CN109869438B - Sling vibration damping method - Google Patents
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- CN109869438B CN109869438B CN201910182097.5A CN201910182097A CN109869438B CN 109869438 B CN109869438 B CN 109869438B CN 201910182097 A CN201910182097 A CN 201910182097A CN 109869438 B CN109869438 B CN 109869438B
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Abstract
The invention discloses a sling damping method, which comprises the following steps: acquiring the vibration frequency of the sling; determining the mass of a first hammer and a second hammer of the multi-tuned mass damper, the type of a steel strand, the distance from the first hammer to a supporting part and the distance from the second hammer to the supporting part according to the vibration frequency of the sling; determining a position of a multi-tuned mass damper mounted on a sling; and installing multiple tuned mass dampers to damp the sling. The invention can effectively solve the problem that the position of the connecting point of the damper and the sling cable is changed and needs to be continuously adjusted along with the change of the construction progress.
Description
Technical Field
The invention relates to the technical field of sling damping, in particular to a sling damping method.
Background
The sling structure has large slenderness ratio, small damping and multiple vibration modes, and is easy to generate various types of vibration, mainly comprising wind-induced vibration (such as vortex-induced vibration, wake relaxation vibration, buffeting and the like) and end excitation vibration. The continuous large vibration of the sling can cause fatigue and corrosion of the cable strand in a short time, and can cause discomfort for pedestrians or vehicles and doubts of the use safety of the bridge, so that corresponding measures are taken to control the vibration of the sling.
The control measures for the vibration of the sling mainly comprise two methods, namely an aerodynamic method for treating the surface of the sling to achieve the effect of vibration reduction. Secondly, the method of external damper to increase the damping of sling, the commonly used sling damper has: oil dampers, friction dampers, rubber dampers, and the like, but these dampers must be installed between the slings and the support structure, which is required to be provided near the fixed ends of the slings.
When a girder needs to be erected, a bridge deck is paved, a dead load is increased, the alignment of the bridge needs to be adjusted and the like in the construction period of the bridge, the cable force of the sling needs to be adjusted, the elongation of the sling is changed, the position of the connecting point of the damper and the sling is changed, continuous adjustment is needed along with the change of the construction progress, and meanwhile, the damper needs to be protected in the construction process so as to be prevented from being damaged.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a sling damping method. The invention can effectively solve the problem that the position of the connecting point of the damper and the sling cable is changed and needs to be continuously adjusted along with the change of the construction progress.
In order to achieve the above purposes, the technical scheme adopted by the invention is as follows:
the invention provides a sling damping method, which comprises the following steps:
acquiring the vibration frequency of the sling;
confirm the quality of first tup and the second tup of multiple harmonious mass damper, the model of steel strand wires, the distance of first tup to the supporting part and the distance of second tup to the supporting part according to the vibration frequency of hoist cable, specifically:
step A: selecting the mass of the first hammer head and the mass of the second hammer head according to the mass ratio of the mass of the first hammer head to the mass of the second hammer head to the modal mass of the sling;
and B: determining the rigidity of the steel strand according to the diameter of the steel strand of the selected type;
and C: calculating the natural frequencies of the first hammer head and the second hammer head:
wherein: k is a radical of1,22 natural frequencies, k, of the first hammer 3,42 natural frequencies, k, of the second ramaIs the stiffness of the steel strand, M1Mass of the first hammer, M2Mass of the second ram, L1L is more than or equal to 0.2 and is the distance from the first hammer head to the supporting part1≤1，L2L is more than or equal to 0.2 and is the distance from the second hammer head to the supporting part2≤1，S1Is the distance between the connecting point of the first hammer head and the steel strand and the mass center of the first hammer head, s2The distance between the connecting point of the second hammer head and the steel strand and the mass center of the second hammer head, Ja1Is the moment of inertia of the first ram, Ja2The moment of inertia of the second hammer head;
step D: according to the selected mass of a plurality of groups of first hammers and second hammers, a plurality of groups of steel strands with different types, the distance from the first hammers to a supporting part and the distance from the second hammers to the supporting part, calculating to obtain the natural frequencies of a plurality of groups of 4 different first hammers and second hammers, determining the range of each group of 4 natural frequencies covering the frequency of the sling, selecting one group with the maximum frequency range of the sling covered by the 4 natural frequencies, and selecting the mass of the first hammers and the second hammers, the type of the steel strands, the distance from the first hammers to the supporting part and the distance from the second hammers to the supporting part corresponding to the group;
determining a position of the multi-tuned mass damper mounted on a sling;
and installing the multiple tuned mass dampers to damp the sling.
On the basis of the technical scheme, the mass ratio of the mass of the first hammer head to the mass of the second hammer head to the modal mass of the sling is 0.5-2%.
On the basis of the technical scheme, the multiple tuned mass dampers are arranged at the maximum amplitude position of the sling.
On the basis of the technical scheme, when the multiple tuned mass dampers are installed, the first hammer head and the second hammer head are located in the vibration direction of the sling.
On the basis of the technical scheme, when the sling vibrates along a plurality of different directions, the corresponding multiple tuned mass dampers are arranged according to the number and the directions of the vibration directions of the sling.
On the basis of the technical scheme, when the multiple tuned mass dampers are installed, the first hammer head is installed below the second hammer head.
Compared with the prior art, the invention has the advantages that: when the tuned mass damper is used, the multiple tuned mass damper is arranged on the sling, the first hammer head is larger than the mass of the second hammer head, the distance from the first hammer head to the supporting part is different from the distance from the second hammer head to the supporting part, so that the first hammer head is larger than the second hammer head and has two different natural frequencies, and the multiple tuned mass damper has four different natural frequencies. When the sling produces vibration, the relative motion of the multiple tuned mass dampers hung on the sling absorbs the vibration energy, thereby reducing and eliminating the vibration of the sling, and the multiple tuned mass dampers have four different natural frequencies and can adapt to wider vibration frequencies.
Drawings
FIG. 1 is a schematic structural diagram of a multiple tuned mass damper in an embodiment of the present invention;
FIG. 2 is a schematic illustration of the installation of a multiple tuned mass damper in an embodiment of the present invention;
FIG. 3 is a graph of multiple tuned mass dampers versus sling frequency ratio and damping ratio.
In the figure: 1. a sling clamp; 11. a clamping portion; 12. a support portion; 2. steel strand wires; 31. a first ram; 32. a second hammer head; 4. a sling; 10. a multiple tuned mass damper.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Fig. 1 is a schematic structural diagram of a multiple tuned mass damper in an embodiment of the present invention. As shown in fig. 1, an embodiment of the present invention provides a multi-tuned mass damper, comprising:
the sling clamp 1 comprises a clamping part 11 and a supporting part 12, wherein the clamping part 11 is fixedly connected with one end of the supporting part 12;
the steel strand 2 is fixed at the other end of the supporting part 12, and the steel strand 2 is vertical to the length direction of the supporting part 12;
the first hammer 31 and the second hammer 32 are respectively arranged at two ends of the steel strand 2, the first hammer 31 is larger than the second hammer 32 in mass, and the distance from the first hammer 31 to the supporting part 12 is different from the distance from the second hammer 32 to the supporting part 12.
When in use, the multiple tuned mass damper is arranged on the sling, the first hammer head 31 is larger than the mass of the second hammer head 32, the distance from the first hammer head 31 to the supporting part 12 is different from the distance from the second hammer head 32 to the supporting part 12, so that the first hammer head 31 is larger than the second hammer head 32 and has two different natural frequencies, and the multiple tuned mass damper has four different natural frequencies. When the sling produces vibration, the relative motion of the multiple tuned mass dampers hung on the sling absorbs the vibration energy, thereby reducing and eliminating the vibration of the sling, and the multiple tuned mass dampers have four different natural frequencies and can adapt to wider vibration frequencies.
Preferably, the first ram 31 is U-shaped, the U-shaped opening of the first ram 31 faces the support portion 12, and the width of the U-shaped opening of the first ram 31 is greater than the diameter of the steel strand 2. Such design can prevent that multiple harmonious mass damper when vibration, first tup 31 rubs the steel strand wires.
Preferably, the second ram 32 is U-shaped, the U-shaped opening of the second ram 32 faces the support portion 12, and the width of the U-shaped opening of the second ram 32 is greater than the diameter of the steel strand 2. Such design can prevent that multiple harmonious mass damper when vibrating, second tup 32 friction steel strand wires.
In another aspect, the present invention further provides a method for damping a suspension cable, the method comprising:
acquiring the vibration frequency of the sling;
determining the mass of a first hammer and a second hammer of the multi-tuned mass damper, the type of a steel strand, the distance from the first hammer to a supporting part and the distance from the second hammer to the supporting part according to the vibration frequency of the sling;
determining a position of the multi-tuned mass damper mounted on a sling;
and installing the multiple tuned mass dampers to damp the sling.
Firstly, the vibration frequency of the sling is obtained, and the mass of the first hammer head and the second hammer head, the type of the steel strand, the distance from the first hammer head to the supporting part and the distance from the second hammer head to the supporting part are determined according to the vibration frequency of the sling. And acquiring the position of the multi-tuned mass damper, which is arranged on the sling, namely the position of the sling with the maximum vibration amplitude, and finally installing the multi-tuned mass damper at the position. The selected multiple tuned mass damper can cover wider vibration frequency of the sling, so that better vibration reduction effect is obtained.
Preferably, the mass of the first hammer and the second hammer of the multiple tuned mass damper, the type of the steel strand, the distance from the first hammer to the supporting part and the distance from the second hammer to the supporting part are determined according to the vibration frequency of the sling, and the specific steps comprise:
step A: selecting the mass of the first hammer head and the mass of the second hammer head according to the mass ratio of the mass of the first hammer head to the mass of the second hammer head to the modal mass of the sling;
and B: determining the rigidity of the steel strand according to the diameter of the steel strand of the selected type;
and C: calculating the natural frequencies of the first hammer head and the second hammer head:
wherein: k is a radical of1,22 natural frequencies, k, of the first hammer 3,42 natural frequencies, k, of the second ramaIs the stiffness of the steel strand, M1Mass of the first hammer, M2Mass of the second ram, L1L is more than or equal to 0.2 and is the distance from the first hammer head to the supporting part1≤1，L2L is more than or equal to 0.2 and is the distance from the second hammer head to the supporting part2≤1，S1Is the distance between the connecting point of the first hammer head and the steel strand and the mass center of the first hammer head, s2The distance between the connecting point of the second hammer head and the steel strand and the mass center of the second hammer head, Ja1Is the moment of inertia of the first ram, Ja2The moment of inertia of the second hammer head;
step D: according to the selected multiple groups of first hammers, the mass of the second hammers, multiple groups of steel strands with different models, the distances from the multiple groups of different first hammers to the supporting part and the distances from the second hammers to the supporting part, the natural frequencies of the multiple groups of different 4 first hammers and second hammers are obtained through calculation, the range of each group of 4 natural frequencies covering sling frequency is determined, one group with the largest frequency range of the 4 natural frequencies covering sling is selected, the masses of the first hammers and the second hammers corresponding to the group are selected, the models of the steel strands, the distances from the first hammers to the supporting part and the distances from the second hammers to the supporting part are selected. The mass of the corresponding first hammer head and the second hammer head, the type of the steel strand, the distance from the first hammer head to the supporting part and the distance from the second hammer head to the supporting part are selected as the mass of the first hammer head and the second hammer head of the multi-tuned mass damper, the type of the steel strand, the distance from the first hammer head to the supporting part and the distance from the second hammer head to the supporting part.
In this embodiment, when multiple sets of adaptive solutions are obtained, that is, when multiple sets of solutions capable of covering the frequency of the sling are obtained, the steel strand, the first hammer head and the second hammer head with the smallest mass, and the distance from the first hammer head to the supporting part and the distance from the second hammer head to the supporting part are selected, so that the material and the cost are saved.
The optimal quality of the first hammer head and the second hammer head, the type of the steel strand, the distance from the first hammer head to the supporting part and the distance from the second hammer head to the supporting part can be obtained through the steps. To obtain the best damping effect.
FIG. 3 is a graph of multiple tuned mass dampers versus sling frequency ratio and damping ratio. As shown in fig. 3, the damping required by the sling damping is relatively small, the effective damping can be realized when the damping target damping ratio of the sling is 0.5%, and the coverage frequency range is 0.8-1.2 times of the dominant frequency when the mass ratio of the multi-tuned mass damper to the sling is 1.0%; when the mass ratio of the multi-tuned mass damper to the sling is 2.0%, the coverage frequency range is 0.7-1.3 times of the main frequency.
Preferably, the mass ratio of the mass of the first hammer head to the mass of the second hammer head to the modal mass of the sling is 0.5-2%.
Preferably, the multiple tuned mass dampers are mounted at the maximum amplitude of the sling.
The installation of the multiple tuned mass dampers at the maximum amplitude of the sling can achieve better damping effect.
Further, the maximum amplitude of the sling is obtained by field actual measurement or computer numerical simulation. In this embodiment, the maximum amplitude of the sling is obtained by computer numerical simulation. Of course, this can also be obtained by actual measurement by installing an inductor in the suspension cable.
Preferably, when the multiple tuned mass dampers are installed, the first ram and the second ram are located in the vibration direction of the sling. The first hammer and the second hammer are located in the vibration direction of the sling, so that a better vibration reduction effect can be obtained.
Figure 2 is a schematic illustration of the installation of a multiple tuned mass damper in an embodiment of the present invention. As shown in fig. 2. Further, when the sling vibrates along a plurality of different directions, the corresponding multi-tuned mass dampers are arranged according to the number and the directions of the vibration directions of the sling. When the sling has a plurality of vibrations along the direction of the sling, the multiple tuned mass dampers with corresponding quantity and directions are arranged in different vibration directions, so that the vibrations in all the vibration directions can be controlled.
Further, when installing multiple harmonious mass damper, first tup is installed in the below of second tup. The installation can make the steel strand wires of big hammer end draw like this, and the steel strand wires of little hammer end are compressed, makes the stability of steel strand wires better.
The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention. Those not described in detail in this specification are within the skill of the art.
Claims (6)
1. A method of damping a sling, providing a multiple tuned mass damper, comprising:
the sling clamp (1) comprises a clamping part (11) and a supporting part (12), wherein the clamping part (11) is fixedly connected with one end of the supporting part (12);
the steel strand (2) is fixed to the other end of the supporting part (12), and the steel strand (2) is perpendicular to the length direction of the supporting part (12);
a first hammer head (31) and a second hammer head (32) which are respectively arranged at two ends of the steel strand (2), wherein the first hammer head (31) is larger than the mass of the second hammer head (32), the distance from the first hammer head (31) to the supporting part (12) is different from the distance from the second hammer head (32) to the supporting part (12),
the method is characterized in that: the sling damping method comprises the following steps:
acquiring the vibration frequency of the sling;
confirm the quality of first tup and the second tup of multiple harmonious mass damper, the model of steel strand wires, the distance of first tup to the supporting part and the distance of second tup to the supporting part according to the vibration frequency of hoist cable, specifically:
step A: selecting the mass of the first hammer head and the mass of the second hammer head according to the mass ratio of the mass of the first hammer head to the mass of the second hammer head to the modal mass of the sling;
and B: determining the rigidity of the steel strand according to the diameter of the steel strand of the selected type;
and C: calculating the natural frequencies of the first hammer head and the second hammer head:
wherein: k is a radical of1,22 natural frequencies, k, of the first hammer3,42 natural frequencies, k, of the second ramaIs the stiffness of the steel strand, M1Mass of the first hammer, M2Mass of the second ram, L1L is more than or equal to 0.2 and is the distance from the first hammer head to the supporting part1≤1，L2L is more than or equal to 0.2 and is the distance from the second hammer head to the supporting part2≤1，s1Is the distance between the connecting point of the first hammer head and the steel strand and the mass center of the first hammer head, s2The distance between the connecting point of the second hammer head and the steel strand and the mass center of the second hammer head, Ja1Is the moment of inertia of the first ram, Ja2The moment of inertia of the second hammer head;
step D: according to the selected mass of a plurality of groups of first hammers and second hammers, a plurality of groups of steel strands with different types, the distance from the first hammers to a supporting part and the distance from the second hammers to the supporting part, calculating to obtain the natural frequencies of a plurality of groups of 4 different first hammers and second hammers, determining the range of each group of 4 natural frequencies covering the frequency of the sling, selecting one group with the maximum frequency range of the sling covered by the 4 natural frequencies, and selecting the mass of the first hammers and the second hammers, the type of the steel strands, the distance from the first hammers to the supporting part and the distance from the second hammers to the supporting part corresponding to the group;
determining a position of the multi-tuned mass damper mounted on a sling;
and installing the multiple tuned mass dampers to damp the sling.
2. The method for damping vibration in a suspension cable according to claim 1, wherein the mass ratio of each of the first and second hammers to the modal mass of the suspension cable is 0.5% to 2%.
3. The sling damping method as defined in claim 1 wherein the multiple tuned mass dampers are mounted at maximum amplitude of the sling.
4. The method for damping vibration in a sling according to claim 1, wherein the first ram and the second ram are positioned in a vibration direction of the sling when the multiple tuned mass dampers are installed.
5. The method for damping vibration in a sling according to claim 4 wherein the multiple tuned mass dampers are arranged in correspondence with the number and direction of vibration directions of the sling when the sling is vibrated in a plurality of different directions.
6. The method for damping vibration in a sling according to claim 1 wherein the first ram is mounted below the second ram when the multiple tuned mass dampers are installed.
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112130599B (en) * | 2020-08-28 | 2022-02-25 | 同济大学 | Cable multi-mode vibration control method considering damper performance frequency dependency |
| CN112211468A (en) * | 2020-09-29 | 2021-01-12 | 温州市滨江建设投资有限公司 | Multiple harmonious mass damper |
| CN112227180B (en) * | 2020-09-30 | 2022-07-01 | 中铁大桥局集团有限公司 | Stay cable combined vibration reduction device and method |
| CN112695609A (en) * | 2020-12-18 | 2021-04-23 | 中铁大桥局集团有限公司 | Multi-directional multi-tuning mass damper for cable structure vibration reduction |
| CN115030016A (en) * | 2022-06-23 | 2022-09-09 | 河海大学 | Double-tuned mass damper for vibration reduction of suspension cable of suspension bridge |
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