JPH1171711A - Wind-resisting and vibration-proofing device for bridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce vibration of a bridge caused by wind, by providing bridge girders, protection walls hung at both sides of the bridge girders, and wind- shielding walls hung at the upper part thereof and arranging diagonally upward and downward plates respectively from the horizontal direction, in the upper part of the wind-shielding walls and in the lower part of the protection walls. SOLUTION: Protection walls 2 are installed at both sides of bridge girders and diagonally upward plates 4 from the horizontal direction are arranged respectively at the outside of respective upper ends of the wind-shielding wall 3 arranged at the upper part of respective protection walls 2. In this case, the plates 4 are fitted to the whole length of the wind-shielding wall 3 in the axial direction of the bridge. Or diagonally downward plates from the horizontal direction are arranged at the whole length of the wind-shielding wall 3 in the axial direction of the bridge, at the outside of respective lower ends of both protection walls 2 Accordingly, generation of a Karman vortex having a predominant period is prevented and the vibration amplitude can be reduced in a scope of wind speed. Thereby, the upward plates or the downward plates reduces the curvature of the Karman vortex and prevents engulfing phenomena and further, the deflection vibration of the bridge 1 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bridge, and more particularly to a structure for stabilizing wind resistance.

[0002]

2. Description of the Related Art Generally, a bridge is provided with a bridge girder 1 as shown in FIG. 5, and vertical protection walls 2 for securing the safety of passing vehicles are provided on both left and right sides of the bridge girder 1, respectively. A vertical wind shield wall (or wind shield wall) 3 for blocking wind is attached to the upper part of each protection wall 2.

[0003]

By the way, in a bridge to which the wind shield wall 3 is attached, the vibration amplitude of the bridge girder in a certain wind speed region is larger than that of a bridge having no wind shield wall.
As a result, there is a problem that the wind resistance deteriorates. That is, when no plate is attached to the wind shield wall, that is, in the conventional bridge shown in FIG. 5, Karman vortices are generated on the leeward side of the wind shield walls, and the vortex exciting force caused by the Karman vortices acts on the bridge. Vibration occurs on the bridge. The present invention seeks to solve the above-mentioned problems in a bridge in which wind shield walls are provided on both left and right sides of a bridge girder.

[0004]

According to the present invention, there is provided a bridge girder, a protective wall vertically installed on each of the left and right sides of the bridge girder,
In a bridge provided with a wind shield wall vertically attached to the upper part of each protective wall, a plate obliquely upward from horizontal is attached to the upper outside of each of the wind shield walls as a means for solving the problem.

Further, in a bridge having a bridge girder, a protection wall vertically installed on each of the left and right sides of the bridge girder, and a wind shield wall vertically mounted on the upper part of each protection girder, At the lower part of the protection wall, plates that are obliquely downward from the horizontal are attached as means for solving the problem.

Further, in a bridge having a bridge girder, a protection wall vertically installed on each of the left and right sides of the bridge girder, and a wind shield wall vertically mounted on the upper part of each of the protection girder, Outside the central part in the height direction of the wind shield wall, a plate that is obliquely upward from the horizontal is attached as a means for solving the problem.

In the present invention, the plate acts to suppress the separation of the flow and reduce the curvature of the Karman vortex, so that the entrainment due to the Karman vortex is suppressed, and as a result, the flexural vibration of the bridge can be prevented. become.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front sectional view of a bridge wind / vibration isolator according to a first embodiment of the present invention, and FIG. Front sectional view of a bridge wind proof vibration isolator as a second embodiment,
FIG. 3 is a front cross-sectional view of a bridge wind and vibration isolator as a third embodiment of the present invention, and FIG. 4 is a front cross-sectional view of a bridge wind and vibration isolator as a fourth embodiment of the present invention. The same reference numerals in FIGS. 1 to 4 as those in FIG. 5 indicate substantially the same members.

The first embodiment will be described with reference to FIG. In this embodiment as well, protective walls 2 are installed on both left and right sides of the bridge girder 1, and each of the wind shield walls 3 attached to the upper part of each protective wall 2 is outwardly and obliquely upward from the upper end. Are mounted respectively.
The plate 4 is made of a flat plate made of metal, resin, or the like, and is attached along the bridge axis direction over the entire length of the wind shield wall 3.

In the second embodiment shown in FIG. 2, outside the lower ends of the protective walls 2 on the left and right sides, plates 5 that are obliquely downward from the horizontal are attached. Plate 5
Is made of a flat plate made of metal, resin, or the like, and is provided over the entire length of the wind shield wall 3 in the bridge axis direction.

In the third embodiment shown in FIG. 3, plates 4 that are obliquely upward from the horizontal are mounted outside the upper ends of the wind shield walls 3 on both the left and right sides, respectively. Outside the lower end, plates 5 that are obliquely downward from horizontal are attached.

In the fourth embodiment shown in FIG. 4, a plate 4 that is obliquely upward from the horizontal is attached to the outside of the center in the height direction of the left and right wind shield walls 3, and the wind shield wall 3 and the protective wall 2 are attached. A plate 5 that is obliquely downward from the horizontal is attached to the outside of the connection portion with.

In FIG. 1 to FIG. 4, reference numeral θ ₁ denotes an obliquely upward angle of the plate 4 in each of the first to fourth embodiments, and reference numeral θ ₂ denotes an obliquely downward angle of the plate 5. The dimension L ₁ indicates the width of the plate 4 and the dimension L ₂ indicates the width of the plate 5.

The angles θ ₁ and θ ₂ and the dimensions L ₁ and L ₂
Are determined by wind tunnel experiments, etc., but as an example, θ
₁ = 0 ° to 25 °, θ ₂ = 0 ° to 45 °, and L ₁ = L ₂ = [height of wind shield wall 3] × are appropriate.

In the case of the conventional bridge shown in FIG. 5, a Karman vortex having an excellent period is generated in the downstream area (leeward area) of the bridge girder cross section, and the Karman vortex generates vibration in a certain wind speed region. As in the first to third embodiments, the wind shield wall 3
By providing an obliquely upward plate 4 or an obliquely downward plate 5 over the entire length of the wind shield wall 3 at the upper end portion of the protection wall 2 or at the lower end portion of the protection wall 2 or both, the Karman vortex having an excellent period is formed. Generation is suppressed, and the vibration amplitude in a certain wind speed range can be reduced.

The same applies to the case where the plates 4 and 5 are attached to the center of the wind shield wall 3 in the height direction (fourth embodiment). In the fourth embodiment, either the plate 4 or the plate 5 is used. It is confirmed by a wind tunnel test that the same is true even when one of them is removed.

[Table 1]

Table 1 shows the results of a wind tunnel test of the vortex excitation amplitude (single amplitude) for each angle of attack α.
o.1 is that of the third embodiment, θ ₁ = 10 °, θ ₂
No. 2 is the case of θ ₂ = 45 ° in the second embodiment, No. 3 is the case of θ ₁ = 10 ° in the first embodiment, No. 4 Is the case of θ ₁ = 10 ° and θ ₂ = 45 ° in the fourth embodiment,
No. 5 shows that in the fourth embodiment, θ ₁ = 20 °, θ
It is a test result in the case of ₂ = 45 degrees.

The angle of attack α is an angle between the horizontal direction of the wind (arrows shown in FIGS. 1 to 5) acting on the cross section of the main girder, and is also called an airflow inclination angle. The angle in the upward direction from the horizontal is +, and the angle in the downward direction is-. In this wind tunnel test, the test is performed in the range of α = ± 7 °.

FIG. 6 is a graph showing wind tunnel test data of the angle of attack α and the amplitude change of the limited vibration, wherein a line a represents the case of the conventional bridge shown in FIG. 5, and a line b represents the third embodiment. Is shown. In this test, θ ₁ = 10 ° and θ ₂ = 4
Performed at 5 °.

[Table 1] and FIG. 6 show that the angle of attack α is + 3 °.
Within the range of -7 °, the generation of vortex excitation is suppressed, and +
At 5 ° <α + 7 °, although a vibration of 0.07 to 0.1 m is generated, the vibration is suppressed to 以下 or less as compared with the conventional one, indicating that a vibration damping effect can be obtained.

[0021] Note that although the theta ₁ can assumed that almost the same effect can be obtained even slightly greater than the maximum angle 20 ° in wind tunnel testing, the theta ₂ is at approximately the maximum angle 45 ° or less in the range in wind tunnel tests It can be assumed that a similar effect can be obtained.

Further, with respect to L ₁ and L ₂ , taking into consideration reinforcement of the wind shield wall and wind resistance, [height of wind shield wall 3] × 1/1.
3 is considered an appropriate value. The above wind tunnel tests were also performed on L ₁ and L ₂
Was performed at this dimension.

FIG. 7 is a visualized photograph of a wind tunnel test. FIG. 7A is a photograph showing the state of the flow of wind when the third embodiment of the present invention is tested at an angle of attack of 7 °. ) Is a photograph similar to the conventional one shown in FIG. In the case of FIG.
Periodic vortices are observed on the leeward side of the bridge model.
In the case of (a), the curvature of the vortex is small on the leeward side of the bridge model, and there is no occurrence of periodic vortex entrainment.

[0024]

As described in detail above, according to the bridge wind-vibration isolating device of the present invention, the bridge girder, the protection walls provided on both the left and right sides of the bridge girder, and the upper part of each of the protection girder. For bridges equipped with attached wind shields, an upward plate may be attached to the upper outside of each wind shield or the center outside in the height direction, or a downward plate may be attached to the lower outside of the protective wall. Therefore, the curvature of the Karman vortex generated on the leeward side can be reduced, whereby the bending vibration of the bridge can be prevented.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a bridge wind and vibration isolator as a first embodiment of the present invention.

FIG. 2 is a front sectional view of a bridge anti-vibration device according to a second embodiment of the present invention.

FIG. 3 is a front sectional view of a bridge wind and vibration proof device according to a third embodiment of the present invention.

FIG. 4 is a front cross-sectional view of a bridge wind / vibration isolator as a fourth embodiment of the present invention.

FIG. 5 is a front sectional view showing a conventional bridge.

FIG. 6 is a graph showing the results of a wind tunnel test of a wind-vibration isolator for a bridge according to the present invention.

FIG. 7A is a visualized photograph of a third embodiment of the present invention in a wind tunnel test. (b) Similar photograph of the conventional one.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bridge 2 Protective wall 3 Wind shield wall 4 Plate that is diagonally upward from the horizontal 5 Plate that is diagonally downward from the horizontal

Claims (3)

[Claims] 1. A bridge comprising a bridge girder, protection walls vertically installed on both left and right sides of the bridge girder, and a wind shield wall vertically mounted on an upper part of each protection girder. An anti-vibration device for bridges, characterized in that a plate that is obliquely upward from the horizontal is attached to the upper outside of the wind shield wall. 2. A bridge comprising a bridge girder, protection walls vertically installed on left and right sides of the bridge girder, and a wind shield wall vertically mounted on an upper part of each protection girder. An anti-vibration device for a bridge, characterized in that a plate obliquely downward from the horizontal is attached to a lower outer side of the protection wall. 3. A bridge comprising a bridge girder, protection walls vertically installed on both left and right sides of the bridge girder, and a wind shield wall vertically mounted on an upper part of each protection girder. On the outside of the height direction center part of the wind shield wall, a plate that is obliquely upward from horizontal is attached,
Wind-proof anti-vibration device for bridges.