Out-of-plane damping and warning device for a stay cable and a warning method

Abstract

The present application belongs to the technical field of damping and vibration reduction of stay cables, and particularly relates to a device and method for damping and early warning of stay cables out of plane. The present application comprises a damping box, a planetary gear train is arranged in the cylinder cavity of the damping box; a lower connecting rod extends radially at the rotating shaft, the extension section of the lower connecting rod is hinged to an upper connecting rod, the upper connecting rod is hinged to a connecting block fixed on the stay cable, the axis of each hinge is parallel to the axis of the rotating shaft; a conductive energy-consuming rotor is further arranged on the rotating shaft, and each energy-consuming rotor is insulated from the rotating shaft; in the axial direction of the rotating shaft, the cylinder cavity space between adjacent conductive energy-consuming rotors is filled with damping liquid; magnets are further arranged at both ends of the rotating shaft to provide magnetic induction lines for the conductive energy-consuming rotors to cut, and the current amount generated after cutting the magnetic induction lines is obtained by a current sensor. The present application can provide a basic platform for monitoring and early warning of the vibration amplitude of stay cables during operation, thereby ensuring the stable and reliable operation of the stay cables and avoiding safety accidents caused by excessive amplitude vibration of the stay cables.

Description

Technical Field

[0001] This invention belongs to the field of cable-stayed bridge damping and vibration reduction technology, specifically relating to a vibration reduction early warning device and method for cable-stayed bridges outside the plane. Background Technology

[0002] Cable-stayed bridges, also known as axial-tensioned bridges, are a type of bridge where the main girder is directly connected to the bridge towers by numerous cables. They possess strong spanning capacity and a rational structural stress distribution, making them an important bridge type in the design of long-span bridges. With the construction of kilometer-long cable-stayed bridges, the dynamic load response problem faced by ultra-long cable stays has become increasingly prominent. Especially since cable stays are the main load-bearing components of cable-stayed bridges, despite their characteristics of high flexibility, small mass, and low damping, they are highly susceptible to large-amplitude vibrations under loads such as earthquakes, wind, rain, and traffic loads. Cable stay vibrations not only cause psychological distress to users but also lead to fatigue damage at the cable anchor points, damage to the cable's anti-corrosion system, and in severe cases, fatigue fracture. Therefore, effective monitoring of cable stay vibration is a pressing technical problem that needs to be solved.

[0003] Currently, passive vibration reduction methods are more commonly used to address the vibration phenomenon of cable-stayed bridges. These are described in patent publications such as "Damping Vibration Reduction Device for Long Suspension Cables of Suspension Bridges" (CN108660904A), "A Temporary Vibration Reduction Device for Cable-Stayed Bridges" (CN218951998U), and "An Electromagnetic Three-Element Vibration Reduction Device Applicable to Multi-Order Vibration of Cable-Stayed Bridges" (CN109706832A). These devices focus on passive defense, i.e., buffering and reducing the vibration of the current cable-stayed bridge, while neglecting active monitoring and even early warning of cable-stayed bridge vibration amplitude. Once the cable-stayed bridge exceeds its specified vibration amplitude during operation, it often leads to danger or even accidents, causing significant problems. Therefore, a solution is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a compact, reasonable, flexible and convenient vibration reduction and early warning device for cable stays outside the plane. It can provide a basic platform for monitoring and early warning of the vibration amplitude of cable stays during operation, thereby ensuring the stable and reliable operation of cable stays and ultimately avoiding safety accidents caused by excessive vibration of cable stays.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A vibration reduction and early warning device for cable stays outside the plane is characterized by: a damping box fixed to a base surface, a rotating shaft coaxially arranged inside the cylindrical cavity of the damping box; a large gear coaxially fixed to the end of the rotating shaft, an internal gear ring arranged on the wall of the cylindrical cavity of the damping box, and a small gear connecting the external teeth of the large gear and the internal teeth of the internal gear ring, so that the large gear, the small gear and the internal gear ring together form a planetary gear system; a lower connecting rod extends radially from the rotating shaft, the extension of the lower connecting rod is hinged to an upper connecting rod, and the upper connecting rod is hinged to a connecting block fixed on the cable stay, with the axis of each hinge point parallel to the axis of the rotating shaft;

[0007] The shaft is also equipped with conductive energy-dissipating rotors, and each energy-dissipating rotor is insulated from the shaft. The cylindrical cavity between adjacent conductive energy-dissipating rotors is filled with damping fluid along the shaft axis. Magnets are also arranged at both ends of the shaft to allow the conductive energy-dissipating rotors to cut magnetic field lines, and the current generated after cutting the magnetic field lines is obtained through a current sensor.

[0008] Preferably, the middle section of the damping box is isolated by a sealing plate, thereby forming two sets of symmetrically distributed sub-boxes that are coaxial with each other and have axial clearance; the lower connecting rod is fixed to a section of the rotating shaft at the axial clearance; the planetary gear train consists of two sets and is placed on the adjacent surfaces of the two sets of sub-boxes.

[0009] Preferably, the connecting block is a snap-fit ​​type; a connecting shaft is provided on the side of the connecting block facing the damping box; the end collar of the upper connecting rod is sleeved on the connecting shaft, thereby forming a hinged fit between the two.

[0010] Preferably, the length of the lower link is less than the length of the upper link.

[0011] Preferably, the rotating shaft is an insulated shaft, and the conductive energy-consuming rotor is made of a conductive metal material.

[0012] Preferably, the early warning method, which applies the aforementioned vibration reduction early warning device for out-of-plane operation of the cable-stayed bridge, is characterized by comprising the following steps:

[0013] S1. Calculate the peak current of the current sensor using the following formula. I a :

[0014]

[0015] in:

[0016] B The magnetic flux density of the magnet;

[0017] l 2 This is the length of the upper connecting rod;

[0018] When the shaft is arranged horizontally, the horizontal plane coinciding with the axis of the hinge point of the two connecting rods is taken as the reference plane, and the angle between the upper connecting rod and this reference plane is . β The angle between the lower connecting rod and the reference plane is... α ;

[0019] C v The damping coefficient of the damping fluid;

[0020] ρ The density of the damping fluid;

[0021] A The contact area between the conductive energy-consuming rotor and the damping fluid;

[0022] r The width of the conductive energy-dissipating rotor;

[0023] f u For the out-of-plane vibration load of the stay cable;

[0024] S2. Calculate the current amplification factor using the following formula. :

[0025]

[0026] in:

[0027] ; t for; EI The flexural stiffness of the stay cable; for t The out-of-plane deflection generated when the cable-stayed cable vibrates;

[0028] ; It is the coefficient of meshing friction between the large gear and the small gear in a planetary gear train; The coefficient of friction between the pinion and the internal gear ring. This refers to the torque of the pinion gear; The speed of the pinion gear. The helix angle on the pitch circle. The gear wear correction factor is related to the usage time of the invention. The slip ratio at the engagement point. The slip ratio at the disengagement point; The end face engagement angle;

[0029] ; For the number of teeth of the large gear, This refers to the number of teeth on the pinion. The radius of the tip circle of the large gear is... The pitch circle radius of the large gear;

[0030] ; The radius of the pinion tooth tip circle is... The pitch circle radius of the pinion;

[0031] S3. Calculate the current correction peak value of the current sensor using the following formula. :

[0032]

[0033] S4. Set the current limit threshold when the stay cable is under the extreme amplitude. ,when When the amplitude exceeds the limit of the cable stays, an early warning is triggered.

[0034] Preferably, the out-of-plane vibration load of the cable-stayed bridge f u Calculate using the following formula:

[0035]

[0036] in, For the flexural stiffness of the stay cable, The out-of-plane deflection generated by the cable vibration at time t is solved using the following equation of motion:

[0037]

[0038] The initial tension of the stay cable. This represents the tension increment during cable vibration. For the unit weight of the stay cable, It is the acceleration due to gravity. The initial deflection of the stay cable. x This is the length of the stay cable.

[0039] The beneficial effects of this invention are as follows:

[0040] 1) Through the above scheme, the present invention, on the one hand, uses a planetary gear train in conjunction with a shaft with an impeller to achieve the purpose of vibration reduction of the stay cable in a damping fluid environment; on the other hand, it transforms the impeller into a conductive energy-dissipating rotor and, in conjunction with a magnet, utilizes the current generated by the conductive energy-dissipating rotor cutting magnetic field lines to achieve online current monitoring, so as to provide a basic platform for monitoring and early warning of the vibration amplitude of the stay cable during operation, thereby ensuring the stable and reliable operation of the stay cable and ultimately avoiding safety accidents caused by excessive vibration of the stay cable.

[0041] 2) As the gear transmission wears down with the increase in the usage time of this invention, the torque transmission ratio decreases, the current decreases, and the early warning effect of this invention on the out-of-plane vibration amplitude of the cable stays weakens. To ensure the accuracy of the current sensing of this invention, a current amplification factor is also proposed here to describe the degree of gear wear in this invention over time, thereby correcting the current under different usage periods of this invention and improving the accuracy of the measurement data. Attached Figure Description

[0042] Figure 1 This is a diagram illustrating the working state of the present invention;

[0043] Figure 2 This is a diagram showing the fit between the rotating shaft, the conductive energy-dissipating rotor, the planetary gear train, and one of the sub-boxes.

[0044] Figure 3 This diagram shows the changes in the motion states of the upper and lower links.

[0045] Figure 4 This is a graph showing the relationship between the vibration amplitude and vibration period of the stay cable.

[0046] Figure 5 for Figure 4 A simplified diagram;

[0047] Figure 6 The diagram shows the induced current of the cable under three vibration processes.

[0048] The actual correspondence between the reference numerals and component names in this invention is as follows:

[0049] 10-Damping box; 10a-Sealing plate; 11-Sub-box body;

[0050] 20-Spindle;

[0051] 30 - Planetary gear train; 31 - Large gear; 32 - Small gear; 33 - Internal gear ring;

[0052] 41 - Lower link; 42 - Upper link;

[0053] 50 - Connecting block; 51 - Connecting shaft;

[0054] 61-Conductive energy-consuming rotor; 62-Magnet; 63-Current sensor. Detailed Implementation

[0055] For ease of understanding, this section combines... Figures 1-6 The specific structure and operation of the present invention are further described below:

[0056] The actual embodiments of the present invention are constructed as follows Figures 1-2As shown, its main body can be placed on a support, which is then fixed to a base surface such as the ground. Meanwhile, the upper connecting rod 42 is hinged to the stay cable via a connecting block 50, and connected via long and short drive shafts, i.e. Figure 3 The upper connecting rod 42 and lower connecting rod 41 shown transmit the out-of-plane vibration of the stay cable. Subsequently, the vertical vibration energy is transmitted to the large gear 31 via the rotating shaft 20. When the large gear 31 rotates, it drives the rotating shaft 20 to rotate simultaneously. The conductive energy-dissipating rotor 61 on the rotating shaft 20 agitates the built-in damping fluid to dissipate energy, thus consuming the vibration energy of the stay cable and achieving vibration reduction. Simultaneously, the large gear 31 drives the small gear 32 to rotate within the internal gear ring 33. Because... Let be the coefficient of meshing friction between the large gear 31 and the small gear 32 in the planetary gear train. Let the coefficient of meshing friction between the pinion 32 and the internal gear ring 33 be denoted as . For simplified calculations, let . = Furthermore, all the aforementioned components are located within the damping box 10, and the damping box 10 has fixed magnets 62 at both ends. When the conductive energy-dissipating rotor 61 rotates, it cuts the magnetic field lines between the magnets 62 at both ends, generating a current that is transmitted to the current sensor 63. Simultaneously, the rotating shaft 20 isolates the current generated by each rotor, allowing the current generated by each rotor to accumulate without canceling out. By detecting the current magnitude through the current sensor 63, the vibration amplitude of the stay cable can be monitored, further enabling the monitoring and early warning of the stay cable's vibration amplitude, preventing the stay cable from exceeding its specified vibration amplitude during operation and causing danger.

[0057] In actual design, such as Figures 1-2 As shown, the damping box 10 is formed by combining two sets of sub-boxes 11 with axial clearance between them; the adjacent surfaces of the sub-boxes 11 are closed by the sealing plate 11a and a planetary gear train 30 is arranged thereon, while magnets 62 are arranged at the opposite surfaces, or opposite end faces. After the upper connecting rod 42 and the lower connecting rod 41 are hinged to each other, the bottom of the lower connecting rod 41 is hinged to a section of the shaft 20 located at the aforementioned axial clearance, so that the shaft 20 is pulled to rotate by the action of the two connecting rods.

[0058] Thus, this invention transmits energy through corresponding gears, converting the energy of vertical vibration into torque for gear rotation. This torque then drives the damping box 10 and the liquid damper formed by its internal components to rotate and dissipate energy. However, the gear transmission will wear down with the increase in the usage time of this invention, resulting in a decrease in the torque transmission ratio and current, thereby weakening the early warning effect of the invention on the out-of-plane vibration amplitude of the cable-stayed bridge. To ensure the accuracy of the current sensing in this invention, a current amplification factor is also proposed here. This is used to describe the degree of gear wear over time in this invention, thereby correcting the current under different usage durations to improve the accuracy of the measurement data. The specific calculation method is as follows:

[0059] The input torque is calculated based on parameters such as the stay cables. The response torque is calculated using parameters of the liquid in the liquid damper and the rotor. When both are equal, the gears are in a wear-free state with a transmission ratio of 1:1. The calculation of this state is then performed. As the service life increases, the wear on the gears gradually increases. The current correction peak value of the current sensor 63 under different service lifespans is obtained by calculating the ratio of the device's input power to its output power, where the input power is the power generated by the input torque and the output power is the power after removing gear meshing wear that increases with service life. .

[0060] To go even further:

[0061] length l 1 The upper connecting rod 42 and its length l 2 The initial state of the lower link 41 is referenced. Figure 3 As shown, the initial included angle at this time β 0 for:

[0062]

[0063] When the amplitude of the stay cable vibration is A and the period of vibration is T, refer to the curve showing the relationship between the amplitude of vibration and the period of vibration of the stay cable. Figure 4 As shown. However, during actual vibration, due to the vibration frequency of the cable... f If the vibration period T is extremely small, the vibration can be simplified to uniform vibration, such as... Figure 5 As shown.

[0064] Taking the upward vibration of the stay cable as an example, that is Figure 5 The vibration in segment a is marked as A. a The current oscillation period is marked as T. a Then the vibration frequency f a =1 / T a At this moment, the upper connecting rod 42 is stretched upward, causing the lower connecting rod 41 to extend, as shown. Figure 3 As shown.

[0065] When the stay cable vibrates upwards to its maximum amplitude, the current amplitude of the stay cable's vibration is... :

[0066]

[0067] At the same time Figure 3 In , , , There is a geometric relationship:

[0068]

[0069]

[0070] Setting parameters This refers to the distance from the anchor point in this invention. for Total length of cable stay The proportion is then:

[0071]

[0072] At this time, the out-of-plane vibration load of the cable stays for:

[0073]

[0074] in, For the flexural stiffness of the stay cable, Let be the out-of-plane deflection generated by the cable vibration at time t, which is solved using the following equation of motion:

[0075]

[0076] in, The initial tension of the stay cable. This represents the tension increment during cable vibration. For the unit weight of the stay cable, It is the acceleration due to gravity. The initial deflection of the stay cable. x This is the length of the stay cable.

[0077] At this point, the torque acting on the gear is as shown in the following formula:

[0078]

[0079] The torque calculation formula for the conductive energy-dissipating rotor 61 in the liquid damper is shown below:

[0080]

[0081] in, The damping coefficient of the damping fluid is denoted as . The density of the damping fluid, The contact area between the conductive energy-consuming rotor 61 and the damping fluid is [missing information]. The width of the conductive energy-dissipating rotor is 61. The angular velocity of the conductive energy-consuming rotor is 61.

[0082] When the input torque is directly transmitted to the rotor, it can be known that That is, the angular velocity of the conductive energy-consuming rotor 61 is:

[0083]

[0084] The coil at the end of the conductive energy-dissipating rotor 61 cuts magnetic field lines to generate an induced current, with the magnetic induction intensity of the magnet 62 as the... B The formula for calculating the induced current is:

[0085]

[0086] When the amplitude of the cable vibration is At that time, peak current I a The calculation formula is as follows:

[0087]

[0088] like Figures 4-5 As shown, when the cable vibrates upwards to its extreme point during process a, it then vibrates downwards. The conductive energy-dissipating rotor 61 rotates in the opposite direction, generating an induced current in the opposite direction. Assuming the current generated during process a is positive, then the corresponding a... b, c The segment generates induced current, such as Figure 6 As shown, the vibration time of process a can be obtained from the duration of the positive current. T a .

[0089] During the monitoring process, it was known that I a and T a The above formula can be used to calculate... A a Similarly, we can find A b 、A c By calculating subsequent amplitudes, the corresponding amplitudes were continuously solved.

[0090] Meanwhile, because gears transmit power loads, losses occur during gear meshing during vibration, and these losses increase year by year with usage time, reducing the transmission ratio. This leads to a decrease in the rotational speed of the conductive energy-dissipating rotor 61 in the liquid damper formed by the damping box 10, resulting in a smaller current sensed by the current sensor 63 and affecting normal operation. Therefore, a current amplification factor is proposed here. This coefficient varies with the service life of the stay cables. It increases with the increase of, specifically:

[0091]

[0092] In the formula, This represents the power during the vibration of the cable-stayed bridge. The power loss due to meshing consumption caused by the gear's increased usage time is calculated using the following formula.

[0093]

[0094]

[0095]

[0096]

[0097] in,

[0098] Current correction peak value of current sensor 63 The result adjusted for usage time shall prevail, that is:

[0099]

[0100] Example 1:

[0101] All parameters in Embodiment 1 of the present invention are shown in Table 1 below:

[0102] Table 1

[0103]

[0104] Meanwhile, the time-related gear wear correction factor varies with the service life as shown in Table 2 below:

[0105] Table 2

[0106]

[0107] The calculation process can be obtained using the parameters mentioned above, as shown below:

[0108] Based on the above parameters, the peak value of the current input to the current sensor can be obtained. :

[0109] =35.926A.

[0110] Assuming the invention is used for one year, the current amplification factor of the current sensor can be obtained. :

[0111] =1.000506.

[0112] The current correction peak value of the current sensor under the above parameters can be obtained after one year of use of the invention. :

[0113] =35.944A.

[0114] What will be obtained in the end The current limit threshold of the stay cable under the pre-set limiting amplitude Comparison: When When the amplitude exceeds the cable's limit in a single monitoring instance, an early warning alarm should be triggered to notify maintenance personnel to perform necessary maintenance and prevent potential accidents. Alternatively, depending on the site conditions, a specific number of instances exceeding the limit can be used before issuing a direct alarm; this will not be elaborated upon here. If the amplitude does not exceed the cable's limit, the monitoring process continues until an alarm is triggered or the cable reaches its rated service life, at which point maintenance should be performed.

[0115] Of course, those skilled in the art will recognize that the present invention is not limited to the details of the exemplary embodiments described above, but also includes the same or similar structures that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0116] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0117] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A device for out-of-plane vibration damping and warning for a stay cable, characterized in that: The damping box (10) is fixed to the base surface, and a rotating shaft (20) is coaxially arranged in the cylinder cavity of the damping box (10); a large gear (31) is coaxially fixed to the end of the rotating shaft (20); an inner gear ring (33) is arranged at the wall of the cylinder cavity of the damping box (10); a small gear (32) is arranged between the outer gear of the large gear (31) and the inner gear of the inner gear ring (33) to connect each other, so that the large gear (31), the small gear (32) and the inner gear ring (33) together form a planetary gear system; the rotating shaft (20) extends radially to have a lower connecting rod (41), and the extension section of the lower connecting rod (41) is hinged to an upper connecting rod (42), and the upper connecting rod (42) is hinged to a connecting block (50) fixed on a stay cable; the axis of each hinge is parallel to the axis of the rotating shaft (20); The rotating shaft (20) is further provided with a conductive energy consumption rotor (61), and each energy consumption rotor (61) is insulated from the rotating shaft (20); in the axial direction of the rotating shaft (20), the cylinder cavity space between adjacent conductive energy consumption rotors (61) is filled with damping liquid; the both ends of the rotating shaft (20) are further provided with a magnet (62) for cutting the magnetic induction lines of the conductive energy consumption rotor (61), and the amount of current generated after cutting the magnetic induction lines is obtained through a current sensor (63).

2. The out-of-plane vibration warning device for a stay cable according to claim 1, characterized in that: The middle section of the damping box (10) is isolated by a sealing plate (10a), thereby forming two groups of symmetrically distributed sub-boxes (11) coaxial with each other and having an axial gap; the lower connecting rod (41) is fixed to a section of the rotating shaft (20) shaft in the axial gap; the planetary gear system is divided into two groups and arranged at the adjacent surfaces of the two groups of sub-boxes (11).

3. The out-of-plane vibration warning device for a stay cable according to claim 1 or 2, characterized in that: The connecting block (50) is a half-joint type buckle; the side of the connecting block (50) facing the damping box (10) is provided with a connecting shaft (51); the end of the upper connecting rod (42) is sleeved on the connecting shaft (51), thereby forming the hinged connection of the two.

4. The out-of-plane vibration warning device for a stay cable according to claim 1 or 2, characterized in that: The length of the lower connecting rod (41) is less than the length of the upper connecting rod (42).

5. The out-of-plane vibration warning device for a stay cable according to claim 1 or 2, characterized in that: The rotating shaft (20) is an insulating shaft, and the conductive energy consumption rotor (61) is a metal material that can conduct electricity.

6. A method for early warning, the method for early warning applying the device for early warning of damping out of plane of a stay cable according to claim 1, characterized in that The method comprises the following steps: S1, the following formula calculates the current peak value of the current sensor (63) I a : Wherein: B B is the magnetic induction strength of the magnet (62); l 2 L is the length of the upper link (42); When the rotating shaft (20) is arranged in a horizontal state, the upper connecting rod (42) and the lower connecting rod (41) make angles of β and α with a reference plane coinciding with the axis of the two connecting rod hinges, respectively. C v D is the damping coefficient of the damping fluid; ρ D is the density of the damping fluid; A A is the contact area of the electrically conductive energy-consuming rotor (61) with the damping liquid; r W is the width of the conductive energy-consuming rotor (61); f u out-of-plane vibration load for the stay cable; S2, the current amplification factor is calculated by the following formula : Wherein: ; t for; EI is the cable sag stiffness; is t out-of-plane deflection generated by the cable vibration; ; is the meshing friction factor of the large gear (31) and the pinion (32) in the planetary gear train; is the meshing friction factor of the pinion (32) and the ring gear (33); is the torque of the pinion (32), is the rotational speed of the pinion (32), is the helix angle on the pitch circle, is the gear wear correction factor related to the time of use of the invention, is the sliding ratio at the meshing-in, is the sliding ratio at the meshing-out; is the face meshing angle; ; N is the number of teeth of the large gear (31), n is the number of teeth of the small gear (32), R is the addendum radius of the large gear (31), r is the pitch radius of the large gear (31). ; is the addendum radius of the pinion (32), is the pitch radius of the pinion (32); S3, the following formula calculates the current correction peak value of the current sensor (63) : S4, setting a current limit threshold for the stay cable at the limit amplitude When it is indicated that the limit amplitude of the stay cable is exceeded, a warning is triggered.

7. The early warning method of claim 6, wherein: Out-of-plane vibration loads of a stay cable f u The following formula is calculated: wherein is the cable sag stiffness, is the out-of-plane deflection of the cable at time t, which is solved by the following equation of motion: T0is the initial tension of the stay cable, ΔΤ is the increment of the tension of the stay cable when it vibrates, ρ is the unit weight of the stay cable, g is the acceleration of gravity, δ0is the initial deflection of the stay cable, L is the length of the stay cable.

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