JP3123987B2 - Cable damping device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable damping device for damping the vibration of a cable stretched between a girder and a tower of a cable-stayed bridge.

[0002]

2. Description of the Related Art A cable stretched between a girder and a tower of a cable-stayed bridge vibrates due to wind and rain. When this frequency coincides with the natural frequency of the cable, a resonance phenomenon occurs, the vibration amplitude of the cable becomes extremely large, and the mechanical load on the fixed parts at both ends of the cable becomes large. Becomes

Under such a background, there is a cable-stayed bridge in which a vibration damping device for attenuating cable vibration is provided to prevent an excessive load from being applied to a connecting portion such as a cable end and a girder. For example, in the vibration damping device shown in FIG. 7, the lower end of the cable (1) whose upper end is connected to the tower (4) is connected and fixed to the beam (3) by the anchor member (31). The vicinity of the lower end of the cable (1) is surrounded by a fixing tube (2) fixed to the spar (3), and a fixing plate (21) extending from the upper edge of the fixing tube (2) to the center thereof. ) (21) is a rubber block (22) (22)
Is bonded on one side.

On the other hand, one surface of the rubber blocks (22) (22) is adhered to the surfaces of the arm plates (17) (17) projecting from the holder (45) externally fitted and fixed to the cable (1). This allows
Rubber block (22) between arm plate (17) (17) and fixed plate (21) (21)
(22) is interposed. Also, the fixing tube
The upper end of (2) is surrounded by a protective cover (16). In this device, when the arm plates (17) (17) and the fixed plates (21) (21) move relatively with the vibration of the cable (1), the rubber blocks (22) (22) The vibration of the cable (1) is attenuated by the shear stress generated in the tissue, and the amplitude of the vibration is reduced.

[0005]

However, in the above-mentioned conventional device, the anchor member (31) of the cable (1) is not provided.
Root part of the side (anchor member (31)
When (1) vibrates in a standing wave manner, the cable (1) is a portion near the anchor member (31) and the surface of the beam (3) is a node.
When the cable (1) vibrates, the portion where the cable (1) escapes upward from the spar (3)) is greatly bent with an increase in amplitude, and the bending direction changes repeatedly in accordance with the vibration of the cable (1). . For this reason, there has been a problem that the fatigue of the cable (1) occurs over time in the structure of the root portion.

[0006] The present invention has been made in view of the above point, and it is an object of the present invention to make it difficult for the tissue of the root portion of the cable (1) to suffer aging tissue fatigue. [First invention]

[0007]

The technical means of the present invention for solving the above-mentioned problem is as follows: "The vibration of a cable (1) stretched between a structure and a fixing member for supporting the structure"; A cable damping device for surrounding said cable (1) at a predetermined interval, and being fixed at a predetermined location.
(2) a vibration damping member that connects the fixing tube (2) and the cable (1) and generates a shear stress in an internal tissue with the vibration of the cable (1); When the amplitude exceeds the set value, the cable (1) and the fixing tube
(2) an elastic member compressed on the opposing surface is provided. "

The above technical means operates as follows. When the cable (1) starts to vibrate, the cable (1) and the fixing tube
(2) Shear stress is generated in the tissue of the damping member connecting
The vibration of the cable (1) is attenuated by the shear stress.
On the other hand, when the vibration amplitude of the cable (1) becomes equal to or larger than the set value, the elastic member is compressed on the opposing surface of the fixing tube (2) and the cable, so that the increase in the vibration amplitude of the cable (1) is reduced. . Therefore, an increase in the bending angle of the root of the cable (1) with respect to the fixing member can be suppressed.

[0009]

The present invention has the following specific effects. When the vibration of the cable (1) is small, the vibration can be attenuated by the shear stress of the damping member, but when the amplitude of the vibration increases, the magnitude of the bending angle of the root of the cable (1) with respect to the fixing member increases. Increase can be suppressed,
The fatigue of the root portion of the cable (1) over time is suppressed, and the durability of the cable (1) is improved.

<Others> * Item a In the above invention, "elastic rubber may be adopted as the elastic member". More specifically, a polybutadiene-based sealing material of an on-site filling type may be used as the material of the elastic rubber. It has been confirmed that the adoption of the method has a remarkable effect of attenuating the vibration of the cable (1).

* B Section In the above invention, it is possible that "the elastic member and the cable (1) are in contact with each other via soft urethane", and that the elastic member and the cable (1) are in contact with each other without using the soft urethane. It is also possible to adopt a configuration in which the cables (1) face each other with a certain gap. [Second invention]

[0012]

The technical means of the present invention for solving the above-mentioned problem is as follows: "The vibration of a cable (1) stretched between a structure and a fixing member for supporting the structure"; A vibration damping method for a cable (1), wherein when the vibration amplitude of the cable (1) is equal to or less than a set value, only the vibration is attenuated, and when the amplitude exceeds the set value, the vibration of the cable (1) is damped. And the expansion of the amplitude is alleviated. "

As a method of attenuating vibration having an amplitude equal to or less than the set value, a vibration damping member that generates a shear stress in an internal tissue with the vibration of the cable (1) can be used.
Further, as a method of alleviating the increase in the vibration amplitude that has become equal to or larger than the set value, an elastic member compressed on the opposing surface of the cable (1) and the fixing tube (2) can be used. In the method invention, as in the case of the cable damping device described above, when the vibration amplitude of the cable (1) exceeds the set value, the amplitude expansion is reduced, so that the root portion of the cable (1) is fixed to the fixing member. The bending of the base portion is relieved greatly, so that the tissue fatigue of the root portion over time can be suppressed.

[0014]

Next, embodiments of the present invention will be described. As shown in Fig. 1, the girders (3) and the tower
A cable (1) covered with a polypropylene pipe (a) (see FIG. 3) is stretched between (4) and the cable (1).
The lower end portion is inserted into the fixing tube (2), and the tip end of the fixing tube (2) penetrates the spar (3). The distal end of the cable (1) is fixed to the back surface of the spar (3) by an anchor member (31).

As shown in FIGS. 1 to 3, between the end of the fixing tube (2) and the cable (1), elastic rubbers (51) are sequentially coaxially overlapped from the outside (the invention is already described as a specific matter). It corresponds to the "elastic member" described above.) And a filling cylinder made of soft urethane
(53), cable (1), filling cylinder (5
The outer diameters of 3) and the elastic rubber (51) are 16cm, 20cm and 3cm, respectively.
It is set to 0 cm. A disk-shaped backup material (B) made of soft urethane is in contact with the lower end surfaces of the elastic rubber (51) and the filling tube (53), and the outer peripheral surface of the backup material (B) and the fixing tube are fixed. (2) is glued. Backup material
The reason why (B) is provided is to support the elastic rubber (51) and the filling tube (53) from below to prevent them from deviating from the proper disposition position. Incidentally, the elastic rubber (51) is specifically formed of a polybutadiene-based sealing material that is filled in place, and the filling cylinder (53) and the backup material (B) are made of a cable.
(1) It is soft enough not to substantially exhibit resistance to the vibration. However, the filling cylinder (53) does not necessarily need to be provided.

As shown in FIG. 2, FIG. 5, and FIG.
On the outer peripheral flange (23) welded to the tip of (2), fixing plates (21) (21) extending toward the cable (1) are overlapped with bolts (33) (33) and nuts (34) (34). The cable (1) is fixed near the cable (1) side end of the fixing plate (21).
Elongated holes (24) and (25) are formed extending in the direction of coming into contact with and separating from (1).

The fixing plates (21) and (21) are connected to a holder (45) holding the cable (1) via vibration damping units (20) and (20). The holder (45) is composed of a pair of halves (43) and (44) that hold the outer periphery of the cable (1), and the halves (43) and (44) have the same structure. These halves
(43) and (44) are bolts (77) and (7) attached to bolt insertion holes (40) and (41) formed in tightening flanges (47) and (48) described later.
8) and cable (1) with nut (not shown)
Are held together and integrated.

The structure of one half (43) will be described by way of example. The half (43) is composed of a semi-cylindrical body (46) and a clamping flange (47) that is bent in opposite directions from both circumferential ends thereof. ) (48), and the fastening flanges (47) (48) have bolt insertion holes (40) (4).
1) is formed. The arm plate (17) protruding from the outer peripheral surface of the semi-cylindrical body (46) is formed with long holes (18) and (19) extending in a direction parallel to the longitudinal direction of the arm plate (17). I have.

Each half (43) (44) of the holder (45) and a fixing plate
(21) The vibration damping unit (20) interposed between (21) has the structure shown in FIG. FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 5, showing the arm plate (17) of the holder (45) and the fixing tube.
(2) The vibration damping unit (20) interposed between the fixed plate (21) projecting inward is a rubber as a vibration damping member between the metal top plate (26) and the base plate (27). It has a configuration in which a block (22) is bonded, and a high-attenuation rubber is employed as the rubber block (22).

The top plate (2) of the vibration suppression unit (20)
6) is formed with screw holes (28) and (28), and the screw holes (28) and (28) are provided with arm plates provided on the half bodies (43) and (44) of the holder (45). (17) Bolt (61) (6) inserted from slot (18) (19)
2) is screwed in (see FIGS. 5 and 6).
On the other hand, in the base plate (27) of the vibration damping unit (20), elongated holes (37) and (38) extending in the width direction are formed, and the elongated holes (37) and (38) and the fixing plate (21) are formed. Slots (24) (25) already formed in
The parts are tightened and fixed by bolts (65) (66) and nuts (67) (68).

In this case, the outer peripheral flange of the fixing tube (2)
Attach the fixing plates (21) and (21) to the predetermined position of (23) and bolt (33) (3
4) Tighten the fixing plate (21) (21) and the vibration suppression unit.
(20) Set the relative posture of (20) as appropriate and tighten the bolts (65) (66) and nuts (67) (68) to make the half of the vibration suppression unit (20) (20) and the holder (45) ( Set the relative posture of (43) and (44) as appropriate and tighten the bolts (61) and (62).
When holding (1) and tightening bolts (77) and (78) as described above, even if the axes of cable (1) and fixing tube (2) are relatively displaced, they are connected to each other. be able to. And
In this connection state, no shear stress is accumulated in the tissue of the rubber block (22) as a vibration damping member constituting the vibration damping unit (20).

Also, the arrangement of the vibration damping units (20) and (20) at the end of the fixing tube (2) is surrounded by a rubber protective cover (7) as shown in FIG. It has become. Because of this,
The protective cover (7) is formed in a conical shape as a whole, and is provided with fastening flanges (72) (72) opposed to each other across a notch (71) formed in the side wall of the protective cover (7) over the entire axial direction. ing. By expanding the protective cover (7) at the notch (71), the large-diameter end and the small-diameter end are fixed to the fixing tube.
(2) and the cable (1) are fitted separately, and then the notches (7
1) Tightening the bolt insertion holes (73) (73) formed in (71) with bolts and nuts (not shown) completes the work of attaching the protective cover (7).

Next, the operation of the vibration damping device will be described. digit
(3) Cables for vehicles running on top and wind and rain
When (1) starts to vibrate, under conditions where the amplitude of the vibration is small (before the cable (1) starts to compress the elastic rubber (51)), the holder (45) vibrating integrally with the cable (1) Arm plate
(17) (17) and fixing plate (21) (21) projecting over the inner circumference of the fixing tube (2)
Rubber block of vibration suppression unit (20) (20) interposed between
(22) Shear stress is generated in the tissue of (22), and the vibration damping function of the cable (1) is exhibited. That is, the amplitude of the vibration of the cable (1) is attenuated with time.

Next, when the amplitude of the cable (1) increases and the cable (1) starts to compress the elastic rubber (51), the elastic vibration (51) is reduced by the vibration damping unit (20). The expansion of the amplitude of the cable (1) in the fixing tube (2) is reduced by the compression of the rubber (51). Therefore, as shown in FIG. 1, the root of the cable (1), which serves as a node of vibration (the part where the cable (1) escapes from the surface of the girder (3) as a fixing member)
(A)) The bending angle (θ1−θ2) in (1) is prevented from increasing. Therefore, the fatigue of the root portion of the cable (1) over time is suppressed, and the durability of the cable (1) is improved.

In FIG. 1, the cable (1) is shown as vibrating with the portion that escapes from the surface of the spar (3) as a node, but the cable (1) is connected to the upper end of the anchor member (31). When vibrating with C) as a node, an increase in the bending angle (θ3-θ4) of the cable (1) at the upper end (C) of the anchor member (31) is suppressed for the same reason as described above. . As described above, in the above-described cable, when the vibration amplitude of the cable (1) is small, the cable (1) utilizes the shear stress generated in the rubber blocks (22) (22) of the vibration damping units (20) (20). When the vibration amplitude exceeds the set value, the elastic rubber (51)
It is also possible to mitigate an increase in the bending angle of the root (the above (A) and (C)) portions of the cable (1) due to the compression.

[Brief description of the drawings]

FIG. 1 is a side view of a partial cross section showing a tensioning mode of a cable according to an embodiment of the present invention.

FIG. 2 is a sectional view of an arrangement portion of the cable damping device according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of a filling portion of the elastic rubber (51).

FIG. 4 is a perspective view of a protective cover (7).

FIG. 5 is a perspective view of the vicinity of an opening of the fixing tube (2).

FIG. 6 is an enlarged sectional view of an arrangement portion of the vibration damping unit (20).

FIG. 7 is an explanatory view of a conventional example.

[Explanation of symbols]

 (1) ・ ・ ・ Cable (2) ・ ・ ・ Fixing tube (5) ・ ・ ・ Soft urethane (51) ・ ・ ・ Elastic rubber

Claims (3)

(57) [Claims] 1. A cable damping device for damping the vibration of a cable (1) stretched between a structure and a fixing member for supporting the structure, wherein the cable (1) is arranged at a predetermined interval. A fixing tube (2) that is placed and surrounded and fixed at a predetermined location; a connecting member that connects the fixing tube (2) and the cable (1); and a shear stress is applied to the internal tissue with the vibration of the cable (1). A cable damping member comprising: a damping member that is generated; and an elastic member that is compressed on a facing surface of the cable (1) and the fixing tube (2) when the amplitude of the cable (1) becomes larger than a set value. apparatus. 2. The cable damping device according to claim 1, wherein an elastic rubber is used as said elastic member. 3. The cable damping device according to claim 1, wherein the elastic member and the cable (1) are in contact with each other via a soft urethane.