57) [Claims] 1. A liquid weight for changing the position of the center of gravity of a bridge girder, a storage tank provided at both edges of the bridge girder for storing the liquid weight, and injecting the liquid weight into the storage tank. And a discharge means for discharging the liquid weight stored in the storage tank. 2. A liquid weight for changing the position of the center of gravity of the bridge girder, a storage tank provided on both edges of the bridge girder for storing the liquid weight, and a communication pipe for communicating the storage tanks with each other; And a pump for moving the liquid weight between the storage tanks through the communicating pipes. 3. A communication pipe that communicates the storage tanks with each other, and a pump that moves the liquid weight between the storage tanks through the communication pipe and injects and discharges the liquid weight into and from the storage tank. Item 2. A vibration isolator using movable additional water for a bridge according to item 1.