JPS5856762B2 - Bridge vibration prevention method - Google Patents

Description

[Detailed description of the invention] This invention relates to a method for preventing vibration of a bridge.

Conventionally, as a method for preventing vibrations caused by Karman vortices in bridges having rectangular, trapezoidal, etc. cross sections, as shown in FIG.
As shown in FIG. 2, there is a method of attaching curved current restraining plates 4 along the upper and lower corners of the bridge 1.

However, the conventional bridge vibration isolation method using flow control plates has the following problems.

That is, ■ Depending on the cross-sectional shape of the bridge, the vibration-proofing effect of the flow control plates may be small.

■ The distance between the flow control plates and the bridge body (indicated by d in Figure 1) has a significant effect on the vibration isolation effect of the bridge, and it is recommended that they be installed at different intervals in the span direction or intermittently in the span direction. This makes the appearance undesirable.

■ Vertical ribs for reinforcement may be required on the flow control plate, but depending on the arrangement of the vertical ribs, the vibration isolation effect may be reduced.

This invention was made in order to solve the problems of the conventional bridge vibration prevention method, and includes: a method of preventing wind-induced vibrations of a bridge by providing a current restraining plate along the bridge; In this method, a restraining member is provided continuously or intermittently along the flow restraining plate, and thus,
The present invention is characterized in that the suppression member receives the wind flowing between the current suppression plate and the bridge from the side of the current suppression plate, thereby preventing vibration of the bridge due to the wind.

The present invention will be explained by way of examples with reference to the drawings.

FIG. 3 is a front view of an embodiment of the invention, and FIG. 4 is a perspective view of the same portion.

In this embodiment, a current restraining plate 5 having vertical ribs 6 along the lower part of both widthwise ends of the bridge 1 shown in FIG.
A restraining member 7 is installed along the upper end of the rear (inner side of the bridge) of the current restraining plate 5.
are installed vertically intermittently at equal intervals.

FIG. 5 shows the vibration-proofing effect of the bridge 1 by intermittently attaching the restraining members 7 to the current restraining plates 5 provided on the bridge 1 in this manner.

As is clear from Figure 5, when only the conventional current restriction plate is provided (indicated by the thin solid line in the figure), the deflection amplitude is much greater than when no current restriction plate is provided (indicated by the dotted line in the figure). It can be seen that the vibration damping effect is small, but when a restraining member is further provided on the current restraining plate as in the present invention (indicated by the thick solid line in the figure), the vibration damping effect becomes even more pronounced. I understand.

Here, H on the vertical axis in FIG. 5 is the girder height as shown in FIG.

In addition, when testing the above-mentioned anti-vibration effect, wind was sent from one direction of the bridge at different wind speeds, and the amount of deflection in the height direction of the bridge at this time was expressed as the deflection amplitude.

The above-mentioned restraining member I may also have a triangular cross-section as shown in FIGS. 6a and 6b.
It may also be triangular as shown in the figure.

Further, although the restraining member in the above embodiment is attached to the current restraining plate intermittently even when it falls down, it may be attached continuously.

In Figures 8 and 9, B in the diagram of bridge 1 shown in Figure 1 is shown.
A plate-like current restraining plate 8 is attached to the pillar 9 so as to be inclined upwardly toward the outside, and a plate-like restraining member 10 is intermittently installed vertically between the mounting bases of the current restraining plate 8 to the pillar 9. Another embodiment is shown.

The deterrent member 10 may be installed at an angle between the attachment bases of the deterrent member 10 to the pillars 9, as shown in FIG. 10, and the side shape of the deterrent member 10 is as shown in FIG. As shown, it may be triangular.

Furthermore, although the suppressing member 10 of the above embodiment is provided with intermittently falling down, it may be provided continuously.

In the above example as well, almost the same results as shown in FIG. 5 were obtained.

There are no particular restrictions on the dimensions in the height direction of the restraining member 7 or 10 in the embodiments described above, but the vibration-proofing effect will appear at a height that closes the gap between the restraining plate 5 or 8 and the bridge 1. I don't like it because there isn't.

According to this invention, a restraining member that provides resistance to the flow of wind flowing between the bridge and the restraining plate is attached continuously or intermittently along the restraining plate provided along the bridge body. This brings about the extremely useful effect that the vibration-proofing effect of the current restriction plate can be significantly improved compared to the case where only the conventional current restriction plate is attached to a bridge.

[Brief explanation of the drawing]

1 and 2 are schematic front views showing how a conventional current restriction plate is attached to a bridge, and FIGS. 3 and 4 are a front view and main parts of a current restriction plate according to an embodiment of the present invention. FIG. 5 is a perspective view showing the relationship between wind speed and deflection amplitude; FIGS. 6 a and b are front views of a modification of the restraining member shown in FIGS. 3 and 4; FIG. 8 and 9 are front views and perspective views of essential parts of another embodiment of the present invention, and FIGS. 10 and 11 are perspective views of the same modification. It is a front view and a principal part perspective view which show the modification of an Example. In the drawings, 1...Bridge, 2...Railway, 3...Current plate, 4...Current plate, 5
...Retardation plate, 6...Vertical rib, T...
... Suppressing member, 8... Suppressing plate, 9...
- Pillar, 10... restraining member.

Claims (1)

[Claims] 1. In a method for preventing wind-induced vibration of a bridge by providing a current restraining plate along the bridge, a restraining member is provided continuously or intermittently along the current restraining plate, and thus the current restraining plate is A method for preventing vibrations of a bridge, characterized in that wind-induced vibrations of the bridge are prevented by receiving the wind flowing between the current restraining plate and the bridge from the side with the suppressing member.