An adjustable vertical ultra-low frequency tuned mass damper based on positive and negative stiffness combination

Abstract

The present application relates to the technical field of vibration control of engineering structure, especially to a vertical ultra-low frequency tuned mass damper with adjustable positive and negative stiffness combination, which is installed on a main structure in need of vibration control and comprises a bottom plate, a vertical spring assembly, a damping assembly, a horizontally adjustable pre-press negative stiffness assembly, a mass block and a structural vibration sensing monitor. The tuned mass damper utilizes the vertical spring to provide positive stiffness, utilizes the horizontally adjustable pre-press negative stiffness assembly to provide negative stiffness, and provides the overall equivalent dynamic stiffness required for bearing and controlling the motion of the mass block through reasonable combination of positive and negative stiffness, so as to effectively reduce the static compression amount of the vertical ultra-low frequency tuned mass damper and adjust the frequency in real time according to the control requirements of the controlled structure, thereby reducing the volume of the tuned mass damper and improving the application range.

Description

Technical Field

[0001] This invention relates to the field of vibration control technology for engineering structures, and in particular to an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness. Background Technology

[0002] Mass-tuned vibration reduction technology is a relatively mature technology in structural vibration control. It has been widely used in the vibration control of large-span and tall structures because it can be installed at the large amplitude of the main structure with only one end and the moving end does not need to be connected to the structure.

[0003] When mass-tuned vibration reduction products are used in civil engineering, they are generally referred to as tuned mass dampers (TMDs). Due to the characteristics of civil engineering project sites, passive tuned mass dampers that do not require additional energy supply and semi-active tuned mass dampers that only require a small amount of energy to adjust some parameters within a short period of time are the most frequently used and widely used mass-tuned vibration reduction devices in the field of civil structure control.

[0004] The working mechanism of TMD is to tune the product's fundamental frequency to be close to the required control fundamental frequency of a certain order of the main structure. When the main structure vibrates under external loads such as strong winds, abnormal vehicle loads, and earthquakes, the mass block will passively resonate with the main structure's fundamental frequency at a certain phase difference due to inertia. By absorbing vibration at the same frequency, the kinetic energy of the structure is converted into the kinetic energy of the mass block and consumed by its own damping unit, thereby reducing the amplitude of the main structure.

[0005] To achieve resonance at the same frequency, the stiffness of the tuned mass damper, after the weight m (kg) of the mass block is determined, is determined by the fundamental frequency of the structure to be controlled. f (Hz) is calculated using the following formula: K =(2· π · f ) 2 · m The weight of the mass block is affected by the gravitational acceleration g (generally taken as g = 9.807 m / s²). 2 The gravity generated below is G=m·g (N), therefore the initial static compression caused by the mass block being placed on the stiffness element can be calculated. It can be seen that its initial static compression is independent of the weight of the mass block, assuming the gravitational acceleration g = 9.807 m / s². 2 , π When the value is 3.14159, its initial static compression is only related to the fundamental frequency. f (Hz) related to the fundamental frequency f It is inversely proportional to the square of, approximately (m). For example, when fAt a frequency of 0.3 Hz, the initial static compression Δ = 2.76 m. When the required control fundamental frequency is further reduced, the initial static compression becomes extremely large, making it impossible to manufacture stiffening components (generally helical springs) and meet installation space requirements. This is the key challenge in realizing vertical ultra-low frequency tuned mass dampers for large-span structures.

[0006] Meanwhile, long-span structures, such as long-span suspension bridges, often have multiple low-frequency modes that may be excited under different external load conditions. When using TMD to control their vibration, the vertical ultra-low frequency tuned mass damper is more difficult to adjust on-site to meet the control requirements of different possible frequencies, or even to be precisely tuned to a single target frequency. This is another practical engineering problem that needs to be solved for the vertical ultra-low frequency tuned mass damper of long-span structures. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to provide an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness. By introducing a negative stiffness mechanism, it reduces static compression while achieving low-frequency motion, and allows for stepless frequency adjustment over a wide range by adjusting the magnitude of the negative stiffness, enabling control of multiple low-frequency modes. Furthermore, by introducing a monitoring and control system, automatic monitoring and frequency adjustment can be achieved. This reduces the size of the vertical ultra-low frequency tuned mass damper and expands its applicability.

[0008] This invention discloses an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness. A vertical spring with a stiffness greater than theoretically calculated is used to support a mass block, causing it to reach equilibrium with only a small initial static compression. Once the mass block is stationary at equilibrium, a horizontally adjustable preload negative stiffness assembly containing a horizontal preload spring is symmetrically installed around it. When the mass block vibrates up and down away from its equilibrium position, this assembly generates negative stiffness that pushes the mass block further away from the equilibrium position, offsetting part of the positive stiffness of the vertical spring, thereby ultimately achieving the required equivalent dynamic stiffness within a certain stroke. Simultaneously, the horizontally adjustable preload negative stiffness assembly containing the horizontal preload spring can be adjusted in real time. By adjusting the preload of the horizontal preload spring, the negative stiffness can be adjusted to achieve different equivalent dynamic stiffnesses to meet the control requirements of different frequencies. Furthermore, this invention introduces a structural vibration sensor (connected to an external control system) to achieve automatic monitoring and frequency adjustment of the overall structural vibration.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] This invention provides an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness (the tuned mass damper plays a role in vibration reduction when the main structure vibrates under external excitation), which is installed on the main structure that requires vibration control and is connected to an external control system during use. The adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness includes a base plate, a vertical spring assembly, a damping assembly, a horizontally adjustable preload negative stiffness assembly, a mass block, and a structural vibration sensor.

[0011] The base plate is disposed on the upper surface of the main structure, and the vertical spring assembly and damping assembly are disposed at the center of the upper surface of the base plate at intervals; the horizontal adjustable preload negative stiffness assembly is disposed at the end of the upper surface of the base plate and is connected to the vertical spring assembly and damping assembly through a mass block; the structural vibration sensor is disposed on the upper surface of the main structure and on one side of the base plate.

[0012] The mass block is disposed on the upper surface of the vertical spring assembly and the damping assembly; the horizontally adjustable preload negative stiffness assembly and the structural vibration sensor are both allowed to be connected to an external control system.

[0013] The base plate is used to support the vertical spring assembly, damping assembly, mass block, and horizontal adjustable preload negative stiffness assembly.

[0014] The vertical spring assembly is used to provide positive stiffness (the amplitude-related force that returns the mass block to its static equilibrium position).

[0015] The damping component is used to convert the structural kinetic energy absorbed by the mass block into heat energy for dissipation.

[0016] The horizontally adjustable preload negative stiffness component is used to provide negative stiffness (an amplitude-related force on the mass block away from its static equilibrium position).

[0017] The mass block is used for energy absorption, providing inertial force, and regulating the system frequency;

[0018] The structural vibration sensor is used to monitor the vibration of the overall structure in real time.

[0019] In this invention, the main structure is a large-span structure or a tall structure.

[0020] The overall equivalent dynamic stiffness of the tuned mass damper is composed of the positive stiffness provided by the vertical spring assembly and the negative stiffness provided by the horizontal adjustable preload negative stiffness assembly.

[0021] In one embodiment of the present invention, the vertical spring assembly includes a plurality of vertical springs arranged in parallel at intervals;

[0022] The damping assembly includes several damping elements arranged in parallel at intervals.

[0023] The damping element is disposed between adjacent vertical springs.

[0024] In one embodiment of the present invention, the damping element is selected from either a viscous damper or an eddy current damper.

[0025] In one embodiment of the present invention, the horizontally adjustable preload negative stiffness assembly includes a negative stiffness assembly fixing base, a spring preload adjustment rod (allowing connection to an external control system), a horizontal preload spring, a horizontal spring pressure plate, and a horizontal spring top rod.

[0026] The negative stiffness component fixing base is located at the end of the base plate, the spring preload adjustment rod extends out of the top of the negative stiffness component fixing base, and a horizontal spring top rod is provided near the end of the mass block; the horizontal preload spring is sleeved on the outside of the spring preload adjustment rod, one end of which is connected to the negative stiffness component fixing base through a rotating support seat, and the other end is connected to the horizontal spring top rod through a horizontal spring pressure plate.

[0027] The preload of the horizontal preload spring is adjusted by adjusting the spring preload adjustment rod.

[0028] In one embodiment of the present invention, a pressure sensor (allowing connection to an external control system) is provided on the side of the horizontal spring pressure plate near the horizontal preload spring; the pressure sensor can monitor the preload of the horizontal preload spring in real time to calculate the real-time negative stiffness, and then calculate the real-time equivalent dynamic stiffness and motion frequency of the tuned mass damper.

[0029] In one embodiment of the present invention, the rotating support is connected to the negative stiffness component fixing base via a transmission pin;

[0030] In one embodiment of the present invention, the horizontal spring rod is hinged to the mass block, and a friction pair is provided at the hinge connection position. The friction pair material is polytetrafluoroethylene or copper alloy friction material. The friction force at the hinge connection position can be reduced or controlled by controlling the friction coefficient of the friction pair material.

[0031] In one embodiment of the present invention, the horizontal spring pressure plate is threadedly connected to the horizontal spring push rod.

[0032] In one embodiment of the present invention, the mass block is made of one or more of the following materials: metal or concrete.

[0033] In this invention, the spring preload adjustment rod in the horizontally adjustable preload negative stiffness assembly is either a manual spring preload adjustment rod or an automatic spring preload adjustment rod.

[0034] In one embodiment of the present invention, the structural vibration sensor is an acceleration sensor that can be connected to an external control system; it can monitor the vibration of the overall structure in real time and feed back the monitored situation to the external control system. The external control system analyzes and calculates the error between the theoretical optimal frequency of the tuned mass damper and its current operating frequency; and based on the error, the external control system gives a warning and signal that adjustment is required. This signal is the horizontal preload spring adjustment target value calculated by the system based on the above error.

[0035] When a warning or signal indicating the need for adjustment is received, 1) when the spring preload adjustment rod is a manual type, the spring preload adjustment rod can be manually rotated to adjust the preload of the horizontal preload spring, and the data obtained by the pressure sensor is compared; 2) when the spring preload adjustment rod is an automatic type, the spring preload adjustment rod is connected to an external control system, and the control system automatically drives the spring preload adjustment rod to rotate, thereby adjusting the preload of the horizontal preload spring, and forms a closed-loop control system with the pressure sensor to control the adjustment amount.

[0036] In this invention, the tuned mass damper can convert the structural kinetic energy into the kinetic energy of the mass block through synchronous vibration absorption and dissipate the energy through the damping component, thereby reducing the amplitude of the main structure.

[0037] The negative stiffness of the tuned mass damper is provided by the thrust generated by the preload of the horizontal preload springs. When the mass is in the equilibrium position, the axial thrust transmitted by the horizontal preload springs around the mass cancels out each other. When the mass leaves the equilibrium position, the axial thrust transmitted by the horizontal preload springs around the mass can be divided into vertical and horizontal components. The horizontal components cancel each other out, while the vertical component generates the negative stiffness that drives the mass away from the equilibrium position.

[0038] The precompression of the horizontal precompression spring can be adjusted by adjusting the spring precompression adjustment rod in the horizontal adjustable precompression negative stiffness assembly, thereby changing the force transmitted by the horizontal precompression spring to the mass block, thus adjusting the negative stiffness and the overall equivalent dynamic stiffness, and thus changing the motion frequency of the tuned mass damper.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention discloses an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness. Through a compact structural design, it achieves high static stiffness and low dynamic stiffness while occupying a small space. It can achieve a pre-designed motion frequency while meeting a small initial static compression. Furthermore, through the reserved horizontal adjustable pre-compression negative stiffness component, it can realize multi-frequency vibration control. With the cooperation of a structural vibration sensor and automatic control, it can further realize automatic adjustment. Attached Figure Description

[0041] Figure 1 This is a schematic front view of an adjustable vertical ultra-low frequency tuned mass damper structure based on a combination of positive and negative stiffness, as shown in Example 1.

[0042] Figure 2 This is a front view of an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness in Example 1, when the mass block moves upward.

[0043] Figure 3 This is a front view of an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness in Example 1, when the mass block moves downward.

[0044] Figure 4 This is a front view of an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness in Example 1, showing the horizontal spring precompression when adjusted.

[0045] Figure 5 This is a front view of an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness in Example 1, when the pre-compression of the horizontal spring is increased.

[0046] Figure 6 This is a front view of the horizontally adjustable preloaded negative stiffness component in an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness in Example 1.

[0047] Figure 7 This is a top view of a horizontally adjustable preloaded negative stiffness component of an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness, as described in Example 1.

[0048] Figure 8 This is a front cross-sectional view of a horizontally adjustable preloaded negative stiffness component of an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness in Example 1.

[0049] Figure 9 This is a front view showing the positions of each length symbol corresponding to the equilibrium position of an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness in Example 1.

[0050] Figure 10 This is a front view showing the positions of each length symbol corresponding to the position of an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness in Example 1 when it leaves the position.

[0051] Figure 11 This is a diagram showing the relationship between the force values ​​and stroke of each vertical component of an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness in Example 1 when the horizontal spring is preloaded by 190mm.

[0052] Figure 12 This is a graph showing the frequency-stroke relationship of the horizontal preload spring of an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness in Example 1 under different preload amounts.

[0053] The following are the labeling elements in the diagram: 1. Main structure; 2. Base plate; 3. Vertical spring; 4. Horizontal adjustable preload negative stiffness assembly; 41. Negative stiffness assembly fixing base; 42. Transmission pin; 43. Spring preload adjustment rod; 44. Rotating support seat; 45. Horizontal preload spring; 46. Pressure sensor; 47. Horizontal spring pressure plate; 48. Horizontal spring top rod; 5. Damping component; 6. Mass block; 7. Structural vibration sensor monitor. Detailed Implementation

[0054] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0055] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0056] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0057] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0058] In the following embodiments, unless otherwise specified, the components and systems used are all commercially available components and commonly used systems in the art, capable of achieving the corresponding functions.

[0059] Example 1

[0060] This embodiment provides an adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness, such as... Figures 1-10 As shown, the tuned mass damper, installed on the main structure 1 (generally a large-span or tall structure) requiring vibration control, allows connection to an external control system. It includes a base plate 2, a vertical spring assembly, a damping assembly, a horizontally adjustable preload negative stiffness assembly 4, a mass block 6, and a structural vibration sensor 7. The base plate 2 is located on the upper surface of the main structure 1, with the vertical spring assembly and damping assembly spaced apart at the center of the upper surface. The horizontally adjustable preload negative stiffness assembly 4 is located at the end of the upper surface of the base plate 2 and connected to the vertical spring assembly and damping assembly via the mass block 6. The structural vibration sensor 7 is located on the upper surface of the main structure 1 and on one side of the base plate 2. The mass block 6 is located on the upper surface of the vertical spring assembly and damping assembly. The horizontally adjustable preload negative stiffness assembly 4 and the structural vibration sensor 7 are connected to an external control system. The mass block 6 is connected to the horizontally adjustable preload negative stiffness assembly 4 on all four sides.

[0061] Among them, the base plate 2 is used to support the vertical spring assembly, the damping assembly, the mass block 6 and the horizontal adjustable preload negative stiffness assembly 4;

[0062] Vertical spring assemblies are used to provide positive stiffness;

[0063] Damping components are used to convert the structural kinetic energy absorbed by mass block 6 into heat energy for dissipation.

[0064] The horizontally adjustable preload negative stiffness component 4 is used to provide negative stiffness;

[0065] Mass block 6 is used for energy absorption, providing inertial force, and regulating the system frequency;

[0066] The structural vibration sensor monitor 7 is used to monitor the vibration of the overall structure in real time.

[0067] The overall equivalent dynamic stiffness of the tuned mass damper is composed of the positive stiffness provided by the vertical spring assembly and the negative stiffness provided by the horizontal adjustable preload negative stiffness assembly 4.

[0068] Furthermore, the vertical spring assembly includes a plurality of parallel-spaced vertical springs 3, and the damping assembly includes a plurality of parallel-spaced damping elements 5; the damping elements 5 are disposed between adjacent vertical springs 3.

[0069] Furthermore, the damping element 5 is selected from either a viscous damper or an eddy current damper.

[0070] Furthermore, the horizontally adjustable preload negative stiffness component 4 includes a negative stiffness component fixing base 41, a spring preload adjustment rod 43, a horizontal preload spring 45, a horizontal spring pressure plate 47, and a horizontal spring top rod 48. The negative stiffness component fixing base 41 is located at the end of the base plate 2, the spring preload adjustment rod 43 extends out of the top of the negative stiffness component fixing base 41, and the horizontal spring top rod 48 is located near the end of the mass block 6. The horizontal preload spring 45 is sleeved on the outside of the spring preload adjustment rod 43, one end of which is connected to the negative stiffness component fixing base 41 through a rotating support 44, and the other end is connected to the horizontal spring top rod 48 through the horizontal spring pressure plate 47. The preload of the horizontal preload spring 45 is adjusted by adjusting the spring preload adjustment rod 43.

[0071] Furthermore, a pressure sensor 46 (allowing connection to an external control system) is installed on the side of the horizontal spring pressure plate 47 near the horizontal preload spring 45. The pressure sensor 46 can monitor the preload of the horizontal preload spring 45 in real time to calculate the real-time negative stiffness, and then calculate the real-time equivalent dynamic stiffness and motion frequency of the tuned mass damper. The rotating support 44 is connected to the negative stiffness assembly fixed base 41 via a transmission pin 42. The horizontal spring top rod 48 is hinged to the mass block 6, and a friction pair is provided at the hinge connection position. The friction pair material is polytetrafluoroethylene or copper alloy friction material. The friction force at the hinge connection position can be reduced or controlled by controlling the friction coefficient of the friction pair material. The horizontal spring pressure plate 47 is threadedly connected to the horizontal spring top rod 48. The mass block 6 is made of one or more of the following materials: metal or concrete.

[0072] In this invention, the spring preload adjustment rod 43 in the horizontally adjustable preload negative stiffness component 4 is either a manual spring preload adjustment rod 43 or an automatic spring preload adjustment rod 43.

[0073] The structural vibration sensor 7 is an acceleration sensor that can monitor the vibration of the overall structure in real time. It can be connected to an external control system and feed back the monitored information to the external control system. The external control system analyzes and calculates the error between the theoretical optimal frequency of the tuned mass damper and the current operating frequency. Based on this error, the external control system issues a warning and signal that adjustment is required. This signal is the adjustment target value of the horizontal preload spring 45, which is further calculated by the system based on the above error.

[0074] When a warning or signal indicating the need for adjustment is received, 1) when the spring preload adjustment rod 43 is a manual type, the spring preload adjustment rod 43 can be manually rotated to adjust the precompression of the horizontal preload spring 45, and the data obtained by the pressure sensor 46 is compared; 2) when the spring preload adjustment rod 43 is an automatic type, the spring preload adjustment rod 43 is connected to an external control system, and the control system automatically drives the spring preload adjustment rod 43 to rotate, thereby adjusting the precompression of the horizontal preload spring 45, and forms a closed-loop control system with the pressure sensor 46 to control the adjustment amount.

[0075] The tuned mass damper can convert the structural kinetic energy into the kinetic energy of the mass block 6 through synchronous vibration absorption and dissipate the energy through the damping components, thereby reducing the amplitude of the main structure 1.

[0076] The negative stiffness of the tuned mass damper is provided by the thrust generated by the preload of the horizontal preload spring 45. When the mass block 6 is in the equilibrium position, the forces transmitted by the horizontal preload spring 45 around the mass block 6 to the mass block 6 are horizontally canceled out. When the mass block 6 leaves the equilibrium position, the forces transmitted by the horizontal preload spring 45 around the mass block 6 to the mass block 6 can be divided into vertical and horizontal components. The horizontal components cancel each other out, while the vertical component generates the negative stiffness that drives the mass block 6 away from the equilibrium position.

[0077] like Figure 4 and Figure 5 As shown, the precompression of the horizontal precompression spring 45 can be adjusted by adjusting the spring precompression adjustment rod 43 in the horizontal adjustable precompression negative stiffness assembly 4, thereby changing the force transmitted by the horizontal precompression spring 45 to the mass block 6, thus adjusting the negative stiffness and the overall equivalent dynamic stiffness, thereby changing the motion frequency of the tuned mass damper.

[0078] Specifically, such as Figure 9 As shown, at the equilibrium position, the weight G of mass block 6 is equal to the restoring force of vertical spring 3, that is:

[0079] F v =G=mg (1)

[0080] Wherein: F v The sum of the restoring forces of all vertical springs 3 (N);

[0081] At this point, the remaining height of the vertical spring 3 is V. p (mm), this position is also the static equilibrium position of TMD;

[0082] The horizontal preload spring 45, originally at a free height of H, is preloaded and then fixed, resulting in a remaining height of H after preloading. p (mm), then its preload is HH p (mm); The total length of the center distance between the rotating parts of the horizontally adjustable preload negative stiffness assembly 4 is H. 0 (mm);

[0083] Because the horizontally adjustable preload negative stiffness components 4 are installed in pairs around the mass block 6, when the mass block 6 is in the equilibrium position V p At that time, the forces of each horizontally adjustable preload negative stiffness component 4 are horizontal and cancel each other out;

[0084] Assumption H p ≈H 0 That is, assuming that the center distance of the rotating parts of the horizontal adjustable preload negative stiffness component 4, except for the horizontal preload spring 45, is much smaller than the length of the horizontal preload spring 45 itself.

[0085] See Figure 10 When mass block 6 leaves its equilibrium position under external load, and its stroke is U (mm), the tilt angle between the horizontally adjustable preload negative stiffness component 4 and the horizontal line is θ (rad). At this point, the remaining height of the horizontal preload spring 45 is H. p / cos(θ), at this time the horizontal components of each horizontally adjustable preload negative stiffness component 4 cancel each other out, and the sum of their total vertical components is:

[0086] (2)

[0087] in: fH K is the sum of the axial thrust (N) generated by all horizontally adjustable preloaded negative stiffness components 4. h The sum of the stiffness coefficients of all horizontal preloaded springs 45 (N / mm); H is the uncompressed free height of the horizontal preloaded springs 45 (mm); F h The sum of the vertical components (N) generated by all the horizontal preloaded springs 45, such as Figure 10 When the mass block 6 shown is above the equilibrium position, F h Direction upwards, and G+F vThe resultant forces are in opposite directions;

[0088] At this time, the equivalent vertical negative stiffness K generated by all the horizontal preloaded springs 45 heq The formula for calculating (N / mm) is:

[0089] (3)

[0090] At this moment, the net vertical force acting on the weight of mass block 6 is:

[0091] F all =G+F v +F h (4)

[0092] Wherein: F all G is the sum of the external forces acting on mass block 6 (N); G is the gravity acting on mass block (N); F v Let N be the total restoring force of the vertical spring 3; where each force value is a scalar, and the downward direction of the force value is a positive value;

[0093] It can be seen that, due to F h The existence of F all Reduction, that is, reduction of equivalent motion stiffness, can be achieved by reasonably controlling F. h This can change the equivalent motion stiffness K of the system. eq (N / mm), that is:

[0094] (5)

[0095] The equivalent motion stiffness K can also be calculated directly through the combination of positive and negative stiffness. eq (N / mm), that is:

[0096] K eq =K v +K heq (6)

[0097] Where: K v The sum of the stiffnesses of all vertical springs 3 (N / mm);

[0098] Due to F h There is a nonlinear correlation with U, so the equivalent motion stiffness has a certain degree of nonlinearity. However, under small amplitude, it can approach a linear relationship and the influence of nonlinearity can be reduced by controlling the geometric dimensions, or this nonlinear characteristic can be used for nonlinear vibration control.

[0099] In one embodiment of the present invention, reference is made to... Figure 4 , Figure 5The pre-compression of the horizontal pre-compression spring 45 can be adjusted by using the spring pre-compression adjustment rod 43 in the adjustable horizontal pre-compression negative stiffness assembly 4, thereby changing the thrust transmitted from the horizontal pre-compression spring 45 to the mass block 6, thus adjusting the negative stiffness and the overall equivalent dynamic stiffness, thereby changing the motion frequency of the tuned mass damper.

[0100] The following examples, in conjunction with embodiments, further illustrate the effects of the present invention in reducing horizontal pre-compression and adjusting frequency:

[0101] Taking the vertical vibration control requirement of a long-span bridge at a certain order of 0.27 Hz as an example, if a conventional stiffness element is used to support the mass block, then... (m) indicates that the initial static compression of the stiffness element is 3407 (mm). Assuming a single TMD mass block is designed to weigh 2000 (kg) and the total stiffness of the vertical spring 3 is designed to be 78.96 (N / mm), the initial static compression can be significantly reduced to 248.4 (mm). At this point, without the horizontally adjustable preload negative stiffness component 4, the fundamental frequency of the TMD motion is 1 (Hz), which is significantly different from the controlled frequency and cannot be used directly; (Refer to...) Figure 11 , Figure 12 The total stiffness of the horizontal preloaded springs is K. h =157.91 (N / mm), each horizontal preload spring 45 has a preload of 190 (mm), H0=600 (mm), then its frequency can be reduced to 0.27 (Hz), and when the preload of the horizontal preload spring 45 is adjusted to 170 (mm) and 150 (mm), the frequency can be adjusted to 0.46 (Hz) and 0.58 (Hz) respectively.

[0102] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the interpretation of the present invention, without departing from the scope of the invention, should be within the protection scope of the present invention.

Claims

1. An adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness, installed on the main structure (1) requiring vibration control, characterized in that, The adjustable vertical ultra-low frequency tuned mass damper based on positive and negative stiffness combination includes a base plate (2), a vertical spring assembly, a damping assembly, a horizontal adjustable preload negative stiffness assembly (4), a mass block (6), and a structural vibration sensor (7). The base plate (2) is disposed on the upper surface of the main structure (1), and the vertical spring assembly and the damping assembly are disposed at intervals at the center of the upper surface of the base plate (2); the horizontal adjustable preload negative stiffness assembly (4) is disposed at the end of the upper surface of the base plate (2) and is connected to the vertical spring assembly and the damping assembly through the mass block (6); the structural vibration sensor (7) is disposed on the upper surface of the main structure (1) and on one side of the base plate (2); the mass block (6) is disposed on the upper surface of the vertical spring assembly and the damping assembly; The horizontally adjustable preload negative stiffness assembly (4) includes a negative stiffness assembly fixing base (41), a spring preload adjustment rod (43), a horizontal preload spring (45), a horizontal spring pressure plate (47), and a horizontal spring top rod (48). The negative stiffness component fixing base (41) is located at the end of the base plate (2). The spring preload adjustment rod (43) extends out of the top of the negative stiffness component fixing base (41). A horizontal spring top rod (48) is provided at the end near the mass block (6). The horizontal preload spring (45) is sleeved on the outside of the spring preload adjustment rod (43). One end is connected to the negative stiffness component fixing base (41) through the rotating support seat (44), and the other end is connected to the horizontal spring top rod (48) through the horizontal spring pressure plate (47). The vertical spring assembly includes a plurality of vertical springs (3) arranged in parallel at intervals; A pressure sensor (46) is provided on the side of the horizontal spring plate (47) near the horizontal preload spring (45). The base plate (2) is used to support the vertical spring assembly, the damping assembly, the mass block (6), and the horizontal adjustable preload negative stiffness assembly (4). The vertical spring assembly is used to provide positive stiffness; The horizontally adjustable preload negative stiffness component (4) is used to provide negative stiffness; The damping component is used to convert the structural kinetic energy absorbed by the mass block (6) into thermal energy for dissipation; The structural vibration sensor (7) is used to monitor the vibration of the overall structure in real time.

2. The adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness according to claim 1, characterized in that, The rotating support (44) is connected to the negative stiffness component fixing base (41) via a transmission pin (42).

3. The adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness according to claim 1, characterized in that, The horizontal spring rod (48) is hinged to the mass block (6), and a friction pair is provided at the hinged connection position.

4. The adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness according to claim 1, characterized in that, The horizontal spring pressure plate (47) is threadedly connected to the horizontal spring top rod (48).

5. An adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness according to claim 1, characterized in that, The damping assembly includes several damping elements (5) arranged in parallel intervals. The damping element (5) is disposed between adjacent vertical springs (3).

6. An adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness according to claim 5, characterized in that, The damping element (5) is selected from either a viscous damper or an eddy current damper.

7. An adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness according to claim 1, characterized in that, The mass block (6) is made of one or more of the following materials: metal or concrete.

8. An adjustable vertical ultra-low frequency tuned mass damper based on a combination of positive and negative stiffness according to claim 1, characterized in that, The structural vibration sensor (7) is an acceleration sensor.

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