JPH0885918A - Vibration control device of asphalt stretched bridge at time of overhead installation - Google Patents

Abstract

PURPOSE: To provide a vibration control device for aslant stretched bridge which effectively reduces vertical vibrations generated by winds etc., applied to a bridge having a large main girder weight and a low natural frequency so as to prevent low frequency vibrations, prevents workmen from falling in a phenomenon like seasickness caused by low frequency vibrations so that the easiness and effectiveness in works are enhanced, also reduces effectively the stresses applied to the main girder likely with strong winds, and exerts the optimum vibration control effect always even though the main girder becomes longer because of the overhead installing works to result in changes in parameters such as natural frequency of the bridge. CONSTITUTION: As arrangement to be installed at the end of the main girder of an aslant stretched bridge when it is to be installed overhead a vibration control weight 9 is installed in a supporting frame 12 through a linear guide 10 in such a way as capable of moving vertically and supporting is made so that it 9 can be driven vertically by a hydraulic cylinder 16. The weight 9 is supported by a spring 17 so as to reduce the burden on the cylinder 16 applied when excitation of the weight 9 is made in the vertical direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device which is applied to a main girder portion when a cable-stayed bridge is erected and which reduces vertical vibration generated by wind or the like.

[0002]

2. Description of the Related Art Among cable-stayed bridges, the PC-stayed bridge is constructed as shown in FIG.
As shown in, the main tower 1 and the main girder 2 are simultaneously installed, and the cable 3 is stretched. Reference numeral 4 in the figure is a construction wagon.
Therefore, since the main girder 2 becomes longer as the construction progresses, the natural frequency of the entire bridge decreases and the amplitude of the vibration also increases.

[0003] The frequency is very low and below 0.3H _z, cause seasickness main girder second end workers are working in part by the low frequency vibrations, also interfere with the work is there. Furthermore, when a strong wind such as a typhoon strikes, the displacement of the main girder 2 may become very large, and a large stress exceeding the allowable range may act.

Therefore, conventionally, as shown in FIGS. 7 and 8, a dynamic vibration absorber for supporting a beam 6 having a weight 5 attached to its tip end by a damping device composed of a torsion spring 7 and a viscoelastic body 8 is installed. We are trying to reduce the vibration generated by wind.

[0005]

However, such a dynamic vibration absorber is effective for a bridge having a relatively high main frequency such as a steel cable-stayed bridge where the weight of the main girder is relatively small. , It is difficult to obtain a sufficient effect for bridges with large main girder weight and low natural frequency such as PC bridges. Further, in such a dynamic vibration absorber, when the overhang length of the main girder becomes long and the natural frequency of the bridge changes, the characteristics must be manually adjusted each time.

Further, a vibration control device for horizontal movement is used in a high-rise building or the like, but since the vibration of the main girder of a cable-stayed bridge moves up and down at the end, this type of vibration control device cannot be applied. .

The object of the present invention is to eliminate the disadvantages of the above-mentioned conventional example, effectively reduce the vertical vibration generated by wind and the like even for a bridge having a large main girder weight and a low natural frequency, and thereby reducing the low frequency. An object of the present invention is to provide a vibration control device for a cable-stayed bridge that can prevent vibration during installation.

[0008]

Means for Solving the Problems In order to achieve the above-mentioned object, firstly, a damping weight is installed through a linear guide, which is installed at an end of a main girder of a bridge when constructing a cable-stayed bridge. Is installed in the support frame so that it can be moved up and down, and this damping weight is supported by a hydraulic cylinder so that it can be driven up and down.The damping weight is supported by a spring, and the damping weight is vertically vibrated. The gist of the invention is to reduce the load on the hydraulic cylinder during the operation, and secondly, to move on the main girder of the bridge and detachably fix it to the tip of the main girder with anchor bolts.

Thirdly, a speedometer for measuring the vertical speed of the main girder is attached to the tip of the main girder of the bridge, and a high-frequency vibration component is removed from the measurement result of the speedometer by a filter in the drive circuit of the hydraulic cylinder. Fourthly, a gain is multiplied and feedback is provided. Fourthly, a displacement gauge is provided in the vibration damping weight, and the vertical displacement of the vibration damping weight measured by the displacement gauge is fed back to the drive circuit of the hydraulic cylinder. To do.

[0010]

According to the first aspect of the present invention, the damping weight is driven up and down by the hydraulic cylinder, and the damping force is applied to the vibration of the bridge by utilizing the reaction force of the weight generated at this time. To reduce vibration. Also, by supporting this damping weight with a load supporting spring, the load on the hydraulic cylinder can be reduced, and a small hydraulic cylinder can be used.

According to the second aspect of the present invention, when the main girder becomes long as the bridge is erected, the main girder can always move to the tip.

According to the third aspect of the present invention, the generated reaction force of the damping weight can act on the main girder as a damping force and is controlled when the speed of the main girder exceeds a certain value. Since the trigger operation of starting is performed, the electric power used for damping can be suppressed to the necessary minimum.

According to the fourth aspect of the present invention, it is possible to give the damping weight a weak rigidity so as to always return to the initial position (center).

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows a vibration damping device 1 for a cable-stayed bridge according to the present invention during installation
FIG. 2 is a front view showing the embodiment, FIG. 2 is a side view of the same as above, and FIG. 3 is a plan view of the same as above.

A linear guide 10 is provided in a box-shaped support frame 12 in which a moving mechanism for wheels 11 and the like is provided in the lower portion, and a damping weight 9 is vertically movable in the support frame 12 via the linear guide 10. Arrange. 14 is a supporting leg by a jack.

Although not shown, a vibration-proof rubber or the like is interposed between the linear guide 10 and the support frame 12 so that even if an unreasonable force is applied to the linear guide 10, it does not affect the movement of the damping weight 9. To do so.

A tiltable support column 15 having its lower end pivotally mounted is erected in a support frame 12 so as to penetrate the vibration damping weight 9, and a hydraulic cylinder 16 provided on the support column 15 moves the vibration damping weight 9 up and down. Supported so that it can be driven. This bearing also has a shaft-mounted structure.

Further, a spring 17 for supporting a load is arranged below the damping weight 9 in the supporting frame 12, and the spring 17 also supports the damping weight 9, but the spring 17 is provided in the hydraulic cylinder. It shall be for reducing such a burden.

Further, an oil buffer 18 is attached below the damping weight 9 in parallel with the spring 17. This oil buffer 18 absorbs a shock when the damping weight 9 falls due to a runaway or the like, and prevents the bridge from being damaged.

As shown in FIG. 5, the vibration damping device A of the present invention is detachably fixed to the tip of the main girder 2 of the bridge at the time of constructing the cable-stayed bridge with anchor bolts.

FIG. 4 is a control block diagram, in which a speedometer 19 for measuring the vertical speed of the main girder is attached to the tip of the main girder 2 of the bridge, and the output of this speedometer 19 is supplied to the drive circuit 20 of the hydraulic cylinder 16. A high-frequency vibration component is introduced through a filter 21 and an amplifier circuit 22, and the measurement result of the speedometer 19 is filtered by the filter 21 to remove the high-frequency vibration component to the drive circuit 20, and the result is multiplied and fed back.

This speedometer 19 is for low frequency vibration, and if a large impact is applied due to erection work or the like, it may interfere with its operation. To reduce.

Further, a displacement meter 23 is provided on the vibration damping weight 9, and the output of the displacement meter 23 is introduced into the drive circuit 20 of the hydraulic cylinder 16 through an amplifier circuit 24 to measure the vibration of the displacement meter 23. Weight 9
The vertical displacement of is fed back.

Next, usage and operation will be described. As described above, the vibration damping device A is detachably fixed to the tip of the main girder 2 of the bridge with anchor bolts. When the main girder 2 becomes longer as the bridge is erected, it is fixed with the anchor bolts. Is released, the supporting legs 14 by the jack are contracted, and the wheels 11 are moved. It may be possible to use a winch or a hydraulic jack for this movement.
If it is attached to the wagon 4, the wagon 4 for construction can be moved without a moving mechanism, so that it can always be installed at the tip.

A high-speed vibration component is removed from the measurement result by a speedometer 19 attached to the tip of the main girder 2 by a filter 21, a gain is applied, and the result is fed back to the drive circuit 20.
As a result, the vibration damping weight 9 is driven up and down by the hydraulic cylinder 16, and the damping force is applied to the vibration of the bridge by utilizing the reaction force of the weight generated at this time to reduce the vibration.

Since the weight of the main body of the concrete bridge is large, the damping weight 9 also has a large weight (for example,
10 tons) must be used. Frequency of the vibration further in question is less than 0.3H _Z, in order to generate a large reaction force must be longer stroke of movement of the damping weight 9. (For example ± 30 to 50 cm)

The load supporting spring 17 has a role of reducing the load on the hydraulic cylinder 16.

Further, if the trigger operation of starting the control when the speed of the main girder 2 measured by the speedometer 19 exceeds a certain value, the electric power used for damping can be suppressed to the necessary minimum. You can

On the other hand, by feeding back the vertical displacement of the damping weight 9 measured by the displacement gauge 23, a weak rigidity is given so that the damping weight 9 always returns to the initial position (center).

[0030]

As described above, the vibration damping device for a cable-stayed bridge according to the present invention effectively reduces the vibration generated by wind even for a bridge having a large main girder and a low natural frequency. Therefore, the low frequency vibration can be prevented, and the motion sickness phenomenon caused by the low frequency vibration of the worker can be prevented to improve the workability.

Further, it is possible to effectively reduce the stress applied to the main girder, which is a concern in strong winds. Further, even if the main girder becomes long due to the construction work and parameters such as the natural frequency of the bridge change. The optimum damping effect can always be demonstrated.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a vibration damping device for erection of a cable-stayed bridge of the present invention.

FIG. 2 is a side view showing an embodiment of the vibration damping device for erection of a cable-stayed bridge of the present invention.

FIG. 3 is a plan view showing an embodiment of the vibration damping device for erection of a cable-stayed bridge of the present invention.

FIG. 4 is a control block diagram showing one embodiment of the vibration damping device for erection of a cable-stayed bridge of the present invention.

FIG. 5 is an explanatory diagram of a cable-stayed bridge in which the vibration damping device of the present invention is installed.

FIG. 6 is an explanatory diagram of a cable-stayed bridge.

FIG. 7 is a side view showing a conventional example.

FIG. 8 is a plan view showing a conventional example.

[Explanation of symbols]

 1 ... Main tower 2 ... Main girder 3 ... Cable 4 ... Wagon for construction 5 ... Weight 6 ... Beam 7 ... Torsion spring 8 ... Viscoelastic body 9 ... Vibration damping weight 10 ... Linear guide 11 ... Wheel 12 ... Support frame 14 … Support legs 15… Struts 16… Hydraulic cylinder 17… Spring 18… Oil buffer 19… Speedometer 20… Drive circuit 21… Filter 22… Amplification circuit 23… Displacement meter 24… Amplification circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Oshio 19-1 Tobita, Chofu-shi, Tokyo Kashima Construction Co., Ltd. Technical Research Laboratory (72) Inventor Ryuji Nakano 2-1-1, Tobita, Chofu, Tokyo No. Kashima Construction Co., Ltd. Technical Research Institute (72) Inventor Tetsuo Takeda No. 19-1 Tobita, Chofu-shi, Tokyo Kashima Construction Co., Ltd. Technical Research Laboratory (72) Inventor Nobuhide Wada 1-2-2 Moto-Akasaka, Minato-ku, Tokyo No. 7 In Kashima Construction Co., Ltd. (72) Inventor Kihide Oka 1-2-7 Motokakasaka, Minato-ku, Tokyo No. 7 In Kashima Construction Co., Ltd. (72) Inventor Katsuhisa Kanda 1-2, Motoakasaka, Minato-ku, Tokyo No. 7 Kashima Construction Co., Ltd. (72) Inventor Akira Ogawa 2-4-1, Hamamatsucho, Minato-ku, Tokyo World Trade Center Building Kayaba Industry Co., Ltd. (72) Who Agatsuma BunEi Tokyo, Minato-ku, Hamamatsu-cho chome No. 4 No. 1 World Trade Center Building, Kayaba Industry Co., Ltd. in

Claims (4)

[Claims] 1. A damping weight is provided at the end of a main girder of a cable-stayed bridge at the end of a main girder so that the damping weight can be moved up and down in a support frame via a linear guide. It is supported by a cylinder so that it can be driven up and down, and a vibration damping weight is supported by a spring, which reduces the load on the hydraulic cylinder when vertically vibrating the vibration damping weight. apparatus. 2. The vibration control device for a cable-stayed bridge during erection according to claim 1, which moves on the main girder of the bridge and is detachably fixed to the end of the main girder with anchor bolts. 3. A speedometer for measuring the vertical speed of the main girder is attached to the tip of the main girder of the bridge, and a high-frequency vibration component is removed from the measurement result of the speedometer by a filter in the drive circuit of the hydraulic cylinder to obtain a gain. The vibration control device for erection of a cable-stayed bridge according to claim 1, wherein feedback is provided. 4. The suspension system for a cable-stayed bridge according to claim 1, wherein the damping weight is provided with a displacement gauge, and the displacement of the damping weight measured by the displacement gauge is fed back to the drive circuit of the hydraulic cylinder. Shaking device.