JPH0841819A - Vibration control device on erection of diagonal tension bridge - Google Patents

Abstract

PURPOSE:To reduce the vibration of the main girder of a diagonal tension bridge, by providing a vibration control weight so as to be vertically movable in the support frame through a linear guide and providing a sine vibratory device on the weight by a crank mechanism. CONSTITUTION:A vibration control weight 9 is provided in a support frame 12 through a linear guide 10 so as to be vertically movable and a sine vibrator with a crank mechanism 15 by use of a servo motor 13 as the driving source is installed in the vibration control weight 9 to form a vibration controller A. The vibration controller A is detachably fixed to the front end of a bridge main girder. The measured results by a speed meter detecting the vertical speed of the main girder are filtered to remove high frequency oscillation components. The gain obtained is input in the driving circuit of the servo motor 13. And further, the servo motor 13 is driven and the vibration control weight 9 is vertically vibrated by a sine vibrator through the crank mechanism 15 to attenuate the vibration of bridge.

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 inconvenience of the conventional example, and to effectively reduce the vertical vibration generated by the wind and the like even for a bridge having a large main girder weight and a low natural frequency, and thereby a low frequency vibration. It is to provide a vibration control device for a cable-stayed bridge during installation.

[0008]

In order to achieve the above object, the present invention is to install a damping weight in a support frame through a linear guide, which is installed at an end of a main girder of a bridge when constructing a cable-stayed bridge. The movable weight is provided with a sinusoidal vibration device with a crank mechanism using a motor as a drive source or a sinusoidal vibration device with a cam mechanism using a motor as a drive source. It is a summary.

[0009]

According to the first and second aspects of the present invention, the sinusoidal vibrating device vibrates the damping weight in the vertical direction to exert a damping force on the vibration of the bridge, and Effectively reduce.

[0010]

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 an embodiment, and FIG. 2 is a side view of the same, in which 9 denotes a damping weight.

A linear guide 10 is provided in a vertical direction in a box-shaped support frame 12 provided with a moving mechanism for wheels 11 and the like at the bottom,
A frame supporting the damping weight 9 through the linear guide 10.
Arranged in 12 so as to be movable in the vertical direction.

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 servo motor 13 and a reduction gear 14 connected to the servo motor 13 are provided on the upper portion of the support frame 12. A rotary shaft of the reduction gear 14 is a main shaft 15a, and a crank arm piece 15 provided on the main shaft 15a.
A sinusoidal vibration device having a crank mechanism 15 in which b and a connecting rod 15c are connected by a crank shaft 15d is provided between the reduction gear 14 and the damping weight 9. The tip of the connecting rod 15c is pivotally attached to the lowermost one of the damping weights 9. In the figure, 16 is a rolling bearing.

FIG. 4 is a control block diagram. Such a 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 erection for a cable-stayed bridge with anchor bolts.

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 a drive circuit 20 for the servomotor 13 has a filter 21 for removing the high frequency vibration component from the output of the speedometer 19. Also, it is introduced through the amplifier circuit 22, and the measurement result of the speedometer 19 is multiplied by the gain obtained by removing the high frequency vibration component by the filter 21 and fed back to the drive circuit 20.

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.

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 unlocked and the wheels 11 move. It is possible to use a winch or a hydraulic jack for this movement, but if the vibration damping device A is attached to the construction wagon 4, the construction wagon 4 can be moved without a moving mechanism, so it is always installed at the tip. can do.

A speedometer 19 attached to the tip of the main girder 2 multiplies the measurement result by a filter 21 with a gain that removes high frequency vibration components, and feeds it back to the drive circuit 20 of the servomotor 13. This drives the servo motor 13,
With the sinusoidal vibrating device by the crank mechanism 15, the damping weight 9 vibrates vertically to exert a damping force on the vibration of the bridge,
Effectively reduce vibration.

At this time, as shown in FIG. 5, when the speed of the main girder 2 measured by the speedometer 19 exceeds a certain allowable value, the damping weight 9 is sinusoidally driven in a phase opposite to this speed. Then it is effective. To do this, use the speed of main girder 2
The natural frequency of the bridge is identified at the time of measurement at 19, and the rotation frequency of the motor is adjusted so that the vibration frequency of the damping weight 9 is always synchronized with the natural frequency of the bridge.

Further, in this apparatus, since the vibration damping weight 9 is vibrated with a constant amplitude, the vibration damping weight 9 is stopped when the vibration level becomes equal to or lower than a constant value. By repeating this, the vibration of the bridge can be suppressed within the allowable range. Further, since the speedometer 19 is used only as a trigger for starting and stopping the control, there is no fear that the sensor noise is fed back and the control is adversely affected.

Further, the vibration amplitude of the vibration damping weight 9 is the main shaft 15a.
Since it can be adjusted by adjusting the distance between the crankshaft 15d and the crankshaft 15d, if the main girder 2 becomes long during installation and the natural frequency of the bridge is different, it may be adjusted accordingly.

FIG. 3 shows a second embodiment of the present invention.
A cam consisting of a shaft 17b mounted on a gear 17a rotated by a servomotor 13 in place of the sinusoidal vibrating device by the crank mechanism 15 of the first embodiment so as to be displaced from the shaft of the gear 17a.
It is also possible to incorporate a sinusoidal vibrating device by a cam mechanism in which an elongated hole 18 with which the shaft 17b of the cam 17 is engaged is provided on the damping weight 9 side.

When the gear 17a is rotated by the servomotor 13, the shaft 17b moves in the elongated hole 18 without frictional resistance, and vibrates the damping weight 9 sinusoidally in the vertical direction.

[0024]

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 a strong wind, and furthermore, even if the main girder becomes long due to the erection work, the optimum vibration damping effect can be always exhibited.

[Brief description of drawings]

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

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

FIG. 3 is a front view showing a second 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 a vibration waveform of a damping weight.

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 ... Damping weight 10 ... Linear guide 11 ... Wheel 12 ... Support frame 13 … Servo motor 14… Reduction gear 15… Crank mechanism 15a… Main shaft 15b… Crank arm piece 15c… Connecting rod 15d… Crankshaft 16… Rolling bearing 17… Cam 17a… Gear 17b… Shaft 18… Slot 19… Velocity meter 20… Drive Circuit 21 ... Filter 22 ... Amplifier circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirofumi Midorikawa 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. (72) Inventor Kazuo Otsuka 1-2-7 Moto-Akasaka, Minato-ku, Tokyo No. Kashima Construction Co., Ltd. (72) Inventor Kenji Ueno No. 191-1 Tobita, Tokyo Chofu City Kago Construction Co., Ltd. (72) Inventor Yuji Niihara No. 19-1 Hibita, Tokyo Chofu City Kashima Construction Co., Ltd.

Claims (2)

[Claims] 1. A damping weight is installed at the end of a main girder of a cable-stayed bridge at the end of the main girder of the bridge, and is vertically movable in a support frame via a linear guide. A vibration damping device for erection of a cable-stayed bridge, characterized in that a sinusoidal vibration device with a crank mechanism using a motor as a drive source is provided in the. 2. A damping weight is installed at the end of the main girder of the cable-stayed bridge at the end of the main girder so that the damping weight can be moved vertically in the support frame via a linear guide. 2. A vibration control device for a cable-stayed bridge when installed, characterized in that a sinusoidal vibration device using a cam mechanism using a motor as a drive source is provided in the.