Swing type pneumatic device for controlling vortex vibration of cantilever box girder bridge and cantilever box girder

Abstract

The invention discloses a swing type pneumatic device for controlling vortex vibration of a cantilever box girder bridge and a cantilever box girder. The pneumatic device comprises a hook, a suspension component and a mass block, and the swing type pneumatic devices are arranged on the lower surfaces (3) of cantilevers on the two sides of a cantilever box girder in a bilateral symmetry mode. The method overcomes the defects that a traditional cantilever box girder pneumatic measure is single in acting effect and practical engineering construction is difficult, formation of vortex at the bottom of the cantilever box girder is disturbed fundamentally, the effect of improving the vortex vibration performance of cantilever box girders with different pneumatic shapes is achieved, the vortex vibration amplitude of a main girder is reduced, and the service life of the main girder is prolonged. The driving comfort of the upper portion of the bridge is improved, and the operation safety of the cantilever box girder bridge structure is guaranteed. Compared with a traditional fixed pneumatic measure, the pneumatic measure is more convenient to install and maintain, larger in adjustable range and higher in economical efficiency, and does not conflict with other structures of the bridge.

Description

Technical Field

[0001] The invention relates to the fields of bridge engineering and disaster prevention engineering, and in particular to a swinging pneumatic device for controlling vortex vibration of a cantilever box girder bridge. Background Art

[0002] Cantilever box girders have been widely used in my country's high-speed railway bridges and urban municipal bridges due to their convenient construction and superior mechanical performance. This type of bridge piers occupy less space, do not affect the passage of vehicles under the bridge, support the width of the bridge deck, and can effectively meet the increasing traffic volume on the bridge and the large amount of pedestrian and vehicle traffic under the bridge. At the same time, it saves construction land and reduces the number of demolitions of surrounding residential buildings and buildings. However, its blunt body shape makes the vortex shedding around the main beam surface under wind load more obvious and more complex than that of streamlined box girders, making the vortex-induced vibration response of this type of bridge more significant. Although vortex-induced vibration will not cause devastating damage to the bridge like flutter and galloping divergent vibration, large-scale vortex vibration will affect driving comfort and accelerate the fatigue of bridge components, thus affecting the operational safety of the bridge. Therefore, it is of great significance to take effective aerodynamic measures to control the vortex vibration amplitude of the bridge.

[0003] At present, the measures to improve the vortex-induced vibration performance of cantilever box girder sections mainly adopt Figure 2 The integral air nozzles (the shadowed parts on both sides, i.e. the sharp-angled air nozzles) at the same height as the main beam are used to improve the aerodynamic shape of the main beam section and thus improve its vortex-induced vibration performance. This type of measure has the disadvantages of high difficulty in processing and construction of the air nozzles and large amount of steel used, which makes the actual engineering construction unchanged and has poor economic efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide a swinging pneumatic device for controlling vortex-induced vibration of a cantilever box girder bridge, so as to solve the problem that the cantilever box girder is prone to vortex-induced vibration. To this end, the present invention adopts the following technical solutions: A swinging pneumatic device for controlling vortex vibration of a cantilever box girder bridge comprises a suspension component, a mass block and a connecting structure; the lower surfaces of the cantilevers on both sides of the cantilever box girder are connected to the suspension component symmetrically through the connecting structure, and the mass block is then suspended by the suspension component so that the mass block can swing.

[0005] Furthermore, the hanging member can rotate around the hook, and the rotation angle α ranges from 10° to 180°, and the rotation angle α is the angle between the hanging member and the horizontal line.

[0006] Furthermore, the material of the suspension member can be a hard rod, or a flexible rope, chain, etc., and the length of the suspension member is 1 / 3 to 2 / 3 of the cantilever box beam height, preferably 1 / 2 times the beam height.

[0007] Further, the length of the suspension member is adjusted according to the cantilever box beam shape.

[0008] Further, the connection structure is a hook, or a ring, a rope buckle, or other connection structures suitable for fixing and allowing the suspension member to swing. The fixing structure arranged on the bottom surface of the cantilever on both sides of the box beam and matched with the connection structure can also be a hook, a ring, or the like.

[0009] Furthermore, the shape of the mass block includes but is not limited to square, cylindrical, conical, and pyramidal shapes, and any form of mass block is within the scope of this patent.

[0010] Furthermore, the pneumatic device is arranged along the axial direction of the bridge, and the number of the pneumatic devices arranged on each side of the box girder is n, where n is greater than 1.

[0011] The present invention also provides a cantilever box beam, wherein the above-mentioned swinging pneumatic device is symmetrically arranged on the lower surfaces (3) of the cantilevers on both sides of the cantilever box beam.

[0012] Compared with traditional static, fixed pneumatic measures (such as Figure 2 The pneumatic measures of the present invention are more convenient to install and maintain, have a larger adjustable range, are better adaptable to cantilever box girders of different sections, are more economical, and will not conflict with other structures of the bridge.

[0013] In summary, the present invention is based on the traditional cantilever box girder, and suspends swingable mass blocks on the lower side of the cantilever on both sides. In the case of incoming wind or the vibration of the bridge itself, the mass block will swing, thereby changing the flow field characteristics at the bottom of the cantilever box girder, fundamentally disrupting the formation of vortices at the bottom of the cantilever box girder. The pneumatic device can affect the formation, separation and shedding of vortices on the cross-section of the cantilever box girder, reduce the pressure difference between the upper and lower surfaces of the cross-section, eliminate the vortex-induced vibration of the main beam, thereby improving driving comfort and safety, and to a certain extent reduce bridge fatigue and thus extend the service life of the bridge.

[0014] The present invention will be further described below in conjunction with the accompanying drawings to fully illustrate the purpose, technical features and technical effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the standard cross-section diagram of the existing cantilever box girder.

[0016] Figure 2 It is a traditional vortex-induced vibration suppression measure for existing cantilever box sections.

[0017] Figure 3a It is a schematic diagram of the layout of the swing type pneumatic device of the present invention.

[0018] Figure 3b This is an enlarged schematic diagram of the swing type pneumatic device of the present invention, and a schematic diagram of its dimensions and installation position.

[0019] Figure 4 This is a schematic diagram of the dimensions and installation position of the pneumatic device of an implementation example of the present invention, where the units of the dimensions are cm.

[0020] Figure 5 The vertical vortex vibration amplitude at 0° attack angle is compared between the original cantilever beam section of the implementation case of the present invention and the cantilever beam section equipped with the swinging pneumatic device of the present invention. DETAILED DESCRIPTION

[0021] The technical scheme of the present invention is further described below through specific examples. The following examples are for further explanation of the present invention, but not for limiting the scope of the present invention.

[0022] Figure 1 , Figure 3a , Figure 3b , Figure 4 , Figure 5 A specific embodiment of the present invention is shown. In this embodiment, the swinging pneumatic device for controlling the vortex vibration of a cantilever box girder bridge of the present invention includes a suspension member 1, a mass block 2 and a hook 4. The suspension member 1 is connected to the lower surface 3 of the cantilever 101 on both sides of the cantilever box girder 100 symmetrically through the hook 4), and the mass block 2 is then suspended by the suspension member 1. The suspension member 1 can rotate around the hook 4, and the rotation angle α ranges from 10° to 180°, and the rotation angle α is the angle between the suspension member 1 and the horizontal line. The material of the suspension member 1 can be a hard rod or a rope with a flexible structure. The length of the suspension member is 1 / 3 to 2 / 3 of the height of the cantilever box girder, preferably 1 / 2 times the height of the beam. The shape of the mass block 2 is not limited to a square, and any form of mass block is within the scope of this patent.

[0023] The fixing structure 102 matched with the connection structure and arranged on the lower bottom surface of the cantilever on both sides of the box beam can also be a hook, a ring, etc.

[0024] In a specific embodiment, the width of the cantilever box beam, that is, the width of the bridge, is 25m, the height of the main beam is 4m, and in the swinging pneumatic device, the suspension member is a hard rod with a length of 1 / 2 of the height of the cantilever box beam, that is, 2m, and a rotatable angle α ranging from 10° to 180°. A square mass block is used, and the cantilevers 101 on each side are arranged at intervals of 5m along the axis of the bridge.

[0025] In a specific embodiment, the pneumatic device for vortex vibration control of a cantilever box girder bridge includes a suspension member 1, a mass block 2 and a hook 4. Figure 2 Compared with the traditional nozzle measures shown in the figure, the structure is simpler, the engineering construction and installation are more convenient, and the economy is better. The pneumatic measures are more convenient to install and maintain, have a larger adjustable range, and are more economical.

[0026] Vortex vibration test The results of the vortex-induced vibration test of the main beam segment model of the cantilever box beam show that the main beam without any aerodynamic measures has obvious vertical vortex-induced vibration at an angle of attack of 0° ( Figure 5 As shown in the figure, the maximum vertical amplitude of the main beam exceeds the allowable amplitude, and there is a vertical vortex-induced vibration zone.

[0027] The test results after installing the pneumatic device of the present invention on the main beam are as follows: Figure 5 As shown, from Figure 5 It can be seen that the vertical amplitude of the vortex-induced vibration of the segment model is significantly reduced, the vortex-induced vibration phenomenon disappears, and the allowable value requirements of the specification are met. Figure 4 The specific parameters of the corresponding pneumatic device are as follows: the suspension component is a hard rod with a length of 2m, a rotatable angle α ranging from 10° to 180°, and a square mass block arranged at intervals of 5m along the axis of the bridge.

[0028] Test conclusion: According to the vortex-induced vibration test results of the cantilever box girder main beam segment model, a swinging pneumatic device consisting of a hard rod with a length of 2m and a rotatable angle α ranging from 10° to 180° is set under the cantilevers on both sides. It can effectively reduce the vertical amplitude of the vortex-induced vibration and suppress the occurrence of vortex-induced vibration response.

[0029] The preferred specific embodiments of the present invention are described in detail above. It should be noted that ordinary technology in the field can make many modifications and evolutions based on the concept of the present invention without creative work. Therefore, any technical solutions or technical means that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A swing type pneumatic device for controlling vortex vibration of a cantilever box girder bridge, characterized in that: The invention comprises a suspension component (1), a mass block (2) and a connection structure; the lower surfaces (3) of the cantilevers on both sides of the cantilever box beam are symmetrically connected to the suspension component (1) through the connection structure, and the mass block (2) is then suspended through the suspension component (1) so that the mass block can swing.

2. A swinging pneumatic device for controlling vortex vibration of a cantilever box girder bridge as claimed in claim 1, characterized in that: The suspension component (1) can rotate around the hook (4), and the rotation angle α ranges from 10° to 180°. The rotation angle α is the angle between the suspension component and the horizontal line.

3. A swinging pneumatic device for controlling vortex vibration of a cantilever box girder bridge as claimed in claim 1, characterized in that: The material of the suspension member (1) can be a hard rod or a rope with a flexible structure. The length of the suspension member is 1 / 3 to 2 / 3 of the height of the cantilever box beam.

4. A swinging pneumatic device for controlling vortex vibration of a cantilever box girder bridge as claimed in claim 1, characterized in that: The connecting structure is a hook.

5. A swinging pneumatic device for controlling vortex vibration of a cantilever box girder bridge as claimed in claim 1, characterized in that: The pneumatic devices are arranged along the axial direction of the bridge, and the number of the pneumatic devices arranged on each side of the box girder is n, where n is greater than 1.

6. A cantilever box beam, characterized in that The lower surfaces (3) of the cantilevers on both sides of the cantilever box beam are symmetrically provided with the swinging pneumatic device according to claim 1, 2, 3, 4 or 5.

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