CN118332947A - Method for judging flutter stability of construction state of large-span bridge - Google Patents
Method for judging flutter stability of construction state of large-span bridge Download PDFInfo
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- CN118332947A CN118332947A CN202410390196.3A CN202410390196A CN118332947A CN 118332947 A CN118332947 A CN 118332947A CN 202410390196 A CN202410390196 A CN 202410390196A CN 118332947 A CN118332947 A CN 118332947A
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Abstract
The invention provides a method for judging the flutter stability of a construction state of a large-span bridge, which comprises the steps of firstly, using SPACECLAIM2021 to build a geometric model, leading in an ICEM2021 to carry out grid division, converting grids into unstructured grids, defining boundary conditions, setting the overall dimension of the grids, carrying out local encryption on the grids, and checking the quality of the grids. Then, fulent2021 is imported, the grid quality is checked again, boundary conditions and solving methods are set, the convergence of the solution is judged, and finally, the section M value is used for judging the flutter stability of the section. The method overcomes the defects of high hardware cost, complex field arrangement and the like of the traditional method, and achieves the purpose of ensuring the safety of bridge construction by judging the flutter stability of the bridge construction state, and judging the flutter stability rapidly, intuitively and efficiently, thereby greatly reducing the construction risk and improving the construction safety and the construction efficiency.
Description
Technical Field
The invention relates to the technical field of road and bridge construction, in particular to a method for judging the flutter stability of a construction state of a large-span bridge.
Background
Since the innovation is open, in order to realize the development goal of southwest areas, perfecting the traffic infrastructure thereof, especially encrypting southwest mountain traffic networks, the bridge means that a large number of bridges with larger spanning capacity are applied, and the effective measure for traversing mountain canyons is a large-span flexible bridge, and the bridge has low structural rigidity and is easy to generate flutter stability in the construction state process.
At present, the main stream method for judging the vibration stability of the construction state comprises the following steps: classical theory analysis method, direct test method, combination of theory and test method, wind tunnel test method and numerical simulation method, etc. However, in the test method, a longer test time and higher test cost are required for making a model, and in the numerical simulation method, a truncation error is introduced, so that a certain difficulty is brought to identifying the flutter derivative.
In summary, in the existing method for judging the vibration stability, a relatively quick, visual and efficient method for judging the vibration stability of the bridge is still lacking.
Disclosure of Invention
In order to solve the problems, the invention discloses a method for judging the flutter stability of a construction state of a large-span bridge, which achieves the purpose of ensuring the safety of bridge construction by judging the flutter stability of the construction state of the bridge, greatly reduces the construction risk and improves the construction safety and the construction efficiency.
A method for judging the vibration stability of a large-span bridge in the construction state comprises the steps of obtaining a three-component-force coefficient of a typical section through CFD numerical simulation, and calculating to obtain a corresponding M parameter value for judging the vibration stability of the construction state.
The specific implementation of the invention is as follows:
(1) Using SPACEC L A IM2021 to build a geometric model, typically scaled by 1/40 to improve computational efficiency;
(2) The I CEM2021 performs meshing to convert the mesh into unstructured mesh;
(3) Defining boundary conditions, setting grid global dimensions, adopting 2D plane grids in calculation, and defining the size of the global grids to be 1/10 of the width of the main beam;
(4) The grid is locally encrypted, the grid quality is checked, the grids near the main beam are encrypted, other grids can be set to be sparser grids, the middle is reasonably transited, and the grid quality is more than 0.8;
(5) The Fu agent 2021 is imported, the grid quality is checked again, and inaccuracy of the calculation result caused by lower grid quality is avoided;
(6) Setting boundary conditions and solving methods, wherein a non-slip wall surface is adopted on the main beam wall surface, a free-slip wall surface is adopted on the upper boundary, a speed inlet is adopted on the inlet boundary, a 0-pressure outlet boundary is adopted on the outlet boundary, and the solving methods are set as SIMPLE methods of pressure-speed coupling;
(7) Judging the convergence of the solution, calculating and solving by setting the iteration number of solution or time steps, and if the solution can not be converged, adjusting the iteration number of solution or checking whether the solution method is accurate;
(8) Displaying and outputting a calculation result, processing to obtain a static three-component force coefficient of each section construction stage, and establishing a parameter M formula based on the relation between the three-component force coefficient and the flutter stability:
Wherein: c 'M represents the derivative of the lift moment, C' L represents the derivative of the lift moment, and C L、CD、CM represents the lift coefficient, drag coefficient, and lift moment coefficient, respectively. The method is used for judging the flutter stability of the section, and when the calculated section M value is obtained, the flutter stability of the section 2 is higher than that of the section 1 if M1< M2, and the flutter stability of the section 2 is lower than that of the section 1 if M1> M2.
The invention has the technical advantages that:
The method for judging the flutter stability of the construction state of the large-span bridge achieves the aim of guaranteeing the safety of bridge construction by judging the flutter stability of the construction state of the bridge, and is quick, visual and efficient in judgment, greatly reduces the construction risk and improves the construction safety and the construction efficiency.
Drawings
FIG. 1 is a flow chart of a method for determining stability according to the present invention.
FIG. 2 is a schematic diagram of the encryption of the grid near the main beam of the present invention;
FIG. 3 is a schematic diagram of the interface partitioning of the present invention.
Detailed Description
The present invention is further illustrated in the following drawings and detailed description, which are to be understood as being merely illustrative of the invention and not limiting the scope of the invention. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings, and the words "inner" and "outer" refer to directions toward or away from, respectively, the geometric center of a particular component.
As shown in FIG. 1, the invention provides a method for judging the vibration stability of a construction state of a large-span bridge shown in FIG. 1, which is realized by the following steps:
(1) Using SPACEC L A IM2021 to build a geometric model, typically scaled by 1/40 to improve computational efficiency;
(2) The I CEM2021 performs meshing to convert the mesh into unstructured mesh;
(3) Defining boundary conditions, setting grid global dimensions, adopting 2D plane grids in calculation, and defining the size of the global grids to be 1/10 of the width of the main beam;
(4) The grid is locally encrypted, the grid quality is checked, the grids near the main beam are encrypted, other grids can be set to be sparser grids, the middle is reasonably transited, and the grid quality is more than 0.8, as shown in figure 2;
(5) The Fu agent 2021 is imported, the grid quality is checked again, and inaccuracy of the calculation result caused by lower grid quality is avoided;
(6) Setting boundary conditions and solving methods, wherein a non-slip wall surface is adopted on the main beam wall surface, a free-slip wall surface is adopted on the upper boundary, a speed inlet is adopted on the inlet boundary, a 0-pressure outlet boundary is adopted on the outlet boundary, and the solving method is a SIMPLE method of pressure-speed coupling, as shown in figure 3;
(7) Judging the convergence of the solution, calculating and solving by setting the iteration number of solution or time steps, and if the solution can not be converged, adjusting the iteration number of solution or checking whether the solution method is accurate;
(8) Displaying and outputting a calculation result, processing to obtain a static three-component force coefficient of each section construction stage, and establishing a parameter M formula based on the relation between the three-component force coefficient and the flutter stability: and judging the flutter stability of the section, wherein when the calculated section M value is obtained, if M1 is smaller than M2, the flutter stability of the section 2 is higher than that of the section 1, and if M1 is larger than M2, the flutter stability of the section 2 is lower than that of the section 1.
Taking a flat section, a Jiangyin section and a Siemens section as examples: the calculated M (plate section) parameter value was 0.14782, M (Jiangyin section) parameter value was 0.2087, and M (Siemens section) parameter value was 1.1936. The size relation of the parameter M is as follows: the cross section of the flat plate is < Jiangyin cross section < Siemens cross section. The flutter critical wind speeds are respectively as follows: 16.5m/s,71.3m/s and 89.2m/s. Relationship between the critical wind speed of flutter: the cross section of the flat plate is < Jiangyin cross section < Siemens cross section. From this, the flutter stability is positively correlated with the parameter M, which proves that the method is reliable.
The technical means disclosed by the scheme of the invention is not limited to the technical means disclosed by the embodiment, and also comprises the technical scheme formed by any combination of the technical features.
Claims (5)
1. A method for judging the vibration stability of a large-span bridge in a construction state is characterized by comprising the following steps: the method comprises the following implementation steps:
step 1 uses SPACECLAIM to build a geometric model, typically scaled by 1/40 to improve computational efficiency;
Step 2, introducing ICEM2021 to carry out grid division, and converting the grids into unstructured grids;
Step 3, defining boundary conditions, setting grid global dimensions, adopting 2D plane grids in calculation, and defining 1/10 of the width of the main beam of the global grid;
Step 4, local encryption of grids, checking the quality of the grids, encrypting the grids near the main beam, and setting other grids as sparser grids, wherein the middle is reasonably transited, and the quality of the grids is more than 0.8;
Step 5, importing Fulent to 2021, checking the grid quality again, and avoiding inaccurate calculation results caused by lower grid quality;
Step 6, setting boundary conditions and solving methods, wherein a non-slip wall surface is adopted on the wall surface of the main beam, a free-slip wall surface is adopted on the upper boundary, a speed inlet is adopted on the inlet boundary, a 0-pressure outlet boundary is adopted on the outlet boundary, and the solving methods are set as SIMPLE methods for pressure-speed coupling;
step 7, judging the convergence of the solution, calculating and solving by setting the iteration number of solution or time steps, and if the solution can not be converged, adjusting the iteration number of solution or checking whether the solution method is accurate;
And step 8, displaying and outputting the calculation result, processing, and judging the vibration stability of the construction state based on the parameter M.
2. The method for judging the vibration stability of the construction state of the large-span bridge according to claim 1, wherein the method comprises the following steps: the step 2: and the ICEM2021 is imported for grid division, the grid is converted into an unstructured grid, the unstructured grid is adopted in the calculation of the unstructured grid, the unstructured grid has no obvious row lines and column lines in space distribution, the calculation accuracy can be ensured, and the grids are connected together through nodes in the whole calculation domain.
3. The method for judging the vibration stability of the construction state of the large-span bridge according to claim 1, wherein the method comprises the following steps: the step 4: the grid is locally encrypted, the quality of the grid is checked, the grids near the main beam are encrypted, other grids can be set to be sparser grids, under the method, the flow field can be fully developed, the flow field change near the main beam can be more accurately simulated, the accurate three-component force coefficient is obtained, and the grid quality is kept above 0.8 so as to ensure the reasonable calculation result.
4. The method for judging the vibration stability of the construction state of the large-span bridge according to claim 1, wherein the method comprises the following steps: the step 6: setting boundary conditions and solving methods, wherein the inlet boundary adopts a speed inlet, if the actual measured wind speed data at the height of the main beam exists, the wind speed can be used, and the wind speed can also be 10m/s which is commonly used in wind tunnel tests as an inlet wind speed value. The outlet boundary adopts a 0-pressure outlet boundary, a solving method is set to be a SIMPLE method of pressure velocity coupling, and the pressure of body Force weighted and quickmomentum are adopted for calculation.
5. The method for judging the vibration stability of the construction state of the large-span bridge according to claim 1, wherein the method comprises the following steps: the step 8: obtaining a static three-component force coefficient of each section construction stage, and establishing a parameter M formula based on the relation between the three-component force coefficient and the flutter stability: Wherein: c 'M represents the derivative of the lift moment, C' L represents the derivative of the lift moment, and C L、CD、CM represents the lift coefficient, the drag coefficient and the lift moment coefficient, respectively; the parameter is used for judging the flutter stability of the section, and when the calculated section M value is obtained, the flutter stability of the section 2 is higher than that of the section 1 if M 1<M2, and the flutter stability of the section 2 is lower than that of the section 1 if M 1>M2.
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| Publication Number | Publication Date |
|---|---|
| CN118332947A true CN118332947A (en) | 2024-07-12 |
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