Inertial bridge transverse dynamic deflection measuring device and method

Abstract

The invention discloses an inertial bridge transverse dynamic deflection measuring device and method. The inertial bridge transverse dynamic deflection measuring device comprises a shell, a spring, a mass block, a first limiting mechanism and a displacement meter. The mass block is located in the shell, one ends of the springs are symmetrically fixed to the two ends of the mass block, the other ends of the springs are fixed to the inner wall of the shell, a through hole is formed in an end plate, connected with the springs, of one side of the shell, and the testing end of the displacement meter measures the relative displacement of the mass block and the shell through the through hole. The first limiting mechanism is used for offsetting the total gravity of the mass block and the magnets arranged on the mass block. The device can be adaptive to direct testing of the transverse dynamic deflection of the main beam with different requirements of bridges with different spans on the transverse dynamic deflection precision, and has the remarkable advantages of high measurement precision, rapidness and high efficiency in installation and arrangement, simple structural form, better natural environment adaptability and economy and the like.

Description

Technical Field

[0001] The invention relates to the field of bridge main beam lateral dynamic deflection testing, and in particular to an inertial bridge lateral dynamic deflection measuring method and device. Background Art

[0002] The lateral dynamic deflection of the bridge main beam reflects the degree of lateral dynamic bending deformation of the beam under external loads such as wind, vehicles, crowds, and earthquake vibrations, which has a significant impact on pedestrian comfort and the service life and safety of the bridge, especially the most intuitive parameter for the lateral vibration performance of large-span pedestrian bridges. Accurate and efficient acquisition of the lateral dynamic deflection of the bridge main beam has become one of the important issues that need to be paid attention to in bridge engineering. Accurate measurement of the lateral dynamic deflection of the bridge main beam helps to evaluate the walking comfort, structural health and safety performance of the bridge. At present, the commonly used methods for measuring the lateral dynamic deflection of the bridge main beam include direct measurement and indirect measurement methods. For example, the Beidou system and GPS used in extra-large span bridges, the graphic method and the table displacement meter method used in small and medium span bridges are all direct measurement methods, and the commonly used acceleration method and inclinometer method are indirect measurement methods. The measurement accuracy of various existing technical methods is unrelated to the dynamic deflection of structures such as bridges. After the equipment is produced, the accuracy is a certain value, and it cannot adapt to the different accuracy requirements of large and small displacement values. In addition, the Beidou system and GPS require that the measuring point is unobstructed, the technology is complex, and the price is expensive. The image acquisition equipment used in the graphic method is difficult to adapt to the adverse effects of rain, snow, fog, and foundation vibration. In addition, the safety protection problem of the equipment itself is difficult to effectively solve during long-term monitoring. Good quality lenses are also expensive. It is even more difficult to effectively measure when facing mountainous areas across rivers and gullies. The table displacement meter has high accuracy and is inexpensive, but it requires a fixed reference point during the test, which greatly limits its scope of use. Indirect measurement methods all obtain the dynamic deflection value through complex mathematical operations after obtaining the values ​​of other physical quantities. The data's own errors and the actual boundary conditions during data processing are difficult to accurately account for, and the empirical attributes are obvious, resulting in unsatisfactory accuracy of the results. The microwave radar method that has emerged in recent years is still in the research stage, has limited practical value, and is extremely expensive. It is difficult to determine the fixed reference point for lateral dynamic deflection testing.

[0003] By the end of 2023, there will be 10,239 super-large bridges in my country's highway bridges. With the improvement of urbanization and the development of transportation construction, the number of pedestrian bridges has increased year by year. In particular, the demand for urban landscape in recent years has made pedestrian bridges increasingly develop in the direction of complex structures and super-large spans. Many pedestrian bridges have a span of more than 200m or even about 300m. The lateral vibration of such large-span bridges has caused increasingly prominent problems in traffic comfort, structural durability and safety, which puts forward higher requirements for the accurate and efficient acquisition of bridge lateral vibration displacement.

[0004] Therefore, it is necessary to provide a method and device for measuring the lateral dynamic deflection of a bridge to accurately and quickly obtain the lateral dynamic deflection of the beam body, which is a technical problem that needs to be solved urgently. Summary of the invention

[0005] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0006] Another object of the present invention is to provide a method and device for directly testing the lateral dynamic deflection of the main beam that can adapt to different span bridges with different lateral dynamic deflection accuracy requirements, and has the significant advantages of fast and efficient installation and layout, better structural form and adaptability to the natural environment, and good economy.

[0007] The technical solution adopted by the present invention to solve this technical problem is: an inertial bridge lateral dynamic deflection measuring device, including a housing, a spring, a mass block, a first limit mechanism, and a displacement meter; The mass block is located in the shell, one end of a pair of springs are symmetrically fixed to the two ends of the mass block, and the other end of the spring is fixed to the inner wall of the shell. One side end plate of the shell connected to the spring is provided with a through hole, and the displacement meter test end measures the relative displacement between the mass block and the shell through the through hole. The first limiting mechanism is used to offset the gravity of the mass block.

[0008] As a further solution of the present invention, the mass block is a hollow structure.

[0009] As a further solution of the present invention, the top plate of the shell is made of conductive material, thereby providing a suitable damping ratio.

[0010] As a further solution of the present invention, it also includes a power supply component and a data transmission module; the power supply component is electrically connected to the displacement meter and continuously supplies power to the displacement meter, and the data transmission module is electrically connected to the displacement meter and saves and transmits the measurement data, thereby realizing automatic measurement.

[0011] As a further solution of the present invention, the first limiting mechanism includes a first magnet and a second magnet, the first magnet is fixed to the bottom of the shell, the second magnet is fixed to the bottom of the mass block, the first magnet and the second magnet have the same magnetic poles, and the repulsive magnetic force between the first magnet and the second magnet is the same as the total gravity of the mass block and the magnets arranged thereon.

[0012] As a further solution of the present invention, it also includes a second limiting mechanism, which includes a third magnet and a fourth magnet, the fourth magnet is arranged on both sides of the mass block where no spring is arranged, the fourth magnet is fixed to the side of the inner wall of the shell relative to the third magnet, and the third magnet and the fourth magnet have the same magnetic pole.

[0013] As a further solution of the present invention, the first limiting mechanism includes a sliding device, the mass block is placed on the sliding device, and the sliding device can move in a direction parallel to the spring axis.

[0014] As a further solution of the present invention, the first limiting mechanism is a liquid medium filled in the shell, and the buoyancy provided by the liquid medium is the same as the gravity of the mass block.

[0015] As a further solution of the present invention, a fifth magnet is arranged on the top of the mass block.

[0016] The present invention also provides a method for using the inertial bridge lateral dynamic deflection measuring device, comprising: S1. Fix the measuring device on the bridge beam to be measured so that the axial direction of the spring is parallel to the beam in the horizontal direction; S2. The lateral displacement of the mass block measured by the displacement meter is the lateral dynamic deflection of the bridge.

[0017] The present invention at least includes the following beneficial effects: the classical theory of inertial displacement meter shows that when the frequency ratio (frequency of the structure to be measured / frequency of the device itself) is greater than 2.5 and the damping ratio is 0.6-0.7, the measured value of the displacement of the structure to be measured is substantially equal to the actual value, and the displacement test accuracy increases with the increase of the frequency ratio. Therefore, an inertial bridge lateral dynamic deflection measurement method and device are proposed, in which the change of the mass block relative to the shell is the displacement value of the structure to be measured, which is directly measured by the displacement meter arranged at the end, and the device can be made portable and miniaturized through structural design.

[0018] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of an inertial bridge lateral dynamic deflection measuring device according to an embodiment of the present invention; Figure 2 It is a side view of an inertial bridge lateral dynamic deflection measuring device according to one embodiment of the present invention; Figure 3 It is a schematic diagram of establishing the coordinate system of the inertial bridge lateral dynamic deflection measurement device.

[0020] Among them, 1-housing, 2-spring, 3-mass block, 4-displacement meter, 5-power supply assembly, 6-data transmission module, 7-first magnet, 8-second magnet, 9-third magnet, 10-fourth magnet. DETAILED DESCRIPTION

[0021] The present invention is described in detail and completely below in conjunction with the accompanying drawings. A person of ordinary skill in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly pointed out that the technical solutions and technical features provided in each part of the present invention, including the following description, can be combined with each other without conflict.

[0022] In addition, the embodiments of the present invention involved in the following description are generally only a part of the embodiments of the present invention, rather than all the embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings and implementations, and its specific implementation process is as follows: like Figures 1 to 3 As shown, the present invention provides an inertial bridge lateral dynamic deflection measuring device, which does not require line of sight, liquid pipeline laying, and fixed reference point during use, and includes a housing 1, a spring 2, a mass block 3, a first limit mechanism, and a displacement meter 4; The mass block 3 is located in the shell 1, one end of a pair of springs 2 are symmetrically fixed at both ends of the mass block 3, and the other end of the spring 2 is fixed to the inner wall of the shell 1. One side end plate of the shell 1 connected to the spring 2 is provided with a circular through hole, and the test end of the displacement meter 4 measures the relative displacement between the mass block 3 and the shell 1 through the through hole. Since the spring 2 is relatively soft, in order to avoid a large shake of the mass block 3, a first limiting mechanism is provided. The first limiting mechanism is used to offset the total gravity of the mass block 3 and the magnet arranged thereon, to ensure that the mass block 3 always moves laterally along the bridge in the middle of the shell 1.

[0024] This technical solution may also include the following technical details to better achieve the technical effect: the mass block 3 is a hollow structure.

[0025] The technical solution may also include the following technical details to better achieve the technical effect: the top plate of the shell 1 is made of conductive material, which may be an aluminum plate or a copper plate, but is not limited to the two materials listed. The top plate of the shell 1 is made of a material with good conductive properties, and a certain eddy current damping is generated by the relative movement between the top plate and the fifth magnet arranged on the upper surface of the mass block 3, thereby achieving high precision and environmental adaptability of the bridge lateral deflection measurement device.

[0026] The present technical solution may also include the following technical details to better achieve the technical effect: it also includes a power supply assembly 5 and a data transmission module 6 fixed on the surface of the shell 1; the power supply assembly 5 is electrically connected to the displacement meter 4 and continuously supplies power to the displacement meter 4, and the data transmission module 6 is electrically connected to the displacement meter 4 and saves and transmits the measured data.

[0027] The present technical solution may also include the following technical details to better achieve the technical effect: the first limiting mechanism includes a first magnet 7 and a second magnet 8, the first magnet 7 is fixed to the bottom of the shell 1, and the second magnet 8 is fixed to the bottom of the mass block 3, the first magnet 7 and the second magnet 8 have the same magnetic poles, and the repulsive magnetic force between the first magnet 7 and the second magnet 8 is the same as the total gravity of the mass block 3 and the magnets arranged thereon.

[0028] This technical solution may also include the following technical details to better achieve the technical effect: it also includes a second limiting mechanism, which includes a third magnet 9 and a fourth magnet 10, the fourth magnet 10 is arranged on both sides of the mass block 3 where the spring 2 is not arranged, the fourth magnet 10 is fixed to the side of the inner wall of the shell 1 relative to the third magnet 9, and the third magnet 9 and the fourth magnet 10 have the same magnetic poles, thereby eliminating the lateral deviation of the mass block 3 during the movement. In this way, the automatic high-precision measurement of the lateral dynamic deflection of the bridge without line of sight is realized, and the miniaturization and portability of the measuring device are realized.

[0029] The technical solution may also include the following technical details to better achieve the technical effect: the first limiting mechanism includes a sliding device, the mass block 3 is placed on the sliding device, and the sliding device can move in a direction parallel to the axis of the spring 2. The structural form of the sliding device is more economical and practical, and the sliding device includes a roller, a transverse limiting plate arranged laterally in the center of the inner side of the roller, and a connection structure of the roller connecting the mass block 3.

[0030] The technical solution may also include the following technical details to better achieve the technical effect: the first limiting mechanism is a liquid medium, which is filled in the shell 1. The through hole at the shell 1 needs to be sealed with a transparent thin plate, but it does not affect the measurement of the displacement meter 4. The buoyancy provided by the liquid medium is the same as the total gravity of the mass block 3 and the magnets arranged thereon. The existence of the liquid damping force can improve the lateral dynamic displacement measurement accuracy of the device and its environmental adaptability. When the first limiting mechanism includes both the liquid medium and the sliding device, the role of the liquid medium is mainly to provide damping, thereby improving the accuracy of the measuring device.

[0031] The present technical solution may also include the following technical details to better achieve the technical effect: a fifth magnet is arranged on the top of the mass block 3, and the fifth magnet is arranged to be combined with the metal shell 1 at the top, so that the damping size can be adjusted according to the distance between the metal shell 1 at the top and the fifth magnet.

[0032] The present invention also provides a method for measuring the lateral dynamic deflection of a bridge using an inertial bridge, comprising: S1. Fix the measuring device on the bridge beam to be measured so that the axis direction of the spring 2 is parallel to the beam in the horizontal direction; S2. Record the lateral displacement of the mass block 3 measured by the displacement meter 4 as the lateral dynamic deflection of the bridge.

[0033] It should be noted that the measuring device of the present invention can also be used in the field of monitoring / measuring the horizontal dynamic displacement of bridge towers, bridge piers and high-rise buildings.

[0034] Theoretical explanation of the accuracy of the inertial bridge lateral dynamic deflection measurement device: Establish as Figure 3 In the coordinate system shown, y is the lateral displacement of the main beam (also the displacement of the device housing), x is the displacement of mass block 3, and the lateral dynamic displacement y of the main beam is: (1) Among them, A is the amplitude of the transverse dynamic displacement of the main beam, ω is the transverse vibration circular frequency of the main beam, and t is the time.

[0035] Then the differential equation of motion of mass block 3 is: (2) The measured value u of the displacement meter 4 in the bridge lateral dynamic deflection measuring device is the relative displacement between the mass block 3 and the shell 1, that is: (3) Substituting equation (3) into equation (2), the relative motion differential equation of mass block 3 is obtained as follows: (4) The solution of steady-state vibration of formula (4) is: (5) in, (6) (7) λ is the frequency ratio, (ω n is the natural circular frequency of the measuring device); ζ is the damping ratio.

[0036] The displacement amplitude U of the mass block 3 measured by the displacement meter 4 is taken as the output. hour, ,have: (8) Formula (8) shows that when the frequency ratio (frequency of the structure to be tested / frequency of the equipment itself) λ>2.5 and the damping ratio ζ is 0.6~0.7, the measured value of the lateral dynamic deflection to be tested is basically equal to the actual value, and the test accuracy increases with the increase of the frequency ratio.

[0037] In actual engineering applications, as the span of the bridge continues to decrease, the frequency of the change of the lateral dynamic deflection of the structure continues to increase. When the test device remains unchanged, the frequency ratio λ continues to increase, and the accuracy of the lateral dynamic deflection test of the bridge will be further improved. That is, the amplitude of the lateral dynamic deflection of the large-span bridge is large, and the accuracy requirements of the test device are low; the amplitude of the lateral dynamic deflection of the small-span bridge is small, and the accuracy requirements of the test device are high; these requirements are completely consistent with the characteristics of the above-mentioned device itself. During the bridge lateral dynamic deflection test, the device has good adaptive characteristics, which meets the actual needs of the project very well.

[0038] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. An inertial bridge lateral dynamic deflection measuring device, characterized in that: It includes a housing, a spring, a mass block, a first limiting mechanism, and a displacement meter; The mass block is located in the shell, one end of a pair of springs are symmetrically fixed to the two ends of the mass block, and the other end of the spring is fixed to the inner wall of the shell. One side end plate of the shell connected to the spring is provided with a through hole, and the displacement meter test end measures the relative displacement between the mass block and the shell through the through hole. The first limiting mechanism is used to offset the total gravity of the mass block.

2. The inertial bridge lateral dynamic deflection measuring device according to claim 1, characterized in that: The mass block is a hollow structure.

3. The inertial bridge lateral dynamic deflection measuring device according to claim 1, characterized in that: The top plate of the shell is made of conductive material.

4. The inertial bridge lateral dynamic deflection measuring device according to claim 1, characterized in that: It also includes a power supply component and a data transmission module; the power supply component is electrically connected to the displacement meter and continuously supplies power to the displacement meter, and the data transmission module is electrically connected to the displacement meter and saves and transmits the measured data.

5. The inertial bridge lateral dynamic deflection measuring device according to claim 1, characterized in that: The first limiting mechanism includes a first magnet and a second magnet, the first magnet is fixed to the bottom of the shell, and the second magnet is fixed to the bottom of the mass block. The first magnet and the second magnet have the same magnetic poles, and the repulsive magnetic force between the first magnet and the second magnet is the same as the total gravity of the mass block and the magnets arranged thereon.

6. The inertial bridge lateral dynamic deflection measuring device according to claim 5, characterized in that: It also includes a second limiting mechanism, which includes a third magnet and a fourth magnet. The fourth magnet is arranged on both sides of the mass block where no spring is arranged. The fourth magnet is fixed to the side of the inner wall of the shell relative to the third magnet. The third magnet and the fourth magnet have the same magnetic pole.

7. The inertial bridge lateral dynamic deflection measuring device according to claim 3, characterized in that: A fifth magnet is arranged on the top of the mass block.

8. A method for using the inertial bridge lateral dynamic deflection measuring device according to any one of claims 1 to 7, characterized in that: include: S1. Fix the measuring device on the bridge beam to be measured so that the axial direction of the spring is parallel to the beam in the horizontal direction; S2. The lateral displacement of the mass block measured by the displacement meter is the lateral dynamic deflection of the bridge.

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