JPH01239205A - Vibration-proof structure in long span construction - Google Patents

Abstract

PURPOSE:To restrain uncomfortable oscillations generated in the vertical direction by the running of vehicles and walking of pedestrians by providing a vertical oscillation damper on a long span construction such as a bridge or a pedestrians' bridge or the like. CONSTITUTION:A pedestrians' bridge 1 of long span construction is composed of bridge legs 3, 3 installed on the ground 2 vertically, on which legs 3, 3 a bridge beam 5 is provided in the form of a span L1, on which beam 5 a way 5a for pedestrians. Under the central part of the beam 5, a vertical oscillation dumper 6 is arranged. When pedestrians pass along the way 5a, the whole beam 5 oscillates in the directions shown by arrows A, B. In this case, the movement is zero (0) on the legs 3, 3, but becomes the maximum at a vertical oscillation dumper 6 part of the central part of the beam 5. Since the phase of oscillation of the dumper 6 shifts with that of oscillation of the beam 5, however, the oscillation energy of the beam 5 and that of the dumper 6 cancels each other, so the oscillation of the beam 5 in the vertical direction can be effectively attenuated.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a vibration damping structure that imparts vibration damping properties to long span structures such as bridges and pedestrian bridges.

(b), Conventional technology Normally, vertical vibrations occur in such long-span structures due to running vehicles, people walking, jumping, etc., but conventionally no measures have been taken to prevent such vibrations. There wasn't.

(C) 6 Problems to be Solved by the Invention However, this method has the drawback of causing unpleasant vibrations in long span structures such as bridges and pedestrian bridges.

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned drawbacks, the present invention aims to provide a vertical vibration damping structure for long-span structures that can effectively suppress vertical vibrations that occur in long-span structures. It is.

(d) Means for solving the zero problem, that is, the present invention has a supporting means (3), and the supporting means (
3) In a long-span structure (1) having a supported body (5) supported in a long-span state above, vertical vibration dampers (6, 1
1, 31, 41, 51).

Note that the numbers in parentheses are for convenience and indicate corresponding elements in the drawings, and therefore, this description should not be limited to the descriptions in the drawings. The following r (el
The same applies to the column ``, action''.

(e) 0 effect With the above-described configuration, the vertical vibration generated in the supported body (5) can be suppressed by the vertical vibration damper (6, 11, 31).
, 41, 51).

(f), Example Embodiments of the present invention will be described below based on the drawings.

Fig. 1 is a diagram showing an example of a pedestrian bridge to which an embodiment of the distribution structure according to the present invention is applied, Fig. 2 is a diagram showing an example of a vertical vibration damper, and Fig. 3 is a diagram showing another example of the vertical vibration damper. 4 is a diagram showing still another example of a vertical vibration damper, FIG. 5 is a diagram showing still another example of a vertical vibration damper, FIG. 6 is a diagram showing still another example of a vertical vibration damper, FIG. 7 is a diagram showing still another example of the vertical vibration damper.

The pedestrian bridge 1, which is a long-span structure, has piers 3.3 erected on the ground 2, as shown in FIG.
A bridge girder 5 is supported on the piers 3.3 in a circular shape with a span of Ll. The bridge girder 5 is provided with a walkway 5a in the left-right direction in the drawing, and furthermore, a vertical vibration damper 6 is provided on the lower surface of the center of the bridge girder 5. As shown in FIG. 2, the vertical vibration damper 6 has a box-shaped main body 12, and the main body 12 is filled with a liquid 15 such as water.

Further, in the center of the main body 12, a weight passing passage 13 is formed in the vertical direction in a loop shape and separated by meshes 26.
A weight 27 is provided in the weight passage f@13 so as to be elastically supported on the upper and lower surfaces of the main body 12 by springs 19 and 20. On both sides of the weight passage 13 in the figure, there are bypass passages 21.2.
1 is provided to connect the upper and lower spaces of the weight passing path 13, and each bypass path 21 is provided with meshes 22 in multiple stages in the stacking direction so as to block the bypass $21.

Since the pedestrian bridge 1 has the above configuration, the pedestrian bridge 1
When a person walks on the sidewalk 5a of
It vibrates in the B direction, that is, in the vertical direction in FIG. This vibration is
It is zero at the 5.5 part of the bridge girder, and is maximum at the vertical vibration damper 6 part at the center of the bridge girder 5.5. Then, the vertical vibration damper 6 also vibrates in the directions of arrows A and B, and as a result, the weight 27 suspended inside via springs 19 and 20 also vibrates in the directions of arrows A and B within the weight passage path 13. Start. &
! 27 vibrates and moves, for example, in the direction of arrow B, the weight 2
7 The liquid 15 in the weight passage 13 below moves &! 2
7, it flows from the menonyu 26 into the bypass paths 21 and 21 on both sides of the weight passage 13, and further flows into the bypass paths 21 and 21.
The liquid flows upward through the inside and flows into the weight passageway 13 above the weight 27. At this time, a mesh 22 is provided in the bypass passage 21 to prevent the flow of the liquid 15, so that the liquid 15 acts to prevent the weight 27 from moving in the B direction. This is true even when the weight 27 moves in the direction of arrow A, that is, upward, and the weight 27 receives a force from the liquid 15 in a direction that prevents it from moving in the A direction. Therefore, the liquid 15 prevents the weight 27 from vibrating in synchronization with the vertical vibration of the bridge girder 5, and the phase of the vibration is out of phase with the vibration of the bridge girder 5, resulting in the vibration of the bridge girder 5. The vibration energy of the weight 27 and the weight 27 cancel each other out, and the vertical vibration of the bridge girder 5 is effectively damped.

Note that various types of vertical vibration dampers other than those shown in FIG. 2 are conceivable. Another example of the vertical vibration damper will be described below.

For example, the vertical vibration damper 3], as shown in FIG.
The main body 32 has a box-like shape, and an opening 32a is provided in the center of the main body 32. Opening 32a
Partition plates 32b132b are provided on both sides of the
A plurality of meshes 33 are provided between the partition plates 32b, 32b and the outer peripheral surface 32c of the main body. Main body 32
A liquid 34 such as water is stored inside, and the main body 32
35.35.
is separated by a liquid surface 34b and the main body 32 on both sides of the opening 32a (therefore, the liquid surface of the liquid 34 is divided into a liquid surface 34a on the opening 32a side and a liquid surface 34b on the decompression chamber 35 side). ).

Therefore, when the bridge girder 5 vibrates in the vertical direction, that is, in the directions of arrows A and B, the vertical vibration damper 31 also vibrates in the direction of arrows AXB. The liquid 34 of the vertical vibration damper 31 flows through the opening 32a.
Since the liquid surface 34a facing the is open to the atmosphere, a liquid level difference H1 occurs between the liquid surfaces 34a and 34b due to the pressure difference with the pressure reduction chamber 35 side. Therefore, due to the mass difference between the decompression chamber 35 and the liquid 34 on the opening 32a side caused by the liquid level difference H1, the liquid 34 is caused by the vibration of the bridge girder 5, and the internal liquid 34 is lowered to the liquid level 3.
It vibrates in a flowing manner between 4a and 34b in the directions of arrows C and D. However, when the liquid 34 tries to flow in the direction of the arrow C1D, the mesh 33 acts in a direction to prevent the flow, and the vibration of the bridge girder 5 is suppressed and damped by the resistance force.

Note that in the above embodiment, the liquid 34 stored in the main body 32 is
One liquid surface 34a is opened to atmospheric pressure, and the other liquid surface 34a is opened to atmospheric pressure.
In the above case, the main body 32 has the liquid level 34a of the liquid 34,
Of course, any configuration may be used as long as a predetermined liquid level difference H1 is generated between 34 and 34b. Therefore, for example,
As shown in FIG. 4, pressurized chambers 37.37 whose pressure is higher than atmospheric pressure are provided on both sides of the opening 32a, and between the pressurized chambers 37.37 and the opening 32a. , liquid level difference H
Of course, it is also possible to configure it so that 1 is generated.

Furthermore, as shown in FIG.
It is also possible to provide a pressurized chamber 37, 37 (with a higher pressure than 9), thereby forming the liquid level difference H1.

Furthermore, the vertical vibration damper 41 shown in FIG. 6 has a main body 42 formed in a box shape, and a gas 45 such as air is introduced into the lower part of the main body 42 via a flexible sheet 42a. A sealed first gas chamber 42b is provided. A liquid 43 such as water is stored above the first gas chamber 42b, and a second gas chamber 42c filled with a gas 45 such as air is provided above the liquid 43. A mesh 44 is provided in multiple stages in the horizontal direction in the portion of the main body 42 where the liquid 43 is stored.

Since the vertical vibration damper 41 has the above configuration, when the bridge girder 5 vibrates in the vertical direction, that is, in the directions of arrows A and B, the main body 42 of the vertical vibration damper 41 also vibrates in the directions of arrows A and B. The liquid 43 of the vertical vibration damper 41 is
Since the main body 42a is located above the first gas chamber 42b at the bottom thereof, it tends to vibrate in the directions of arrows A and B in synchronization with the vibration of the main body 42 due to the elasticity of the gas 45 in the first gas chamber 42b.

However, when the liquid 44 tries to flow in the directions of the arrows A and B, the mesh 44 acts in a direction that blocks the flow, so the vibration of the bridge girder 5 is suppressed and damped by the resistance force.

Furthermore, the vertical vibration damper is not limited to one in which liquid is stored inside, and various other types can be considered. That is, as shown in FIG. 7, it has a weight 59 suspended via a plurality of springs 57 adjusted to have the same frequency as the natural vibration period of the bridge girder 5, and the weight 59 and the bridge girder A plurality of dampers 60 are provided between the dampers 5 and 5.

In this vertical vibration damper 51, when the bridge girder 5 vibrates in the vertical direction in FIG.
Figure 7: Vibration starts synchronously in the vertical direction. This weight 5
When the bridge 9 swings, the vibration of the beam is reduced by the mass damper effect, and the vibration generated in the bridge girder 5 is effectively absorbed.

Note that the mass of the weight 59 should be about 0.5 to 2% of the bridge girder 5 to exhibit a sufficient vibration damping effect.

Furthermore, although the above-described embodiment has been described in the case where the long-span structure is the pedestrian bridge 1, the present invention can be applied to any structure that is supported in a long-span state by support means such as the piers 3.3. Of course, such a structure may also be used.

(g) 0 Effects of the Invention As explained above, according to the present invention, the supported body such as the bridge girder 5, which has support means such as the bridge girder 3, and is supported in a long span state on the support means. In a long span structure such as a pedestrian bridge 1, a vertical vibration damper 6.11.31.41.51 is provided at the location where the maximum amplitude occurs in the vertical direction of the supported body. It is possible to effectively absorb the vibrations generated in long span structures such as the above, and it is possible to prevent unpleasant vibrations from occurring.

[Brief explanation of the drawing]

Fig. 1 shows an example of a pedestrian bridge to which an embodiment of the damping structure according to the present invention is applied, Fig. 2 shows an example of a vertical vibration damper, and Fig. 3 shows another example of a vertical vibration damper. FIG. 4 is a diagram showing yet another example of a vertical vibration damper; FIG. 5 is a diagram showing yet another example of a vertical vibration damper; FIG. 6 is a diagram showing yet another example of a vertical vibration damper. , FIG. 7 is a diagram showing yet another example of the vertical vibration damper. 1...Pedestrian bridge 3...Supporting means (pier) 5...Supported body (bridge girder) 6.1 construction, 31.41.51...Vertical vibration gunpa applicant Mitsui Construction Co., Ltd. Company agent Patent attorney Phase 1) Shinji 23"20 31 Susuri Ryo t Kakuso\. Figure 4 (\ ゝ・ 2c Figure 5 Engineer 3 (33"2C33)

Claims (2)

[Claims] (1) In a long-span structure having a supporting means and a supported body supported in a long-span state on the supporting means, a vertical vibration damper is installed at a portion of the supported body where the maximum amplitude occurs in the vertical direction. A vibration damping structure for long span structures. (2) A vibration damping structure for a long span structure according to claim 1, wherein the long span structure is a pedestrian bridge.