JP2888764B2 - Damping device for cable-stayed bridge during construction and control method therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping device for reducing vibration of a main girder of a cable-stayed bridge being erected and a control method thereof.

[0002]

2. Description of the Prior Art A cable-stayed bridge is always placed in a state of being subjected to wind-induced vibration from the start of construction, and before a main girder between adjacent main towers is connected, as shown in FIG. As shown in the figure, the vibration characteristics are symmetrical with respect to the main tower. Therefore, it is an issue to reduce the vibration during construction in order to maintain the working environment. In particular, in the method in which the construction of the main girder and the main tower proceed at the same time, the extension length of the main girder from the main tower and the height of the main tower increase with the progress, the amplitude at the end of the main girder gradually increases, and the vibration The vibration at the end of the main girder becomes a problem because the number is reduced. The vibration frequency at the end of the main girder is very low at 0.3Hz or less in the case of the PC cable-stayed bridge, so the vibration may cause motion sickness to the worker working at the end of the main girder and hinder the work. Results.

In a strong wind such as a typhoon, the vertical displacement of the main girder becomes excessively large, so that a stress exceeding the allowable stress may act on the main girder.

FIG. 12 shows a conventional vibration reducing device. This is a dynamic vibration absorber in which the beam with the weight connected to the tip is cantilevered by the spring and the damping device. The beam vibrates around the fulcrum by the inertia of the weight and the kinetic energy absorbs the vibration of the main girder. However, since the beam is supported in a cantilever manner by the spring, the weight of the weight cannot be increased due to the balance between the size of the spring and the weight of the weight, and the amount of energy consumption is limited. The applicable object is limited to a bridge having a relatively small main girder, such as a steel cable-stayed bridge, and is not suitable for a bridge having a large main girder such as a PC bridge.

Since the natural frequency of a PC cable-stayed bridge is as low as 0.3 Hz as compared with a steel cable-stayed bridge, a passive type dynamic vibration absorber using a spring as shown below is required to support a weight. The displacement of the spring becomes 3 m or more, which is difficult to realize. Further, the length of the main girder increases as the construction progresses, and the characteristics must be manually adjusted each time the natural frequency of the bridge changes.

Japanese Patent Application Laid-Open Nos. 60-60344 and 6-147257 disclose a vibration damping device that vibrates a weight vertically using an actuator to attenuate vertical vibration of a structure. Japanese Unexamined Patent Publication No. Hei 6-147257 discloses a method of performing vibration suppression using forced vibration of a weight by an actuator as in Japanese Patent Application Laid-Open No. 60-60344, and functions as a dynamic vibration absorber when the actuator fails. As described in Japanese Patent Application Laid-Open No. 60-60344, the frequency of the coil spring is limited to 1 Hz due to the occurrence of its static deflection, so it is not possible to set the frequency within a range smaller than 1 Hz. It is virtually impossible. In other words, in Japanese Patent Application Laid-Open No. 6-147257, when the full load of the weight is
If it vibrates at a frequency below Hz, the vibration cannot be attenuated by the coil spring.

Since it is actually impossible to manufacture a coil spring for a frequency of 1 Hz or less, a vibration damping device for attenuating the vertical vibration of a cable stayed bridge using a coil spring has been put to practical use. There is no example. When the weight of the bridge is supported by the coil spring, the frequency of the weight is limited to a specific value. Cannot respond.

The present invention has been made in view of the above background, and proposes a vibration damping device effective for reducing vibration of a main girder even for a PC cable-stayed bridge having a large weight and a small natural frequency. .

[0009]

According to the present invention, the weight is actively vibrated while the weight movable in the vertical direction is simply supported by the actuator, and the reaction force at that time is applied to the tip of the main girder. In addition, the displacement of the main girder is suppressed to increase the efficiency of vibration reduction of the heavier main girder, and a coil spring is used by incorporating a gas spring that bears a part of the load of the weight in the actuator. JP 6-14
Eliminates the problem of static bending encountered when a coil spring supports a weight in a passive type vibration damping device such as 7257.

The weight is held vertically reciprocally by a guide post vertically provided in a frame fixed to the main girder, and the actuator vibrates the weight in the vertical direction while supporting the weight. .

A vibration damping device comprising a weight and an actuator is installed at the tip of the main girder of the cable-stayed bridge being erected, and the actuator moves the weight in the direction of displacement of the main girder when a vertical displacement of the tip of the main girder occurs. By applying vibration and applying a reaction force in the opposite direction to the main girder, displacement is suppressed and vibration of the main girder is reduced.

The gas spring built into the actuator bears part of the weight of the weight, and is mechanically structured even when the gas spring supports the weight while the actuator vibrates at a frequency within the range of 0.1 to 0.3 Hz. No deflection problem occurs. Since the actuator does not bear the entire weight of the weight, the weight of the weight can be increased, so that the weight can be vibrated in the vertical direction at a low frequency. It has the effect of reducing vibration even for low-PC cable-stayed bridges.

To prevent excessive vertical displacement of the main girder in a strong wind, when the displacement of the weight reaches a predetermined allowable displacement, a limit switch installed on the guide post is operated, and the weight is moved by the actuator. After returning the weight to the normal position, the cylinder of the actuator is protected by automatically restarting the operation. If the weight exceeds the allowable displacement due to runaway, etc., install a damper at the frame at a position away from the normal weight position by the allowable displacement to avoid collision between the weight and the frame. To avoid excessive force on the main girder.

The control of the vibration damping device is performed by measuring the speed of the main girder and the displacement and speed of the weight, feeding them back to the controller, and using the feedback gain set in advance by the controller based on the optimal control law. A command signal to the actuator is determined from the signal, and the driving of the weight is controlled based on the command signal.In particular, robust control is used as a control law, and as the construction progresses, Even if the parameters such as the natural frequency change, the optimum vibration damping effect can always be obtained.

[0015]

1 to 3 show a vibration damping device 1 according to a first embodiment of the present invention.
As shown in the figure, a frame 2 fixed to the main girder 7, a weight 3 supported vertically reciprocally by a guide post 10 erected vertically in the frame 2, and vibrates the weight 3 It consists of an actuator 4 with a built-in gas spring 12 and is installed at the tip of the main girder 7 of the cable stayed bridge being erected to reduce its vibration.

The frame 2 is assembled in a box shape from a vertical frame 21 and a horizontal frame 22, and the guide post 10 is erected between the horizontal frames 22,22. The weight 3 is housed and held in the frame 2 by the guide roller 31 so as to be freely movable in the vertical direction along the guide post 10 without any resistance. The actuator 4 is installed at the center on the plane of the frame 2 as shown in FIG.

The frame 2 is fixed to the main girder 7 by anchor bolts during work in a certain construction section, but the wheel 5 is connected to the lower end of the frame 2 because it needs to move with the transition of the construction section. .

The weight of the weight 3 is determined according to the weight of the bridge under construction including the weight of the main girder 7 and the main tower 8, and when the main girder 7 is made of concrete, it is several tons to several tens tons. If the weight 4 is vibrated up and down while the weight 4 is independently supported by the actuator 4, the load on the actuator 4 becomes excessive.
The load on the actuator 4 is reduced by incorporating the gas spring 12 which bears a part of the weight of the actuator 4. Gas spring 12
Bears several tens of percent of the weight of the weight 3.

As shown in FIG. 6, a cylinder 42 of the actuator 4 has a hydraulic chamber for pressure oil supplied to both sides of the piston 40.
Separately from 43, 43, there is a hydraulic chamber 45 filled with oil 48, which is partitioned by a partition wall 44. The hydraulic chamber 45 communicates with the pressure oil in the hydraulic chamber 45, and is filled with gas 47 across a piston 49. Tank
The gas spring 12 is composed of the hydraulic chamber 45 and the tank 46. The piston rod 41 on the contraction side of the actuator 4 penetrates the partition wall 44 and is located in the hydraulic chamber 45 of the gas spring 12, and a part of the load borne by the piston rod 41 is
The gas 47 in the tank 46 bears through the oil 48.

A hydraulic unit for driving a piston rod 41 is connected to the hydraulic chambers 43 via switching valves connected to respective ports, and the piston rod 41 is connected to both hydraulic chambers by the switching valves.
As the pressure oil is supplied alternately to 43, 43, it moves up and down.

In order to reduce the vibration having a large amplitude at the low frequency of 0.3 Hz or less, it is necessary to increase the stroke of the weight 3 in accordance with the amplitude of the main girder 7. Is ensured by setting the length of Movement exceeding this required stroke is not only in strong winds,
When a collision with the frame 2 occurs due to runaway or the like, a limit switch 11 is provided on the guide post 10, and when the weight 3 reaches a preset allowable displacement, the actuator 4
After the weight 3 is returned to the normal position, the operation is automatically resumed, so that the oil buffer and the like are further separated from the position of the weight 3 by the required stroke (allowable displacement). This can be avoided by installing the damper 6. In FIG. 1, the chain line indicates the position of the weight 3 at the time of the maximum displacement. The vibration damping device 1 provided with the limit switch 11 on the frame 2 corresponds to the invention described in claim 2, and the vibration damping device 1 provided with the damper 6 in addition to the limit switch 11 corresponds to the invention described in claim 3.

The actuator 4 vibrates the weight 3 in the direction of displacement when the tip of the main girder 7 is displaced, and suppresses the displacement by applying a reaction force to the main girder 7 in a direction opposite to the displacement, thereby reducing vibration. I do. As shown in FIG. 5, when the main girder 7 is displaced together with the main tower 8, the main girder 7 is inclined with respect to the horizontal, so that the vibration direction of the weight 3 is not strictly vertical, but it is substantially Included vertically.

Here, a specific design procedure of the vibration damping device 1 will be described.

The maximum overhang length from the main tower 8 is, for example, 13
When the main girder 7 becomes 0 m, it is predicted that the tip of the main girder 7 will vibrate with an amplitude of ± 20 cm due to the wind of 20 m / s at the time of 85% overhang (during construction). The goal of vibration suppression is to reduce the vibration of the tip up to an amplitude of 20 cm to 1/3. Since the natural frequency of the entire bridge at that time is expected to be 0.155 Hz based on the result of eigenvalue analysis, the damping device 1 was designed. The required damping force of the actuator 4 of the device 1 is determined.

FIG. 7 shows the relationship between the maximum damping force of the vibration damping device 1 and the reduction rate of the amplitude of the main girder obtained from the result of the analysis of the model. %), It is sufficient to generate a vibration damping force of about 3600 N. If the installation weight constraints were the weight of the weight 3 and 11t, the maximum damping force F of the vibration damping device 1 is maximum stroke l ₀ of the natural frequency f ₀ and the weight 3 weight M _d and weight 3 systems ｛M _d (2π
FIG. 8 shows an analysis result when a sine wave having an amplitude of the main digit of 20 cm is input to the model using this value and f ₀ ) ² l ₀ = F｝. From this result, the vibration having an amplitude of 20 cm generated at the tip of the main girder 7 was reduced by the installation of
It can be seen that it has been reduced to 1/3.

The driving of the actuator 4 is first started by releasing the trigger when the vertical speed at the tip of the main girder 7 exceeds a certain value. Thereafter, as shown in FIG.
, And the displacement and speed of the weight 3 are measured, and these values are fed back to the controller.

The controller determines a command signal to the actuator 4 from the feedback signal using a preset feedback gain based on the optimal control law.
The weight 3 is driven based on this command signal. By using the optimal control law, the displacement and speed of the main girder 7 can be effectively reduced, and at the same time, the output of the actuator 4 can be reduced.

However, when the main girder 7 is erected, parameters such as the natural frequency and the effective mass of the entire bridge under construction change with the progress of the construction. May decrease. Therefore,
If robust control is used in which the control performance does not change even if the parameters of the model change to some extent, it is possible to cope with changes in parameters accompanying the progress of construction. H for robust control
∞ Control and other applications are possible.

FIGS. 9 and 10 show the operation method of the vibration damping device 1 when the amplitude of the tip of the main girder 7 is within 20 cm and when it exceeds 20 cm. When the displacement of the weight 3 exceeds 35 cm, the displacement of the weight 3 is suppressed to within 35 cm by the following vibration control operation.
Safe driving is implemented.

FIG. 11 shows a flowchart of the vibration suppression operation. In FIG. 11, the damping braking means that the supply of the oil to the actuator 4 is stopped by returning the servo valve to the neutral position, and the gas spring
Returning the weight 3 to the neutral position by the restoring force of 12,
This is performed when the displacement of the weight 3 exceeds 35 cm. The valve braking means that the stop valve applies pressure to both ports of the cylinder 42 of the actuator 4 so that the piston 40
Means that the movement of the weight 3 is restrained and the piston rod 41 is braked, and is performed when the displacement of the weight 3 exceeds 40 cm. The buffer braking means stopping the weight 3 by colliding the weight 3 with a damper 6 installed above and below the weight 3, and is performed when the displacement of the weight 3 exceeds 45 cm. | Weight displacement | indicates the absolute value of the weight displacement.

As described above, the vibration damping device 1 performs triple safe driving depending on the magnitude of the displacement of the weight 3,
In case of emergency, if the displacement of the weight 3 exceeds 50 cm, the control command is interrupted by the operation of the limit switch 11, the hydraulic unit stops, the operation of the actuator 4 and the weight 3 stop, and an emergency stop occurs. Becomes After the emergency stop, the actuator 4 is reset, the position of the piston 40 is returned to the neutral position, the weight 3 is returned to the normal position, and the vibration suppression operation is restarted.

The speed meter for feedback control installed at the tip of the main girder 7 is for low-frequency vibration. If a large shock is applied during the erection work, the operation of the main girder 7 is hindered. Is fixed to the main girder 7 via an anti-vibration rubber having a spring constant of a sufficient magnitude not to give

As described above, the vibration damping device 1 is fixed to the distal end of the main girder 7 by the anchor bolt, but is moved to the distal end side by the wheels 5 and the winch or the hydraulic jack together with the work 9 as the construction proceeds. Set the vibration damping device 1 to Wagen 9
If it can be installed inside, it does not need to be moved independently and can always be arranged at the tip of the main girder 7.

[0034]

The present invention is as described above. The weight which is movable in the vertical direction is simply vibrated while the weight is simply supported by an actuator having a built-in gas spring. It applies force to the tip of the main girder to suppress the displacement of the main girder, eliminating the static bending problem faced by passive type vibration damping devices using coil springs, while supporting the weight. And the weight can be increased, and the weight can be vibrated at a low frequency. As a result, even for a PC cable-stayed bridge having a large weight and a low natural frequency, the efficiency of vibration reduction of the main girder can be increased, and workability during construction can be improved.

By installing a limit switch or a damper on the frame, it is possible to cope with an excessive vertical displacement of the main girder in a strong wind, and to avoid a situation in which a large force is applied to the main girder. Can be.

Further, by using the robust control as a control law, the main girder becomes longer due to the erection work, and an optimum vibration damping effect can always be obtained even if parameters such as the natural frequency of the bridge change.

[Brief description of the drawings]

FIG. 1 is an elevation view showing a vibration damping device.

FIG. 2 is a longitudinal sectional view of the side view of FIG.

FIG. 3 is a cross-sectional view of FIG.

FIG. 4 is a block diagram when feedback control is performed on the vibration damping device.

FIG. 5 is a schematic diagram showing vibration characteristics of a cable stayed bridge.

FIG. 6 is a sectional view showing a gas spring incorporated in the actuator.

FIG. 7 is a graph showing a relationship between a damping force of an actuator and a main girder amplitude reduction rate.

FIG. 8 is a graph showing the response of the main girder when the vibration damping device is installed and when it is not installed.

FIG. 9 is a graph showing a state of vibration of the main girder tip and the weight when the amplitude of the main girder tip is within 20 cm.

FIG. 10 is a graph showing vibrations of the main girder tip and the weight when the amplitude of the main girder tip exceeds 20 cm.

FIG. 11 is a flowchart illustrating a procedure for performing a vibration control operation of the vibration control device.

FIG. 12 is an elevation view showing a conventional vibration damping device.

[Explanation of symbols]

1 ... damping device, 2 ... guide frame, 21 ... vertical frame,
22 ... horizontal frame, 3 ... weight, 31 ... guide roller, 4 ...
Actuator, 40 ... Piston, 41 ... Piston rod, 42 ... Cylinder, 43 ... Hydraulic chamber, 44 ... Partition wall, 45 ...
... Hydraulic chamber, 46 ... Tank, 47 ... Gas, 48 ... Oil, 49 ...
... piston, 5 ... wheels, 6 ... dampers, 7 ... main girder,
8 ... Tower, 9 ... Wagen, 10 ... Guide post, 11
...... Limit switch, 12 ... Gas spring.

Continued on the front page (72) Inventor Ryuji Nakano 2-9-1-1, Tobita-Shi, Chofu-shi, Tokyo Kashima Construction Co., Ltd. (72) Inventor Tetsuo Takeda 2-191-1, Tobita-Shi, Chofu-shi, Tokyo Shika Shima Construction Co., Ltd. (72) Inventor Yuji Niihara 2-191-1, Tobita-Shi, Chofu-shi, Tokyo Kashima Construction Co., Ltd. (72) Inventor Akira Ogawa 2--4, Hamamatsucho, Minato-ku, Tokyo No. 1 World Trade Center Building Kayaba Kogyo Co., Ltd. (72) Inventor Fumihide Uesuma 2-4-1 Hamamatsucho, Minato-ku, Tokyo World Trade Center Building Kayaba Kogyo Co., Ltd. (58) Field surveyed (Int. Cl. ⁶⁾ , DB name) E01D 1/00

Claims (5)

(57) [Claims] 1. A vibration damping device which is installed at the tip of a main girder of a cable-stayed bridge being erected and reduces the vibration thereof, and a frame fixed to the main girder and a guide vertically installed in the frame. The post consists of a weight that is held reciprocally in the vertical direction on the post, and an actuator with a built-in gas spring that supports the weight and vibrates it vertically to bear a part of the load of the weight. When a vertical displacement of the main girder occurs, the actuator vibrates the weight in the direction of displacement of the main girder, and applies a reaction force to the main girder in a direction opposite to the direction, so that the vibration is applied to a cable-stayed bridge during construction. 2. A limit switch, which operates when the weight reaches a preset allowable displacement and automatically resumes operation after returning the weight to a normal position by an actuator, is installed in the frame. The vibration damping device for a cable-stayed bridge during construction according to claim 1, wherein 3. The cable-stayed bridge according to claim 2, wherein a damper for avoiding collision between the weight and the frame is provided at a position of the frame at a position away from the position of the weight in a normal state by an allowable displacement. Damping device. 4. The speed of the main girder and the displacement and speed of the weight are measured, and these are fed back to the controller. Based on the optimal control law, the controller uses a feedback gain set in advance to convert the feedback signal to the actuator. A method for controlling a vibration damping device for a cable-stayed bridge during erection, the method comprising: determining a command signal; controlling driving of the weight based on the command signal; 5. The method for controlling a vibration damping device for a cable-stayed bridge during erection according to claim 4, wherein the driving of the weight is controlled based on the robust control.