JP4332976B2 - Cable-stayed bridge cable damping device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vibration control device for a cable stayed bridge cable used to suppress wind vibration generated in the cable of a cable stayed bridge.
[0002]
[Prior art]
The cable-stayed bridge is a structure that elastically supports the main structure of the continuous girder with a cable that is slanted from the main tower. Like the suspension bridge, the cable is used for the main members. Sufficient confirmation is required.
[0003]
That is, it is well known that the cable stayed bridge cable is likely to generate vibration due to wind because of its small attenuation. In particular, it is well known that the parallel cable tends to generate vibration with a large amplitude called wake galloping.
[0004]
[Problems to be solved by the invention]
Here, various vibration suppression measures have been researched and developed to suppress the vibration of cable-stayed bridge cables, including wake galloping, and typical examples include dampers using viscous materials and high-damping rubber. However, such a damper has the disadvantage that the damping force decreases sharply as the amplitude becomes larger, the longer the cable length and the longer the cable length, as well as the temperature dependence. There was a limit to its application as a cable damping device.
[0005]
On the other hand, recently, studies have been made to change the vibration mode using a permanent magnet and to suppress the vibration of the cable-stayed bridge cable using the damping force generated at that time.
[0006]
However, with such a method, while the amplitude is small, no vibration damping action can be expected, and there is room for studying durability and reliability of operation under harsh environments due to the use of permanent magnets.
[0007]
The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a cable-stayed bridge cable damping device capable of obtaining a sufficient damping action regardless of the magnitude of the amplitude.
[0008]
[Means for Solving the Problems]
To achieve the above object, the present onset Ming as described in claim 1, and stayed bridge cable extension limiting mechanism total length is constructed variably setting maximum length a limit to force the deformation of the extending direction swash become be interposed between the digits are tensile supported by stayed bridge cable-stayed bridge the setting maximum length, the growth of the self-excited vibration of the cable-stayed bridge cable is set to be inhibited In the cable damping device, the extension limiting mechanism is sequentially connected such that the plurality of connecting elements are rotatable at their ends, and the plurality of connecting elements are arranged in a straight line. The length is constituted by an expansion / contraction mechanism having the set maximum length .
[0010]
In the cable-stayed bridge cable damping device according to the present invention, a friction surface is provided at each connection portion of the connection elements adjacent to each other among the connection elements, and the friction surface is slidable in the rotation direction. Are brought into contact with each other.
[0011]
In the cable-stayed bridge cable damping device according to the present invention, an extension limiting mechanism is interposed between the cable-stayed bridge cable and the girder supported by the cable-stayed bridge cable.
[0012]
Here, the extension limiting mechanism is configured so that the total length is variable up to the set maximum length with respect to forced deformation in the extension direction. For such a set maximum length, the self-excited vibration growth of the cable stayed bridge cable Is set to be suppressed.
[0013]
In the vibration of a structure, etc., unless the forced external force is applied, the amplitude generally decreases with time due to the damping force, but when the structure vibrates due to the flow of fluid in contact with it, In addition to fluid force, self-excited force governed by vibration response is added, and self-excited vibration due to negative fluid damping force is generated. That is, a circulation phenomenon occurs such that the self-excited force accompanying the vibration further increases the vibration, and manifests in the form of galloping in bending vibration and torsional flutter in torsional vibration.
[0014]
When the cable stayed bridge cable receives a hydrodynamic force due to wind, the cable stayed at the cable stayed at both ends is fixed and the amplitude is increased by self-excited vibration. When an extension limit mechanism is interposed between the cable stayed bridge cable and the girder and the vibration of the cable stayed bridge cable reaches an amplitude corresponding to the set maximum length of the extension limit mechanism, the extension limit mechanism The full length is fixed, and the cable stayed bridge cable shifts to a vibration mode in a state where the fixing point of the end portion is shifted to the attachment position of the extension restriction mechanism. With the transition of the vibration mode, higher-order mode vibration is generated in the cable-stayed bridge cable, and the vibration energy of the cable-stayed bridge cable is consumed in the form of damping of the higher-order vibration mode. The vibration of the Zhangqiao cable converges quickly without growing as self-excited vibration. Note that if the amplitude of the cable stayed bridge cable falls below the amplitude corresponding to the maximum length set by the extension restriction mechanism as a result of the decrease in the amplitude, the cable stayed bridge cable is not restrained by the extension restriction mechanism and the fixed point at the end. Shifts to the original position again, and the above-described operation is repeated.
[0015]
Stretching limiting mechanism, and made of an elastic mechanism connecting elements multiple, which are sequentially connected so as to be rotatable at their ends, the set maximum length, the tie-angle of each connecting element each other 180 time, i.e. shall be the length of the state in which the respective coupling element arranged in a straight line.
[0016]
Here, when the cable stayed bridge cable vibrates within the limit of the set maximum length of the expansion / contraction mechanism, the expansion / contraction mechanism follows the vibration of the cable as its connecting elements rotate relative to each other. Among such connecting elements, if friction surfaces are provided at respective connecting portions of adjacent connecting elements and the friction surfaces are brought into contact with each other so as to be slidable in the rotation direction, Since frictional damping occurs with the dynamic operation, vibration energy can be attenuated in the form of frictional damping even for vibrations of a cable-stayed bridge cable with a small amplitude at which the extension limiting mechanism does not operate.
[0017]
It goes without saying that the cable-stayed bridge cable referred to in the present invention is not limited to the parallel cable.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a vibration control device for a cable-stayed bridge cable according to the present invention will be described with reference to the accompanying drawings. Note that components that are substantially the same as those of the prior art are assigned the same reference numerals, and descriptions thereof are omitted.
[0019]
FIG. 1 is an overall view showing a cable-stayed bridge cable damping device according to the present embodiment. As can be seen from the figure, the cable-damping device 1 for the cable-stayed bridge cable according to the present embodiment includes a cable-stayed bridge cable 3 and a girder that is tension-supported by the cable-stayed bridge cable. 7 is interposed.
[0020]
Here, the expansion / contraction mechanism 2 is configured by sequentially connecting a plurality of connecting elements 4a and 4b so that the connecting elements 4a and 4b are rotatable at their end portions, and at the lower end thereof to the attachment portion 5 of the beam 7 and at the upper end thereof. Each of the connecting elements 4a and 4b is hinged to the attachment portion 6 of the cable-stayed bridge cable 3, and in this configuration, the connecting elements 4a and 4b rotate with respect to each other so that the total length is variable. The joint angle is 180 degrees, that is, the length when the connecting elements 4 are aligned is the set maximum length, and the forced deformation in the extension direction exceeding the set maximum length is restricted.
[0021]
The set maximum length is set so that the growth of self-excited vibration of the cable-stayed bridge cable 3 is suppressed.
[0022]
FIG. 2 shows in detail the connecting portions of the connecting elements 4a and 4b. As can be seen in the figure, a hollow cylindrical portion 12 having a friction surface formed on the inner peripheral surface 11 is fixed to the end portion of the connecting element 4b, and a bracket portion 13 provided at the end portion of the connecting element 4a. , 13, a cylindrical portion 15 having a friction surface formed on the outer peripheral surface 14 is fixed, and the friction surface of the cylindrical portion and the friction surface of the hollow cylindrical portion 12 are in the rotational direction (see FIG. 2A). The cylindrical portion 15 is fitted into the hollow cylindrical portion 12 so as to be slidable in the direction of the arrow) and brought into contact with each other.
[0023]
A predetermined friction material may be attached to the friction surface of the hollow cylindrical portion 12 or the friction surface of the cylindrical portion 15, and irregularities are formed on the inner peripheral surface of the hollow cylindrical portion 12 or the outer peripheral surface of the cylindrical portion 15. May be configured.
[0024]
In the cable-stayed bridge cable damping device 1 according to the present embodiment, when the cable-stayed bridge cable 3 receives a fluid force due to wind, the cable-stayed bridge cable generates vibration with both ends fixed. At the same time, the amplitude tends to increase due to self-excited vibration. In the present embodiment, the expansion / contraction mechanism is an expansion limiting mechanism between the cable-stayed bridge cable 3 and the girder 7 that is tension-supported by the cable-stayed bridge cable. 2 is interposed.
[0025]
Therefore, while the cable stayed bridge cable 3 has a small amplitude, the telescopic mechanism 2 expands and contracts so as to follow the movement of the cable stayed bridge cable 3, but the vibration of the cable stayed bridge cable 3 is as shown in FIG. When the amplitude corresponding to the set maximum length L of the expansion / contraction mechanism 2 is reached, the total length of the expansion / contraction mechanism 2 is fixed to L, and the vibration mode of the cable-stayed bridge cable 3 is the maximum length L set by the expansion / contraction mechanism 2 yet. The vibration mode (FIG. 3 (c)) in which the fixed point at one end is shifted to the attachment position of the telescopic mechanism 2 from the vibration mode (FIG. 3 (b)) when both ends are not reached. )).
[0026]
With the transition of the vibration mode, higher-order mode vibration occurs in the cable-stayed bridge cable 3, and the vibration energy of the cable-stayed bridge cable 3 is consumed in the form of attenuation of the higher-order vibration mode, thus The vibration of the cable stayed bridge cable 3 converges immediately without growing as self-excited vibration.
[0027]
If the amplitude of the cable-stayed bridge cable 3 falls below the amplitude corresponding to the set maximum length L of the extension / contraction mechanism 2 as a result of the decrease in the amplitude, the cable-stayed bridge cable 3 is not restrained by the extension / contraction mechanism 2 and ends. The fixed point is shifted again to the original position as shown in FIG. 3B, and the above-described operation is repeated thereafter.
[0028]
On the other hand, when the cable stayed bridge cable 3 vibrates within the limit of the set maximum length L of the expansion / contraction mechanism 2, the expansion / contraction mechanism 2 follows the vibration of the cable as its connecting elements 4a and 4b rotate relative to each other. However, the friction surface formed on the outer peripheral surface of the cylindrical portion 15 and the friction surface formed on the inner peripheral surface of the hollow cylindrical portion 12 slide with each other as the connecting elements 4a and 4b rotate. Frictional damping occurs.
[0029]
Therefore, the vibration energy is attenuated in the form of frictional damping even for the vibration of the cable-stayed bridge cable 3 with a small amplitude at which the telescopic mechanism 2 does not operate.
[0030]
As explained above, according to the vibration control device 1 for a cable stayed bridge cable according to the present embodiment, the expansion / contraction mechanism 2 that is an extension restriction mechanism is interposed between the cable stayed bridge cable 3 and the girder 7, When the vibration of the cable stayed bridge cable 3 reaches a predetermined amplitude, the vibration mode is changed, and the vibration energy of the cable stayed bridge cable 3 can be quickly consumed by the vibration of the higher order mode generated at that time. It becomes possible.
[0031]
Therefore, the cable stayed bridge cable 3 can be quickly converged without growing as self-excited vibration. And unlike the conventional damping device using a permanent magnet, reliable operability and durability can be expected over a long period of time even under harsh environments.
[0032]
Further, according to the cable-stayed bridge cable damping device 1 according to the present embodiment, when the cable-stayed bridge cable 3 vibrates within the limit of the set maximum length L of the telescopic mechanism 2, the rotation of the connecting elements 4a and 4b is performed. With the movement, the friction surface formed on the outer peripheral surface of the cylindrical portion 15 and the friction surface formed on the inner peripheral surface of the hollow cylindrical portion 12 slide with each other to generate friction damping.
[0033]
Therefore, it is possible to attenuate the vibration energy in the form of frictional damping even with respect to the vibration of the cable-stayed bridge cable 3 with a small amplitude at which the telescopic mechanism 2 does not operate.
[0034]
Thus, according to the cable-stayed bridge cable damping device 1 according to the present embodiment, the vibration mode changes in addition to the friction damping when the amplitude of the cable-stayed bridge cable 3 is small and by friction damping when the amplitude is large. Due to the accompanying attenuation, the vibration of the cable-stayed bridge cable 3 can be attenuated, so that it is possible to adapt to various types and sizes of vibration.
[0035]
In the present embodiment, the expansion / contraction mechanism 2 is configured by sequentially connecting the plurality of connecting elements 4a and 4b so as to be rotatable at their end portions, and at the lower end thereof, the attachment portion 5 of the girder 7 is connected. At the upper end, the cable is connected to the mounting portion 6 of the cable-stayed bridge cable 3 by hinges. As a reference example, a pantograph-like structure is shown in FIG .
[0036]
That is, the expansion / contraction mechanism 21 shown in the figure is constructed by sequentially connecting a plurality of connecting elements 22a and 22b hinged at each center so that the connecting elements 22a and 22b are rotatable at their ends. The lower end is hinged to the mounting portion 5 of the girder 7 via the connecting element 23, and the upper end is hinged to the mounting portion 6 of the cable-stayed bridge cable 3 via the connecting element 23.
[0037]
Even in such a configuration, the function and effect are substantially the same as those of the telescopic mechanism 2, and the description thereof is omitted here.
[0038]
【The invention's effect】
As described above, according to the cable-stayed bridge cable damping device according to the present invention, the extension restriction mechanism is interposed between the cable-stayed bridge cable and the girder. When the amplitude is reached, the vibration mode is changed, and the vibration energy of the cable stayed bridge cable can be quickly consumed by the vibration of the higher order mode generated at that time. Therefore, the cable stayed bridge cable can be quickly converged without growing as self-excited vibration.
[0039]
[Brief description of the drawings]
FIG. 1 is an overall view of a vibration control device for a cable-stayed bridge cable according to the present embodiment.
FIG. 2 is a detailed view of a telescopic mechanism constituting the vibration damping device for a cable-stayed bridge cable according to the present embodiment, (a) is a detailed view of a connecting portion of the telescopic mechanism, and (b) is a line AA. FIG.
FIG. 3 is a diagram showing the operation of the cable-stayed bridge cable vibration damping device according to the present embodiment.
FIG. 4 is an overall view of a vibration control device for a cable-stayed bridge cable according to a reference example .
[Explanation of symbols]
1 Damping device for cable-stayed bridge cable 2 Expansion / contraction mechanism (extension restriction mechanism)
3 Cable-stayed bridge cables 4a, 4b Connecting elements 7 digits

Claims (2)

An extension limiting mechanism, which is configured to be variable in total length up to the maximum set length for forced deformation in the extension direction, is interposed between the cable stayed bridge cable and the girder supported by the cable stayed bridge cable. In the vibration control device for the cable stayed bridge cable, the set maximum length is set so that the growth of self-excited vibration of the cable stayed bridge cable is suppressed .
The extension limiting mechanism is sequentially connected such that a plurality of connecting elements are rotatable at their ends, and the length when the plurality of connecting elements are aligned is the set maximum length. A cable-damping device for a cable-stayed bridge cable, characterized by comprising an extension mechanism . Wherein one of the coupling elements, the friction surfaces provided with the respective connecting portions of the connecting element adjacent to each other, cable-stayed of claim 1, wherein the manner is in contact with each other for sliding the friction surface in the rotational direction Damping device for bridge cable.

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