Structure for improving flutter performance of closed steel box girder bridge and mounting method

Abstract

The invention discloses a structure for improving the flutter performance of a closed steel box girder bridge and an installation method. The structure comprises the closed steel box girder, and further comprises a first central guardrail and a second central guardrail which are located on the closed steel box girder; the first central guardrail and the second central guardrail are symmetrically distributed along the center line of the bridge span; the first central guardrail and the second central guardrail both comprise sealing units, and the sealing units on the first central guardrail and the sealing units on the second central guardrail are arranged in a staggered mode. The invention provides a structure for improving the flutter performance of a closed steel box girder bridge and an installation method so as to solve the problem that in the prior art, the flutter suppression effect of a large-span and high-design-wind-speed bridge is insufficient, and the flutter performance is improved on the premise that bridge design and construction difficulty are not increased. And meanwhile, the construction and operation and maintenance cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of bridge engineering, and in particular to a structure and an installation method for improving the flutter performance of a closed steel box girder bridge. Background Art

[0002] Closed steel box girders have large vertical bending stiffness and torsional stiffness, as well as excellent aerodynamic shape, and are one of the main beam types commonly used in large-span bridge projects. As the span of bridges continues to increase, the natural frequency of the structure decreases, resulting in the deterioration of the flutter performance of closed steel box girder bridges. Flutter instability is extremely destructive to bridges and is an important issue that needs to be considered in the wind-resistant design of bridges.

[0003] For the wind-resistant design of large-span bridges, the bridge's design flutter critical wind speed must be greater than the flutter test wind speed, so effective and reasonable measures need to be taken to ensure that the bridge's flutter performance meets the wind-resistant design requirements. The design wind speed of bridges in coastal and mountainous areas is relatively high, and strict requirements are placed on the flutter test wind speed of bridges in such areas, resulting in the traditional design scheme using closed steel box girders often being unable to meet the flutter stability requirements of bridges in such areas. In the prior art, a more commonly used technical means is to install a central stabilizer plate on the closed steel box girder to improve the flutter performance of large-span bridges. The central stabilizer plate can increase the flutter critical wind speed of the main beam.

[0004] Although the central stabilizer is an effective flutter suppression measure, it still has the following problems in its application in long-span bridges in coastal and mountainous areas with high design wind speeds: (1) The central stabilizer has limited effect on improving the flutter performance of bridges with large spans and high design wind speeds. For bridges with very high flutter test wind speeds, it is difficult to meet the flutter design requirements by relying solely on the central stabilizer, a traditional flutter suppression measure. However, if other traditional flutter suppression measures are added, the difficulty in bridge design and construction will be significantly increased. (2) The central stabilizer needs to be installed independently during the bridge construction process, which is inconvenient for mountain bridge construction in remote geographical locations and difficult working environments, and requires a large amount of construction and transportation costs. (3) Since the central stabilizer needs to set up a separate support structure, it needs to be specially maintained regularly during the bridge operation and maintenance stage, which increases the operation and maintenance costs of the bridge.

[0005] In summary, it is necessary to conduct more in-depth research and optimization on the flutter performance of bridges with large spans and high design wind speeds. Summary of the invention

[0006] The present invention provides a structure and an installation method for improving the flutter performance of a closed steel box girder bridge, so as to solve the shortcomings of the prior art in the flutter suppression effect on bridges with large spans and high design wind speeds, thereby achieving the purpose of improving the flutter performance without increasing the difficulty of bridge design and construction, and reducing the construction and operation and maintenance costs.

[0007] The present invention is achieved through the following technical solutions:

[0008] A structure for improving the flutter performance of a closed steel box girder bridge, comprising a closed steel box girder, and also comprising a first central guardrail and a second central guardrail located on the closed steel box girder;

[0009] The first central guardrail and the second central guardrail are symmetrically distributed along the centerline of the bridge span;

[0010] The first central guardrail and the second central guardrail both include closed units, and the closed units on the first central guardrail are arranged alternately with the closed units on the second central guardrail.

[0011] In view of the problems in the prior art of the flutter suppression effect on bridges with large spans and high design wind speeds, such as poor flutter suppression effect, the need to superimpose multiple vibration suppression measures leading to design and construction difficulties, and excessively high construction and operation and maintenance costs, the present invention first proposes a structure for improving the flutter performance of a closed steel box girder bridge, which is installed on a closed steel box girder bridge and includes a first central guardrail and a second central guardrail symmetrically distributed along the center line of the bridge span; as the name implies, the first central guardrail and the second central guardrail are both located in the central area in the width direction of the bridge main beam, rather than in the side positions in the width direction of the bridge main beam. The present application provides a plurality of closed units on both the first central guardrail and the second central guardrail, and the closed units on the first central guardrail are arranged in an alternating manner with the closed units on the second central guardrail, wherein the closed units are used to close the central guardrails of the corresponding areas, and the areas on the central guardrails where no closed units are provided are in a hollow state, that is, unclosed areas. The present application ensures that all enclosed areas on the first central guardrail correspond to the unenclosed areas on the second central guardrail, and all unenclosed areas on the first central guardrail correspond to the enclosed areas on the second central guardrail. Similarly, all enclosed areas on the second central guardrail correspond to the unenclosed areas on the first central guardrail, and similarly, all unenclosed areas on the second central guardrail correspond to the enclosed areas on the first central guardrail.

[0012] It can be seen that the present application abandons the central stabilizing plate vibration suppression measure commonly used in large-span bridges in the prior art, and instead sets two rows of central guardrails on both sides of the center line of the bridge, and sets staggered closed units in the two rows of central guardrails. Compared with the existing large-span bridge flutter suppression measures: (1) Both rows of central guardrails can increase the degree of participation of the vertical bending mode of the closed steel box girder and reduce the effect of the torsional amplitude on the closed steel box girder, that is, the closed steel box girder with a bending-torsion coupling flutter form has a significantly increased degree of participation in the vertical bending mode when flutter occurs, while reducing the torsional amplitude. The inventor has verified through experiments that the present application is significantly better than the traditional method of setting a central stabilizing plate in terms of the effect of increasing the critical wind speed of flutter under large span and high design wind speed conditions; (2) The present application achieves a simple The structure can achieve a flutter suppression effect that is superior to the traditional central stabilizer plate, without the need to superimpose other vibration suppression measures. At the same time, the first central guardrail and the second central guardrail in the present application can also play the function of anti-collision guardrails, which will not only not cause additional problems to the design and construction of the bridge, but also can simultaneously improve driving safety and improve the flutter suppression effect, achieving unexpected technical effects; (3) Since the first central guardrail and the second central guardrail in the present application can be used as anti-collision guardrails, the traditional bridge guardrail installation method can be adopted, and there is no need to install and transport the central stabilizer plate separately, which reduces the material and construction costs; at the same time, the structure of the present application does not require special maintenance during use, so compared with the technical means of setting a central stabilizer plate, it can also reduce the operation and maintenance costs. In summary, the present application has strong functionality and good economy, and is particularly suitable for flutter suppression of bridges with large spans and high design wind speeds.

[0013] It should be noted that the structure of the present application is not a simple addition of the number of traditional central stabilizers; most traditional central stabilizers are fully enclosed structures. The inventors of this case found in the research process that if it is only a simple addition of the number, the improvement of the flutter suppression effect is very limited, and it will also cause the vortex cyclone structure to produce a strong synergistic effect along the span of the bridge, which will have an adverse effect on the overall aerodynamic force of the bridge. However, the present application can significantly overcome the synergistic effect of the cyclone vortex along the span of the bridge through the structural design of the first central guardrail, the second central guardrail and the staggered closed units, and avoid adverse effects on the overall aerodynamic force of the bridge; at the same time, the first central guardrail and the second central guardrail are not fully enclosed structures, and there is a gap between them for airflow to pass through. The airflow is blocked by the closed unit in the gap and cannot pass through in a straight line, forming an incoherent and non-synergistic cyclone in the gap. This is the core of the present application that can significantly improve the flutter stability of the closed steel box girder.

[0014] Furthermore, along the width direction of the bridge main beam, the spacing between the first central guardrail and the second central guardrail is less than or equal to 3m. If the spacing between the first central guardrail and the second central guardrail is too large, it will not only occupy too much bridge deck width, but also make it difficult to form an incoherent and non-cooperative cyclone between the first central guardrail and the second central guardrail, which is conducive to improving flutter stability. Therefore, this solution limits the spacing to no more than 3m, which has obvious technical advantages.

[0015] Furthermore, the first central guardrail and the second central guardrail are arranged along the entire length of the bridge span, that is, the overall length of the first central guardrail and the second central guardrail is equal to the main span of the bridge, thereby ensuring the overall flutter stability of the bridge.

[0016] Furthermore, a plurality of closed units are evenly distributed along the span direction on the first central guardrail and the second central guardrail; and the closing rates of the first central guardrail and the second central guardrail are both 50%.

[0017] Those skilled in the art should understand that the closure rate described in this solution refers to the laying rate of the closure units on the corresponding first central guardrail or second central guardrail; a closure rate of 50% means that 50% of the areas on the first central guardrail and the second central guardrail are provided with closure units. This solution allows the closure units to be evenly distributed on the first central guardrail and the second central guardrail, and the total closure rate meets 50%, which can ensure the integrity and uniformity of the vibration suppression effect of the bridge, avoid the situation of insufficient vibration suppression capacity in local areas, and further improve the safety and stability of use.

[0018] Furthermore, the first central guardrail and the second central guardrail each include a plurality of columns equidistantly distributed along the span direction of the bridge and railings connected to the columns. By installing the columns on the surface of the closed steel box girder, the corresponding central guardrail can be installed in place.

[0019] Furthermore, along the bridge span direction, the length of the closed unit is an integer multiple of D; wherein D is the distance between two adjacent columns along the bridge span direction.

[0020] This solution can divide the first central guardrail and the second central guardrail into several small sections through several columns. In the area where the closed unit needs to be set up, the closed unit can be installed on the surface corresponding to one or more continuous small sections, which is convenient for the rapid positioning and installation of the closed unit and avoids the cumbersome installation and positioning process of the closed unit.

[0021] Furthermore, the height of the enclosed unit is 1.0 to 1.2 times of Z; wherein Z is the height of the column. This solution can ensure that the enclosed unit completely blocks the area where the guardrail is located in terms of height, so as to achieve full closure of the designated area, thereby ensuring that the application fully exerts the flutter suppression effect.

[0022] Furthermore, the closed unit is an alloy plate or a composite material plate; such plates have the advantages of low density and high rigidity, and are used as closed units in the present application to extend service life and further reduce operation and maintenance costs.

[0023] Furthermore, the first central guardrail and the second central guardrail are both formed by a plurality of guardrail units connected in sequence along the span direction; and the closing unit is fixed on a portion of the surface of the guardrail unit.

[0024] In this solution, the first central guardrail and the second central guardrail are segmented into a number of guardrail units. Adjacent guardrail units are sequentially connected to form the required central guardrail. The closed unit can be fixed on the inner or outer surface of the guardrail unit in any manner.

[0025] The installation method of the structure for improving the flutter performance of the closed steel box girder bridge in the present application comprises:

[0026] Prefabricate the first central guardrail and the second central guardrail in sections, and install the enclosed unit during the prefabrication process;

[0027] Transported to the bridge construction site and installed on the closed steel box girder.

[0028] It can be seen that this method divides the first central guardrail and the second central guardrail into several small sections, and prefabricates the closed units on the corresponding small sections in advance. It is only necessary to install the first central guardrail and the second central guardrail on site to simultaneously complete the installation of the flutter suppression structure without increasing the difficulty of construction. The entire installation process only needs to adopt the traditional installation process of the bridge guardrail, which is simple and fast, and is conducive to improving construction efficiency and reducing construction costs.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] 1. The present invention provides a structure and installation method for improving the flutter performance of a closed steel box girder bridge. The two rows of central guardrails are used to increase the degree of vertical bending modal participation of the closed steel box girder and reduce the effect of the torsional amplitude on the closed steel box girder. For working conditions with large spans and high design wind speeds, the present application is significantly better than the traditional method of setting a central stabilizing plate in terms of the effect of increasing the flutter critical wind speed.

[0031] 2. The present invention provides a structure and installation method for improving the flutter performance of a closed steel box girder bridge. The structural design of the first central guardrail, the second central guardrail and the staggered closed units can significantly overcome the synergistic effect of cyclonic vortices along the span of the bridge, thereby avoiding adverse effects on the overall aerodynamic force of the bridge. At the same time, the first central guardrail and the second central guardrail are not fully enclosed structures, but have gaps between them for airflow to pass through. The airflow is blocked by the closed units in the gap and cannot pass through in a straight line, thereby forming an incoherent, non-synergistic cyclone in the gap, thereby significantly improving the flutter stability of the closed steel box girder.

[0032] 3. The present invention provides a structure and installation method for improving the flutter performance of a closed steel box girder bridge. A flutter suppression effect that is superior to a traditional central stabilizer plate can be achieved through a simple structure without the need to superimpose other vibration suppression measures. At the same time, the first central guardrail and the second central guardrail in the present application can also function as anti-collision guardrails, which not only does not cause additional difficulties to the design and construction of the bridge, but can also simultaneously improve driving safety and improve the flutter suppression effect, and has unexpected technical effects.

[0033] 4. The present invention provides a structure and installation method for improving the flutter performance of a closed steel box girder bridge. The traditional installation method of bridge deck guardrails is adopted, and there is no need to additionally install and transport a central stabilizer plate, thereby reducing material and construction costs. At the same time, the structure of the present application does not require special maintenance during use, so compared with the technical means of setting a central stabilizer plate, it can also reduce operation and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0035] Figure 1 It is a schematic cross-sectional view of a main beam of a specific embodiment of the present invention;

[0036] Figure 2 It is a schematic diagram of installation of a specific embodiment of the present invention;

[0037] Figure 3 It is a schematic diagram of the partial arrangement of the closed unit in a specific embodiment of the present invention;

[0038] Figure 4 is a schematic diagram of a single closed unit in a specific embodiment of the present invention;

[0039] Figure 5 It is a schematic diagram of the arrangement of the present invention in one embodiment;

[0040] Figure 6 The figure is a schematic diagram of the arrangement of the present invention in another embodiment.

[0041] Marks and corresponding parts names in the attached drawings:

[0042] 1- first central guardrail, 2- second central guardrail, 3- closed unit, 4- railing, 5- column, 6- base, 7- closed steel box girder. DETAILED DESCRIPTION

[0043] In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the examples and the accompanying drawings. The schematic embodiments of the present invention and the description thereof are only used to explain the present invention and are not intended to limit the present invention. In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inside", "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application.

[0044] Embodiment 1:

[0045] like Figures 1 to 3 A structure for improving the flutter performance of a closed steel box girder bridge shown in the figure comprises a closed steel box girder 7, and also comprises a first central guardrail 1 and a second central guardrail 2 located on the closed steel box girder 7;

[0046] The first central guardrail 1 and the second central guardrail 2 are symmetrically distributed along the center line of the bridge span;

[0047] The first central guardrail 1 and the second central guardrail 2 both include closed units 3 , and the closed units 3 on the first central guardrail 1 and the closed units 3 on the second central guardrail 2 are arranged alternately.

[0048] In this embodiment, the first central guardrail 1 and the second central guardrail 2 are both arranged along the entire length of the bridge span.

[0049] Along the width direction of the bridge main beam, the distance between the first central guardrail 1 and the second central guardrail 2 is less than or equal to 3m.

[0050] In this embodiment, the first central guardrail 1 and the second central guardrail 2 are both formed by connecting a plurality of guardrail units in sequence along the span direction; the enclosed unit 3 is fixed on the surface of a portion of the guardrail units, and the structure of a single enclosed unit 3 is as follows: Figure 4 shown.

[0051] Preferably, the sealing unit 3 is made of an aluminum alloy plate or a carbon fiber composite plate.

[0052] Embodiment 2:

[0053] A structure for improving the flutter performance of a closed steel box girder bridge. Based on Example 1, the closed units 3 are evenly distributed along the span direction on the first central guardrail 1 and the second central guardrail 2; and the length of a single closed unit 3 is equal to the spacing between two adjacent closed units 3, thereby ensuring that the closing rates of the first central guardrail 1 and the second central guardrail 2 are both 50%.

[0054] like Figure 1 and Figure 2 As shown, the first central guardrail 1 and the second central guardrail 2 both include a plurality of columns 5 equidistantly distributed along the span direction of the bridge, and railings 4 connected to the columns 5. In this embodiment, the columns 5 are installed on the bridge deck via a base 6.

[0055] like Figure 3 and Figure 4 As shown: along the bridge span direction, the length of the closed unit 3 is L, and L is an integer multiple of D; wherein D is the distance between two adjacent columns 5 along the bridge span direction, and in this embodiment, L=D=3.0m.

[0056] Along the longitudinal direction, the height of the closed unit 3 is H, which is 1.0 to 1.2 times of Z; wherein Z is the height of the column 5, and in this embodiment, H=Z=1.5 m.

[0057] This embodiment provides specific structures of the enclosed unit 3 under two different arrangement schemes:

[0058] Structure 1: Figure 5 As shown, every other enclosed unit 3 is enclosed one by one, and the overall enclosed rate of the first central guardrail 1 and the second central guardrail 2 is 50%.

[0059] Structure 2: Figure 6 As shown, the closed unit 3 is sealed in two, and the overall closing rate of the first central guardrail 1 and the second central guardrail 2 is 50%.

[0060] In order to fully verify the technical effect of the present application, this embodiment also provides the following comparative examples:

[0061] Comparative Example 1: A closed steel box girder main beam segment model without adding any pneumatic devices / structures / facilities.

[0062] Comparative Example 2: A central stabilizer is installed along the span of the bridge on the closed steel box girder segment model. The actual bridge height of the central stabilizer is 1.5m.

[0063] The applicant conducted a flutter wind tunnel test on the above structure and the comparative example at different wind attack angles under a damping ratio of 0.15%. This test directly measured the critical flutter wind speed under different working conditions through the main beam segment model wind tunnel test, and calculated the critical flutter wind speed value of the actual bridge through the wind speed ratio (the ratio of the test wind speed to the actual wind speed at the bridge site); in all the flutter wind tunnel tests of this embodiment, the flutter test wind speed was 84.2m / s. The specific test results are shown in the following table:

[0064]

[0065]

[0066] According to the results of the segment model wind tunnel test, it can be seen that after the structure in the present application is installed on the main beam of the closed steel box girder, the critical flutter wind speed under different wind attack angles is higher than the corresponding flutter test wind speed, and has a large safety reserve; at the same time, compared with the technical solution of using the traditional central stabilizer plate, after the installation of the structure of the present application, the flutter stability performance under different wind attack angles is significantly improved, and the safety margin is also significantly increased. This proves that the structure in the present application can withstand greater instantaneous wind speeds compared to the traditional central stabilizer plate flutter suppression measures, and has a better flutter suppression effect on bridges with large spans and high design wind speeds.

[0067] Embodiment 3:

[0068] An installation method for installing the structure in embodiment 1 or 2, comprising:

[0069] Prefabricate the first central guardrail 1 and the second central guardrail 2 in sections, and install the enclosed unit 3 during the prefabrication process;

[0070] It is transported to the bridge construction site and installed on the closed steel box girder 7.

[0071] In a more preferred embodiment, the first central guardrail 1 and the second central guardrail 2 are assembled with column units having a length equal to the distance between adjacent columns, and the size of the single closed unit 3 matches the single column unit.

[0072] In a more preferred embodiment, the closing unit 3 is fixed to the column 5 by bolting or welding.

[0073] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0074] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In addition, the term "connected" used in this article can be directly connected or indirectly connected via other components without special explanation.

Claims

1. A structure for improving the flutter performance of a closed steel box girder bridge, comprising a closed steel box girder (7), characterized in that: It also includes a first central guardrail (1) and a second central guardrail (2) located on the closed steel box girder (7); The first central guardrail (1) and the second central guardrail (2) are symmetrically distributed along the center line of the bridge span; The first central guardrail (1) and the second central guardrail (2) both include closed units (3), and the closed units (3) on the first central guardrail (1) and the closed units (3) on the second central guardrail (2) are arranged alternately.

2. The structure for improving the flutter performance of a closed steel box girder bridge according to claim 1, characterized in that: Along the width direction of the bridge main beam, the distance between the first central guardrail (1) and the second central guardrail (2) is less than or equal to 3m.

3. The structure for improving the flutter performance of a closed steel box girder bridge according to claim 1, characterized in that: The first central guardrail (1) and the second central guardrail (2) are both arranged along the entire length of the bridge span.

4. The structure for improving the flutter performance of a closed steel box girder bridge according to claim 1, characterized in that: The enclosed units (3) are evenly distributed along the span direction on the first central guardrail (1) and the second central guardrail (2); the enclosed rates of the first central guardrail (1) and the second central guardrail (2) are both 50%.

5. The structure for improving the flutter performance of a closed steel box girder bridge according to claim 1, characterized in that: The first central guardrail (1) and the second central guardrail (2) both comprise a plurality of columns (5) equidistantly distributed along the span direction of the bridge, and railings (4) connected to the columns (5).

6. The structure for improving the flutter performance of a closed steel box girder bridge according to claim 5, characterized in that: Along the bridge span direction, the length of the closed unit (3) is an integer multiple of D; wherein D is the distance between two adjacent columns (5) along the bridge span direction.

7. The structure for improving the flutter performance of a closed steel box girder bridge according to claim 5, characterized in that: The height of the closed unit (3) is 1.0 to 1.2 times of Z; wherein Z is the height of the column (5).

8. The structure for improving the flutter performance of a closed steel box girder bridge according to claim 1, characterized in that: The closed unit (3) is an alloy plate or a composite material plate.

9. The structure for improving the flutter performance of a closed steel box girder bridge according to claim 1, characterized in that: The first central guardrail (1) and the second central guardrail (2) are both formed by a plurality of guardrail units connected in sequence along the span direction; the enclosing unit (3) is fixed on the surface of part of the guardrail unit.

10. A method for installing a structure for improving the flutter performance of a closed steel box girder bridge according to any one of claims 1 to 9, characterized in that: include: Prefabricate the first central guardrail (1) and the second central guardrail (2) in sections, and install the enclosed unit (3) during the prefabrication process; It is transported to the bridge construction site and installed on the closed steel box girder (7).

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