Mechanical damping control device for ultralow-frequency vortex-induced vibration of large-span bridge girder

Abstract

The invention relates to a mechanical damping control device for ultralow-frequency vortex-induced vibration of a large-span bridge girder, and belongs to the field of bridge structure vortex-induced vibration control. Comprising a horizontal guide rail, a vertical guide rail, a horizontal guide rail support, a vertical guide rail support, two groups of connecting rods, a vertical mass block, a horizontal mass block, a vertical elastic spring, a horizontal spring, a vertical viscous damper and a horizontal viscous damper, the right end of the horizontal mass block is hinged to the right end of the first connecting rod, the right end of the second connecting rod is hinged to the middle of the first connecting rod, and when the static elongation of the vertical spring is zero, the horizontal spring is in a compressed state; when vortex-induced vibration occurs, transmitted energy is dissipated through the vertical tuned mass damper and the horizontal tuned mass damper, and therefore control over the vortex-induced vibration is achieved. The spring static elongation of the low-frequency vertical vibration reduction tuned mass damper can be remarkably reduced, and the defect that an existing damper is large in occupied space is overcome.

Description

Technical Field

[0001] The invention belongs to the field of vortex-induced vibration control of bridge structures, and in particular relates to a mechanical damping control device for ultra-low frequency vortex-induced vibration of a main beam of a large-span bridge. Background Art

[0002] Because the modes of super-long span bridges are dense, there are more potential modes of vortex vibration under wind speed, and the risk of vortex vibration is also higher. Therefore, it is of great significance to control the vortex-induced vibration of the main beam of a large-span bridge during service. According to the currently published research results, the control methods of vortex-induced vibration of the main beam of a large-span bridge mainly include two types of methods. One method is pneumatic control measures, which can directly reduce the force acting on the structure. For example, wind nozzles, guide plates and auxiliary device adjustment are installed at both ends of the main beam section. The other method is mechanical damping control measures. The tuned mass damper (TMD) is currently widely used in bridges. TMD consists of a mass block, a spring and a liquid viscous damper. By tuning the frequency of TMD to the vicinity of the vortex-induced vibration frequency, it can resonate with the main beam, and then dissipate the energy absorbed by the resonance through the damper. Although TMD has a good control effect, for super-long span bridges, box girders are often used as main beams and ultra-low frequency vortex-induced vibration occurs. The tuning frequency of TMD is too small, resulting in a large static elongation, and the equipment installation is extremely inconvenient and complicated. Therefore, it is necessary to provide a novel bidirectional tuned mass damper device based on a connecting rod mechanism to solve the above technical problems. Summary of the invention

[0003] Based on the above shortcomings, the purpose of the present invention is to provide a mechanical damping control device for ultra-low frequency vortex-induced vibration of the main beam of a large-span bridge, which can significantly reduce the static elongation of the spring of the low-frequency vertical vibration-damping tuned mass damper, overcome the shortcomings of the existing low-frequency vertical vibration-damping tuned mass damper that occupies a large space and has a high installation cost, and at the same time avoid the performance degradation problem caused by the large static elongation of the spring.

[0004] The technical solution adopted by the present invention is as follows: a mechanical damping control device for ultra-low frequency vortex-induced vibration of a main beam of a long-span bridge, comprising a horizontal guide rail, a vertical guide rail, a horizontal guide rail support, a vertical guide rail support, a first connecting rod, a second connecting rod, a vertical mass block, a vertical spring, a vertical viscous damper, a horizontal mass block, a horizontal spring and a horizontal viscous damper,

[0005] The horizontal guide rail is horizontally fixed inside the main beam box girder through the horizontal guide rail support, the upper end of the vertical guide rail support is fixedly connected to the lower surface of the top plate of the main beam box girder, the lower end of the horizontal guide rail support is fixedly connected to the upper surface of the bottom plate of the main beam box girder, and the vertical guide rail is vertically fixed inside the main beam box girder through the vertical guide rail support.

[0006] The vertical spring, vertical viscous damper and vertical mass block constitute a vertical tuned mass damper. The vertical spring and vertical viscous damper are placed vertically side by side. The upper end of the vertical spring is fixedly connected to the lower surface of the top plate of the main beam box girder, the lower end of the vertical spring is fixedly connected to the upper plane of the vertical mass block, the upper end of the vertical viscous damper is fixedly connected to the lower surface of the top plate of the main beam box girder, the lower end of the vertical viscous damper is fixedly connected to the upper plane of the vertical mass block, and the vertical mass block is slidably connected to the vertical guide rail;

[0007] The horizontal spring, horizontal viscous damper and horizontal mass block constitute a horizontal tuned mass damper, the horizontal spring and the horizontal viscous damper are placed horizontally in parallel, the right end of the horizontal guide rail is fixedly connected with a right baffle, the right end of the horizontal spring is fixedly connected to the right baffle, the left end of the horizontal spring is fixedly connected to the right wall of the horizontal mass block, the right end of the horizontal viscous damper is fixedly connected to the right baffle, the left end of the horizontal viscous damper is fixedly connected to the right wall of the horizontal mass block, and the horizontal mass block is slidably connected to the horizontal guide rail;

[0008] The intersection point of the horizontal guide rail and the vertical guide rail is point O, and the length of the first connecting rod is twice the length of the second connecting rod; the lower end of the vertical mass block is hinged to the left end of the first connecting rod, and the hinge point is point A; the right end of the horizontal mass block is hinged to the right end of the first connecting rod, and the hinge point is point B; the right end of the second connecting rod is hinged to the middle of the first connecting rod, and the hinge point is point C; the left end of the second connecting rod is hinged at point O, and the three points AOB form a right triangle. When the static elongation of the vertical spring is 0, the horizontal spring is in a compressed state; when vortex-induced vibration occurs, the transmitted energy is dissipated through the vertical and horizontal tuned mass dampers, thereby realizing vortex-induced vibration control of large-span bridges.

[0009] Another object of the present invention is to provide a method for optimizing parameters of a mechanical damping control device for ultra-low frequency vortex-induced vibration of a main beam of a long-span bridge as described above, the steps of which are as follows:

[0010] S1: Determine the installation space of the damping control device according to the internal structural dimensions of the main beam and box beam: the length of the vertical spring itself, the static elongation of the vertical spring x 10 , the maximum downward stroke during the vibration of the vertical spring, and the initial vertical projection length l1 of the first connecting rod, that is, the range of the maximum vertical length of the damping control device; similarly determine: the initial horizontal projection length l2 of the first connecting rod, the static compression amount x of the horizontal spring 20 , the length of the horizontal spring itself, that is, the range of the maximum length of the damping control device in the horizontal direction;

[0011] S2: After determining the maximum length that the damping control device can occupy in the vertical and horizontal directions, the constraint conditions are calculated. According to the static equilibrium equation of the vibration reduction device, the static extension / compression of the vertical and horizontal springs satisfies the following relationship:

[0012] m1g-k1x 10 =k2x 20 tanθ (1)

[0013] Where m1 is the mass of the vertical mass block; g is the acceleration of gravity; k1 is the stiffness of the vertical spring; k2 is the stiffness of the horizontal spring; θ is the initial angle between the first link and the horizontal direction,

[0014] From equation (1), it can be concluded that increasing the stiffness k2 of the horizontal spring and reducing the mass m1 of the vertical mass block can effectively reduce the static extension x of the vertical spring. 10 The static compression x of the horizontal spring 20 , static extension of vertical spring x 10 The static compression x of the horizontal spring 20 The range of is determined by engineering requirements, thereby obtaining the constraints of the mass m1 of the vertical mass block, the stiffness k2 of the horizontal spring and the initial angle θ in the horizontal direction of the first connecting rod. The vibration control equation of the damping control device is shown in equations (2)-(3):

[0015]

[0016] Where m is the mass of the controlled structure; Y is the vertical displacement of the controlled structure; d is the inherent damping of the controlled structure; k is the inherent stiffness of the controlled structure; θ is the initial angle between the first link and the horizontal direction; d1 is the damping coefficient of the vertical damper; d2 is the damping coefficient of the horizontal damper; l is the length of the first link; F VIV is the vortex excitation force; l1 is the initial vertical projection length of the first connecting rod, l2 is the initial horizontal projection length of the first connecting rod;

[0017] S3: Solve the vibration control equation. The solution results include the response time history curve of the controlled structure under the control of the damping control device. By comparing the vibration time history curves of the structure under controlled and uncontrolled conditions at a certain vortex vibration wind speed, the vibration control effect η of the damper, i.e., the vibration reduction rate, is obtained.

[0018] η=(RMS s -RMS t ) / RMS s ×100% (4)

[0019] Where, RMS s RMS is the root mean square value of displacement in the vortex-vibration stable stage of the uncontrolled structure; tis the RMS value of displacement of the controlled structure in the vortex-vibration stable stage;

[0020] S4: Optimize and design the control parameters of the damping control device: By taking the vibration control effect η of the structure as the objective function and setting constraints on the mass m1 of the vertical mass block, the stiffness k2 of the horizontal spring and the initial angle θ of the first connecting rod, a genetic algorithm is used to find the global optimal value of the control parameters of the device.

[0021] Compared with the prior art, the present invention has the following beneficial effects: the present invention has a simple structure and a clear vibration reduction principle. Through two sets of connecting rod mechanisms, the gravity that the vertical spring should originally bear is effectively transferred to the horizontal spring for bearing, and the characteristics of the large width direction of the internal space of the box girder of a large-span bridge are cleverly utilized. Through the vertical and horizontal guide rail mechanisms, the accuracy of the movement direction of the mass block and the connecting rod mechanism during movement and the stability of the speed transmission between the two mass blocks are guaranteed, while the vibration reduction capacity of the entire system is also guaranteed. The present invention can also realize the control of vortex-induced vibration in the torsional direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the arrangement of the damping control device of the present invention in a bridge box girder;

[0023] Figure 2 It is a comparison diagram of the vortex vibration time history curves under controlled and uncontrolled conditions of the segment model;

[0024] Figure 3 It is a displacement time history comparison diagram of the damping control device of the present invention and the traditional vertical TMD;

[0025] Figure 4 It is the vibration reduction rate of the damping control device of the present invention at different segment model frequencies. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] Example 1

[0028] Combination Figure 1 The present embodiment provides a mechanical damping control device for ultra-low frequency vortex-induced vibration of a main beam of a long-span bridge, comprising a horizontal guide rail 2, a vertical guide rail 3, a horizontal guide rail support 4, a vertical guide rail support 5, a first connecting rod 6, a second connecting rod 14, a vertical mass block 8, a vertical spring 9, a vertical viscous damper 10, a horizontal mass block 11, a horizontal spring 12 and a horizontal viscous damper 13, characterized in that:

[0029] The horizontal guide rail 2 is horizontally fixed to the inside of the main beam box girder 1 through the horizontal guide rail support 4, the upper end of the vertical guide rail support 5 is fixedly connected to the lower surface of the top plate of the main beam box girder 1, the lower end of the horizontal guide rail support 4 is fixedly connected to the upper surface of the bottom plate of the main beam box girder 1, and the vertical guide rail 3 is vertically fixed to the inside of the main beam box girder 1 through the vertical guide rail support 5.

[0030] The vertical spring 9, the vertical viscous damper 10 and the vertical mass block 8 constitute a vertical tuned mass damper. The vertical spring 9 and the vertical viscous damper 10 are placed vertically side by side. The upper end of the vertical spring 9 is fixedly connected to the lower surface of the top plate of the main beam box girder 1, the lower end of the vertical spring 9 is fixedly connected to the upper plane of the vertical mass block 8, the upper end of the vertical viscous damper 10 is fixedly connected to the lower surface of the top plate of the main beam box girder 1, the lower end of the vertical viscous damper 10 is fixedly connected to the upper plane of the vertical mass block 8, and the vertical mass block 8 is slidably connected to the vertical guide rail 3;

[0031] The horizontal spring 12, the horizontal viscous damper 13 and the horizontal mass block 11 constitute a horizontal tuned mass damper. The horizontal spring 12 and the horizontal viscous damper 13 are placed horizontally in parallel. The right end of the horizontal guide rail 2 is fixedly connected with the right baffle plate 7. The right end of the horizontal spring 12 is fixedly connected to the right baffle plate 7. The left end of the horizontal spring 12 is fixedly connected to the right wall of the horizontal mass block 11. The right end of the horizontal viscous damper 13 is fixedly connected to the right baffle plate 7. The left end of the horizontal viscous damper 13 is fixedly connected to the right wall of the horizontal mass block 11. The horizontal mass block 11 is slidably connected to the horizontal guide rail 2.

[0032] The intersection point of the horizontal guide rail 2 and the vertical guide rail 3 is point O, and the length of the first connecting rod 6 is twice the length of the second connecting rod 14; the lower end of the vertical mass block 8 is hinged to the left end of the first connecting rod 6, and the hinge point is point A, the right end of the horizontal mass block 11 is hinged to the right end of the first connecting rod 6, and the hinge point is point B, the right end of the second connecting rod 14 is hinged to the middle of the first connecting rod 6, and the hinge point is point C, and the left end of the second connecting rod 14 is hinged at point O, and the three points AOB form a right triangle. When the static elongation of the vertical spring 9 is 0, the horizontal spring 12 is in a compressed state; when vortex-induced vibration occurs, the transmitted energy is dissipated through the vertical and horizontal tuned mass dampers, thereby realizing vortex-induced vibration control of large-span bridges.

[0033] This embodiment aims to solve the problem of excessive static elongation of TMD during ultra-low frequency vortex-induced vibration control of long-span bridges. Two sets of connecting rods are used to transfer the gravity of the vertical mass block to the horizontal spring. The static elongation of the vertical spring can be set to 0 by adjusting the mass block m1, stiffness k2 and the initial angle θ of the connecting rod. At this time, the horizontal spring is in a compressed state. According to the actual size of the internal structure of the box girder, the box girder of a long-span bridge is generally 3-5m high and 30-40m wide. Even considering the longitudinal partition inside the box girder, there is still a width of about 6m in the beam width direction. The actual available space in the direction of the bridge cross section is an important constraint for the parameter design of the new mechanical damping device. When vortex-induced vibration (including torsion and vertical) occurs in a long-span bridge, the vertical mass block will cause movement. Due to the lag of the vertical mass block compared to the vertical vibration of the bridge, there is a speed difference between the two. At the same time, since the horizontal mass block is installed on the horizontal guide rail, it is believed that the vertical speed of the horizontal mass block and the bridge is consistent at this time. Therefore, a vertical speed difference will be generated at both ends of the connecting rod, causing the connecting rod to move in the plane. During the movement of the system composed of the connecting rod and the two mass blocks, resonance occurs with the bridge to achieve energy transfer, and the transferred energy is dissipated by the vertical and horizontal dampers, thereby realizing vortex-induced vibration control of large-span bridges.

[0034] Example 2

[0035] This embodiment provides a method for optimizing parameters of the damping control device described in the embodiment, and the method steps are as follows:

[0036] S1: Determine the installation space of the damping control device according to the internal structural dimensions of the main beam and box beam 1: the length of the vertical spring 9 itself, the static elongation of the vertical spring 9 x 10 , the maximum downward stroke of the vertical spring 9 during vibration, and the initial vertical projection length l1 of the first connecting rod 6, that is, the range of the maximum vertical length of the damping control device; similarly determine: the initial horizontal projection length l2 of the first connecting rod 6, the static compression amount x of the horizontal spring 12 20 , the length of the horizontal spring 12 itself, that is, the range of the maximum length of the damping control device in the horizontal direction;

[0037] S2: After determining the maximum length that the damping control device can occupy in the vertical and horizontal directions, the constraint conditions are calculated. According to the static equilibrium equation of the vibration reduction device, the static extension / compression of the vertical and horizontal springs satisfies the following relationship:

[0038] m1g-k1x 10 =k2x 20 tanθ (1)

[0039] Wherein, m1 is the mass of the vertical mass block 8; g is the acceleration of gravity; k1 is the stiffness of the vertical spring 9; k2 is the stiffness of the horizontal spring 12; θ is the initial angle between the first connecting rod 6 and the horizontal direction,

[0040] From equation (1), it can be concluded that increasing the stiffness k2 of the horizontal spring 12 and reducing the mass m1 of the vertical mass block 8 can effectively reduce the static extension x of the vertical spring 9. 10 The static compression x of the horizontal spring 12 20 , the static extension x of the vertical spring 9 10 The static compression x of the horizontal spring 12 20 The range of is determined by engineering requirements, thereby obtaining the constraint conditions of the mass m1 of the vertical mass block 8, the stiffness k2 of the horizontal spring 12 and the initial angle θ in the horizontal direction of the first connecting rod 6. The vibration control equation of the damping control device is shown in equations (2)-(3):

[0041]

[0042]

[0043] Wherein, m is the mass of the controlled structure; Y is the vertical displacement of the controlled structure; d is the inherent damping of the controlled structure; k is the inherent stiffness of the controlled structure; θ is the initial angle between the first connecting rod 6 and the horizontal direction; d1 is the damping coefficient of the vertical damper; d2 is the damping coefficient of the horizontal damper; l is the length of the first connecting rod 6; F VIV is the vortex excitation force; l1 is the initial vertical projection length of the first connecting rod 6, and l2 is the initial horizontal projection length of the first connecting rod 6;

[0044] S3: Solve the vibration control equation. The solution results include the response time history curve of the controlled structure under the control of the damping control device. By comparing the vibration time history curves of the structure under controlled and uncontrolled conditions at a certain vortex vibration wind speed, the vibration control effect η of the damper, i.e., the vibration reduction rate, is obtained.

[0045] η=(RMS s -RMS t ) / RMS s ×100% (4)

[0046] Where, RMS s is the root mean square value of the displacement of the uncontrolled structure in the vortex vibration stability stage, RMS t is the RMS value of displacement of the controlled structure in the vortex-vibration stable stage;

[0047] S4: Optimize and design the control parameters of the damping control device: take the vibration control effect η of the structure as the objective function, and set constraints on the mass m1 of the vertical mass block 8, the stiffness k2 of the horizontal spring 12 and the initial angle θ of the first connecting rod 6, and use optimization algorithms such as genetic algorithms to find the global optimal values ​​of the control parameters of the device, such as θ, k1, k2, d1, and d2.

[0048] Example 3

[0049] At present, two-dimensional theoretical modeling and numerical calculation have been carried out on the segment model of a certain long-span bridge installed with the damping control device of the present invention. The following is the whole process of parameter optimization design of the new damper based on the segment model: First, the total mass of the segment model is 165.5kg, the mass per unit length is 45.97kg / m, and the natural frequency of the segment model is 4.358Hz. The wind speed ratio designed according to the wind tunnel test is converted to 0.23Hz for the original bridge, and the incoming wind speed of the wind tunnel test is 5.62m / s, which is converted to about 5.92m / s for the actual bridge. It can be seen from this that if a traditional vertical tuned mass damper is used to control this order of vortex-induced vibration, the static elongation of the TMD will be approximately g / ω 2 =4.7m, which obviously exceeds the bridge beam height of 3.5m and is difficult for common industrial springs to reach such a high elongation. If the damping control device of the present invention is adopted, first, according to formula (1), x 10 = 0, then x 20 =m1g / k2tanθ, it can be seen that the static compression of the horizontal spring is related to the mass m1 of the vertical mass block 8, the stiffness k2 of the horizontal spring 12, and the initial angle θ between the first connecting rod 6 and the horizontal direction. Compared with the static extension of the traditional vertical TMD, x 20 =m1ω 2 l2 / ω2l1×(g / ω 2 ), so the static compression of the horizontal spring 13 is the static extension of the traditional vertical TMD (m1ω 2 l2) / (k2l1) times. Since the static elongation of the traditional vertical TMD is about 4.7m, (m1ω 2 l2) / (k2l1)<0.4 is used as a constraint condition for the optimal design of the control parameters. Under this constraint condition, the static compression of the designed horizontal spring 12 is less than 1.88m. In a real bridge environment, the frequency and damping ratio of the bridge will show randomness over time, so the robustness design of the damping control device is also very important. In this example, the Monte Carlo simulation method was used to simulate the frequency values ​​within the natural frequency range of the ±5% segment model, and the vortex-vibration displacement time history curves of the controlled bridge at these frequency values ​​were calculated, and the vibration reduction rate η of each simulation result was recorded. The robustness index of the damper is represented by R: R=αμη +(1-α)σ η , where α is the weight coefficient, μ η is the mean value of the vibration reduction rate η of several test results obtained by Monte Carlo simulation, σ η is the standard deviation of the vibration reduction rate η of several test results. In this example, α=0.5 is selected, and R is used as the objective function of the genetic algorithm, k1, k2, d1, and d2 are used as optimization parameters, and m1ω is used as the optimization parameter. 2 l2 / k2l1<0.4 is used as a constraint condition, and the total mass ratio of the new damper is set to μ=0.8%, m2=2m1, l2 / l1=4. The following results can be obtained:

[0050] The parameters obtained by genetic algorithm optimization are as follows: the stiffness coefficient of the horizontal spring 12 is k2=1083.23N / m, the stiffness coefficient of the vertical spring is k1=35.8N / m, the damping coefficient of the vertical damper 10 and the horizontal damper 13 is d1=d2=0.25Ns / m, the calculated damping rate of the damper is η=99.9% (calculated according to the actual stiffness and damping of the segment model), the robustness index R=0.4238 (the stiffness of the variable segment model is obtained through Monte Carlo simulation), m1ω 2 l2 / k2l1=0.34<0.4, which is converted to the static compression of the horizontal spring of the real bridge is only 1.6m, which greatly reduces the static extension of the spring compared with the traditional TMD. The above results show that by optimizing the control parameters through genetic algorithm, the static extension of the vertical spring can be reduced to 0, and the static compression of the horizontal spring can be reduced to about 1 / 3 of the static extension of the traditional TMD under the same conditions, and the vertical vortex-induced vibration of the bridge can be effectively controlled.

[0051] like Figure 2 The figure shows the comparison between the vortex displacement time history curve of the segment model under the control of the damping control device under the optimal control parameters calculated by the genetic algorithm and the traditional vertical TMD control designed according to the optimal parameters and without control. Figure 3 The displacement changes of the new damper and the traditional vertical TMD during vibration control are shown in Figure 2. Figure 4 The figure shows how the system's damping rate η changes with frequency when the frequency (stiffness) of the segment model is changed. Figure 2 It can be seen from the figure that the vortex displacement of the segment model under the control of the damping control device of the present invention is completely controlled, and the control effect is not much different from that of the traditional vertical TMD. Figure 3 It can be seen from the figure that during the vibration control of the two controllers, the vibration stroke of the vertical mass block 8 and the horizontal mass block 11 of the damping control device of the present invention are smaller than the vibration stroke of the traditional TMD during the entire vibration process. Figure 4It can be seen that when the segment model frequency changes within ±2.5%, the control effect of the damping control device of the present invention remains basically unchanged, but when the segment model frequency changes too much, the control effect will be affected to a certain extent. By changing the form of the horizontal tuned mass damper, such as replacing the mass block with a water tank, or installing multiple damping control devices with similar frequencies in the bridge, the robustness of the new damper device can be effectively improved.

[0052] Therefore, the damping control device of the present invention can significantly reduce the static elongation of the spring of the low-frequency vertical vibration-damping tuned mass damper, overcome the shortcomings of the existing low-frequency vertical vibration-damping tuned mass damper that occupies a large space and has a high installation cost, and at the same time avoid the performance degradation problem caused by the large static elongation of the spring.

Claims

1. A mechanical damping control device for ultra-low frequency vortex-induced vibration of a main beam of a long-span bridge, comprising a horizontal guide rail (2), a vertical guide rail (3), a horizontal guide rail support (4), a vertical guide rail support (5), a first connecting rod (6), a second connecting rod (14), a vertical mass block (8), a vertical spring (9), a vertical viscous damper (10), a horizontal mass block (11), a horizontal spring (12) and a horizontal viscous damper (13), characterized in that: The horizontal guide rail (2) is horizontally fixed inside the main beam box girder (1) through the horizontal guide rail support (4), the upper end of the vertical guide rail support (5) is fixedly connected to the lower surface of the top plate of the main beam box girder (1), the lower end of the horizontal guide rail support (4) is fixedly connected to the upper surface of the bottom plate of the main beam box girder (1), and the vertical guide rail (3) is vertically fixed inside the main beam box girder (1) through the vertical guide rail support (5); The vertical spring (9), the vertical viscous damper (10) and the vertical mass block (8) constitute a vertical tuned mass damper. The vertical spring (9) and the vertical viscous damper (10) are placed vertically side by side. The upper end of the vertical spring (9) is fixedly connected to the lower surface of the top plate of the main beam box girder (1), the lower end of the vertical spring (9) is fixedly connected to the upper plane of the vertical mass block (8), the upper end of the vertical viscous damper (10) is fixedly connected to the lower surface of the top plate of the main beam box girder (1), the lower end of the vertical viscous damper (10) is fixedly connected to the upper plane of the vertical mass block (8), and the vertical mass block (8) is slidably connected to the vertical guide rail (3); The horizontal spring (12), the horizontal viscous damper (13) and the horizontal mass block (11) constitute a horizontal tuned mass damper. The horizontal spring (12) and the horizontal viscous damper (13) are placed horizontally in parallel. The right end of the horizontal guide rail (2) is fixedly connected to the right baffle plate 7. The right end of the horizontal spring (12) is fixedly connected to the right baffle plate 7. The left end of the horizontal spring (12) is fixedly connected to the right wall surface of the horizontal mass block (11). The right end of the horizontal viscous damper (13) is fixedly connected to the right baffle plate 7. The left end of the horizontal viscous damper (13) is fixedly connected to the right wall surface of the horizontal mass block (11). The horizontal mass block (11) is slidably connected to the horizontal guide rail (2). The intersection point of the horizontal guide rail (2) and the vertical guide rail (3) is point O, and the length of the first connecting rod (6) is twice the length of the second connecting rod (14); the lower end of the vertical mass block (8) is hinged to the left end of the first connecting rod (6), and the hinge point is point A; the right end of the horizontal mass block (11) is hinged to the right end of the first connecting rod (6), and the hinge point is point B; the right end of the second connecting rod (14) is hinged to the middle of the first connecting rod (6), and the hinge point is point C; the left end of the second connecting rod (14) is hinged at point O, and the three points AOB form a right triangle. When the static elongation of the vertical spring (9) is 0, the horizontal spring (12) is in a compressed state; when vortex-induced vibration occurs, the transmitted energy is dissipated through the vertical and horizontal tuned mass dampers, thereby realizing vortex-induced vibration control of large-span bridges.

2. The parameter optimization method of a mechanical damping control device for ultra-low frequency vortex-induced vibration of a long-span bridge main beam according to claim 1 is characterized in that: The steps are as follows: S1: Determine the installation space of the damping control device according to the internal structural dimensions of the main beam and box beam (1): the length of the vertical spring (9), the static elongation of the vertical spring (9) x 10 , the maximum downward stroke of the vertical spring (9) during vibration, and the initial vertical projection length l1 of the first connecting rod (6), that is, the range of the maximum vertical length of the damping control device; similarly, determine: the initial horizontal projection length l2 of the first connecting rod (6), the static compression amount x of the horizontal spring (12) 20 , the length of the horizontal spring (12) itself, that is, the range of the maximum length of the damping control device in the horizontal direction; S2: After determining the maximum length that the damping control device can occupy in the vertical and horizontal directions, the constraint conditions are calculated. According to the static equilibrium equation of the vibration reduction device, the static extension / compression of the vertical and horizontal springs satisfies the following relationship: m1g-k1x 10 =k2x 20 tanθ (1) Wherein, m1 is the mass of the vertical mass block (8); g is the acceleration due to gravity; k1 is the stiffness of the vertical spring (9); k2 is the stiffness of the horizontal spring (12); θ is the initial angle between the first link (6) and the horizontal direction, From equation (1), it can be concluded that increasing the stiffness k2 of the horizontal spring (12) and reducing the mass m1 of the vertical mass block (8) can effectively reduce the static elongation x of the vertical spring (9): 10 The static compression x of the horizontal spring (12) 20 , the static extension x of the vertical spring (9) 10 The static compression x of the horizontal spring (12) 20 The range of is determined by engineering requirements, thereby obtaining the constraint conditions of the mass m1 of the vertical mass block (8), the stiffness k2 of the horizontal spring (12) and the initial angle θ of the first connecting rod (6) in the horizontal direction. The vibration control equation of the damping control device is shown in equations (2)-(3): Wherein, m is the mass of the controlled structure; Y is the vertical displacement of the controlled structure; d is the inherent damping of the controlled structure; k is the inherent stiffness of the controlled structure; θ is the initial angle between the first connecting rod (6) and the horizontal direction; d1 is the damping coefficient of the vertical damper; d2 is the damping coefficient of the horizontal damper; l is the length of the first connecting rod (6); F VIV is the vortex excitation force; l1 is the initial vertical projection length of the first connecting rod (6), and l2 is the initial horizontal projection length of the first connecting rod (6); S3: Solve the vibration control equation. The solution results include the response time history curve of the controlled structure under the control of the damping control device. By comparing the vibration time history curves of the structure under controlled and uncontrolled conditions at a certain vortex vibration wind speed, the vibration control effect η of the damper, i.e., the vibration reduction rate, is obtained. η=(RMS s -RMS t ) / RMS s ×100% (4) Where, RMS s RMS is the root mean square value of displacement in the vortex-vibration stable stage of the uncontrolled structure; t is the RMS value of displacement of the controlled structure in the vortex-vibration stable stage; S4: Optimizing and designing the control parameters of the damping control device: taking the vibration control effect η of the structure as the objective function and setting constraints on the mass m1 of the vertical mass block (8), the stiffness k2 of the horizontal spring (12) and the initial angle θ of the first connecting rod (6), a genetic algorithm is used to find the global optimal value of the control parameters of the device.

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