CN111809508A - A Low-Frequency Lever Tuned Mass Damper - Google Patents

Abstract

The invention discloses a low-frequency lever-type tuned mass damper, comprising a lever frame (1), comprising a lever bracket (11) and a lever cantilever (12); a fixing mechanism (6) vertically connected with the lever frame (1), The fixing mechanism (6) is provided with a spring assembly (2) and a damper (5), and the end of the lever cantilever (12) away from the fixing mechanism (6) is provided with a mass unit (3), the mass unit (3) passing through The bearing (4) is movably connected with the lever cantilever (12), the mass unit (3) and the lever cantilever (12) constitute a tuned mass damper power and power arm, the spring assembly (2), the damper (5) and the lever cantilever The part between (12) and the lever bracket (11) constitutes a resistance and a resistance arm; and the mass unit (3) includes a mass (31). The tuned mass damper of the present invention can effectively prevent the main structure from being damaged due to large-scale vibration, thereby protecting the main structure from damage.

Description

A Low-Frequency Lever Tuned Mass Damper

technical field

The present invention relates to the technical field of mass dampers, in particular to a low-frequency lever-type tuned mass damper.

Background technique

Tuned Mass Damper (TMD) is widely used in bridge structure vibration control because of its clear principle and simple structure, especially for vortex-induced vibration control of large-span bridges caused by wind vibration. At present, the main control frequency of TMD is generally greater than 0.3HZ, and there are relatively few TMDs for low frequency (less than 0.3HZ) control. The vibration frequency of the TMD is directly related to the performance of the entire device. Generally, the lower the natural vibration frequency of the TMD, the longer the vibration period, the smaller the stiffness, and the larger the stroke.

The TMD is generally installed inside the steel box girder. At present, the main types of TMD structures used for vertical vibration reduction of the structure are stacked and suspended. The main difference is that the former uses compression springs and the latter uses tension springs. In the conventional TMD design, the spring and the mass are directly connected, and the dynamic strokes of the spring, damper and mass are often the same.

Due to its long natural vibration period, small spring stiffness and large vertical load, the design and selection of springs will be very difficult for low-frequency TMDs. Springs with low stiffness will also be difficult to process and install due to their long length, excessive static load compression displacement, and large dynamic stroke, and even instability during use.

SUMMARY OF THE INVENTION

In view of the above defects or improvement requirements of the prior art, the present invention provides a low-frequency lever-type tuned mass damper, which utilizes the lever principle to amplify the force of the spring, thereby improving the overall stiffness of the spring, and compressing the dynamic stroke of the spring and the damper. , which is more conducive to the design and selection of springs and dampers, and can reduce the height of the entire TMD and save installation space. The low-frequency lever-type TMD can be designed as a stacked TMD with a compression spring, or a suspended TMD with an extension spring. The springs can be arranged in layers according to actual needs, and the design and selection of springs are more flexible and convenient. The quality of the mass block is adjustable, which can also ensure that the design parameters of the TMD are more accurate.

In order to achieve the above object, the present invention provides a low-frequency lever-type tuned mass damper, comprising:

a lever frame, which includes a lever bracket and a lever cantilever, the lever cantilever is movably connected to the lever bracket through a bearing;

A fixing mechanism vertically connected to the lever frame, a spring assembly and a damper are arranged in the fixing mechanism, and the bottom or top of the lever bracket and the fixing mechanism are fixedly connected to the bottom plate of the steel box girder through the steel box girder fixing bracket to form a tuning The fulcrum of the mass damper;

The end of the lever cantilever away from the fixing mechanism is provided with a mass unit, the mass unit is movably connected with the lever cantilever through a bearing, the mass unit and the lever cantilever constitute a tuned mass damper power and power arm, and the spring assembly , The part between the damper and the lever cantilever to the lever bracket constitutes the resistance and resistance arm; and,

The mass unit includes a mass block, the mass of which can be adjusted, and the frequency of the lever-type tuned mass damper is adjusted to be consistent with the frequency of the main structure, so that when the main structure is vibrated by an external force, an inertial force opposite to its vibration is generated. , reducing the amplitude of the main structure.

Further, the fixing mechanism includes an upper connecting plate, a lower connecting plate and a fixing plate;

the upper connecting plate is fixedly connected with the fixing plate;

The lower connecting plate is fixedly connected with the bottom plate of the steel box girder.

Further, the spring assembly includes a spring and a guide post;

the guide posts are respectively arranged on the upper connecting plate and the lower connecting plate;

Both ends of the spring are respectively sleeved on the corresponding guide posts.

Further, a sleeve is installed on the outside of the spring for fixing the movement direction of the spring.

Further, the mass unit includes a screw, and the mass block is fixedly connected by the screw.

Further, the lever bracket includes a lever beam and a lever longitudinal beam vertically arranged with the lever beam.

In general, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

1. The low-frequency lever-type tuned mass damper of the present invention adjusts the frequency of the TMD by adjusting the number of mass blocks. When the frequency of the TMD is consistent with the frequency of the main structure, and the main structure is vibrated by an external force, the TMD will be in the main structure. The inertial force opposite to the vibration of the main structure is generated on the structure, thereby reducing the vibration amplitude of the main structure, avoiding the damage of the main structure due to large-scale vibration, and protecting the main structure from damage.

2. The low-frequency lever-type tuned mass damper of the present invention is suitable for low-frequency (less than 0.3HZ) and large-stroke TMDs. Through the lever principle, the force of the spring is amplified, thereby improving the overall stiffness of the spring, and compressing the spring and The dynamic stroke of the damper is more conducive to the design and selection of springs and dampers, and can reduce the height dimension of the entire TMD, saving installation space.

3. The low-frequency lever-type tuned mass damper of the present invention can be designed as a stacked TMD by using a compression spring, or can be designed as a suspended TMD by using a tension spring. The springs can be arranged in layers according to actual needs, and the design and selection of the springs can be used. More flexible and convenient. The quality of the mass block is adjustable, which can also ensure that the design parameters of the TMD are more accurate.

4. In the low-frequency lever-type tuned mass damper of the present invention, the guide columns are correspondingly installed on the lower surface of the upper connecting plate 61 and the upper surface of the lower connecting plate, and the springs are sleeved on the guide columns. On the outer circumference, on the one hand, it plays a guiding role, forcing the spring to only have a vertical displacement along the guide column, and at the same time restricting the other degrees of freedom movement of the spring, improving the accuracy of the damper.

5. The low-frequency lever-type tuned mass damper of the present invention adopts the bearing design to make the lever bracket and the lever cantilever in a movable state, which is convenient to realize the lever function, and the mass unit is arranged at one end of the lever, which passes through itself. The effect of gravity makes the spring in a state of compression. When the bridge structure is disturbed by external force, this balance is broken, that is, the mass element moves vertically under the action of external force, the spring is correspondingly elongated or compressed, and the vibration frequency is consistent with the frequency of the main structure, thus It can offset external disturbance and protect the main structure.

Description of drawings

1 is a schematic diagram of the overall installation structure of a low-frequency lever-type tuned mass damper according to an embodiment of the present invention;

2 is a schematic front view of a three-dimensional structure of a low-frequency lever-type tuned mass damper according to an embodiment of the present invention;

3 is a right side view of a low-frequency lever-type tuned mass damper according to an embodiment of the present invention;

4 is a front view of a low-frequency lever-type tuned mass damper according to an embodiment of the present invention;

5 is a schematic diagram of a lever of a low-frequency lever-type tuned mass damper according to an embodiment of the present invention;

FIG. 6 is a force analysis diagram of a mass unit of a low-frequency lever-type tuned mass damper according to an embodiment of the present invention.

In all drawings, the same reference numerals denote the same technical features, specifically: 1-lever frame, 11-lever bracket, 111-lever beam, 112-lever longitudinal beam, 12-lever cantilever, 2-spring assembly , 21-spring, 22-guide column, 3-mass block unit, 31-mass block, 32-screw, 4-bearing, 5-damper, 6-fixing mechanism, 61-upper connecting plate, 62-lower connecting plate , 63-fixed plate, 8-steel box girder fixed bracket, 9-steel box girder bottom plate.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

As shown in FIGS. 1-4 , an embodiment of the present invention provides a low-frequency lever-type tuned mass damper, which is installed inside a box beam and includes a lever frame 1, a spring assembly 2, a mass unit 3, a damper 5 and a fixed Institution 6. The lever frame 1 includes a lever bracket 11 and a lever cantilever 12. The lever bracket 11 is welded from steel plates, and the lower end of the lever bracket 11 is connected to the steel box girder fixing bracket 8 pre-installed on the steel box girder bottom plate 9 through bolts, and then fixed. Installed on the steel box girder bottom plate 9, as the fulcrum of the lever structure in the present invention; the lever cantilever 12 is installed on both sides of the lever bracket 11 through the bearing 4, and the lever cantilever 12 is the lever bracket 11. For the fulcrum, it can move moderately, such as rotating around the bearing 4 . The fixing mechanism 6 includes an upper connecting plate 61 , a lower connecting plate 62 and a fixing plate 63 . The upper connecting plate 61 is installed above the middle support portion of the lever cantilever 12 , and a spring is installed below the upper connecting plate 61 . Assembly 2, damper 5 and lower connecting plate 62, the lower end of the damper 5 is mounted on the lower connecting plate 62; the spring assembly 2 includes a spring 21 and a guide column 22, the guide column 22 corresponds to is installed on the lower surface of the upper connecting plate 61 and the upper surface of the lower connecting plate 62, the spring 21 is sleeved on the outer circumference of the guide column 22, on the one hand, it plays a guiding role, forcing the spring 21 Only vertical displacement occurs along the guide column 22, while other degrees of freedom movement of the spring 21 are restricted, and a sleeve is installed on the outside of the spring 21 to fix the movement direction of the spring and make it easy to return; the upper connection The plate 61 is also fixedly connected with the fixing plate 63, and the fixing plate 63 is connected with the lever cantilever 12 through a bearing, so that the upper connecting plate 61, the spring assembly 2, the damper 5 and all the The vertical vertical movement of the lower connecting plate 62; the lower connecting plate 62 is connected with the steel box girder fixing bracket 8 through bolts and then installed on the steel box girder bottom plate 9; the mass unit 3 is installed on the The end of the lever cantilever 12, as the power structure of the lever structure in the present invention, the mass unit 3 is formed by connecting n steel plates with fixed mass through the screw 32, the mass is adjustable, and is used to control the frequency of the TMD. During operation, the frequency of this TMD is adjusted by adjusting the number of mass blocks 31. When the frequency of this TMD is consistent with the frequency of the main structure, and when the main structure is vibrated by external force, the TMD will generate a vibration opposite to that of the main structure on the main structure. Inertia force, thereby reducing the vibration amplitude of the main structure, avoiding the damage of the main structure due to large vibration, and protecting the main structure from damage.

Further, as shown in FIG. 1 , the lever bracket 11 is composed of a top beam 111 and a side bracket 112 , forming an upright door-like structure, which serves as a fulcrum part of the TMD and mainly plays a supporting role. The lever cantilever 12 is connected with the lever bracket 1 through the bearing 4 to form a frame structure. The lever cantilever 12 is preferably two on the left and right, and at the same time, the bearing 4 is preferably four. The bearing design is adopted to make the lever bracket 11 and the lever cantilever 12 in a movable state, which is convenient for realizing the lever function. Moreover, the mass unit is located at one end of the lever, which acts by its own gravity to make the spring 21 in a compressed state. When the bridge structure is disturbed by an external force, this balance is broken, that is, the mass unit 3 is subjected to an external force to move vertically, and the spring 21 Corresponding to elongation or compression, the vibration frequency is consistent with the frequency of the main structure, thereby offsetting the external force disturbance and protecting the main structure.

Further, in an embodiment of the present invention, as shown in FIG. 3 , the spring assembly 2 is preferably 6 springs 21 and corresponding 6 pairs of guide columns, which can be added in the middle according to actual requirements such as stiffness and displacement. The partitions are arranged in layers, so that the design and selection of the spring is more flexible and convenient. The upper end of the spring assembly 2 is connected to the upper connecting plate 61, and the lower end is connected to the lower connecting plate 62. Such an installation method can easily maintain the vertical stiffness of the TMD.

Further, the damper 5 is fixedly installed on the lower surface of the upper connecting plate 61 and the upper surface of the lower connecting plate 62. The number of the dampers 5 is preferably two, and is fixedly installed in the middle of the spring assembly 2, In this way, the movement trajectory of the damper and the movement trajectory of the TMD main structure are kept consistent, which is convenient for control. Dampers already belong to the prior art, and are devices that use damping characteristics to slow down mechanical vibrations and consume kinetic energy.

Further, the fixing plate 63 is connected with the lever cantilever 12 through the bearing 4 , the length of the fixing plate 63 is less than the height of the lever bracket 11 and can meet the requirements of basic lever movement. The fixing plate 63 is installed below both ends of the upper connecting plate 61 , so that the upper connecting plate 61 , the spring assembly 2 , the damper 5 and the lower connecting plate 62 can form an integral structure Perform a vertical vertical movement.

Optionally, according to different installation forms required, the upper connecting plate 61 is connected with the fixing plate 63, and at the same time, the lower connecting plate 62 is fixedly connected with the steel box girder fixing bracket 8 and then fixedly installed on the On the bottom plate of the steel box beam, due to the self-gravity action of the lever cantilever 12, the upper connecting plate 61, the fixing plate 63 and the mass unit 3, the lever cantilever 12, the upper connecting plate 61, the fixing plate 63 and the mass unit 3 are spring-loaded. The integral structure formed by the assembly 2 and the damper 5 is stacked on the lower connecting plate 62 and the bottom plate 9 of the steel box girder to form a stacked TMD; the upper connecting plate 61 can be fixed with the top of the steel box girder At the same time, the lower connecting plate 62 is fixedly connected with the fixing plate 63, and the upper connecting plate 61 and the The lower end of the integral structure formed by the spring assembly 2 and the damper 5 is fixed on the lower connecting plate 61. Due to the natural characteristics of the spring assembly, the entire TMD is in a suspended state, thereby forming a suspended TMD; the stacked TMD generally adopts The vibration reduction process is completed by the compression spring method, and the suspension TMD generally uses the tension spring method to complete the vibration reduction process. The conventional TMD spring and the mass block are designed in an integrated manner, and the motion trajectory is basically the same. The present invention is different from the conventional TMD design. The spring assembly and the mass block are installed separately to form different components of the lever, and the motion trajectory of each other is separated or even opposite. The installation method can be seen. Diverse and highly flexible;

Further, both sides of the mass unit 3 are connected with the lever cantilever 12 through bearings 4, so that the mass unit 3 maintains vertical vertical movement; the mass unit 3 is connected to the lever bracket 11 and the lever cantilever 12 forms a closed frame, enclosing the upper connecting plate 61 and the lower connecting plate 62 and the integral structure formed by the spring assembly 2 and the damper 5 installed between them, and the upper connecting plate 61 can be connected. The dynamic range of the vibration damping structure formed by the plate 61 , the spring assembly 2 , the damper 5 and the lower connecting plate 62 is limited to a certain range, thereby reducing the height dimension of the entire TMD and saving installation space.

Further, the mass unit 3 includes a mass block 31 composed of n steel plates and a screw rod 32 that is fixedly connected to each other inside the mass block 31; The parameters are more accurate, and the weight of the mass unit 3 can be easily and conveniently increased or deleted by adjusting the screws and nuts between the steel plates, so as to realize the frequency adjustment of the TMD simply and conveniently; The frequency of the structure is consistent. When the main structure is vibrated by an external force, the TMD generates an opposite inertial force acting on the main structure. On the one hand, the amplitude of the TMD can be effectively controlled, and the control instability caused by collision and stroke overrun during the movement of the TMD can be reduced. Therefore, the performance of TMD in low-frequency vertical vibration control can be improved, and the performance degradation problem caused by the large static deformation of the spring can be avoided;

As shown in FIG. 5 , the specific working principle of the low-frequency lever-type tuned mass damper of the embodiment of the present invention is as follows: using the lever principle, the lever bracket 11 is used as the fulcrum; the upper connecting plate 61 , the spring assembly 2 , the The overall structure formed by the lower connecting plate 62 and the damper 5 is used as a resistance structure; the mass unit 3 is used as a dynamic structure; in a natural state, the mass unit 3 has a natural downward gravitational effect due to its own gravitational effect. , and at the same time the lever will give it a supporting reaction force against its gravitational action, thereby maintaining the balance of the lever; when the controlled structure vibrates, it will cause the mass unit 3 to move vertically and linearly. At this time, the mass unit 3 The movement will be transmitted to the resistance structure formed by the upper connecting plate 61, the spring assembly 2 and the damper 5 through the lever cantilever 12, so that it produces a movement pattern in the opposite direction to the mass unit 3, and then Complete the vibration reduction process.

According to the conventional TMD design input parameters: natural frequency f=0.2HZ, mass m=2t, stroke ±500mm, damping ratio 0.1. At this time, according to the total spring stiffness k=m·ω ² =m·(2πf) ² =3.22N/mm, it can be known that the spring static compression displacement s=mg/k=20000/3.22=6211mm, due to the small spring stiffness, the spring The compression displacement reaches 6.2m, and considering the dynamic stroke of the spring ±500mm and the ultimate compression height of the spring itself, the length of the spring will be very long and the stability will be poor. Under the same conditions, even the design length of the viscous damper will reach more than 2.5m, so the installation space is limited. It can be seen that it is difficult for the conventional design to meet the TMD parameters. In summary, in order to increase the total stiffness of the spring and reduce the dynamic stroke of the spring and damper, consider the following lever-type TMD, and its working principle is shown in Figure 5-Figure 6:

以及杠杆对其产生的支反力F，因此质量块的动力平衡方程为：As shown in Figure 6, taking the mass block as the research object, it is assumed that the damping during the motion process is ignored, and the mass of the lever and spring is ignored. The mass block bears its own gravity mg during the motion process, which will form an inertial force

And the support reaction force F generated by the lever, so the dynamic balance equation of the mass block is:

Then according to the principle of leverage:

F·L=k·x1·L1 (2)

Bring it into equation (1) to get:

Taking n=L/L ₁ as the leverage magnification factor, then equation (4) can be written as

It can be seen that after the lever-type TMD is adopted, if the structural frequency f and mass m remain unchanged, the spring stiffness should be amplified by n2 times. The stroke of the spring and damper can be shortened to 1/n times the stroke of the mass.

The conventional low-frequency TMD has a long natural vibration period, small spring stiffness, and large vertical load, so the design and selection of the spring will be very difficult. Springs with low stiffness will also be difficult to process and install due to their long length, excessive static load compression displacement, and large dynamic stroke. The present invention adopts the lever principle. According to the above analysis, if the structural frequency f and mass m are If it remains unchanged, the spring stiffness should be enlarged by n2 times, and the stroke of the spring and damper can be shortened to 1/n times the stroke of the mass block. This design can make the spring not easily deformed under the same stress conditions, and will not be excessively stretched. The overall stiffness of the spring 21 is improved, and the stroke of the spring and the damper is shortened. Compared with the conventional design, the height dimension of the entire TMD can be reduced and the installation space can be saved. In addition, by adjusting the mass block to make the TMD frequency consistent with the frequency of the main structure, when the main structure is vibrated by external force, the TMD generates an opposite inertial force acting on the main structure, which can effectively control the amplitude of the TMD and reduce the vibration amplitude. In this way, the control instability caused by collision and stroke overrun during the movement of the TMD is alleviated, the stroke damage of the TMD is avoided, the control stability of the TMD is ensured, and the main structure is protected from damage. Finally, the fixing plate 63 can be selectively fixed with the upper connecting plate 61 or with the lower connecting plate 62, so as to realize the free choice of the stacked TMD and the suspended TMD, and the installation methods are various; the mass block 31 is composed of It is composed of n steel plates, and the steel plates are connected and fixed by screws 32, the quality is clear and easy to adjust, which makes the design parameters of the TMD more accurate. The invention has the characteristics of reasonable and compact structure, convenient processing, stable performance and excellent vibration reduction effect, which not only overcomes the defects of the existing TMD, but also improves the vibration reduction effect.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (6)

1. A low frequency lever tuned mass damper, comprising:

the lever frame (1) comprises a lever bracket (11) and a lever cantilever (12), wherein the lever cantilever (12) is movably connected with the lever bracket (11) through a bearing (4);

the fixed mechanism (6) is vertically connected with the lever frame (1), a spring assembly (2) and a damper (5) are arranged in the fixed mechanism (6), and the bottom or the top of the lever support (11) and the fixed mechanism (6) is fixedly connected with a steel box girder bottom plate (9) through a steel box girder fixed support (8) to form a fulcrum of the tuned mass damper;

a mass unit (3) is arranged at one end, far away from the fixing mechanism (6), of the lever cantilever (12), the mass unit (3) is movably connected with the lever cantilever (12) through a bearing (4), the mass unit (3) and the lever cantilever (12) form a power and power arm of a tuned mass damper, and a resistance arm are formed between the spring assembly (2), the damper (5) and the lever cantilever (12) and the lever bracket (11); and the number of the first and second electrodes,

the mass unit (3) comprises a mass block (31), the mass of the mass block (31) can be adjusted, and the frequency of the lever-type tuned mass damper is adjusted to be consistent with the frequency of the main structure, so that when the main structure is vibrated by external force, an inertia force opposite to the vibration of the main structure is generated, and the amplitude of the main structure is reduced.

2. A low frequency lever tuned mass damper according to claim 1, wherein said fixing mechanism (6) comprises an upper connecting plate (61), a lower connecting plate (62) and a fixing plate (63);

the upper connecting plate (61) is fixedly connected with the fixing plate (63);

and the lower connecting plate (62) is fixedly connected with the steel box girder bottom plate (9).

3. A low frequency lever tuned mass damper as claimed in claim 2, wherein said spring assembly (2) comprises a spring (21) and a guide post (22);

the guide columns (22) are respectively arranged on the upper connecting plate (61) and the lower connecting plate (62);

two ends of the spring (21) are respectively sleeved on the corresponding guide posts (22).

4. A low frequency lever tuned mass damper according to claim 3, wherein said spring (21) is externally fitted with a sleeve for fixing the direction of movement of the spring (21).

5. A low frequency lever tuned mass damper according to any of the claims 1-4, characterized in that the mass unit (3) comprises a screw (32), the masses (31) being fixedly connected by means of the screw (32).

6. A low frequency leverage tuned mass damper according to any of the claims 1-4 characterized in that the lever bracket (11) comprises a lever cross beam (111) and a lever longitudinal beam (112) arranged perpendicular to the lever cross beam (111).

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