Pneumatic structure for inhibiting vortex vibration of cantilever box girder bridge

Abstract

The invention discloses a pneumatic structure for suppressing vortex vibration of a cantilever box girder bridge, relates to the technical field of bridge engineering, and solves the problem that an effective pneumatic structure which can effectively control the vortex vibration amplitude of a bridge is lacked in the prior art. The box girder comprises a box girder body and cantilevers arranged on the two sides of the box girder body respectively, skirt plates are symmetrically arranged on the lower portions of the ends of the two cantilevers respectively, and the skirt plates are arranged on the sides, away from the box girder body, of the cantilevers; the apron board and the cantilever form an inclined angle and incline towards the box girder main body on the corresponding side; rectification plates are symmetrically arranged at the turning positions of the two sides of the lower portion of the box girder body respectively, the rectification plates are in a bevel shape, the two rectification plates are obliquely arranged, and the inclination directions of the turning positions of the lower sides of the rectification plates are consistent with the inclination directions of the apron boards on the corresponding sides respectively; the invention aims to fundamentally suppress or weaken the formation of vortexes at the windward side end part and the beam bottom of a cantilever and a box beam main body, reduce the pressure difference between the upper surface and the lower surface of a cross section and eliminate the vortex-induced vibration of a main beam.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge engineering, and in particular relates to an aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge. Background Art

[0002] A cantilever box girder is a bridge structure characterized by one end being fixed and the other end being extended and freely suspended without support. The beam of this structure is subjected to bending moment and shear force caused by the load at the extended end, i.e. the cantilever end. These forces increase with the increase of the cantilever length. Cantilever box girders are widely used in bridge construction, especially when it is necessary to cross rivers, roads or other obstacles. They can provide a large spanning capacity. Cantilever box girders are usually made of prestressed concrete, structural steel or a combination of steel and reinforced concrete. This type of beam has high torsional stiffness and strength because their cross-section forms a closed hollow box, which provides better torsional performance than an open cross-section. This structural characteristic of cantilever box girders makes them It is very popular in modern bridge design, especially in long-span bridges. When designing cantilever box girders, engineers need to consider many factors, including the span, load, material properties and construction methods of the beam. Through precise design and construction control, cantilever box girders can provide beautiful, economical and structurally efficient solutions, suitable for a variety of bridge projects. Therefore, cantilever box girders have been widely used in high-speed railway bridges and urban municipal bridges due to their convenient construction and superior force performance. This type of bridge piers occupies a small area, does not affect the passage of vehicles under the bridge, supports 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 houses and buildings.

[0003] However, the blunt-body shape of the existing cantilever box girder makes the vortex shedding around the main girder surface after the airflow passes through the main girder more obvious and complex than that of the streamlined box girder, making the vortex-induced vibration response of this type of bridge also more significant. Although the 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, thereby affecting the operational safety of the bridge. Therefore, there is currently a lack of an effective aerodynamic structure that can effectively control the vortex vibration amplitude of the bridge. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge. A skirt plate with a certain angle is arranged under the cantilevers on both sides, and a straightening plate is arranged at the lower turning point of the box girder main body. The structure can change the flow field characteristics of the windward end and bottom of the cantilever and the box girder main body, so that the vortex on the cross-sectional surface is suppressed or the large vortex is blown away or reduced by the incoming flow; the formation of vortex on the windward end and bottom of the cantilever and the box girder main body is fundamentally suppressed or weakened, the pressure difference between the upper and lower surfaces of the cross-section is reduced, and the vortex-induced vibration of the main beam is eliminated, thereby improving driving comfort and safety, and reducing bridge fatigue to a certain extent, thereby extending the service life of the bridge.

[0005] The technical solution adopted by the present invention is as follows:

[0006] An aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge comprises a box girder body and cantilevers respectively arranged on both sides of the box girder body, the cantilevers and the box girder body are arranged along the length direction of the main beam, the lower parts of the two cantilever ends are symmetrically provided with skirt plates, the skirt plates are arranged on the side of the cantilever away from the box girder body; the skirt plates extend along the length direction of the cantilever, the skirt plates form an inclined angle with the cantilever and are inclined toward the box girder body on the corresponding side; rectifier plates are symmetrically provided at the turning points on both sides of the lower part of the box girder body, the rectifier plates are angled, the rectifier plates extend along the length direction of the box girder body, the two rectifier plates are inclined, and the inclination directions of the lower turning points of the rectifier plates are respectively consistent with the inclination directions of the skirt plates on the corresponding sides.

[0007] By adopting the above technical scheme, a skirt plate with a certain angle is arranged under the cantilevers on both sides, and a straightening plate is arranged at the lower turning point of the box girder main body. This structure can change the flow field characteristics of the windward end and bottom of the cantilever and the box girder main body, so that the vortex on the cross-sectional surface is suppressed or the large vortex is blown away or reduced by the incoming flow; it fundamentally suppresses or weakens the formation of vortices at the windward end and bottom of the cantilever and the box girder main body, reduces the pressure difference between the upper and lower surfaces of the cross-section, eliminates the vortex-induced vibration of the main beam, thereby improving driving comfort and safety, and reducing bridge fatigue to a certain extent, thereby extending the service life of the bridge.

[0008] Preferably, a plurality of first stiffening ribs are respectively arranged between each of the skirt plates and the cantilever on the corresponding side, and the plurality of first stiffening ribs are respectively arranged at intervals along the length direction of the skirt plates.

[0009] Preferably, a plurality of second stiffening ribs are respectively arranged between the lower turning point of each of the rectifier plates and the box beam body on the corresponding side, and the plurality of second stiffening ribs are respectively arranged at intervals along the length direction of the rectifier plates.

[0010] Preferably, the length A of the skirt plate in the extension direction toward the box beam body is equal to (0.4-0.7)*H, wherein H is the height of the main beam.

[0011] Preferably, the angle θ between the skirt plate and the horizontal plane is 45° to 75°.

[0012] Preferably, the angle θ between the skirt plate and the horizontal plane is 60°.

[0013] Preferably, the distance between the skirt plate and the first stiffening rib on the corresponding side and the cantilever fixing point is C=(0.35-0.45)*A, where A is the length of the skirt plate.

[0014] Preferably, the length D of the lower turning point of the rectifier plate in the extension direction of the box beam main body is (0.35-0.6)*H, where H is the height of the main beam.

[0015] Preferably, the angle β between the lower turning point of the rectifier plate and the horizontal plane is 15° to 25°.

[0016] Preferably, the angle β between the lower turning point of the rectifier plate and the horizontal plane is 20°.

[0017] Preferably, the length F of the second stiffening rib is 90-130 cm.

[0018] Preferably, the length E of the outer turning point of the rectifier plate toward the cantilever extension direction is (0.35-0.6)*H, where H is the height of the main beam.

[0019] Preferably, the angle α between the outer turning point of the rectifier plate and the vertical direction is 5° to 15°.

[0020] Preferably, the angle α between the outer turning point of the rectifier plate and the vertical direction is 10°.

[0021] Preferably, a plurality of third stiffening ribs are respectively arranged between the outer turning point of each of the rectifier plates and the box beam body on the corresponding side, and the plurality of third stiffening ribs are respectively arranged at intervals along the length direction of the rectifier plates.

[0022] Preferably, the length G of the third stiffening rib is 80-120 cm.

[0023] Preferably, the number m of the first stiffening ribs is 1 、Number of second stiffeners m 2 and the number of the third stiffener m 3 All>1.

[0024] Preferably, the skirt plate, the rectifier plate, the cantilever, the box beam body, the first stiffening rib, the second stiffening rib and the third stiffening rib are all connected by welding.

[0025] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0026] 1. The function of the skirt is to weaken the vortex effect generated by the cantilever end of the box girder on the windward side and guide it to the bottom of the beam body. The remaining vortex is then eliminated by the rectifier installed here, thereby suppressing vortex vibration.

[0027] 2. By providing the first stiffening rib, the second stiffening rib and the third stiffening rib, the connection strength and performance between the skirt plate and the cantilever and between the rectifier plate and the box beam body are increased.

[0028] 3. Based on the original cantilever and box girder body, the present invention arranges skirts with a certain angle under the cantilevers on both sides, and arranges a straightening plate at the lower turning point of the box girder body. This structure can change the flow field characteristics of the windward end and bottom of the cantilever and the box girder body, so that the vortex on the cross-sectional surface is suppressed or the large vortex is blown away or reduced by the incoming flow; it fundamentally suppresses or weakens the formation of vortices at the windward end and bottom of the cantilever and the box girder body, reduces the pressure difference between the upper and lower surfaces of the cross-section, eliminates the vortex-induced vibration of the main beam, thereby improving driving comfort and safety, and to a certain extent reduces bridge fatigue and thus extends the service life of the bridge.

[0029] 4. In the aerodynamic structure for suppressing vortex vibration of the cantilever box girder bridge in the present application, the length and angle parameters are set in a targeted manner according to the main beam, box girder body and cantilever. The adjustable range of each parameter is large, and a good vortex vibration suppression effect is shown for various types of cantilever box girders, with good adaptability and high economy. Through the combination of the two, the formation of vortices at the windward end and the bottom of the cantilever box girder is fundamentally suppressed or weakened, the vortex vibration amplitude of the main beam is significantly reduced or completely eliminated, the driving comfort of the bridge deck is guaranteed, and the operational safety of the cantilever box girder bridge structure is guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0031] Figure 1 It is the standard cross-section diagram between the existing cantilever and the box girder body;

[0032] Figure 2 It is a schematic structural diagram of the aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge in the present invention;

[0033] Figure 3 It is a schematic diagram of the dimensions and installation angles of the aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge in the present invention;

[0034] Figure 4It is a schematic diagram of a partial structure of a pneumatic structure for suppressing vortex vibration of a cantilever box girder bridge in the present invention from a top view;

[0035] Figure 5 is a schematic structural diagram of an aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge in Example 1 of the present invention;

[0036] Figure 6 It is a schematic diagram of the dimensions and installation angles of the aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge in Example 1 of the present invention;

[0037] Figure 7 This is a wind tunnel test photo of a cross-section model in the experiment of the present invention;

[0038] Figure 8 It is the vertical vortex vibration amplitude of the original section without vibration suppression measures at attack angles of 0° and ±3° in Comparative Example 1 of the present invention.

[0039] Fig. 9 The vertical vortex vibration amplitude at attack angles of 0° and ±3° after the aerodynamic structure for suppressing vortex vibration of the cantilever box girder bridge is set in the section of Example 1 of the present invention.

[0040] Reference numerals

[0041] 1-skirt plate, 2-first stiffening rib, 3-rectifier plate, 4-second stiffening rib, 5-cantilever, 6-turning part. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0043] An aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge comprises a box girder body and cantilevers respectively arranged on both sides of the box girder body, the cantilevers and the box girder body are arranged along the length direction of the main beam, the lower parts of the two cantilever ends are symmetrically provided with skirt plates, the skirt plates are arranged on the side of the cantilever away from the box girder body; the skirt plates extend along the length direction of the cantilever, the skirt plates form an inclined angle with the cantilever and are inclined toward the box girder body on the corresponding side; rectifier plates are symmetrically provided at the turning points on both sides of the lower part of the box girder body, the rectifier plates are angled, the rectifier plates extend along the length direction of the box girder body, the two rectifier plates are inclined, and the inclination directions of the lower turning points of the rectifier plates are respectively consistent with the inclination directions of the skirt plates on the corresponding sides.

[0044] Among them, main beam is a special term, which refers to the entire beam that carries traffic.

[0045] A plurality of first stiffening ribs are respectively arranged between each of the skirt plates and the cantilever on the corresponding side, and the plurality of first stiffening ribs are respectively arranged at intervals along the length direction of the skirt plates.

[0046] A plurality of second stiffening ribs are respectively arranged between the lower turning point of each rectifier plate and the box beam body on the corresponding side, and the plurality of second stiffening ribs are respectively arranged at intervals along the length direction of the rectifier plate.

[0047] The length A of the skirt plate in the direction of extension toward the box beam body = (0.4-0.7)*H, where H is the height of the main beam.

[0048] The angle between the skirt plate and the horizontal plane is θ.

[0049] The distance between the skirt plate and the first stiffening rib on the corresponding side and the cantilever fixing point is C=(0.35-0.45)*A, where A is the length of the skirt plate.

[0050] The length D of the lower turning point of the rectifier plate toward the extension direction of the box beam main body is (0.35-0.6)*H, where H is the height of the main beam.

[0051] The angle between the lower turning point of the rectifier plate and the horizontal plane is β.

[0052] The length of the second stiffening rib is F.

[0053] The length E of the outer turning point of the rectifier plate toward the cantilever extension direction is (0.35-0.6)*H, where H is the height of the main beam.

[0054] The angle between the outer turning point of the rectifier plate and the vertical direction is α.

[0055] A plurality of third stiffening ribs are respectively arranged between the outer turning point of each rectifier plate and the box beam body on the corresponding side, and the plurality of third stiffening ribs are respectively arranged at intervals along the length direction of the rectifier plate.

[0056] The length of the third stiffening rib is G.

[0057] The number m of the first stiffening ribs 1 、Number of second stiffeners m 2 and the number of the third stiffener m 3 All>1.

[0058] The connection methods among the skirt plate, the rectifier plate, the cantilever, the box beam body, the first stiffening rib, the second stiffening rib and the third stiffening rib are all welding.

[0059] See attached Figure 7 , and conduct wind tunnel tests on cross-section segment models.

[0060] The specific values ​​of the parameters in Examples 1 to 6 and Comparative Examples 1 to 6 are shown in Table 1

[0061]

[0062]

[0063] See attached Figure 8 The results of the vortex-induced vibration test on the main beam segment model of the cantilever box beam showed that the original cross-section main beam without any aerodynamic measures experienced obvious vertical vortex-induced vibration at attack angles of 0° and ±3°. There was an obvious vertical vortex-induced vibration zone in the main beam at each attack angle, and the maximum vertical amplitude exceeded the allowable amplitude.

[0064] The test results after installing pneumatic measures on the main beam are shown in the attached Fig. 9 The vertical amplitude of the vortex-induced vibration of the segment model is significantly reduced, meeting the allowable value requirements of the specification.

[0065] Test conclusion: According to the test results of the vortex-induced vibration of the cantilever box girder main beam segment model, skirts are set below the cantilever ends on both sides of the box girder, and rectifier plates are set at the turning point on the lower side of the main body of the box girder. This can significantly reduce the vertical amplitude of the vortex-induced vibration of the cantilever box girder, play a positive and effective inhibitory role, and suppress the vortex-induced vibration.

[0066] It should be noted that:

[0067] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge, comprising a box girder body and cantilevers respectively arranged on both sides of the box girder body, wherein the cantilevers and the box girder body are arranged along the length direction of the main beam, and characterized in that: The lower parts of the two cantilever ends are symmetrically provided with skirt plates, which are arranged on the side of the cantilever away from the box beam body; the skirt plate extends along the length direction of the cantilever, forms an inclined angle with the cantilever and is inclined toward the box beam body on the corresponding side; rectifier plates are symmetrically provided at the turning points on both sides of the lower part of the box beam body, the rectifier plates are angled, and extend along the length direction of the box beam body, the two rectifier plates are inclined, and the inclination direction of the lower turning point of the rectifier plate is consistent with the inclination direction of the skirt plate on the corresponding side.

2. The aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge according to claim 1, characterized in that: A plurality of first stiffening ribs are respectively arranged between each of the skirt plates and the cantilever on the corresponding side, and the plurality of first stiffening ribs are respectively arranged at intervals along the length direction of the skirt plates.

3. The aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge according to claim 1, characterized in that: A plurality of second stiffening ribs are respectively arranged between the lower turning point of each rectifier plate and the box beam body on the corresponding side, and the plurality of second stiffening ribs are respectively arranged at intervals along the length direction of the rectifier plate.

4. The aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge according to claim 1, characterized in that: The length A of the skirt plate in the direction of extension toward the box beam body = (0.4-0.7)*H, where H is the height of the main beam body.

5. The aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge according to claim 1, characterized in that: The included angle θ between the skirt plate and the horizontal plane is 45° to 75°.

6. The aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge according to claim 4, characterized in that: The distance between the skirt plate and the first stiffening rib on the corresponding side and the cantilever fixing point is C=(0.35-0.45)*A, where A is the length of the skirt plate.

7. The aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge according to claim 1, characterized in that: The length D of the lower turning point of the rectifier plate toward the extension direction of the box beam main body is (0.35-0.6)*H, where H is the height of the main beam.

8. The aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge according to claim 1, characterized in that: The angle β between the lower turning point of the rectifier plate and the horizontal plane is 15° to 25°.

9. The aerodynamic structure for suppressing vortex vibration of a cantilever box girder bridge according to claim 1, characterized in that: The length F of the second stiffening rib is 90-130 cm.

Images