JP3467536B2 - Method and apparatus for controlling parallel cables in cable-stayed bridge - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for damping parallel cables in a cable-stayed bridge.

[0002]

2. Description of the Related Art In parallel cables constituting a cable-stayed bridge, wake galloping often occurs in which the downstream cable vibrates significantly due to cross wind. In the conventional vibration damping device shown in FIG. 6, the parallel cable 1
The spacers 2 are coupled to each other, and the parallel cables 1 and the ropes 3 on the adjacent stages are crossed and coupled to each other to suppress the vibration of the cable 1. There is no rotation between the inner pipe 4 and the outer pipe 5 at the joint between the cable 1 and the spacer 2, so that the cable 1 is not twisted. (For example, see “Showa 1988, Examination and report on wind resistance of cable-stayed bridge cables” issued by the National Land Development Technology Research Center in February 1989.) In this device, the distance between parallel cables is set by spacers. It is intended to restrain the movement of the parallel cable by restraining it and connecting it to the parallel cable of the other stage by a rope.As a result, the structural damping of the cable becomes large and the vibration of the cable is suppressed. It is effective for shaking to some extent. However, it is difficult to predict the damping effect on the desk in advance. In addition, the device is also large.

Further, as shown in FIG. 7, a parallel cable 1
A mounting metal fitting 2a is attached to a, and a pair of arms 3a for amplitude amplification are axially attached to the pair of mounting metal fittings 2a, and a hydraulic damper 4a is provided between each pair of opposed tips of the arms 3a.
A vibration damping device equipped with is proposed. (For example, see Japanese Utility Model Laid-Open No. 3-50609) According to this vibration damping device,
By installing the hydraulic damper, the vibration of the cable is expanded and transmitted to the pivot axis between the pair of expansion arms, and the expanded amplitude is absorbed and damped by the hydraulic damper. Although it is said that there will be no backlash or the influence of the dead zone of the hydraulic damper, and the relative vibration limiting performance and reliability can be improved, but there are many shaft fulcrums, and there is a design problem in ensuring durability.

An object of the present invention is to provide a method and device for damping cable vibration by dissipating vibration energy by shear deformation of a vibration absorbing means having elasticity such as a high damping rubber fixed between a cable supporting frame of a spacer and a cable. Is intended to be provided.

[0005]

[Means for Solving the Problems] A structure of the present invention for solving the problems of the prior art is to connect required portions of a parallel cable forming a cable-stayed bridge with a spacer,
Between the cable support frame and the cable.
And equipped with elastic vibration absorbing means such as high damping rubber
The vibration absorbing means to the cable support frame of the spacer and the cable.
Adhesively fixed to the spacer and the parallel cable
Connect the cable around the cable axis between the cable support frame and the cable.
By connecting to apply the rotational force of the parallel
Cable by wake galloping cable etc.
The vibration energy of the
Damping the vibration of the cable, connecting the required parts of the parallel cable forming the cable-stayed bridge with a spacer, and using a high-damping rubber between the cable support frame of the spacer and the cable with an appropriate gap. And the like, and the spacer is fixed to the cable supporting frame of the spacer and the cable by adhesive.
The cable support frames are connected at the straight frame and
The space between the support frames is reinforced by stiffeners .

[0006]

[Operation] In parallel cables that form a cable-stayed bridge, wake galloping in which the downstream cable vibrates greatly due to cross winds often occurs. Due to the different amplitudes of the cables on the upstream side and the downstream side, a rotational force about the cable axis acts between the cable support frame of the spacer and the cables. Utilizing this rotational force, contact between the spacer and the cable
Dissipates vibration energy by shearing deformation of the vibration absorbing means having an elastic property such as high damping rubbers wearing fixed, reasonably can be damping the cable vibration.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, details of embodiments of the present invention will be described with reference to the drawings. 1 is an overall view showing an example of a cable-stayed bridge in which the vibration damping device of the present invention is installed, FIG. 2 is a partially cutaway front view of the vibration damping device of the present invention, FIG. 3 is a plan view, and FIG. 5A and 5B are comparative explanatory diagrams of the cable vibration due to the difference in the coupling condition between the spacer and the cable.

The structure of the vibration damping device A of the present invention will be described with reference to FIGS. 2 and 3. Reference numeral 11 denotes a spacer member consisting of a pair of two cable support frames 12 each having a semicircular front shape connected by a linear frame portion 13. Then, the spacer members 11 are combined with each other as shown in FIG.
4 around the outer periphery of the straight frame portion 13 and the bolt nut 15
And the stays 16 at the overlapping edges of both cable support frames 12 are connected by bolts and nuts 17. A cylindrical portion 12a having a diameter larger than that of the cable 14 is formed by coupling the cable support frames 12, and a required area and height are provided at the center of the inner surface of one cable support frame 12 and the left and right inner surfaces of the other cable support frame 12. The outer surface of the vibration absorbing means 18 having elasticity such as a high damping rubber is adhered and fixed, and the inner surface of the vibration absorbing means 18 is adhered and fixed to the outer surface of the cable support frame inner tube 20 fixed to the surface of the cable 14. It is a thing. 19 is a stiffener for reinforcement. The vibration damping device A is configured as described above. Incidentally, the width of the spacer member 11 is substantially the same as the diameter of the cable 14. When the cable surface is covered with a polyethylene pipe or the like, the cable supporting frame inner pipe 20 may be omitted. Although not shown in the drawing, support members are attached to the upper and lower portions of both cables 14 corresponding to the cable supporting frames 12 to prevent the vibration damping device A from moving. In addition, as shown in FIG. 4, the shear deformation of the vibration absorbing means 18 is calculated under the condition of the following equation.

[Equation 1] However, l: height S of the vibration absorbing means 18: cross-sectional area of the vibration absorbing means F: shearing force in the circumferential direction acting on the vibration absorbing means 18 due to rotational force δ: shear deformation of the vibration absorbing means 18 G: vibration absorbing means 18 Shear modulus of

Next, the effect of the spacer, that is, the vibration damping device A of the present invention, on the vibration characteristics of the parallel cable will be described. In the double deck steel cable-stayed bridge and the PC cable-stayed bridge B as shown in FIG. 1, there are many cases in which two or more cables 14 are arranged in parallel due to an increase in cable load and restrictions on cable construction. In the parallel cable 14, vibration (wake galloping) may occur due to wind due to aerodynamic interference between the upstream cable and the downstream cable. As one of the measures against wind vibration damping of the parallel cable 14, the cable 14
A means for connecting the spaces with a spacer member 11 is often used, but the restraining effect and the vibration damping mechanism are not always clear. The result of vibration analysis regarding the action of the spacer on the vibration characteristic of the parallel cable 14 will be described.

[0010]

[Vibration analysis] The cable 14 to be analyzed is two parallel cables 14 of the Seto Ohashi (Iwagurojima Bridge) class. Table 1 shows an example of the structural specifications of the cable 14.

[Table 1] The cable 14 is modeled as a beam member under tension,
It is supposed to resist not only tension but also bending and twisting.
For the calculation of the second moment of inertia of the cable 14, 15% of the value of the full section of the cable was adopted, and the same reduction rate (15% of the full section) was applied to the twist constant for the time being.

[0011]

[Vibration analysis result]

(A) Influence of the coupling condition between the spacer and the cable: 6 as the coupling condition between the spacer member 11 and the parallel cable 14.
FIG. 5 shows the result of vibration analysis for each case in which the degree of freedom is fixed, only the rotation around the cable axis is released, and the remaining 5 degrees of freedom are fixed (three spacers are arranged at equal intervals). In the case where the rotation around the cable axis is released, the frequency is the same in the out-of-plane anti-phase mode and the out-of-plane in-phase mode. Since the in-phase mode of the parallel cable 14 is a mode that is not affected by the spacer installation, in this case, it is considered that there is no effect of the restraint by the spacer member 11 even in the anti-phase mode of the parallel cable 14. On the other hand, the frequency of the out-of-plane antiphase mode in the case with fixed 6 degrees of freedom that constrains the rotation around the cable axis is about twice as high as the frequency in other cases, and the effect of spacer installation is clear. Is recognized. That is, the effect of restraining the cable vibration by the spacer member 11 is exhibited only when the rotation around the cable axis is fixed. (B) Effect of the number of spacers installed: Table 2 shows the cable frequency when the spacers are arranged at equal intervals and the number of spacers is set to 1, 3, or 5.

[Table 2] The * mark shows the frequency when the spacer position and the vibration mode node position match. When the number of spacers installed is increased, the frequency of the out-of-plane antiphase mode becomes higher, and it is particularly noticeable at low-order vibrations. As a matter of course, when the installation position of the spacer coincides with the position of the node of the vibration mode, the effect of the spacer is not exerted because the cable does not move in the spacer portion. (C) Effect of cable twist constant: In the above examination, the cable twist constant is temporarily reduced to 15% of the cable cross-section value, but the restraint effect of the spacer member 11 is affected by the cable twist constant. Number of spacers installed is 5
As a unit, the cable twist constant is enhanced.
Table 3 shows the frequencies of the out-of-plane anti-phase modes when 5% and 30% are set.

[Table 3] As the cable twisting constant becomes smaller, the restraint effect of the spacer naturally lowers, but even at 5% of the full cross section, the frequency is surely higher than in the state without the effect of the spacer.

[0012]

[Spacer with high damping rubber (vibration damping device A)] When fixing rotation between the spacer member 11 and the cable 14,
It was confirmed that the out-of-plane antiphase frequency of the parallel cable 14 was increased, but at that time, the spacer member 11 and the cable 1
A shearing force that resists a rotational force acts on the joint between the four. Therefore, as shown in FIG.
If the structure in which the vibration absorbing means 18 accompanied by shearing deformation such as high-damping rubber is sandwiched at the joint between the cable 1 and the cable 14, the cable 1
With respect to the out-of-plane anti-phase vibration of No. 4, the vibration absorbing means 18 sandwiched between the spacer member 11 and the cable 14 undergoes shear deformation, and the vibration energy is dissipated as thermal energy due to the internal damping of the vibration absorbing means 18. As a result, increased structural damping,
Furthermore, it is possible to suppress the wake galloping.

[0013]

As described above, according to the structure of the present invention, the following effects can be obtained. Since the vibration damping device can be arranged at a position that is an antinode of the cable vibration, for example, at an intermediate position of the cable, the displacement is large and the effect is good, and in particular, the present invention is a fixed intermediary between the cable support frame of the spacer and the cable. The vibration energy of the cable can be effectively dissipated by the shear deformation of the elastic vibration absorbing member such as the high damping rubber provided, and the vibration of the cable can be efficiently damped, and its configuration is also simple.

[Brief description of drawings]

FIG. 1 is an overall view showing an example of a cable-stayed bridge equipped with a vibration damping device of the present invention.

FIG. 2 is a partially cutaway front view of the vibration damping device of the present invention.

FIG. 3 is a plan view.

FIG. 4 is an explanatory diagram showing the operation of the vibration absorbing means.

FIG. 5 is a comparative explanatory diagram of cable vibration due to a difference in coupling condition between a spacer and a cable.

FIG. 6 is a front view of a conventional technique.

FIG. 7 is a perspective view of a conventional technique.

[Explanation of symbols]

A vibration control device B PC cable-stayed bridge 11 Spacer member 12 Cable support frame 12a cylindrical part 13 Straight frame 14 cables 15 bolt nuts 16 stay 17 bolt nut 18 Vibration absorbing means 19 stiffeners 20 Cable support frame inner tube

Continued from the front page (73) Patent holder 000000099 Ishikawajima Harima Heavy Industries, Ltd. 2-2-1 Otemachi, Chiyoda-ku, Tokyo (73) Patent holder 390029012 SEE Co., Ltd. 2-9 Kanda Surugadai, Chiyoda-ku, Tokyo (73) ) Patent holder 000000549 Obayashi Corporation 4-33 Kitahama East, Chuo-ku, Osaka-shi, Osaka (73) Patent holder 000001373 Kashima Construction Co., Ltd. Moto-Akasaka 1-2-7 (73) Minato-ku, Tokyo (73) Patent holder 000002299 Shimizu Corporation 1-3-2 Shibaura, Minato-ku, Tokyo (73) Patent holder 000174943 Sumitomo Mitsui Construction Co., Ltd. 4-13, Arakicho, Shinjuku-ku, Tokyo (73) Patent holder 000002107 Sumitomo Heavy Industries, Ltd. 5-9-11 Kita-Shinagawa, Shinagawa-ku, Tokyo (73) Patent holder 594128913 Chodai Co., Ltd. 1-20-4 Nihonbashi Kashigaracho, Chuo-ku, Tokyo (73) Patent holder 000235543 Tobishima Construction Co., Ltd. Chiyoda, Tokyo 2-3, Sanbancho, Tokyo (73) Patent holder 000004123 JFE Engineering Marunouchi 1-2-2, Marunouchi, Chiyoda-ku, Tokyo (73) Patent holder 000005119 Hitachi Zosen Corporation 1-89, Minami Kohoku, Suminoe-ku, Osaka-shi, Osaka (73) Patent holder 000005902 Mitsui Engineering & Shipbuilding Co., Ltd. Tokyo 5-6-4 Tsukiji, Chuo-ku, Tokyo (73) Patent holder 000006208 Mitsubishi Heavy Industries, Ltd. 2-16-5 Konan, Minami-ku, Tokyo (72) Inventor Hiroshi Sato 1 Asahi, Tsukuba, Ibaraki Prefectural soil Inside the Tree Research Institute (72) Inventor Takeaki Kusakabe 1 Asahi, Tsukuba, Ibaraki Prefectural Civil Engineering Research Institute Ministry of Construction (72) Kazushi Ogawa 8 Niijima, Harima-cho, Kako-gun, Hyogo Kawasaki Heavy Industries Ltd. Harima Plant ( 72) Inventor Chiaki Nogami 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries, Ltd. Akashi factory (56) Reference JP-A 1-210507 (JP, A) Seki 61-40414 (JP, U) ) Actual Kaihei 5-73012 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) E01D 11/00-11/04 E01D 1/00

Claims (2)

(57) [Claims] 1. A spacer is used to connect required parts of a parallel cable forming a cable-stayed bridge with a spacer.
Between the cable support frame and the cable with an appropriate gap.
By providing elastic vibration absorbing means such as damping rubber,
Attach the vibrating means to the cable support frame of the spacer and the cable
The spacer and the parallel cable.
Force around cable axis between cable support frame and cable
By connecting the parallel cable
Vibration of the cable due to wake galloping
The energy is dissipated by the shear deformation of the vibration absorbing means
A method for damping parallel cables in a cable-stayed bridge, which is characterized by damping the vibration of the cable. 2. A parallel cable constituting a cable-stayed bridge is connected with required parts by a spacer, and a high-damping rubber or the like is provided between the cable supporting frame of the spacer and the cable with an appropriate interval. The vibration absorbing means is provided, and the vibration absorbing means is adhesively fixed to the cable supporting frame of the spacer and the cable, and the spacer has two cable supporting frames which are linear frames.
And the support frames are supplemented by stiffeners.
A method for damping parallel cables in a cable-stayed bridge characterized by being strengthened .