Method and system for evaluating wind environment and safety of double-deck bridge and storage medium

Abstract

The application discloses a kind of double-deck bridge driving wind environment and safety evaluation method, system and storage medium, method includes: collection double-deck bridge site wind environment parameter, constructs and includes the three-dimensional numerical simulation model of double-deck bridge main body and to be evaluated wind barrier component, in combination with measured wind parameter setting matching field topography wind field boundary condition.In the vertical height of each lane of upper and lower deck corresponding size vehicle is laid out monitoring point, and all monitoring point wind speed data is obtained by using CFD calculation.Based on wind speed, the wind reduction factor of each lane of upper and lower deck is calculated as wind environment evaluation index.The reduction factor is compared with the layered safety threshold to evaluate driving safety.If lane index is out of standard, adjust wind barrier parameter and recalculate, repeat iteration until all lane index meets the standard, output compliant wind barrier structure parameter and complete driving safety evaluation result.It provides reliable technical support for double-deck bridge driving safety.

Description

Technical Field

[0001] This invention belongs to the field of bridge wind-resistant design technology, and more specifically, relates to a method, system and storage medium for assessing the wind environment and safety of a double-deck bridge. Background Technology

[0002] Double-deck truss bridges can make efficient use of passage space and are increasingly widely used in large-scale cross-river and cross-sea passage projects. The double-deck bridge has a significant vertical height difference, and the upper and lower decks are at different heights above the ground, resulting in significant differences in the reference wind speed and turbulence intensity. The crosswind distribution pattern of the bridge deck is complex, and strong crosswinds can easily induce vehicle skidding and overturning, seriously threatening road traffic safety. In the engineering field, components such as wind barriers, lower guide vanes, and skirts are usually used to mitigate the impact of crosswinds on the bridge deck.

[0003] Most existing bridge deck wind environment assessment technologies are designed for single-layer bridges, failing to consider the differentiated wind field characteristics of the upper and lower layers of double-layer bridges, and thus unable to establish independent safety judgment standards for each layer. Traditional evaluation methods only select single-point wind speeds for assessment, failing to distinguish the equivalent wind exposure heights of large and small vehicles, and ignoring turbulent disturbances caused by spatial non-uniformity of wind speeds on the bridge deck. Consequently, the calculated wind environment indicators deviate significantly from the actual wind exposure conditions of vehicles.

[0004] Conventional wind barrier optimization relies solely on single simulations comparing different solutions, lacking a closed-loop iterative optimization process. Adjusting wind barrier height and windbreak ratio makes it difficult to simultaneously verify the safety levels of all lanes on both upper and lower levels, failing to ensure consistent safety margins across the entire double-deck bridge. Existing technologies lack a complete quantitative evaluation system, making it difficult to derive permissible thresholds for tiered crosswind reduction based on critical overturning wind speeds for vehicles. Furthermore, they cannot quantitatively assess the wind control effectiveness of various wind barrier components. The industry urgently needs a quantitative evaluation method for driving wind environment and driving safety that is adaptable to double-deck bridge conditions and allows for iterative optimization of wind control structures. Summary of the Invention

[0005] This invention aims to solve the problems of wind field differences between the upper and lower layers of a double-layer bridge deck, insufficient differentiation of wind conditions for different vehicle types, and lack of closed-loop optimization of wind barriers. By calculating the stratified crosswind reduction coefficient through CFD simulation, establishing a stratified safety threshold judgment standard, and iteratively optimizing structures such as wind barriers and deflectors, it achieves quantitative assessment of the driving wind environment on a double-layer bridge deck and optimal design of the wind control structure.

[0006] To address the aforementioned deficiencies or improvement needs of existing technologies, as a first aspect of this invention, the present invention provides a method for assessing the wind environment and safety of a double-deck bridge, comprising: S1. Obtain wind environment parameters at the target double-layer bridge deck location, establish a three-dimensional numerical simulation model including the target double-layer bridge deck and the wind barrier structure to be evaluated, and set the wind field boundary conditions of the three-dimensional numerical simulation model based on the wind environment parameters. S2. In the three-dimensional numerical simulation model, multiple monitoring points are arranged within a preset height range above each lane of the upper and lower bridge decks of the target double-layer bridge deck. The three-dimensional numerical simulation model is solved using computational fluid dynamics to obtain the wind speed data of each monitoring point. S3. Based on the wind speed data of each monitoring point, calculate the crosswind reduction coefficient for each lane position in the upper and lower bridge decks respectively, and use it as an evaluation index for driving wind environment; S4. Compare the crosswind reduction coefficient with the preset allowable threshold for crosswind reduction coefficient to evaluate the driving safety of the target double-layer bridge deck; if the crosswind reduction coefficient at any lane position is greater than the allowable threshold, adjust the parameters of the wind barrier structure to be evaluated and return to execute S2 until the crosswind reduction coefficient at all lane positions is less than or equal to the allowable threshold, and output the target parameters of the wind barrier structure that meet the driving safety requirements and the driving safety evaluation results.

[0007] Further, in S1, a three-dimensional numerical simulation model is established, including the target double-layer bridge deck and the windbreak structure to be evaluated, comprising: Construct a geometric model that includes the cross-section of the double-layer truss main beam, bridge towers, and bridge deck components; The parameters of the windbreak structure to be evaluated include windbreak height, windbreak ratio, and the dimensions of the horizontal guide plate and skirt plate located on the outer side of the lower layer of the main beam.

[0008] Further, in step S1, setting the wind field boundary conditions of the three-dimensional numerical simulation model based on the wind environment parameters includes: Obtain the measured wind speed, wind profile index, and turbulence intensity at the bridge site; Based on the wind profile index and the turbulence intensity, an atmospheric boundary layer wind speed profile that conforms to the landform type of the target double-layer bridge deck is constructed, and the atmospheric boundary layer wind speed profile is used as the inlet wind speed boundary condition of the three-dimensional numerical simulation model.

[0009] Furthermore, in step S2, multiple monitoring points are arranged within a preset height range above each lane of the upper and lower decks of the target double-layer bridge, including: The preset height range includes a first equivalent calculated height corresponding to large vehicles and a second equivalent calculated height corresponding to small vehicles; The monitoring points are arranged at preset intervals along the transverse direction of the bridge deck above the center lines of each lane, and multiple typical cross-sections are selected and arranged along the longitudinal direction of the bridge at the center of the bridge tower, the boundary of the tower column, the mid-span area, and the segmental characteristic positions far from the bridge tower.

[0010] Further, in step S3, based on the wind speed data of each monitoring point, the crosswind reduction coefficient for each lane position on the upper and lower bridge decks is calculated, including: Based on the wind speed data of each monitoring point, integral calculation is performed within the preset height range to obtain the equivalent wind speed at each lane location; Based on the reference height wind speed at the bridge site, the height of the bridge deck above the ground surface, and the wind profile index, the reference height wind speed is calculated. The ratio of the equivalent wind speed at each lane location to the reference height wind speed is used as the crosswind reduction factor for the corresponding lane location.

[0011] Furthermore, the method for calculating the equivalent wind speed is as follows: The equivalent wind speed at each lane location is calculated using the following first formula: In the formula, For the first The equivalent wind speed of each lane; For the first The equivalent vehicle height corresponding to each lane, when the vehicle type is a large vehicle. Take the first equivalent calculation height when the vehicle type is a small vehicle. Take the second equivalent calculation height; The vertical spacing between adjacent monitoring points; For the first The number of monitoring points for each lane within the preset height range; For the first Lane number Lateral wind speed at each monitoring point.

[0012] Furthermore, the equivalent wind speed is based on an adaptive processing principle, specifically as follows: When the wind speed non-uniformity coefficient of the upper or lower bridge deck exceeds a preset non-uniformity threshold, the equivalent wind speed is adaptively corrected according to the following second formula: In the formula, The corrected equivalent wind speed is used to replace the aforementioned... Participate in the calculation of the crosswind reduction factor; The wind speed sensitivity coefficient is associated with the vehicle type, when the vehicle type is a large vehicle. Take the first sensitivity value when the vehicle type is a small vehicle. Take a second sensitivity value that is less than the first sensitivity value; For the first The wind speed non-uniformity coefficient of each lane, ,in For the first The standard deviation of the lateral wind speed at each monitoring point on each lane For the first The arithmetic mean of the lateral wind speed at each monitoring point on each lane.

[0013] Furthermore, the preset crosswind reduction coefficient threshold in S4 is determined based on the principle of consistency of safe passage capability across the entire line; The upper bridge deck and the lower bridge deck correspond to different allowable thresholds for crosswind reduction coefficients, and the allowable threshold for crosswind reduction coefficient of the upper bridge deck is less than the allowable threshold for crosswind reduction coefficient of the lower bridge deck.

[0014] As a second aspect of the present invention, a dual-deck bridge deck driving wind environment and safety assessment system is also provided, comprising: The wind field modeling and boundary setting unit is used to obtain wind environment parameters at the target double-layer bridge deck location, establish a three-dimensional numerical simulation model including the target double-layer bridge deck and the wind barrier structure to be evaluated, and set the wind field boundary conditions of the three-dimensional numerical simulation model based on the wind environment parameters. The monitoring point layout and wind speed solution unit is used to arrange multiple monitoring points within a preset height range above each lane of the upper and lower bridge decks of the target double-layer bridge deck in the three-dimensional numerical simulation model, and to solve the three-dimensional numerical simulation model using computational fluid dynamics to obtain the wind speed data of each monitoring point. The crosswind reduction coefficient calculation unit is used to calculate the crosswind reduction coefficient of each lane position in the upper bridge deck and the lower bridge deck based on the wind speed data of each monitoring point, and to serve as an evaluation index for driving wind environment. The safety assessment and wind barrier optimization unit is used to compare the crosswind reduction coefficient with a preset allowable threshold for the crosswind reduction coefficient to assess the driving safety of the target double-layer bridge deck. If the crosswind reduction coefficient at any lane position is greater than the allowable threshold, the parameters of the wind barrier structure to be assessed are adjusted and the unit returns to the monitoring point layout and wind speed calculation unit until the crosswind reduction coefficient at all lane positions is less than or equal to the allowable threshold. The unit then outputs the target parameters of the wind barrier structure that meet the driving safety requirements and the driving safety assessment results.

[0015] As a third aspect of the invention, a computer-readable storage medium is also provided, on which a computer program is stored, which is executed by a processor as described in any one of the claims: a method for assessing the driving wind environment and safety of a double-deck bridge.

[0016] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. The method for assessing the wind environment and safety of a double-deck bridge deck in this invention constructs a three-dimensional simulation model matching the on-site terrain based on measured wind environment parameters at the bridge site. This model fully incorporates the main body of the double-deck bridge and adjustable components such as wind barriers, guide vanes, and skirts, thus reproducing the actual incoming flow boundary conditions. This method can completely reproduce the differentiated wind field characteristics of the upper and lower bridge decks. Unlike single-deck bridge simulation modes, it pre-determines all optimization variables such as wind barrier height and wind resistance rate, providing a digital carrier that closely matches the actual engineering situation for subsequent full-lane wind speed collection, and avoiding assessment bias caused by the disconnect between the simulated wind field and the actual on-site conditions.

[0017] 2. The method for assessing the wind environment and safety of a double-layer bridge deck in this invention involves deploying multiple monitoring sections at the vertical height of vehicles of corresponding sizes in each lane on both the upper and lower layers. Computational fluid dynamics is used to obtain the lateral wind speed across the entire area, and the equivalent wind speed of each lane is calculated using an integral formula based on vertical measurement points. Adaptive correction can also be performed based on the degree of wind speed unevenness. This calculation method takes into account the differences in wind height experienced by different vehicle types and the influence of bridge deck turbulence fluctuations, uniformly generating a dimensionless crosswind reduction coefficient as an evaluation index. This eliminates the bias caused by single-point wind speed evaluation and objectively quantifies the true crosswind risk level of each lane.

[0018] 3. The method for assessing the wind environment and safety of a double-deck bridge deck in this invention derives the allowable threshold for differentiated crosswind reduction between the upper and lower layers based on the critical crosswind speed for vehicles. It then compares the indicators of each lane to complete a safety judgment. If an indicator fails to meet the standard, the parameters of the windbreak, deflector, and skirt are adjusted sequentially according to priority, and the process is iteratively simulated and verified. This closed-loop iterative process ensures that the safety margin of the entire double-deck bridge deck remains consistent until all lanes meet safety standards. It directly outputs the optimal wind control structure parameters adapted to the bridge's operating conditions, achieving an integrated quantitative assessment of driving safety and windbreak design for double-deck bridge decks. Attached Figure Description

[0019] Figure 1 This is a flowchart of a method for assessing the wind environment and safety of a double-deck bridge under traffic, according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the detection point arrangement according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the streamline distribution in the area near the bridge tower under the wind barrier condition of 60% wind resistance and 1.7m height, according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the system units in an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0021] Example 1 Please refer to Figure 1 This embodiment 1 provides a method for assessing the wind environment and safety of a double-deck bridge, including: S1. Obtain wind environment parameters at the target double-layer bridge deck location, establish a three-dimensional numerical simulation model including the target double-layer bridge deck and the wind barrier structure to be evaluated, and set the wind field boundary conditions of the three-dimensional numerical simulation model based on the wind environment parameters. S2. In the three-dimensional numerical simulation model, multiple monitoring points are arranged within a preset height range above each lane of the upper and lower bridge decks of the target double-layer bridge deck. The three-dimensional numerical simulation model is solved using computational fluid dynamics to obtain the wind speed data of each monitoring point. S3. Based on the wind speed data of each monitoring point, calculate the crosswind reduction coefficient for each lane position in the upper and lower bridge decks respectively, and use it as an evaluation index for driving wind environment; S4. Compare the crosswind reduction coefficient with the preset allowable threshold for crosswind reduction coefficient to evaluate the driving safety of the target double-layer bridge deck; if the crosswind reduction coefficient at any lane position is greater than the allowable threshold, adjust the parameters of the wind barrier structure to be evaluated and return to execute S2 until the crosswind reduction coefficient at all lane positions is less than or equal to the allowable threshold, and output the target parameters of the wind barrier structure that meet the driving safety requirements and the driving safety evaluation results.

[0022] Please refer to Figure 2 as well as Figure 3 This embodiment 1 further elaborates on the above steps.

[0023] (1) Wind field modeling and boundary setting In this embodiment, obtaining the actual wind environment parameters at the target double-layer bridge site is the foundation for constructing the numerical simulation model. Historical wind speed data is collected by anemometers placed at the bridge site or nearby meteorological observation stations, thereby obtaining the measured wind speed, wind profile index, and turbulence intensity at the bridge site. The measured wind speed is used to determine the design reference wind speed at the bridge site, the wind profile index reflects the influence of surface roughness at the bridge site on the variation of wind speed with height, and the turbulence intensity characterizes the pulsating characteristics of the incoming wind. Based on the obtained wind profile index and turbulence intensity, an atmospheric boundary layer wind speed profile conforming to the landform type of the target double-layer bridge deck is constructed using an exponential law. Since different landform types have different frictional resistance effects on airflow, the constructed wind speed profile can objectively reflect the variation of wind speed with height.

[0024] When establishing a 3D numerical simulation model that includes the target double-layer bridge deck and the windbreak structure to be evaluated, a geometric model is constructed based on the bridge design drawings. The geometric model includes the cross-section of the double-layer truss main beam, the bridge towers, and the bridge deck system components. The cross-section of the double-layer truss main beam reflects the spatial relative position of the upper and lower bridge decks and the cross-sectional dimensions of the truss members; the bridge tower model reflects the outline of the tower columns and their connection relationship with the main beam; the bridge deck system components encompass the bridge deck panels, crash barriers, maintenance walkways, and the upper and lower chords, web members, and longitudinal and transverse beam systems of the truss beam. The truss beam is a permeable structure, and airflow passes through its internal member system. During modeling, the detailed structure of the main beam cross-section is geometrically reconstructed to simulate the flow around and permeability effects of airflow passing through the truss beam, ensuring the rationality of the flow field calculation.

[0025] For the windbreak structure to be evaluated, corresponding parameters are assigned to the geometric model. These parameters include windbreak height, windbreak ratio, and the dimensions of the horizontal guide vanes and skirts located on the outer side of the lower layer of the main beam. The windbreak is positioned at the edges of the upper and lower bridge decks. Its windbreak ratio is achieved by adjusting the ratio of the opening area to the total area in the windbreak's geometric model. The windbreak height and windbreak ratio determine the windbreak's obstruction and permeability of airflow. In actual engineering, windbreaks typically have a certain permeability, which reduces wind speed on the bridge deck while preventing the windbreak itself from bearing excessive wind loads. The horizontal guide vanes are located on the outer edge of the lower layer of the main beam to guide airflow smoothly across the lower bridge deck. The skirts are located at the bottom edge of the lower bridge deck to suppress airflow from the bottom of the bridge deck upwards. The dimensions of the horizontal guide vanes and skirts are used to adjust the airflow separation and flow pattern on the outer side of the lower layer of the main beam.

[0026] After constructing the geometric model, the computational domain of the 3D numerical simulation model is established. The computational domain is the virtual space where fluid calculations occur, and its dimensions must be set to allow for sufficient flow field development. The length of the computational domain is several times the bridge span, while its width and height are greater than the bridge cross-section dimensions to avoid artificial blockage effects caused by excessively close boundary distances, which could interfere with the real flow field around the bridge. The geometric model, including the double-layer bridge deck and the windbreak structure to be evaluated, is placed at a designated location within the computational domain, and the entire computational domain is meshed. In the regions near the bridge cross-section and windbreak structure, where the flow field gradient changes drastically, mesh refinement is performed; in regions far from the bridge, a sparse mesh is used to balance computational resources and solution requirements.

[0027] After the computational domain and mesh are ready, the wind field boundary conditions of the 3D numerical simulation model are set. The previously constructed atmospheric boundary layer wind speed profile is used as the inlet wind speed boundary condition. Simultaneously, turbulence intensity and turbulence dissipation rate profiles at the inlet are set to fully describe the incoming wind field characteristics. The outlet boundary of the computational domain is set as a pressure outlet boundary condition, allowing the airflow to flow freely out of the computational domain after passing over the bridge, avoiding spurious reflected waves interfering with the upstream flow field. The top and side boundaries of the computational domain are set as symmetrical boundary conditions or free-slip wall boundary conditions to simulate infinite atmospheric space. The ground and bridge structure surfaces are set as no-slip wall boundary conditions to reflect the viscous interaction between the airflow and the solid surface, thus completing the initial configuration of the 3D numerical simulation model.

[0028] (2) Layout of monitoring points and wind speed calculation After the three-dimensional numerical simulation model is constructed and the boundary conditions are set, multiple monitoring points need to be arranged above each lane on the upper and lower decks of the target double-deck bridge to extract wind field data for the bridge deck area. The spatial arrangement of the monitoring points covers three dimensions: vertical, horizontal, and longitudinal, to comprehensively capture the wind speed distribution characteristics of the double-deck bridge at different locations.

[0029] Vertically, monitoring points are positioned within a preset height range above each lane. This preset height range includes a first equivalent calculation height corresponding to large vehicles and a second equivalent calculation height corresponding to small vehicles. Large and small vehicles differ in body height, center of gravity position, and lateral windward area, resulting in different heights at which they experience lateral wind loads. By mapping the monitoring point heights to vehicle types, wind speed data at the actual aerodynamic impact height of large and small vehicles during operation can be extracted separately.

[0030] Upwards on the transverse bridge, monitoring points are arranged horizontally along the bridge surface above the center lines of each lane at preset intervals. The center lines of each lane are the main trajectories of vehicles; placing monitoring points above these positions allows for direct acquisition of wind field information along the vehicle's path. The vertical spacing between adjacent monitoring points is determined according to a preset interval. This spacing must be set to ensure that the gradient changes in wind speed along the height direction are captured, avoiding the omission of areas with sudden changes in local wind speed due to excessively large spacing.

[0031] Along the longitudinal direction of the bridge, multiple typical cross-sections were selected for monitoring. These typical cross-sections included the center of the bridge towers, the tower column boundaries, the mid-span region, and characteristic locations of segments far from the towers. Due to the shielding and flow-around effects of the tower structure, the flow field at the center of the towers and the tower column boundaries exhibits significant wake and local acceleration effects. The mid-span region is directly affected by the wind environment, with less interference from the towers. The characteristic locations of segments far from the towers are used to reflect the conventional wind field conditions within standard segments. By arranging typical cross-sections at these characteristic locations, the influence of different structural parts of the bridge on the bridge deck wind field can be comprehensively reflected.

[0032] After completing the spatial layout of the monitoring points, the three-dimensional numerical simulation model was solved using computational fluid dynamics. In the solution preparation stage, the computational domain was meshed, and the mesh was refined for the bridge cross-section and the area near the bridge towers. Regarding boundary conditions, the inlet boundary was set as a wind speed inlet condition, with the incoming wind speed at different heights determined based on the design wind speed and wind profile index at the bridge location; the outlet boundary was set as a pressure outlet condition, with the outlet static pressure set to zero; the top and sides of the computational domain were set as symmetrical boundary conditions, while the bottom surface and the bridge structure surface were set as no-slip wall boundary conditions. During the solution process, a turbulence model suitable for simulating the flow characteristics around the bridge was selected, and corresponding discretization schemes and convergence criteria were set.

[0033] After setting a convergence residual threshold, iterative calculations are initiated, with real-time monitoring of wind speed changes at each monitoring point during the iteration process. When the wind speed values ​​at each monitoring point no longer fluctuate significantly with the number of iterations, and the residuals of the continuity equation and momentum equations for the entire computational domain all fall below the convergence residual threshold, the flow field calculation is considered to have reached a stable state. After convergence, wind speed data for each monitoring point is extracted from the calculation results. This data contains wind speed information for each lane on both the upper and lower bridge decks at different longitudinal sections and equivalent heights, comprehensively reflecting the three-dimensional wind field distribution on the two-layer bridge deck under the set wind field boundary conditions.

[0034] (3) Calculation of crosswind reduction factor After acquiring wind speed data from each monitoring point, it is necessary to calculate the crosswind reduction coefficient for each lane location on both the upper and lower bridge decks based on this data. This coefficient serves as an evaluation index for the driving wind environment. The calculation of the crosswind reduction coefficient depends on the equivalent wind speed at each lane location and the wind speed at a reference height. To obtain the equivalent wind speed at each lane location, the lateral wind speed data from the monitoring points is integrated within a preset height range. Specifically, the equivalent wind speed at each lane location is calculated according to a first formula, which is: In the formula, For the first The equivalent wind speed of each lane; For the first The equivalent vehicle height corresponding to each lane, when the vehicle type is a large vehicle. Take the first equivalent calculation height when the vehicle type is a small vehicle. Take the second equivalent calculation height; The vertical spacing between adjacent monitoring points; For the first The number of monitoring points within the preset height range for each lane; For the first Lane number The lateral wind speed at each monitoring point. By using this root mean square integral method along the height direction, the discrete wind speeds at the monitoring points can be transformed into equivalent wind speeds that reflect the overall wind effect on the vehicle.

[0035] After calculating the initial equivalent wind speed, it is also necessary to evaluate the uniformity of the wind field distribution along the height direction on the bridge deck. Due to the shielding and guiding effects of the bridge cross-section and wind barrier structure, drastic variations in wind speed along height may occur in local areas of the bridge deck. Therefore, an adaptive processing principle is introduced to verify the equivalent wind speed. Specifically, the calculation of the first... Wind speed non-uniformity coefficient of lane The calculation method is as follows: ,in For the first The standard deviation of the lateral wind speed at each monitoring point on each lane For the first The arithmetic mean of the lateral wind speed at each monitoring point on each lane.

[0036] When the wind speed non-uniformity coefficient of the upper or lower bridge deck exceeds the preset non-uniformity threshold, it indicates that the wind speed gradient within the lane height range is large. In this case, the equivalent wind speed is adaptively corrected according to the second formula, which is: In the formula, The corrected equivalent wind speed is used to replace the aforementioned... Participate in the calculation of the crosswind reduction factor; The wind speed sensitivity coefficient is related to vehicle type; when the vehicle type is a large vehicle... Take the first sensitivity value when the vehicle type is a small vehicle. A second sensitivity value, smaller than the first sensitivity value, is used. Large vehicles, due to their large lateral frontal area and high center of gravity, are more sensitive to uneven wind speed distribution along their height. Therefore, a larger first sensitivity value is assigned to amplify the adverse effects of uneven wind speed.

[0037] After calculating or correcting the equivalent wind speed, a reference height wind speed needs to be determined as a comparison benchmark. The reference height wind speed is calculated based on the reference height wind speed at the bridge site, the bridge deck's height above the ground, and the wind profile index. Specifically, the ratio of the bridge deck's height above the ground to the reference height is used as the base, and the wind profile index is used as the power for exponential calculation. The result is then multiplied by the reference height wind speed at the bridge site to obtain the reference height wind speed. This exponential law-based calculation method considers the influence of surface roughness on the frictional resistance of airflow with height, ensuring that the reference wind speed objectively reflects the undisturbed incoming wind speed at the bridge deck's height.

[0038] The ratio of the equivalent wind speed or corrected equivalent wind speed at each lane location to the wind speed at the reference height is calculated. This ratio serves as the crosswind reduction factor for the corresponding lane location and is used as an indicator for evaluating the driving wind environment. The crosswind reduction factor directly reflects the degree to which the bridge structure and wind barrier facilities reduce or amplify the wind speed at the driving height on the bridge deck.

[0039] (4) Safety assessment and windbreak optimization After obtaining the crosswind reduction coefficient at each lane location, it is necessary to compare it with the preset allowable threshold for crosswind reduction coefficient to assess the driving safety of the target double-deck bridge. The determination of the allowable threshold for crosswind reduction coefficient is based on the principle of consistency of safe traffic capacity across the entire line. This principle requires that the driving safety margin of the upper and lower bridge decks remain equal under their respective design reference wind speeds, thereby avoiding frequent traffic closures of one bridge deck due to severe wind conditions, which would affect the overall traffic efficiency.

[0040] Based on the principle of consistent safe passage capacity across the entire line, the allowable threshold for the crosswind reduction factor of each bridge deck is calculated according to the following formula: In the formula, For the first Allowable threshold for crosswind reduction factor on multi-level bridge deck. Indicates the upper bridge deck. Indicates the lower bridge deck; To assess the critical crosswind safety speed for vehicles under dry road conditions; For the first Environmental risk correction factor for bridge deck; For the first The crosswind reduction factor is the allowable threshold value at the reference height of the bridge deck. The physical meaning of this formula is that the allowable crosswind reduction factor reflects the allowable ratio of the actual wind speed on the bridge deck to the reference wind speed. When the actual crosswind reduction factor exceeds this threshold value, it indicates that the wind speed on the bridge deck has exceeded the critical value that vehicles can safely withstand.

[0041] Crosswind safety critical wind speed It is a critical indicator for determining whether a vehicle will skid or roll over under crosswind conditions, and its calculation method is as follows: In the formula To assess the overall vehicle quality for the target purpose; It is the acceleration due to gravity; The wheelbase of the vehicle; The height of the vehicle's center of gravity; This is the coefficient of lateral friction between the tire and the bridge surface; air density; The lateral aerodynamic coefficient of the vehicle; This represents the vehicle's lateral frontal area. This formula comprehensively considers the vehicle's geometric parameters, mass distribution, tire-road adhesion, and aerodynamic characteristics, and can reflect the stability limits of different types of vehicles under crosswind conditions.

[0042] Environmental risk correction factor The formula used to consider the impact of differences in wind field characteristics at different bridge deck heights on driving safety is as follows: In the formula, For turbulence sensitivity coefficient, These are highly sensitive coefficients, all of which are preset constants; For the first The intensity of the incoming turbulence at the bridge deck; For the first The absolute height of the bridge deck above the water surface; The height is used as a reference. The greater the turbulence intensity, the more severe the wind speed fluctuations, the more obvious the transient wind load fluctuations on vehicles, and the worse the driving stability. The higher the bridge deck is above the water surface, the greater the wind speed and the more unstable the wind field. Therefore, it is necessary to reduce the allowable threshold using an environmental risk correction coefficient.

[0043] Due to the height of the upper bridge deck Greater than the height of the lower bridge deck According to the formula for calculating the environmental risk correction factor, the environmental risk correction factor for the upper bridge deck is... The environmental risk correction factor is greater than that of the lower bridge deck. Meanwhile, the wind speed at the reference height of the upper bridge deck It is also greater than the wind speed at the reference height of the lower bridge deck. ,therefore Substituting these two factors into the formula for calculating the allowable threshold of the crosswind reduction coefficient, the ratio of the allowable thresholds for the upper bridge deck to the lower bridge deck can be derived: This constraint indicates that the allowable threshold for the crosswind reduction coefficient of the upper bridge deck is naturally lower than that of the lower bridge deck. This is consistent with the objective fact that the wind environment of the upper bridge deck is more severe and requires stricter control in actual engineering projects.

[0044] After calculating the allowable threshold for the crosswind reduction coefficient, the crosswind reduction coefficient at each lane location is compared with the corresponding allowable threshold. If the crosswind reduction coefficient at all lane locations is less than or equal to the allowable threshold, it indicates that the parameter settings of the current windbreak structure to be evaluated can meet the driving safety requirements of the double-layer bridge deck. The current windbreak structure parameters are then output as target parameters, and driving safety assessment results are generated. If the crosswind reduction coefficient at any lane location is greater than the allowable threshold, it indicates that the current windbreak structure's wind-blocking effect on that lane area is insufficient. The parameters of the windbreak structure to be evaluated need to be adjusted, and the numerical simulation calculation for S2 needs to be performed again.

[0045] When adjusting the structural parameters of the windbreak to be evaluated, priority should be given to adjusting the windbreak's height and / or windbreak ratio. Increasing the windbreak height expands the shielding range of the bridge deck area, while increasing the windbreak ratio enhances the windbreak's blocking effect on airflow; both methods effectively reduce wind speeds at the bridge deck's driving height. If the crosswind reduction coefficients of both the upper and lower bridge decks exceed their respective allowable thresholds, windbreaks of different heights should be installed on the upper and lower bridge decks to adapt to the different wind environment characteristics and allowable threshold requirements of the two bridge decks. Since the allowable threshold for the upper bridge deck is smaller, a higher windbreak or a larger windbreak ratio is usually required to meet safety requirements.

[0046] If adjusting the height or windbreak ratio of the windbreaks does not reduce the crosswind reduction coefficient at certain lane locations beyond the permissible threshold, then the size of the horizontal deflectors or skirts needs to be further increased. The horizontal deflectors are located at the outer edge of the lower layer of the main beam; their function is to guide airflow smoothly across the lower bridge deck, reducing airflow separation and vortexing at the lower bridge deck edge. The skirts are located at the bottom edge of the lower bridge deck; their function is to suppress airflow from the bottom of the bridge deck upwards, reducing the wind speed at the bottom of the lower bridge deck. By increasing the size of these auxiliary guiding structures, the airflow pattern around the lower bridge deck can be improved, further reducing the wind speed in the bridge deck's driving area until the crosswind reduction coefficient at all lane locations meets the permissible threshold requirements.

[0047] Example 2 Please refer to Figure 4 This embodiment 2 provides a double-deck bridge deck driving wind environment and safety assessment system, including: The wind field modeling and boundary setting unit is used to obtain wind environment parameters at the target double-layer bridge deck location, establish a three-dimensional numerical simulation model including the target double-layer bridge deck and the wind barrier structure to be evaluated, and set the wind field boundary conditions of the three-dimensional numerical simulation model based on the wind environment parameters. The monitoring point layout and wind speed solution unit is used to arrange multiple monitoring points within a preset height range above each lane of the upper and lower bridge decks of the target double-layer bridge deck in the three-dimensional numerical simulation model, and to solve the three-dimensional numerical simulation model using computational fluid dynamics to obtain the wind speed data of each monitoring point. The crosswind reduction coefficient calculation unit is used to calculate the crosswind reduction coefficient of each lane position in the upper bridge deck and the lower bridge deck based on the wind speed data of each monitoring point, and to serve as an evaluation index for driving wind environment. The safety assessment and wind barrier optimization unit is used to compare the crosswind reduction coefficient with a preset allowable threshold for the crosswind reduction coefficient to assess the driving safety of the target double-layer bridge deck. If the crosswind reduction coefficient at any lane position is greater than the allowable threshold, the parameters of the wind barrier structure to be assessed are adjusted and the unit returns to the monitoring point layout and wind speed calculation unit until the crosswind reduction coefficient at all lane positions is less than or equal to the allowable threshold. The unit then outputs the target parameters of the wind barrier structure that meet the driving safety requirements and the driving safety assessment results.

[0048] Example 3 This embodiment 3 also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, can implement any step of a method for assessing the driving wind environment and safety of a double-deck bridge.

[0049] The computer-readable storage medium may include various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0050] For a description of the computer-readable storage medium provided in this application, please refer to the above method embodiments; further details will not be repeated here.

[0051] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is 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 within the scope of protection of the present invention.

Claims

1. A method for assessing the wind environment and safety of a double-deck bridge, characterized in that, include: S1. Obtain wind environment parameters at the target double-layer bridge deck location, establish a three-dimensional numerical simulation model including the target double-layer bridge deck and the wind barrier structure to be evaluated, and set the wind field boundary conditions of the three-dimensional numerical simulation model based on the wind environment parameters. S2. In the three-dimensional numerical simulation model, multiple monitoring points are arranged within a preset height range above each lane of the upper and lower bridge decks of the target double-layer bridge deck. The three-dimensional numerical simulation model is solved using computational fluid dynamics to obtain the wind speed data of each monitoring point. S3. Based on the wind speed data of each monitoring point, calculate the crosswind reduction coefficient for each lane position in the upper and lower bridge decks respectively, and use it as an evaluation index for driving wind environment; S4. Compare the crosswind reduction coefficient with the preset allowable threshold for crosswind reduction coefficient to evaluate the driving safety of the target double-layer bridge deck; if the crosswind reduction coefficient at any lane position is greater than the allowable threshold, adjust the parameters of the wind barrier structure to be evaluated and return to execute S2 until the crosswind reduction coefficient at all lane positions is less than or equal to the allowable threshold, and output the target parameters of the wind barrier structure that meet the driving safety requirements and the driving safety evaluation results; In step S3, based on the wind speed data of each monitoring point, the crosswind reduction coefficient for each lane position on the upper and lower bridge decks is calculated, including: Based on the wind speed data of each monitoring point, integral calculation is performed within the preset height range to obtain the equivalent wind speed at each lane location; Based on the reference height wind speed at the bridge site, the height of the bridge deck above the ground surface, and the wind profile index, the reference height wind speed is calculated. The ratio of the equivalent wind speed at each lane location to the reference height wind speed is used as the crosswind reduction coefficient for the corresponding lane location. The method for calculating the equivalent wind speed is as follows: The equivalent wind speed at each lane location is calculated using the following first formula: ； In the formula, For the first The equivalent wind speed of each lane; For the first The equivalent vehicle height corresponding to each lane, when the vehicle type is a large vehicle. Take the first equivalent calculation height when the vehicle type is a small vehicle. Take the second equivalent calculation height; The vertical spacing between adjacent monitoring points; For the first The number of monitoring points for each lane within the preset height range; For the first Lane number Crosswind speed at each monitoring point; The equivalent wind speed is based on an adaptive processing principle, specifically: When the wind speed non-uniformity coefficient of the upper or lower bridge deck exceeds a preset non-uniformity threshold, the equivalent wind speed is adaptively corrected according to the following second formula: ； In the formula, The corrected equivalent wind speed is used to replace the aforementioned... Participate in the calculation of the crosswind reduction factor; The wind speed sensitivity coefficient is associated with the vehicle type, when the vehicle type is a large vehicle. Take the first sensitivity value when the vehicle type is a small vehicle. Take a second sensitivity value that is less than the first sensitivity value; For the first The wind speed non-uniformity coefficient of each lane, ,in For the first The standard deviation of lateral wind speed at each monitoring point on each lane For the first The arithmetic mean of the lateral wind speed at each monitoring point on each lane.

2. The method for assessing the wind environment and safety of a double-deck bridge as described in claim 1, characterized in that, In step S1, a three-dimensional numerical simulation model is established, including the target double-layer bridge deck and the windbreak structure to be evaluated, comprising: Construct a geometric model that includes the cross-section of the double-layer truss main beam, bridge towers, and bridge deck components; The parameters of the windbreak structure to be evaluated include windbreak height, windbreak ratio, and the dimensions of the horizontal guide plate and skirt plate located on the outer side of the lower layer of the main beam.

3. The method for assessing the wind environment and safety of a double-deck bridge as described in claim 1, characterized in that, In step S1, setting the wind field boundary conditions of the three-dimensional numerical simulation model based on the wind environment parameters includes: Obtain the measured wind speed, wind profile index, and turbulence intensity at the bridge site; Based on the wind profile index and the turbulence intensity, an atmospheric boundary layer wind speed profile that conforms to the landform type of the target double-layer bridge deck is constructed, and the atmospheric boundary layer wind speed profile is used as the inlet wind speed boundary condition of the three-dimensional numerical simulation model.

4. The method for assessing the wind environment and safety of a double-deck bridge as described in claim 1, characterized in that, In step S2, multiple monitoring points are arranged within a preset height range above each lane of the upper and lower decks of the target double-layer bridge, including: The preset height range includes a first equivalent calculated height corresponding to large vehicles and a second equivalent calculated height corresponding to small vehicles; The monitoring points are arranged at preset intervals along the transverse direction of the bridge deck above the center lines of each lane, and multiple typical cross-sections are selected and arranged along the longitudinal direction of the bridge at the center of the bridge tower, the boundary of the tower column, the mid-span area, and the segmental characteristic positions far from the bridge tower.

5. The method for assessing the wind environment and safety of a double-deck bridge as described in claim 1, characterized in that, The preset crosswind reduction coefficient threshold in S4 is determined based on the principle of consistency of safe passage capability across the entire line; The upper bridge deck and the lower bridge deck correspond to different allowable thresholds for crosswind reduction coefficients, and the allowable threshold for crosswind reduction coefficient of the upper bridge deck is less than the allowable threshold for crosswind reduction coefficient of the lower bridge deck.

6. A system for assessing the wind environment and safety of a double-deck bridge, used to implement the method for assessing the wind environment and safety of a double-deck bridge as described in claim 1, characterized in that, include: The wind field modeling and boundary setting unit is used to obtain wind environment parameters at the target double-layer bridge deck location, establish a three-dimensional numerical simulation model including the target double-layer bridge deck and the wind barrier structure to be evaluated, and set the wind field boundary conditions of the three-dimensional numerical simulation model based on the wind environment parameters. The monitoring point layout and wind speed solution unit is used to arrange multiple monitoring points within a preset height range above each lane of the upper and lower bridge decks of the target double-layer bridge deck in the three-dimensional numerical simulation model, and to solve the three-dimensional numerical simulation model using computational fluid dynamics to obtain the wind speed data of each monitoring point. The crosswind reduction coefficient calculation unit is used to calculate the crosswind reduction coefficient of each lane position in the upper bridge deck and the lower bridge deck based on the wind speed data of each monitoring point, and to serve as an evaluation index for driving wind environment. The safety assessment and wind barrier optimization unit is used to compare the crosswind reduction coefficient with a preset allowable threshold for the crosswind reduction coefficient to assess the driving safety of the target double-layer bridge deck. If the crosswind reduction coefficient at any lane position is greater than the allowable threshold, the parameters of the wind barrier structure to be assessed are adjusted and the unit returns to the monitoring point layout and wind speed calculation unit until the crosswind reduction coefficient at all lane positions is less than or equal to the allowable threshold. The unit then outputs the target parameters of the wind barrier structure that meet the driving safety requirements and the driving safety assessment results.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, The computer program is executed by a processor as described in any one of claims 1-5: a method for assessing the wind environment and safety of a double-deck bridge.

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