Mechanical damping control device for super-low frequency vortex-induced vibration of main girder of long-span bridge

Abstract

The present application relates to a kind of large-span bridge girder ultra-low frequency vortex-induced vibration mechanical damping control device, belong to bridge structure vortex-induced vibration control field.The present application includes horizontal and vertical guide rail, horizontal and vertical guide rail support, two groups of connecting rods, vertical and horizontal mass, vertical and horizontal spring, vertical and horizontal viscous damper, spring, viscous damper and mass constitute tuned mass damper, the lower end of vertical mass is hinged with the left end of first connecting rod, the right end of horizontal mass is hinged with the right end of first connecting rod, the right end of second connecting rod is hinged with the middle of first connecting rod, when the static elongation of vertical spring is 0, at this time, horizontal spring is compression state;When vortex-induced vibration occurs, the energy transferred is dissipated by vertical and horizontal tuned mass damper, to realize the control of vortex-induced vibration.The present application can significantly reduce the spring static elongation of low-frequency vertical vibration reduction tuned mass damper, overcome the shortcoming that existing damper occupies large space.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of bridge structure vortex-induced vibration control, and particularly relates to a mechanical damping control device for super-low-frequency vortex-induced vibration of a large-span bridge girder. BACKGROUND

[0002] Due to the modal density of super-large-span bridges, more potential modalities of vortex vibration may occur under the common wind speed, and the vortex vibration risk is higher. Therefore, it is of great significance to control the vortex-induced vibration of the large-span bridge girder during the service period. According to the current published research results, the control methods for vortex-induced vibration of the large-span bridge girder mainly include two types. One type is the aerodynamic control measure, which can directly reduce the force acting on the structure. For example, wind fairings, guide plates and auxiliary device positioning are installed at both ends of the girder section. The other type is the mechanical damping control measure, and the widely used device in the bridge is the tuned mass damper (TMD). The TMD is composed of a mass block, a spring and a liquid viscous damper. By tuning the frequency of the TMD to the vicinity of the vortex-induced vibration frequency, resonance can occur with the girder, and then the energy absorbed by the resonance is dissipated through the damper. Although the TMD has good control effect, for the super-large-span bridge, the box girder is often used as the main girder and the super-low-frequency vortex-induced vibration occurs. The small tuning frequency of the TMD leads to a large static elongation of the device, and the installation of the device is extremely inconvenient and complex. Therefore, it is necessary to provide a new type of bidirectional tuned mass damper device based on a connecting rod mechanism to solve the above technical problems. SUMMARY

[0003] In view of the above deficiencies, the purpose of the present application is to provide a mechanical damping control device for super-low-frequency vortex-induced vibration of a large-span bridge girder, which can significantly reduce the static elongation of the spring of the low-frequency vertical vibration tuned mass damper, overcome the defects of large space occupation and high installation cost of the existing low-frequency vertical vibration tuned mass damper, and avoid the performance degradation problem caused by the large static elongation of the spring.

[0004] The technical scheme adopted by the present application is as follows: a mechanical damping control device for super-low-frequency vortex-induced vibration of a large-span bridge girder, 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 in the interior of the main girder box through the horizontal guide rail support, the upper end of the vertical guide rail support is fixedly connected with the lower surface of the top plate of the main girder box, the lower end of the horizontal guide rail support is fixedly connected with the upper surface of the bottom plate of the main girder box, and the vertical guide rail is vertically fixed in the interior of the main girder box through the vertical guide rail support,

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

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

[0008] The intersection point of the horizontal guide rail and the vertical guide rail is O point, 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 hingedly connected with the left end of the first connecting rod, the hinging point is A point, the right end of the horizontal mass block is hingedly connected with the right end of the first connecting rod, the hinging point is B point, the right end of the second connecting rod is hingedly connected with the middle of the first connecting rod, the hinging point is C point, and the left end of the second connecting rod is hingedly connected with O point, AOB three points constitute a right-angled triangle, when the static elongation of the vertical spring is 0, the horizontal spring is in a compression state at this time, when vortex-induced vibration occurs, the transferred energy is dissipated through the vertical and horizontal tuned mass dampers, so that the vortex-induced vibration control of the long-span bridge is realized.

[0009] Another object of the present application is to provide a parameter optimization method of the mechanical damping control device for the vortex-induced vibration of the long-span bridge main beam.

[0010] S1: according to the internal structure size of the main beam box girder, the installable space of the damping control device is determined, the vertical spring itself length, the vertical spring static elongation x 10 , the maximum downward stroke in the vertical spring vibration process, the initial vertical projection length l1 of the first connecting rod, so that the maximum length range occupied by the damping control device in the vertical direction is obtained; similarly, the initial horizontal projection length l2 of the first connecting rod, the static compression amount x 20 of the horizontal spring, the horizontal spring itself length, so that the maximum length range occupied by the damping control device in the horizontal direction is obtained;

[0011] S2: After determining the maximum length of the damping control device in the vertical and horizontal directions, the calculation of the constraint condition is carried out, and according to the static force balance equation of the damping device, the static elongation / compression of the vertical and horizontal springs satisfies the following relationship:

[0012] m1g-k1x 10 =k2x 20 tanθ (1)

[0013] In the formula, 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 connecting rod and the horizontal direction,

[0014] From formula (1), increasing the stiffness k2 of the horizontal spring and reducing the mass m1 of the vertical mass block can effectively reduce the static elongation x of the vertical spring 10 and the static compression x of the horizontal spring 20 , the range of the static elongation x of the vertical spring 10 and the static compression x of the horizontal spring 20 is determined by engineering requirements, thereby obtaining the constraint condition of 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 in the horizontal direction, and the vibration control equation of the damping control device is shown in formulas (2)-(3):

[0015]

[0016] In the formula, 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 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; F VIV is the vortex-induced force; l1 is the initial vertical projection length of the first connecting rod, and l2 is the initial horizontal projection length of the first connecting rod;

[0017] S3: Solving the vibration control equation, the solution includes the response time curve of the controlled structure under the control of the damping control device, and by comparing the vibration time curve of the structure under the controlled and uncontrolled conditions at a certain vortex vibration wind speed, the vibration control effect η of the damper, i.e. the damping rate,

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

[0019] In the formula, RMS s is the root mean square value of the displacement of the uncontrolled structure in the vortex vibration stable stage; RMS tThe root mean square value of the displacement in the controlled structural vortex vibration stabilization stage;

[0020] S4: optimizing and designing the control parameters of the damping control device: by taking the vibration control effect of the structure as the objective function, and setting the constraint conditions of 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, the 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 application has the following beneficial effects: the present application has simple structure and clear damping principle, and effectively transmits the gravity originally borne by the vertical spring to the horizontal spring through the two groups of connecting rod mechanisms, and ingeniously utilizes the characteristics of large internal width direction space of the large-span bridge box girder. 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 ensured, and the damping capacity of the whole system is also ensured. The present application can also control the vortex-induced vibration in the torsional direction. BRIEF DESCRIPTION OF DRAWINGS

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

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

[0024] Figure 3 It is a displacement time history comparison graph of the damping control device of the present application and the traditional vertical TMD.

[0025] Figure 4 It is the damping rate of the damping control device of the present application under different segment model frequencies. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with embodiments, and it should be understood that the specific embodiments described here are only used to explain the present application and do not limit the present application.

[0027] Embodiment 1

[0028] In combination Figure 1 , the present embodiment provides a mechanical damping control device for vortex-induced vibration of a large-span bridge girder at ultra-low frequency, which comprises 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 in the main beam box girder 1 by a horizontal guide rail support 4, the upper end of the vertical guide rail support 5 is fixedly connected with 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 with the upper surface of the bottom plate of the main beam box girder 1, the vertical guide rail 3 is vertically fixed in the main beam box girder 1 by 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 with 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 with the upper surface of the vertical mass block 8, the upper end of the vertical viscous damper 10 is fixedly connected with 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 with the upper surface of the vertical mass block 8, and the vertical mass block 8 is slidably connected with 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 side by side, the right end of the horizontal guide rail 2 is fixedly connected with the right side baffle 7, the right end of the horizontal spring 12 is fixedly connected with the right side baffle 7, the left end of the horizontal spring 12 is fixedly connected with the right side wall surface of the horizontal mass block 11, the right end of the horizontal viscous damper 13 is fixedly connected with the right side baffle 7, the left end of the horizontal viscous damper 13 is fixedly connected with the right side wall surface of the horizontal mass block 11, and the horizontal mass block 11 is slidably connected with the horizontal guide rail 2;

[0032] The intersection of the horizontal guide rail 2 and the vertical guide rail 3 is point O, 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 hingedly connected with the left end of the first connecting rod 6, the hinging point is point A, the right end of the horizontal mass block 11 is hingedly connected with the right end of the first connecting rod 6, the hinging point is point B, the right end of the second connecting rod 14 is hingedly connected with the middle of the first connecting rod 6, the hinging point is point C, the left end of the second connecting rod 14 is hingedly connected with point O, and AOB three points constitute a right-angled triangle, when the static elongation of the vertical spring 9 is 0, the horizontal spring 12 is in a compressed state at this time, when vortex-induced vibration occurs, the transferred energy is dissipated by the vertical and horizontal tuned mass dampers, so that the vortex-induced vibration control of the long-span bridge is realized.

[0033] The embodiment is directed to the problem of excessive static elongation of TMD in the control of super-low frequency vortex-induced vibration of large-span bridge. The gravity of the vertical mass block is transferred to the horizontal spring by two connecting rods. The static elongation of the vertical spring can be 0 by adjusting the mass m1, the stiffness k2 and the initial angle θ of the connecting rod, and the horizontal spring is in compression at this time. According to the actual size of the internal structure of the box girder, the height of the large-span bridge box girder is generally 3-5m, and the width is 30-40m. Even considering the longitudinal partition plate inside the box girder, there is still a width of about 6m in the width direction of the beam. The actual available space in the cross-sectional direction of the bridge is an important constraint condition for the parameter design of the new mechanical damping device. When the large-span bridge occurs vortex-induced vibration (including torsion and vertical), the vertical mass block will move. Due to the hysteresis of the vertical mass block compared with the vertical vibration of the bridge, there is a speed difference between the two. Since the horizontal mass block is installed on the horizontal guide rail, it is considered that the vertical speed of the horizontal mass block and the bridge is consistent at this time. Therefore, the two ends of the connecting rod will produce a vertical speed difference, causing the connecting rod to move in the plane. The system composed of the connecting rod and the two mass blocks resonates with the bridge during the movement process to achieve energy transfer. The transferred energy is dissipated by the vertical and horizontal dampers, thereby achieving the control of vortex-induced vibration of large-span bridge.

[0034] Embodiment 2

[0035] The embodiment provides a parameter optimization method for the damping control device described in the embodiment. The method steps are as follows:

[0036] S1: Determine the installable space of the damping control device according to the internal structure size of the main girder box girder 1: the length of the vertical spring 9 itself, the static elongation x of the vertical spring 9, the maximum downward stroke of the vertical spring 9 during vibration, and the initial vertical projection length l1 of the first connecting rod 6. Thus, the maximum length range occupied by the damping control device in the vertical direction is obtained. Similarly, the initial horizontal projection length l2 of the first connecting rod 6, the static compression amount x of the horizontal spring 12, and the length of the horizontal spring 12 itself are determined. Thus, the maximum length range occupied by the damping control device in the horizontal direction is obtained. 10 20

[0037] S2: After determining the maximum length that can be occupied by the damping control device in the vertical and horizontal directions, the constraint condition is calculated. According to the static force balance equation of the damping device, the static elongation / compression amount 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 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 link 6 and the horizontal direction,

[0040] It is derived from equation (1) that increasing the stiffness k2 of the horizontal spring 12 and decreasing the mass m1 of the vertical mass 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 elongation x of the vertical spring 9 10 The static compression x of the horizontal spring 12 20 The range of the static compression x of the horizontal spring 12 and the static elongation x of the vertical spring 9 is determined by engineering requirements, thereby obtaining the constraint conditions of the mass m1 of the vertical mass 8, the stiffness k2 of the horizontal spring 12 and the initial angle θ between the first link 6 and the horizontal direction, and the vibration control equation of the damper 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 link 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 link 6; F VIV is the vortex-induced force; l1 is the initial vertical projection length of the first link 6, and l2 is the initial horizontal projection length of the first link 6;

[0044] S3: solving the vibration control equation, the solution includes the response time curve of the controlled structure under the control of the damper control device, and by comparing the vibration time curve of the structure under the 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] wherein RMS s is the displacement root mean square value of the uncontrolled structure in the vortex vibration stable stage, and RMS t is the displacement root mean square value of the controlled structure in the vortex vibration stable stage;

[0047] S4: Optimization and design of the control parameters of the damping control device: by taking the vibration control effect η of the structure as the objective function, and setting the constraint conditions about 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, the global optimal value of the control parameters of the device, such as θ, k1, k2, d1 and d2, is found by using the genetic algorithm and other optimization algorithms.

[0048] Embodiment 3

[0049] At present, a two-dimensional theoretical modeling and numerical calculation have been carried out for a segment model of a certain long-span bridge provided with the damping control device of the application. The following is the whole process of the parameter optimization and design of the new damper based on the segment model: firstly, the total mass of the segment model is 165.5 kg, the unit length mass is 45.97 kg / m, the natural frequency of the segment model is 4.358 Hz, the wind speed ratio designed according to the wind tunnel test is converted to the original bridge as 0.23 Hz, and the incoming flow wind speed of the wind tunnel test is 5.62 m / s, which is converted to the actual bridge as about 5.92 m / s. It can be seen that, if the traditional vertical tuned mass damper is used to control the vortex-induced vibration of this order, the static elongation of the TMD will be about g / ω 2 = 4.7 m, which obviously not only exceeds the beam height 3.5 m of the bridge, but also the industrial commonly used spring is difficult to reach such a high elongation. If the damping control device of the application is used, firstly, according to formula (1), x 10 = 0, then x 20 = m1g / k2tanθ, it can be seen that the static compression amount 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 of the first connecting rod 6 with the horizontal direction. Compared with the static elongation of the traditional vertical TMD, x 20 = m1ω 2 l2 / ω2l1×(g / ω 2 ), therefore the static compression amount of the horizontal spring 13 is (m1ω 2 l2) / (k2l1) times of the static elongation of the traditional vertical TMD. Since the static elongation of the traditional vertical TMD is about 4.7 m, therefore (m1ω 2 l2) / (k2l1) < 0.4 is set as the constraint condition of the control parameter optimization and design, and the static compression amount of the horizontal spring 12 designed under this constraint condition is less than 1.88 m. In the actual bridge environment, the frequency and damping ratio of the bridge will present randomness with time, therefore the robustness design of the damping control device is also very important. In this example, the Monte Carlo simulation method is used to simulate the frequency values within the range of ±5% of the natural frequency of the segment model, the vortex vibration displacement time history curves of the controlled bridge under these frequency values are calculated, and the vibration reduction rates η of each simulation result are recorded. The robustness index of the damper is represented by R: R = αμη + (1 - a) s η wherein a is a weight coefficient, m η is the mean value of the damping ratio of a number of test results obtained by Monte Carlo simulation, s η is the standard deviation of the damping ratio of a number of test results. In this example, a = 0.5 is selected, R is taken as the objective function of the genetic algorithm, k1, k2, d1, d2 are taken as the optimization parameters, m1w 2 l2 / k2l1<0.4 is taken as the constraint condition, and the total mass ratio of the new damper is set to m2=2m1, l2 / l1=4. The following results can be obtained:

[0050] The parameters obtained by the genetic algorithm optimization are as follows: the stiffness coefficient of the horizontal spring 12 is k2=1083.23 N / m, the stiffness coefficient of the vertical spring is k1=35.8 N / m, the damping coefficients of the vertical damper 10 and the horizontal damper 13 are d1=d2=0.25 Ns / m, the calculated damping ratio 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 change segment model is changed, and the robustness index R is obtained by Monte Carlo simulation), m1w 2 l2 / k2l1=0.34<0.4, and the static compression amount of the horizontal spring of the actual bridge is only 1.6 m, which is greatly reduced compared with the static elongation of the traditional TMD. The above results show that the static elongation of the vertical spring is 0 and the static compression amount of the horizontal spring is reduced to about 1 / 3 of the static elongation of the traditional TMD under the same conditions by optimizing the control parameters by the genetic algorithm, and the vertical vortex-induced vibration of the bridge can be effectively controlled.

[0051] As Figure 2 shown in the time history curve of the vortex-induced displacement of the segment model under the control of the damper control device calculated by the genetic algorithm and the traditional vertical TMD designed according to the optimal parameters, as Figure 3 shown in the displacement change of the new damper and the traditional vertical TMD in the vibration control process, as Figure 4 shown in the change of the damping ratio η of the system with the frequency (stiffness) of the segment model. As can be seen from Figure 2 , the vortex-induced displacement of the segment model under the control of the damper control device of the present application is completely controlled, and the control effect is not much different from that of the traditional vertical TMD. As can be seen from Figure 3 , in the vibration control process, the vibration stroke of the vertical mass block 8 and the horizontal mass block 11 of the damper control device of the present application is smaller than that of the traditional TMD. As can be seen from Figure 4As can be seen from the table, the control effect of the damping control device of the application is basically unchanged when the segment model frequency changes within ±2.5%, 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, for example, 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 application can significantly reduce the spring static elongation of the low-frequency vertical vibration reduction tuned mass damper, overcome the defects of large space occupation and high installation cost of the existing low-frequency vertical vibration reduction tuned mass damper, and 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) by 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). The vertical guide rail (3) is vertically fixed inside the main beam box girder (1) by the vertical guide rail support (5). The vertical spring (9), vertical viscous damper (10) and vertical mass block (8) constitute a vertical tuned mass damper. The vertical spring (9) and vertical viscous damper (10) are placed side by side vertically. 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). 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 side by side. The right end of the horizontal guide rail (2) is fixedly connected to the right side baffle 7. The right end of the horizontal spring (12) is fixedly connected to the right side baffle 7. The left end of the horizontal spring (12) is fixedly connected to the right side wall of the horizontal mass block (11). The right end of the horizontal viscous damper (13) is fixedly connected to the right side baffle 7. The left end of the horizontal viscous damper (13) is fixedly connected to the right side wall 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. 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. Points A, B, and C 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 energy transmitted is dissipated through the vertical and horizontal tuned mass dampers, thereby realizing the vortex-induced vibration control of the long-span bridge.

2. The parameter optimization method for a mechanical damping control device for ultra-low frequency vortex-induced vibration of a long-span bridge main girder according to claim 1, characterized in that, The steps are as follows: S1: Based on the internal structural dimensions of the main beam box girder (1), determine the installation space for the damping control device; determine the length of the vertical spring (9) itself, and the static elongation x of the vertical spring (9). 10 The maximum downward stroke of the vertical spring (9) during vibration and the initial vertical projection length l1 of the first link (6) are used to obtain the range of the maximum vertical length occupied by the damping control device; similarly, the initial horizontal projection length l2 of the first link (6) and the static compression amount x of the horizontal spring (12) are determined. 20 The length of the horizontal spring (12) itself is obtained, which is the range of the maximum length occupied by 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 elongation / compression of the vertical and horizontal springs satisfy the following relationship: m1g-k1x 10 =k2x 20 tanθ (1) In the formula, m1 is the mass of the vertical mass block (8); g is the gravitational acceleration; 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. Equation (1) shows that increasing the stiffness k2 of the horizontal spring (12) and decreasing 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 of the horizontal spring (12) x 20 The static elongation x of the vertical spring (9) 10 The static compression of the horizontal spring (12) x 20 The range 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 horizontal angle θ of the first connecting rod (6). The vibration control equations of the damping control device are shown in equations (2)-(3): In the formula, 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 (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 link (6); F VIV l1 is the initial vertical projection length of the first link (6), and l2 is the initial horizontal projection length of the first link (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-induced wind speed, the vibration control effect η of the damper, i.e., the vibration reduction rate, can be obtained. η=(RMS s -RMS t ) / RMS s ×100% (4) In the formula, RMS s The root mean square (RMS) value of the displacement during the stable phase of vortex-induced vibration in an uncontrolled structure. t The root mean square value of the displacement during the stable phase of vortex-induced vibration of the controlled structure; 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 (8), the stiffness k2 of the horizontal spring (12) and the initial angle θ of the first link (6), a genetic algorithm is used to find the global optimal value of the control parameters of the device.

Images