A mechanism for suppressing vortex vibration of a box girder bridge

Abstract

The box girder bridge vortex vibration suppression mechanism is used for the box girder bridge connected by multiple hollow box girders, and comprises a pump station, a vortex detection device arranged on the box girder bridge and a filling water tank, the pump station takes water from a river below the box girder bridge, the filling water tank is arranged in the internal cavity of the box girder, the filling water tank is provided with a water inlet and a water outlet, the water inlet of the filling water tank is connected with a water outlet pipeline of the pump station, the water outlet is arranged at the bottom of the filling water tank, the water outlet is provided with a drainage pipeline leading to the outside of the box girder, and the drainage pipeline is provided with an electric drainage valve; the pump station, the vortex detection device and the electric drainage valve are electrically connected with a central controller. The box girder bridge vortex vibration suppression mechanism can dynamically adjust the inherent vortex vibration frequency of the bridge and prevent the occurrence of vortex vibration.

Description

Technical Field

[0001] This invention relates to a vortex-induced vibration suppression mechanism for box girder bridges, belonging to the field of bridge engineering and safety technology. Background Technology

[0002] Bridge vortex-induced vibration refers to the phenomenon of vortex-induced vibration occurring in a bridge within a fluid. When fluid flows over a bridge, it may trigger vortex-induced vibration under certain conditions, leading to vibration and damage to the bridge structure. This is particularly true for box girder bridges. Due to their unique shape, such as the flanges and sidewalls of the cross-section, box girder bridges are prone to airflow separation and the generation of vortices. When the airflow velocity is high, these unique shapes can induce vortex-induced vibration. Furthermore, the hollow box girder of a box girder bridge, while reducing the bridge's self-weight, also makes the lighter bridge structure susceptible to vortex-induced vibration under wind loads. To eliminate vortex-induced vibration in box girder bridges, the following methods are generally used: 1. Adjusting the bridge geometry: By adjusting the bridge's geometry, such as changing the beam width, inclination angle, and flange shape, the flow characteristics of fluid passing over the bridge can be altered, thereby reducing vortex-induced vibration. 2. Installing damping devices: Installing damping devices on the bridge structure, such as vortex-induced vibration dampers and vortex-induced vibration energy absorbers, can reduce the amplitude and frequency of vortex-induced vibration by consuming its energy, thus eliminating it. 3. Adding mass: By adding mass to the bridge structure, such as by adding attachments or increasing the bridge's own mass, the dynamic characteristics of the bridge can be altered, thereby reducing vortex-induced vibration. 4. Controlling fluid flow velocity: By controlling the speed at which fluid flows over the bridge, such as by adjusting the river cross-section or dredging the waterway, the generation of vortex-induced vibration can be reduced.

[0003] However, the methods currently used all adjust the bridge's natural vortex-induced vibration frequency. When the fluid velocity exceeds the bridge structure's specific critical velocity, and encounters a vortex-induced vibration excitation frequency close to the bridge structure's natural frequency, the bridge will still experience vortex-induced vibration. Therefore, these measures can only reduce the probability of vortex-induced vibration in bridges, but cannot completely prevent it from occurring. Summary of the Invention

[0004] The purpose of this invention is to provide a vortex-induced vibration suppression mechanism for box girder bridges, which can dynamically adjust the inherent vortex-induced vibration frequency of the bridge and prevent vortex-induced vibration from occurring.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a box girder bridge vortex-induced vibration suppression mechanism, used for a box girder bridge composed of multiple hollow box girders connected together. The box girder bridge vortex-induced vibration suppression mechanism includes a pump station, a vortex-induced vibration detection device installed on the box girder bridge, and a filling water tank. The pump station draws water from a river channel below the box girder bridge. The filling water tank is installed in the internal cavity of the box girder. The filling water tank is provided with an inlet and an outlet. The inlet of the filling water tank is connected to the outlet pipe of the pump station. The outlet is located at the bottom of the filling water tank and is provided with a drainage pipe leading to the outside of the box girder. An electric drain valve is installed on the drainage pipe. The pump station, the vortex-induced vibration detection device, and the electric drain valve are all electrically connected to a central controller.

[0006] In this invention, when a box girder bridge encounters strong airflow and the vortex-induced vibration sensor detects bridge vibration, the central controller activates the pumping station to pump river water into the injection tank to increase the self-weight of the box girder. The relationship between the vortex-induced vibration frequency of the box girder bridge and the weight of a single box girder can be estimated using the following empirical formula: f=(k×√W / M)) / 2π,

[0007] In the formula:

[0008] f: Vortex frequency, in Hz

[0009] k: an empirical coefficient that depends on factors such as the geometry and material properties of the bridge. For box girder bridges, the value of k is between 0.1 and 1.0.

[0010] W: Weight of a single box girder, in N or kg.

[0011] M: The equivalent mass of a single box girder, in kg. This is a vortex-induced vibration mass correction term introduced when calculating the vortex-induced vibration effect. It is used to account for the additional mass effect of vortex-induced vibration on the bridge. This mass effect can be understood as the extra mass caused by vortex-induced vibration, which affects the vortex-induced vibration frequency. The vortex-induced vibration mass correction term m can be obtained through vortex-induced vibration tests, measured data, or empirical formulas. For box girder bridges, the value of M ranges from 0.1 to 1.0.

[0012] As can be seen from the above formula, for a given box girder bridge, both k and M values ​​are fixed. Therefore, when vortex-induced vibration occurs, this invention can change the weight W of the box girder by injecting water into the injection tank through a pumping station, thereby changing the vortex-induced vibration frequency of the box girder to avoid the current vortex-induced vibration excitation frequency of the fluid. Furthermore, the vortex-induced vibration frequency changes dynamically with the change in the amount of water injected, allowing the box girder bridge using this invention to avoid vortex-induced vibration over a wide range of data. In addition, the weighted box girder can also reduce the vibration amplitude of the bridge and protect the bridge structure from the effects of vibration.

[0013] Furthermore, an inlet flow meter is installed on the outlet pipe of the pumping station, and a drain flow meter is installed on the drainage pipe on the box girder. The inlet and drain flow meters respectively output inlet and drain flow signals to the central controller. The inlet and drain flow meters can be electromagnetic flow meters, ultrasonic flow meters, thermal flow meters, etc., which can output flow data through digital or analog signals and can communicate with the central controller through communication protocols such as RS485, MODBUS, and HART to realize the transmission of flow data. The central controller uses the inlet and outlet flow data to determine whether the inlet and outlet water volume in the filling tank is balanced, so as to determine whether there is a pipe blockage and issue an alarm signal when appropriate.

[0014] Furthermore, the cross-section of the filling tank is a groove shape with high sides and low middle, and a constricted throat channel is provided in the middle part of the bottom of the groove of the filling tank; when the bridge swings, the water in the filling tank also swings, and the flowing water generates eddies when flowing through the throat channel, which strengthens the force between the water flow and the side wall of the filling tank, thus consuming the swing energy.

[0015] Furthermore, a baffle plate is installed inside the injection tank. The baffle plate is arranged parallel to the horizontal centerline of the box girder bridge. The top of the baffle plate is connected to the top of the injection tank, and a water flow channel is provided between the bottom of the baffle plate and the bottom plate of the injection tank. When the bridge sways, the water in the injection tank also sways. At this time, the obstruction effect of the baffle plate on the water causes the water flow to change its direction, resulting in horizontal and vertical forces on the baffle plate and the tank wall. These forces are opposite to the direction of the bridge's sway, thus reducing the sway of the bridge.

[0016] Furthermore, each section of the box girder is equipped with an independent grouting water tank, and the grouting water tanks are connected by water injection pipes. Each grouting water tank is equipped with a drainage pipe, and each drainage pipe is equipped with an electric drainage valve. The electric drainage valves on each grouting water tank are electrically connected to the central controller.

[0017] Furthermore, the pumping station is equipped with filtration devices on both the inlet pipe that draws water from the river and the outlet pipe that supplies water to the filling tank. The filtration devices can be sand filters or various water pretreatment filters, which only need to filter out larger suspended impurities in the water to prevent pipe blockage.

[0018] Furthermore, the vortex-induced vibration detection device is one or more of an accelerometer, a fiber Bragg grating sensor, an acoustic sensor, or a vibration sensor. When vortex-induced vibration occurs, the bridge structure will experience significant vibration. An accelerometer can detect changes in the acceleration of the bridge structure to determine the presence of vortex-induced vibration. A fiber Bragg grating sensor can measure the scattering and reflection of light signals in the optical fiber, thereby acquiring real-time vibration information of the structure, including amplitude and frequency, to determine the presence of vortex-induced vibration. Vortex-induced vibration is usually accompanied by significant noise generation. An acoustic sensor can detect parameters such as the intensity and frequency of sound signals on the structure to determine the presence of vortex-induced vibration. A vibration sensor can be installed at key locations on the bridge structure to determine the presence of vortex-induced vibration by measuring parameters such as the vibration frequency and amplitude of the structure.

[0019] The positive and beneficial technical effects of this invention are as follows: By setting up a water injection tank inside the box girder and injecting water into the water injection tank through a pumping station to change the inherent vortex-induced vibration frequency of the box girder, the potential impact of long-term vortex-induced vibration on the bridge structure can be avoided; when the bridge experiences vortex-induced vibration, increasing the weight of the box girder can also reduce the vibration amplitude of the bridge; the internal cross-section of the water injection tank adopts a groove shape, a constricted throat, and a combination of baffles, which can consume the energy of bridge swaying and reduce the sway amplitude of the bridge; furthermore, the safety protection of the bridge by this invention is also reflected in its ability to effectively suppress divergent vibrations such as bridge flutter and galloping, or, when the bridge encounters floods, injecting water into the water injection tank can also achieve the effect of traditional heavy vehicle load on the beam, protecting the bridge from being washed away by the flood. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a structure according to an embodiment of the present invention.

[0021] Figure 2 This is a schematic cross-sectional view of a box girder according to an embodiment of the present invention. Implementation

[0022] To more fully explain the implementation of the present invention, the following implementation examples are provided. These implementation examples are merely illustrative of the present invention and do not limit the scope of the present invention.

[0023] The invention will be further explained in detail with reference to the accompanying drawings, in which the following are marked: 1. Box girder; 2. Injection tank; 3. Pumping station; 4. River channel; 5. Baffle plate; 6. Throat channel; 8. Inlet pipe; 9. Drainage pipe; 10. Electric drain valve.

[0024] As shown in the figure: A box girder bridge vortex-induced vibration suppression mechanism is used for a box girder bridge composed of multiple hollow box girders 1 connected together. It includes a pump station 3, a vortex-induced vibration detection device installed on the box girder bridge, and a filling water tank 2. The pump station draws water from a river channel 4 below the box girder bridge. The filling water tank is installed in the internal cavity of the box girder. The filling water tank is equipped with an inlet and an outlet. The inlet of the filling water tank is connected to the outlet pipe of the pump station. The outlet is located at the bottom of the filling water tank. The outlet is equipped with a drainage pipe 9 leading to the outside of the box girder. An electric drainage valve 10 is installed on the drainage pipe. An inlet flow meter is installed on the outlet pipe of the pump station, and a drainage flow meter is installed on the drainage pipe installed on the box girder. The inlet flow meter and the drainage flow meter output inlet and drainage flow signals to the central controller, respectively. The inlet and drainage flow meters and the vortex-induced vibration detection device are not shown in the figure. The pump station, the vortex-induced vibration detection device, and the electric drainage valve 10 are all electrically connected to the central controller.

[0025] In this embodiment, the cross-section of the injection tank is a concave groove shape with higher sides and a lower middle. A constricted throat channel 6 is provided in the middle part of the bottom of the groove. A baffle 5 is installed inside the injection tank, and the baffle is arranged parallel to the horizontal centerline of the box girder bridge, that is, the baffle is arranged parallel to the bridge body. Therefore, the baffle mainly deals with the lateral sway of the bridge body. The top of the baffle is connected to the top of the injection tank, and a water flow channel is provided between the bottom of the baffle and the bottom plate of the injection tank. In this embodiment, independent injection tanks are set inside multiple box girder sections. The injection tanks are connected to each other by water injection pipes. Each injection tank is equipped with a drainage pipe, and each drainage pipe is equipped with an electric drainage valve. The electric drainage valves on each injection tank are electrically connected to the central controller. Multiple electric drainage valves can quickly drain the water in the injection tank after the external factors such as strong winds have ended, restoring the normal operation of the bridge. In this embodiment, both the inlet pipe for drawing water from the river and the outlet pipe for supplying water to the injection tank are equipped with filtration devices. The filtration devices are sufficient to prevent pipe blockage and are not shown in the figure.

[0026] After a detailed description of the embodiments of the present invention, those skilled in the art will clearly understand that various changes and modifications can be made without departing from the scope and spirit of the above-mentioned patent applications. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention, and the present invention is not limited to the embodiments of the examples given in the specification.

Claims

1. A vortex-induced vibration suppression mechanism for a box girder bridge, wherein the box girder bridge is composed of multiple hollow box girders connected together, characterized in that: The vortex-induced vibration suppression mechanism for the box girder bridge includes a pumping station, a vortex-induced vibration detection device installed on the box girder bridge, and a water injection tank. The pumping station draws water from a river channel beneath the box girder bridge. The water injection tank is located inside the cavity of the box girder and has an inlet and an outlet. The inlet of the water injection tank is connected to the outlet pipe of the pumping station, and the outlet is located at the bottom of the water injection tank. The outlet has a drainage pipe leading to the outside of the box girder, and an electric drain valve is installed on the drainage pipe. The pumping station, the vortex-induced vibration detection device, and the electric drain valve are all electrically connected to a central controller. The cross-section of the water injection tank is a constricted throat channel located in the middle of the bottom of the constricted groove.

2. The box girder bridge vortex-induced vibration suppression mechanism according to claim 1, characterized in that: The pump station's outlet pipe is equipped with an inlet flow meter, and the drainage pipe on the box girder is equipped with a drainage flow meter. The inlet flow meter and the drainage flow meter respectively output inlet and drainage flow signals to the central controller.

3. The box girder bridge vortex-induced vibration suppression mechanism according to claim 1, characterized in that: The water tank is equipped with a baffle plate, which is parallel to the horizontal centerline of the box girder bridge. The top of the baffle plate is connected to the top of the water tank, and a water flow channel is provided between the bottom of the baffle plate and the bottom plate of the water tank.

4. The vortex-induced vibration suppression mechanism for box girder bridges according to claim 1, characterized in that: Each section of the box girder has an independent grouting water tank, and the grouting water tanks are connected by water injection pipes. Each grouting water tank is equipped with a drainage pipe, and each drainage pipe is equipped with an electric drainage valve. The electric drainage valves on each grouting water tank are electrically connected to the central controller.

5. The box girder bridge vortex-induced vibration suppression mechanism according to claim 1, characterized in that: The pumping station is equipped with filtration devices on both the inlet pipe that draws water from the river and the outlet pipe that supplies water to the filling tank.

6. The box girder bridge vortex-induced vibration suppression mechanism according to claim 1, characterized in that: The vortex vibration detection device is one or more of an accelerometer, fiber optic grating sensor, acoustic sensor, or vibration sensor.

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