Bridge calm wind stability analysis method and analysis device

Abstract

The invention relates to the technical field of bridge wind resistance design, and provides a bridge calm wind stability analysis method and analysis device.The bridge calm wind stability analysis method comprises the following steps that S1, a calm wind load is calculated; s2, structure displacement is calculated according to the static wind load, and a torsion angle is extracted; updating the three-component coefficient, and recalculating the static wind load; s3, updating the structural displacement according to the pulsation response; judging whether the deformation of the bridge structure is acceptable or not; if yes, the wind speed is increased according to the preset step length, and the step S1 to the step S3 are repeated; if not, repeating the steps S2 to S3; s4, when the number of iterations is larger than the preset iteration upper limit value, the wind speed is rolled back by one step, and the value of the preset step length is reduced; repeating the step S1 to the step S4 until the preset step length is smaller than or equal to the preset minimum step length, and completing the analysis. The method can overcome the defect that the analysis result has large deviation due to the fact that the bridge static wind stability analysis method in the prior art cannot accurately reflect the complex wind environment at the bridge site.

Description

Technical Field

[0001] The invention relates to the technical field of bridge wind-resistant design, and in particular to a bridge static wind stability analysis method and an analysis device. Background Art

[0002] As the span of a large-span bridge structure increases, the overall stiffness decreases significantly. In particular, for a cable-bearing bridge structure, as the wind speed increases, the deformation of the structure will gradually increase. When the deformation exceeds the structure's own resistance, the structure will experience static wind instability. Static wind instability will seriously threaten the safety of the bridge structure, especially for some extra-large span bridges, such as the Akashi Kaikyo Bridge, whose critical wind speed for static wind stability may be lower than the critical wind speed for flutter, which is extremely unfavorable to the static wind stability of the bridge.

[0003] However, the existing methods for evaluating the static wind stability of bridges still lack systematic and in-depth research. Generally, they only consider the uneven distribution of wind speed along the span of the bridge, but cannot accurately reflect the complex and changeable actual wind environment. The analysis results are often quite different from the actual situation. With the continuous development of traffic demand in recent years, many bridges across canyons have emerged. The wind environment at their bridge sites is complex and changeable. The existing static wind stability analysis methods are no longer applicable. Therefore, it is urgent to propose a static wind stability evaluation method that can comprehensively reflect the complex wind environment. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art bridge static wind stability analysis method that cannot accurately reflect the complex wind environment at the bridge site, resulting in large deviations in the analysis results, and to provide a bridge static wind stability analysis method and analysis device.

[0005] In a first aspect, the present invention provides a bridge static wind stability analysis method, comprising the following steps:

[0006] S1. Set the wind speed and calculate the static wind load on the bridge structure under the non-uniformly distributed wind speed along the span of the bridge using the three-force coefficient under the turbulent wind field;

[0007] S2. Calculate the structural displacement of the bridge structure according to the static wind load and extract the torsion angle; update the three-force coefficient according to the torsion angle and recalculate the static wind load on the bridge structure;

[0008] S3, updating the structural displacement according to the pulsating response of the bridge structure; judging whether the deformation of the bridge structure is within an acceptable range according to the structural displacement; if so, increasing the wind speed according to a predetermined step length, and repeating steps S1 to S3; if not, repeating steps S2 to S3;

[0009] S4. When the deformation of the bridge structure exceeds the acceptable range for a number of times greater than a predetermined iteration upper limit, the wind speed is retracted by one step according to a predetermined step length, and the value of the predetermined step length is reduced; the wind speed is increased according to a predetermined step length, and steps S1 to S4 are repeated until the predetermined step length is less than or equal to the predetermined minimum step length, and the analysis is completed.

[0010] The non-uniformly distributed wind speed in step S1 can be obtained by, for example, field measurement, empirical value, simulation analysis, etc.

[0011] The three-division force coefficients in step S1 and step S2 can be obtained by, for example, field tests, model tests, simulation analysis, etc.

[0012] The pulsation response in step S4 may be calculated in advance before step S4 or calculated when necessary (after step S3).

[0013] The inventors of the present invention have found that if one wants to accurately reflect the complex wind environment at the bridge site, in addition to considering the uneven distribution of wind speed along the span of the bridge, the three-force coefficient and pulsating load response of the turbulent wind field at the bridge site are also factors that should not be ignored; at the same time, considering that static wind instability is a phenomenon of coupling static wind load and bridge structure deformation, a bridge static wind stability analysis method is proposed that couples multiple factors such as the uneven distribution of wind speed along the span of the bridge, the three-force coefficient and pulsating response of the turbulent wind field at the bridge site, and the structural displacement of the bridge structure. During the analysis process, the wind speed is gradually increased based on the deformation of the bridge structure, so that different The response of the bridge structure under wind speed; when the deformation of the bridge structure is not within an acceptable range, repeated calculations will be performed to eliminate the calculation error caused by one calculation; and during the calculation process, this scheme will update the three-force coefficient through the calculation results of the static wind load and then recalculate the static wind load, and update the structural displacement through the pulsation response. Compared with the existing technology, it can more accurately reflect the complex wind environment at the bridge site, as well as the coupling of the static wind load and the bridge structure deformation, so as to obtain more accurate analysis results, such as the static wind stability wind speed displacement curve and the static wind stability critical wind speed, which is especially suitable for the refined analysis of the static wind stability of large-span bridges under complex wind environments.

[0014] Preferably, the method further comprises the following steps:

[0015] S5. Select the wind speed in the last step as the critical wind speed for calm wind stability.

[0016] The last step of wind speed specifically means that in steps S1 to S4, the wind speed will be increased multiple times according to the predetermined step length until the predetermined step length is less than the predetermined minimum step length, at which time the wind speed will no longer be increased. For example, assuming the wind speed is v i , i is the number of the wind speed. Every time the wind speed increases by a predetermined step, i increases by one. If the wind speed increases f-1 times and reaches v fIf the scheduled step size is less than the minimum step size, the analysis is stopped and v f As the critical wind speed for calm wind stability.

[0017] Preferably, in step S2, the static wind load of the bridge structure is calculated according to the following formula:

[0018] F H =0.5*ρ*U 2 *C H *D

[0019] F V =0.5*ρ*U 2 *C V *B

[0020] M T =0.5*ρ*U 2 *CM*B 2

[0021] In the formula, F H Represents the resistance in body axis coordinates; F V represents the lift in body axis coordinates; M T represents the moment under the body axis coordinate; ρ represents the air density; U represents the current wind speed; C H represents the body axis drag coefficient under turbulent wind field; C V represents the body axis lift coefficient under turbulent wind field; C M represents the body axis moment coefficient under turbulent wind field; D represents the height of the bridge main beam; B represents the width of the bridge main beam.

[0022] Preferably, in step S3, it is compared whether the Euclidean norm of the structural displacement is less than a predetermined threshold; if so, the deformation of the bridge structure is within an acceptable range; if not, the deformation of the bridge structure exceeds the acceptable range.

[0023] The specific judgment formula of step S3 can be referred to as follows:

[0024]

[0025] In the formula, represents the torsion angle of the jth bridge girder node in the i-th load step; represents the torsion angle of the jth bridge girder node in the pulsation response; i represents the load step number, and the number of load steps increases by one every time the wind speed increases by a predetermined step length; j represents the number of the bridge girder node; n is the total number of girder nodes; ε represents the predetermined threshold.

[0026] This scheme can ensure that the slope of the wind speed displacement curve of the bridge is Only the slope of the last segment where Δvmin Indicates the predetermined minimum step size.

[0027] Preferably, the pulsation response of the bridge structure is calculated according to the following steps:

[0028] A. Generate pulsating wind field by spectral method;

[0029] B. Perform finite element analysis on the bridge structure based on the pulsating wind field to obtain the pulsating response.

[0030] Preferably, the three-component force coefficients in a turbulent wind field are obtained through a model wind tunnel test.

[0031] Preferably, the initial value of the predetermined step length is greater than or equal to 10 m / s and less than or equal to 20 m / s.

[0032] If the predetermined step length is too large, the resolution of the analysis result is likely to be too low; if the predetermined step length is too small, the analysis workload is likely to be too large; therefore, this solution recommends a range of values ​​for the predetermined step length. It should be noted that the recommended range of values ​​here refers to the initial value of the predetermined step length, that is, the predetermined step length value before the reduction in step S4, and after the reduction in step S4, the value of the predetermined step length can be lower than the lower limit of the range, that is, less than 10m / s.

[0033] Preferably, the value of the predetermined minimum step length is greater than or equal to 2 m / s and less than or equal to 3 m / s.

[0034] If the predetermined minimum step size is too large, it is easy to cause the resolution of the analysis result to be too low; if the predetermined minimum step size is too small, it is easy to cause the analysis workload to be too large; therefore, this scheme recommends a value range for the predetermined minimum step size.

[0035] Preferably, when reducing the value of the predetermined step length in step S4, the predetermined step length is reduced by half each time.

[0036] For example, assuming that the initial value of the predetermined step length is Δv, when the predetermined step length is reduced for the first time, the predetermined step length is reduced to Δv / 2; when the predetermined step length is reduced for the second time, the predetermined step length is reduced to Δv / 4.

[0037] In a second aspect, the present invention provides a bridge static wind stability analysis device, comprising:

[0038] A memory storing at least one instruction;

[0039] The processor is communicatively connected with the memory, and the processor can execute instructions stored in the memory, thereby executing a bridge static wind stability analysis method of the present invention.

[0040] Storage, including but not limited to mechanical hard disks, solid-state hard disks, and floppy disks.

[0041] Processor, including but not limited to central processing unit and graphics processing unit.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The present invention provides a method for analyzing the static wind stability of a bridge, which couples multiple factors such as the uneven distribution of wind speed along the span of the bridge, the three-force coefficient of the turbulent wind field at the bridge site and its pulsating response, and the structural displacement of the bridge structure. Compared with the existing technology, it can more accurately reflect the complex wind environment at the bridge site and the coupling between the static wind load and the deformation of the bridge structure, thereby obtaining more accurate analysis results, such as the static wind stability wind speed displacement curve and the static wind stability critical wind speed, which is particularly suitable for the refined static wind stability analysis of large-span bridges under complex wind environments.

[0044] 2. The present invention provides a bridge static wind stability analysis device, which can execute a bridge static wind stability analysis method of the present invention, thereby obtaining a more accurate bridge static wind stability analysis result compared with the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic flow chart of a bridge static wind stability analysis method of the present invention;

[0046] Figure 2 It is a schematic diagram of the main beam cross section of a bridge static wind stability analysis method under the first load step of the present invention;

[0047] Figure 3 is a schematic diagram of a main beam cross section of a bridge static wind stability analysis method under the i-th load step of the present invention;

[0048] Figure 4 It is a schematic diagram of the static wind stability wind speed displacement of a bridge static wind stability analysis method of the present invention;

[0049] Figure 5 It is a schematic diagram comparing a wind speed-wind attack angle curve of a bridge static wind stability analysis method of the present invention with that of the prior art;

[0050] Icon: 1- Bridge structure. DETAILED DESCRIPTION

[0051] The present invention is further described in detail below in conjunction with test examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0052] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or position relationship such as "up", "down", "left", "right", "center", "inside", "outside", etc. are all expressions based on the orientation or position relationship shown in the drawings, or the orientation or position relationship when the invented product / equipment / device is usually used. These terms of orientation or position relationship are only for the convenience of describing the scheme of the present invention or simplifying the description in the specific embodiments, so as to facilitate the technicians to quickly understand the scheme, rather than indicating or implying that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the present invention.

[0053] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding devices / components / elements are required to be absolutely horizontal or vertical or overhanging or parallel, but may be slightly tilted or have deviations. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but may be slightly tilted. Alternatively, it can be simplified to mean that the corresponding devices / components / elements are set in directions such as "horizontal", "vertical", "overhanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present invention.

[0054] In addition, the expressions “first”, “second”, “third”, etc. that appear in the terms are merely descriptions used to distinguish the same or similar components and should not be understood as emphasizing or implying the relative importance of specific components.

[0055] In addition, in the description of the embodiments of the present invention, "several", "plurality" and "a number" represent at least 2. It can be any number such as 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9.

[0056] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connect", "connected", "provided with", "laid", and "arranged" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading, and other commonly used connection means in the field. This connection can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0057] Example 1

[0058] like Figure 1 As shown, a bridge static wind stability analysis method includes the following steps:

[0059] S1. Set the wind speed and calculate the static wind load on the bridge structure 1 under the non-uniformly distributed wind speed along the span of the bridge and the three-force coefficient under the turbulent wind field;

[0060] S2. Calculate the structural displacement of the bridge structure 1 according to the static wind load and extract the torsion angle; update the three-force coefficient according to the torsion angle and recalculate the static wind load on the bridge structure 1;

[0061] S3, updating the structural displacement according to the pulsating response of the bridge structure 1; judging whether the deformation of the bridge structure 1 is within an acceptable range according to the structural displacement; if so, increasing the wind speed according to a predetermined step length, and repeating steps S1 to S3; if not, repeating steps S2 to S3;

[0062] S4. When the deformation of the bridge structure 1 exceeds the acceptable range for a number of times greater than a predetermined upper limit of iterations, the wind speed is retracted by one step according to a predetermined step length, and the value of the predetermined step length is reduced; the wind speed is increased according to a predetermined step length, and steps S1 to S4 are repeated until the predetermined step length is less than or equal to the predetermined minimum step length, and the analysis is completed.

[0063] In an optional implementation manner, the non-uniformly distributed wind field and wind speed in step S1 can be obtained by analyzing the wind field characteristics of the bridge site terrain through CFD (Computational Fluid Dynamics) or by field measurement.

[0064] In an optional embodiment, a segment model of the bridge structure 1 is established, and the three-force coefficients are obtained through a model wind tunnel test, such as the three-force coefficients in step S1 or step S2.

[0065] In an optional implementation manner, in step S1, parameters such as wind speed, predetermined step length, predetermined minimum step length, and predetermined iteration upper limit value may also be determined in advance; for example, in this embodiment, v i represents the wind speed, i is the number of the wind speed, the initial value of i is set to 1, and i increases by one every time the wind speed increases by a predetermined step; and the initial value of the wind speed v 1 Set to 20m / s. Δv represents the predetermined step length, and 10m / s≤Δv≤20m / s; Δv represents the predetermined step length. min Indicates the predetermined minimum step size, and 2m / s≤Δv min ≤3m / s, in this embodiment, 2.5m / s is used. max represents the predetermined upper limit of iterations, and N max =3; correspondingly, in step S3, the wind speed is increased according to a predetermined step length, that is, vi =v i-1 +Δv; In step S4, NI is used to represent the number of times the deformation of the bridge structure 1 exceeds the acceptable range. If NI>N max When the wind speed is reduced by one step according to the predetermined step length, the wind speed is changed from v i Return to v i-1 .

[0066] In an optional implementation manner, in step S2, the static wind load of the bridge structure 1 is calculated according to the following formula:

[0067] F H =0.5*ρ*U 2 *C H *D

[0068] F V =0.5*ρ*U 2 *C V *B

[0069] M T =0.5*ρ*U 2 *C M *B 2

[0070] In the formula, F H Represents the resistance in body axis coordinates; F V represents the lift in body axis coordinates; M T represents the moment under the body axis coordinate; ρ represents the air density; U represents the current wind speed; C H represents the body axis drag coefficient under turbulent wind field; C V represents the body axis lift coefficient under turbulent wind field; C M represents the body axis moment coefficient under turbulent wind field; D represents the height of the bridge main beam; B represents the width of the bridge main beam. For more detailed steps and information, please refer to page 56 of Chen Zhengqing's "Bridge Wind Engineering".

[0071] In an optional implementation, the pulsation response of the bridge structure 1 is calculated according to the following steps:

[0072] A. Generate pulsating wind field by spectral method;

[0073] B. Perform finite element analysis on the bridge structure 1 according to the pulsating wind field to obtain the pulsating response.

[0074] Among them, step A can be solved by numerical analysis software such as MATLAB and SCILAB, and step B can be analyzed by simulation software such as ANSYS and ABAQUS; and step A and step B can occur directly in step S4 or before step S4.

[0075] In an optional implementation, in step S3, the structural displacement is updated according to the following formula:

[0076] U′ i =U i +U p

[0077] Where U i represents the unupdated structural displacement, where i is the number of the wind speed used to solve the structural displacement; U p represents the pulsation response; U′ i represents the structural displacement updated according to the pulsation response, that is, according to U′ i Instead of U i It is determined whether the deformation of the bridge structure 1 is within an acceptable range.

[0078] In an optional implementation, in step S3, it is compared whether the Euclidean norm of the structural displacement is less than a predetermined threshold; if so, the deformation of the bridge structure 1 is within an acceptable range; if not, the deformation of the bridge structure 1 exceeds the acceptable range. The specific formula can be referred to as follows:

[0079]

[0080] In the formula, represents the torsion angle of the jth bridge girder node in the i-th load step, and Through U i Instead of U′ i Extracted, represents the torsion angle of the jth bridge main beam node in the pulsation response; i represents the number of the load step, that is, the number of the wind speed; j represents the number of the bridge main beam node; n is the total number of the main beam nodes; ε represents the predetermined threshold value, which is specifically 1 in this embodiment.

[0081] like Figure 4 As shown in the figure, this scheme can ensure that the slope of the wind speed displacement curve of the bridge in each wind speed interval is Only the slope of the last segment

[0082] In an optional implementation, when the value of the predetermined step length is reduced in step S4, the predetermined step length is reduced by half each time. For example, when the predetermined step length is reduced for the first time, the predetermined step length is reduced to Δv / 2; when the predetermined step length is reduced for the second time, the predetermined step length is reduced to Δv / 4.

[0083] In an optional implementation manner, step S4 further includes the following steps:

[0084] S5. Select the wind speed in the last step as the critical wind speed for calm wind stability.

[0085] For example Figure 4As shown, in this embodiment, at the 19th wind speed v 19 = 267.5 m / s, the scheduled step length is less than the scheduled minimum step length and the analysis ends. Therefore, the 19th wind speed v is selected. 19 =267.5m / s is the most stable critical wind speed in calm wind.

[0086] In an optional implementation manner, steps S1 to S4 are all based on finite element analysis using finite element software ANSYS; correspondingly, a spatial finite element model of the bridge structure 1 needs to be established in step S1 or before step S1.

[0087] like Figure 5 The wind speed-wind attack angle curve obtained in this embodiment is compared with the prior art, wherein the physical meaning of the wind attack angle is as follows: Figures 2 to 3 θ 0 and θ i As shown, its value will change with the increase of load steps; it can be seen that, on the basis of considering only the span-wise non-uniform flow field, considering the three-force coefficient and the pulsation response of the turbulent flow field under the turbulent wind field may greatly improve the critical wind speed of the static wind stability of the bridge. Therefore, this embodiment can more accurately complete the static wind stability analysis of the bridge in a complex and changeable wind environment.

[0088] Example 2

[0089] A bridge static wind stability analysis device comprises a memory and a processor; the memory stores at least one instruction; the processor is communicatively connected to the memory, and the processor can execute the instructions stored in the memory, thereby executing a bridge static wind stability analysis method in Example 1.

[0090] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A bridge static wind stability analysis method, characterized in that: The following steps are included: S1. Set the wind speed and calculate the static wind load on the bridge structure (1) using the three-force coefficient in the turbulent wind field under the non-uniformly distributed wind speed along the span of the bridge; S2, calculating the structural displacement of the bridge structure (1) according to the static wind load and extracting the torsion angle; The three-force coefficient is updated according to the torsion angle, and the static wind load on the bridge structure (1) is recalculated; S3, updating the structural displacement according to the pulsating response of the bridge structure (1); judging whether the deformation of the bridge structure (1) is within an acceptable range according to the structural displacement; if so, increasing the wind speed according to a predetermined step length, and repeating steps S1 to S3; if not, repeating steps S2 to S3; S4. When the number of times that the deformation of the bridge structure (1) exceeds the acceptable range is greater than a predetermined upper limit of iterations, the wind speed is reduced by one step according to a predetermined step length, thereby reducing the value of the predetermined step length; The wind speed is increased according to a predetermined step length, and steps S1 to S4 are repeated until the predetermined step length is less than or equal to a predetermined minimum step length, and the analysis is completed.

2. A bridge static wind stability analysis method according to claim 1, characterized in that: It also includes the following steps: S5. Select the wind speed in the last step as the critical wind speed for calm wind stability.

3. A bridge static wind stability analysis method according to claim 1, characterized in that: In step S2, the static wind load of the bridge structure (1) is calculated according to the following formula: F H =0.5*ρ*U 2 *C H *D F V =0.5*ρ*U 2 *C V *B M T =0.5*ρ*U 2 *C M *B 2 In the formula, F H represents the resistance in body axis coordinates; F V represents the lift in body axis coordinates; M T represents the moment under the body axis coordinates; ρ represents the air density; U represents the current wind speed; C H represents the body axis drag coefficient under turbulent wind field; C V represents the body axis lift coefficient under turbulent wind field; C M represents the body axis moment coefficient under turbulent wind field; D represents the height of the bridge main beam; B represents the width of the bridge main beam.

4. A bridge static wind stability analysis method according to claim 1, characterized in that: In step S3, it is compared whether the Euclidean norm of the structural displacement is less than a predetermined threshold; if so, the deformation of the bridge structure (1) is within an acceptable range; if not, the deformation of the bridge structure (1) exceeds the acceptable range.

5. A bridge static wind stability analysis method according to any one of claims 1 to 4, characterized in that: The pulsation response of the bridge structure (1) is calculated according to the following steps: A. Generate pulsating wind field by spectral method; B. Perform finite element analysis on the bridge structure (1) based on the pulsating wind field to obtain the pulsating response.

6. A bridge static wind stability analysis method according to any one of claims 1 to 4, characterized in that: The three-force coefficients in turbulent wind field are obtained through model wind tunnel tests.

7. A bridge static wind stability analysis method according to any one of claims 1 to 4, characterized in that: An initial value of the predetermined step length is greater than or equal to 10 m / s and less than or equal to 20 m / s.

8. A bridge static wind stability analysis method according to any one of claims 1 to 4, characterized in that: The value of the predetermined minimum step size is greater than or equal to 2 m / s and less than or equal to 3 m / s.

9. A bridge static wind stability analysis method according to any one of claims 1 to 4, characterized in that: When the value of the predetermined step length is reduced in step S4, it is reduced by half each time.

10. A bridge static wind stability analysis device, characterized in that: Include: A memory storing at least one instruction; A processor, wherein the processor is communicatively connected to the memory, and the processor is capable of executing instructions stored in the memory, thereby executing a bridge static wind stability analysis method as described in any one of claims 1 to 9.

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