JPH05189059A - Anti-vibration device with movable additional water for bridge - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a vibration isolation device using movable additional water for a bridge capable of suppressing and preventing the occurrence of flutter vibration of a bridge girder. [Structure] A liquid weight for changing the position of the center of gravity of the bridge girder, a storage tank provided at both edges of the bridge girder for storing the liquid weight, and an injection for injecting the liquid weight into the storage tank. An anti-vibration device for movable additional water for bridge, comprising: means and means for discharging the liquid weight stored in the storage tank. Further, it is disclosed that a communication pipe that connects the storage tanks to each other and a pump that moves the liquid weight between the storage tanks and injects and discharges the liquid weight to and from the storage tanks are disclosed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration isolator using movable additional water for a bridge, and more specifically, a device for suppressing flutter vibration of a bridge girder by moving the movable additional water to change 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 tend to bend more easily than medium- and small-sized bridges. The so-called flutter vibration occurs in which the bridge vibrates up and down or in the twisting direction due to the vortices generated in the bridge.

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

Then, the negative pressure due to the vortex of the air acts as an exciting force to generate flutter vibration that vibrates the bridge girder vertically and in a twisting direction, which causes damage to the bridge and, in the worst case, collapse of the bridge. Therefore, conventionally, as a means for suppressing such aerodynamic vibration such as flutter vibration, FIG.
As shown in (a) to (i), rectifying plates such as flaps 52, deflectors 53, and spoilers 54 are provided at both ends of the bridge 51 to prevent air flow separation, or to make the cross section of the bridge girder close to a streamline. Fairings 55 on both ends of the bridge girder
Is provided.

[0005]

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

The present invention utilizes the fact that flutter vibration is suppressed by shifting the position of the center of gravity of the bridge girder from the center of rotation to the windward side, not by the conventional method for changing the aerodynamic properties of the bridge as described above. Accordingly, the present invention provides a vibration isolator using movable additional water for a bridge, which can effectively suppress and prevent the occurrence of flutter vibration of a bridge girder.

[0007]

In order to achieve the above object, a vibration isolator using movable additional water for a bridge according to the invention of claim 1 has 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, an injection means for injecting the liquid weight into the storage tank, and the liquid weight stored from the storage tank And discharging means for discharging.

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 changes the position of the center of gravity of the bridge girder, and the liquid weight is provided at both edges of the bridge girder. A storage tank for storing the weight, 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 communication pipe are provided.

Further, the vibration isolator by the movable additional water for bridge according to the invention described in claim 3 is the vibration isolator by the movable additional water for bridge according to claim 1, which is 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 communication pipe and pouring and discharging the liquid weight to and from the storage tank.

[0010]

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

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

Further, in the vibration isolator using movable additional water for a bridge according to the invention described in claim 2, when the bridge receives a strong wind from the side or the diagonal, it is provided at both edges of the bridge girder. The liquid weight stored in the storage tank is moved from the storage tank on the leeward side to the storage tank on the windward side through the communication pipe by the pump, and the center of gravity of the bridge girder is moved to the windward side in the same manner as in the above device. Suppress flutter vibration.

[0013]

Embodiments of the present invention will be described with reference to the drawings. Figure 1
The schematic configuration of the first embodiment of the present invention is shown in FIG. 1, which is a sectional view as seen from the axial direction of the bridge girder. As shown in the figure, in the vibration isolator using movable additional water for bridge according to the present embodiment, storage tanks 3 and 3a are provided at both edges of the bridge girder 1,
Water is stored in 3a as a liquid weight that changes the position of the center of gravity of the bridge girder, and a water supply pipe 4 and a drain pipe 5 for supplying and discharging the water are provided in the storage tanks 3 and 3a.

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

As described above, in this embodiment, the storage tanks 3 and 3a are installed at the ends of the strength members 2 of the bridge girder. However, the storage tanks are provided in the fairings 9 and 9 provided at both edges of the bridge girder. 3, 3a may be respectively arranged, or may be installed at the lower end 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, and thus 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 installed at regular intervals and installed in a part of the bridge girder.

Further, FIG. 2 shows another embodiment of the present invention. This figure is a cross-sectional view of the vibration isolator according to this embodiment as seen from the axial direction of the bridge girder, as in FIG. As shown in the figure, the vibration damping device according to the present embodiment is provided with storage tanks 22 and 22a installed at both ends of the bridge girder, a water supply pipe 24 and a drainage pipe 25 for supplying and draining the storage tank, and both storages. A pump 8 that communicates between the tanks 22 and 22a and can supply water in both the forward and reverse directions on the way.
Is provided with a communication pipe 26, and valves B1 to B9 are further provided in each of the pipes.

In this device, the pipes 24, 25, 2
6, the valves B1 to B9 and the pump 8 can supply and drain desired storage tanks 22 and 22a at both ends of the bridge girder, and move the stored water between the storage tanks.

That is, when water is poured into the storage tank 22 on the left side of the drawing, 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. Water is injected from. On the contrary, when water is injected into the storage tank 22a on the right side of the drawing, the valves B1 and B2 are opened, the other valves B3 to 9 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. Water is sent in the desired direction.

On the other hand, in order to discharge the stored water in the storage tank 22 on the left side of the drawing, only the valves B8 and B9 are opened, and to discharge the stored water in the storage tank 22a on the right side of the drawing, the valve B is discharged.
If only 3, B4 and B9 are opened, the stored water in the storage tank is discharged from the drain pipe 25. In addition, the storage tanks 22, 2
At the upper part of 2a, air vent pipes 7, 7 for venting the air in the storage tank are provided.

By the above operation, also in the vibration isolator according to this embodiment, as in the first embodiment, the bridge girders are stored by storing water in the windward side storage tank against the wind from the side of the girders. Prevents flutter vibration by moving the center of gravity to the windward side.

Next, the effect of suppressing the flutter vibration by the vibration isolator according to the present invention will be described. The inventor has found that the following equation for flutter vibrations of an aircraft wing in a two-dimensional flow is also applicable to bridges. That is, regarding the flutter vibration of the unit wing width of the aircraft wing in the two-dimensional flow, the following formula has been proposed for the relationship between the flutter-producing wind speed U _F and the position of the center of gravity.

[0023]

[Equation 1]

Where a is the rotation angle of the blade, and ω _h is the _h of the blade.
(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, ρ is the air density, b is the distance from the center of the blade width to the blade tip, and γ _a is a symbol for making the inertia moment I _a around the point x = bc of the blade of unit blade width dimensionless. , Moment of inertia I _a is expressed by the following equation.

[0027]

[Equation 3]

X _a is a symbol for making the static moment S _a around the point x = bc of the blade of unit blade width dimensionless, and the static moment S _a is expressed by the following equation.

[0029]

[Equation 4]

Then, the above expression 1 is ω _h ² / ω _a ² ≈
Although it is applied to a two-dimensional blade having a density ratio of 0 and a density ratio of μ ≧ 10, in a bridge, ω _h / ω _a is about 0.3, that is, ω _h ² / ω _a ² ≈0. It is 0.09.

Further, the density ratio: μ = m / (πρb ² ) is
This shows the effect of altitude on aircraft, but on bridges, the mass m per meter of bridge girder is m = 2.0.
It is about 4.0 tf · s ² / m (weight W = 20 to 40 tf), and 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 bridges.

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

[0033]

[Equation 5]

On the other hand, assuming that the flutter-occurring wind speed when the center of gravity is at the bridge girder center is U _{F 2} , in this case, c = 0 and x _a =
Since it becomes 0, the equation 1 becomes as follows.

[0035]

[Equation 6]

Taking the ratios of these equations, the rate of increase in fluttering wind velocity 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 bridge girder m = 20 tf / m, and the center of gravity of the bridge is moved to the windward, the increase rate of flutter-inducing wind velocity U _{F 1} Calculation of / U _{F 2} results in Table 1.

[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 is generated can be increased, and the flutter vibration of the bridge can be effectively suppressed.

[0041]

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

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of the structure of another embodiment of the present invention as seen from the axial direction of the bridge girder.

FIG. 3 is an explanatory diagram for analyzing flutter vibration, where (a) relates to flutter vibration of a unit blade width in a two-dimensional flow, and (b) 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 diagram showing means conventionally used for suppressing aerodynamic vibration such as flutter vibration.

[Explanation of symbols]

 1 bridge girder 2 strength member 3, 3a, 22, 22a storage tank 4, 24 water supply pipe 5, 25 drainage pipe 26 communication pipe 7 air vent pipe 8 pump 9, 55 fairing 10, 46 wind 11 rotation center 12 center of gravity position of bridge girder B1 to B9 Valves 41, 51 Bridge 42 Main girder 43 Deck 44 Railing 45 Side vertical girder 47 Boundary layer 48 Vortex 49 Line indicating negative pressure strength 52 Flap 53 Deflector 54 Spoiler Incidentally, the same reference numerals in the drawings are the same or corresponding parts. Indicates.

Claims (3)

[Claims] 1. A liquid weight for changing the position of the center of gravity of the bridge girder, a storage tank provided at both edges of the bridge girder for storing the liquid weight, and the liquid weight is injected into the storage tank. A vibration isolation device using movable additional water for a bridge, comprising: an injection unit configured to discharge the liquid weight and a discharge unit configured to discharge 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 at both edges of the bridge girder for storing the liquid weight, and a communication pipe for communicating the storage tanks with each other. A vibration isolation device using movable additional water for bridge, comprising: a pump that moves the liquid weight between the storage tanks through a communication pipe. 3. A communication pipe that connects the storage tanks to each other, and a pump that moves the liquid weight between the storage tanks and injects and discharges the liquid weight to and from the storage tank through the communication pipe. The vibration damping device for movable bridge water according to Item 1.