A method for calculating flood loads on superstructures of highway and railway simply supported beam bridges

Abstract

The present invention relates to the technical field of bridge flood resistance assessment, and specifically to a method for calculating flood loads on the superstructure of a highway and railway simply supported beam bridge. The method of the present invention comprises the following steps: constructing an equivalent model of flood loads on the superstructure of a simply supported beam bridge; obtaining dimensional influencing factors of the equivalent model of flood loads on the superstructure of a simply supported beam bridge, and obtaining dimensionless influencing factors based on the dimensional influencing factors; using the dimensionless influencing factors, obtaining component force coefficients of the equivalent model of flood loads on the superstructure of a simply supported beam bridge, substituting the component force coefficients into the equivalent model of flood loads on the superstructure of a simply supported beam bridge, and obtaining flood loads on the superstructure of a highway and railway simply supported beam bridge. The present invention equates the combined effects of shear stress and pressure around the beam body to three concentrated loads acting at the centroid of the beam cross section, thereby solving the problem of rapid calculation of flood loads on the superstructure of highway and railway simply supported beam bridges with a relatively safe side.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge flood resistance assessment, and in particular to a method for calculating flood loads on the upper structure of a highway or railway simply supported beam bridge. Background Art

[0002] In the event of extreme floods, the superstructures of highway and railway bridges may be partially or completely submerged. Floods will impose large flood loads on bridges, causing damage to the main beams. Simply supported beam bridges have low design standards and are easily submerged and destroyed by water when floods occur. Therefore, determining the magnitude of the flood load on the superstructure of the bridge is crucial for evaluating the flood resistance of the superstructure. When the superstructure of the bridge is submerged by floods, a complex flow field will be formed around it because the beam body hinders the movement of water flow. The beam body will be subjected to unevenly distributed viscous shear stress and pressure in the flow field. The current specification system does not provide a specific calculation formula for the flood load on the superstructure of the bridge. The flood load calculation methods proposed by relevant studies at home and abroad do not take into account comprehensive factors. Therefore, how to accurately and quickly calculate the flood load on the superstructure of highway and railway simply supported beam bridges is an urgent problem that needs to be solved. Summary of the invention

[0003] In view of the shortcomings of the existing methods and the needs of practical applications, in order to solve the problem of fast calculation of flood loads on the superstructure of highway and railway simply supported beam bridges, the present invention provides a method for calculating flood loads on the superstructure of highway and railway simply supported beam bridges, comprising the following steps:

[0004] Construct an equivalent model of flood load for the superstructure of a simply supported beam bridge; obtain the dimensional influencing factors of the equivalent model of flood load for the superstructure of the simply supported beam bridge, and obtain the dimensionless influencing factors according to the dimensional influencing factors; use the dimensionless influencing factors to obtain the component force coefficient of the equivalent model of flood load for the superstructure of the simply supported beam bridge, substitute the component force coefficient into the equivalent model of flood load for the superstructure of the simply supported beam bridge, and obtain the flood load for the superstructure of highway and railway simply supported beam bridges. The present invention constructs an equivalent model of flood load for the superstructure of a simply supported beam bridge according to the action of flood load, sorts out relevant influencing factors to adjust the component force coefficient of the equivalent model of flood load for the superstructure of the simply supported beam bridge, and effectively solves the problem of rapid calculation of flood load for the superstructure of highway and railway simply supported beam bridges with relatively safe side.

[0005] Optionally, the component force coefficients include thrust coefficient, lift coefficient and moment coefficient;

[0006] The flood load equivalent model of the simply supported beam bridge superstructure satisfies the following formula:

[0007]

[0008] Among them, F DThe horizontal thrust represented by the concentrated load in the direction of the water flow, C D represents the thrust coefficient, ρ represents the flood density, V represents the incoming flow velocity, L 0 represents the length of the simply supported beam, H represents the water blocking height, F L Represents the vertical upward force perpendicular to the direction of water flow, C L represents the lift coefficient, W represents the width of the simply supported beam, M 0 is the overturning moment at the centroid of the cross section, C M The equivalent model of flood load on the superstructure of a simply supported beam bridge constructed according to the bridge parameters of the present invention fully represents the flood load, which is beneficial to improving the calculation accuracy of flood load on the superstructure of highway and railway simply supported beam bridges.

[0009] Optionally, the flood load equivalent model of the superstructure of the simply supported beam bridge includes a flood load equivalent model of the superstructure of the highway simply supported beam bridge and a flood load equivalent model of the superstructure of the railway simply supported beam bridge. The present invention divides the model into a highway model and a railway model according to actual conditions, which is conducive to accurately solving the flood load calculation problem of the superstructure of highway and railway simply supported beam bridges.

[0010] Optionally, the dimensionally influential factors include hydraulic factors and structural factors;

[0011] The hydraulic factors include the flow velocity, the water depth, the water density, the gravitational acceleration and the kinematic viscosity coefficient of the water;

[0012] The structural factors include cross-sectional form, simply supported beam height, simply supported beam width and the distance between the simply supported beam bottom and the riverbed. The dimensioned influencing factors of the present invention are further conducive to accurately obtaining the component force coefficients of the equivalent model of the flood load of the superstructure of the simply supported beam bridge.

[0013] Optionally, obtaining the dimensionless influencing factor according to the dimensional influencing factor comprises the following steps:

[0014] Basic variables are set, and the dimensioned influencing factors are analyzed using the basic variables to obtain the dimensionless influencing factors. Dimensionless processing of the dimensioned influencing factors is beneficial to improving calculation efficiency and eliminating the dimensional influence between the indicators.

[0015] Optionally, the dimensionless influencing factor satisfies the following formula:

[0016]

[0017] Among them, h * Indicates the degree of flooding, h u Indicates the depth of incoming water, h brepresents the distance between the bottom of the simply supported beam and the riverbed, S represents the height of the simply supported beam, Pr represents the approach ratio, Fr represents the Froude number, g represents the acceleration of gravity, Ar represents the aspect ratio, and W represents the width of the simply supported beam. The present invention further improves the objectivity and accuracy of the present invention by formulating dimensionless influencing factors.

[0018] Optionally, the thrust coefficient of the equivalent model of flood load of the superstructure of a highway simply supported beam bridge satisfies the following formula:

[0019] C D1 =K s1 K f1 K p1 K a1 ·F 1 (h * )

[0020]

[0021] K f1 =-0.464Fr+1.197

[0022] K p1 =0.742+2.404e -0.544Pr

[0023]

[0024] Among them, C D1 The thrust coefficient of the equivalent model of flood load on the superstructure of a highway simply supported beam bridge, K s1 The cross-sectional shape factor, K, represents the thrust coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge. f1 The Froude number influence coefficient of the thrust coefficient of the equivalent model of flood load on the superstructure of a highway simply supported beam bridge, K p1 The influence coefficient of the approach ratio of the thrust coefficient of the equivalent model of the flood load of the superstructure of the highway simply supported beam bridge, K a1 The aspect ratio influence coefficient of the equivalent model of the flood load of the superstructure of a highway simply supported beam bridge, F 1 (·) represents the inundation function of the thrust coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, h * represents the degree of submergence, Pr represents the approach ratio, Fr represents the Froude number, and Ar represents the aspect ratio;

[0025] The thrust coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge satisfies the following formula:

[0026] C D2 =K s2 K f2 K p2 K a2 ·F2 (h * )

[0027]

[0028] K f2 =-0.606Fr+1.258,0 <Fr<1

[0029] K p2 =0.873+3.188e -0.786Pr

[0030]

[0031] Among them, C D2 The thrust coefficient of the equivalent model of flood load for the superstructure of railway simply supported beam bridge, K s2 The cross-sectional shape factor, K, represents the thrust coefficient of the equivalent model of flood loads for the superstructure of a railway simply supported beam bridge. f2 The Froude number influence coefficient of the thrust coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K p2 The influence coefficient of the approach ratio of the thrust coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K a2 The aspect ratio influence coefficient of the thrust coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge, F 2 (·) represents the inundation function of the thrust coefficient of the equivalent model of flood load for the superstructure of railway simply supported beam bridge.

[0032] Optionally, the lift coefficient of the equivalent model of flood load of the superstructure of a highway simply supported beam bridge satisfies the following formula:

[0033] C L3 =K s3 K f3 K p3 K a3 ·F 3 (h * )

[0034]

[0035]

[0036] Among them, C D3 The lift coefficient of the equivalent model of flood load on the superstructure of a highway simply supported beam bridge, K s3 The cross-sectional shape factor, K, represents the lift coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge. f3 The influence coefficient of the incoming Froude number, K, represents the lift coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge. p3The influence coefficient of the lift coefficient of the equivalent model of flood load on the superstructure of a highway simply supported beam bridge, K a3 The aspect ratio influence coefficient of the lift coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, F 3 (·) represents the inundation function of the lift coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, h * represents the degree of submergence, Pr represents the approach ratio, Fr represents the Froude number, and Ar represents the aspect ratio;

[0037] The lift coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge satisfies the following formula:

[0038] C L 4=K s4 K f4 K p4 K a 4.F 4 (h * )

[0039]

[0040] K f4 =-2.407Fr+2.023,0≤Fr<1

[0041]

[0042] Among them, C D4 The lift coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge, K s4 The cross-sectional shape factor, K, represents the lift coefficient of the equivalent model of the flood load of the superstructure of a railway simply supported beam bridge. f4 The Froude number influence coefficient of the lift coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K p4 The influence coefficient of the lift coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K a4 The aspect ratio influence coefficient of the lift coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, F 4 (·) represents the inundation function of the lift coefficient of the equivalent model of flood load for the superstructure of railway simply supported beam bridge, ST represents a single-track T-beam, and RT represents a double-track T-beam.

[0043] Optionally, the moment coefficient of the equivalent model of flood load of the superstructure of a highway simply supported beam bridge satisfies the following formula:

[0044] C M5 =K s5 K f5 K p5 K a5 ·F5 (h * )

[0045]

[0046] K f5 =-1.564Fr+1.513

[0047] K p5 =1+76.226e -3.694Pr

[0048]

[0049] Among them, C M5 The moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, K s5 The cross-sectional shape factor, K, represents the moment coefficient of the equivalent model of flood loads for the superstructure of a highway simply supported beam bridge. f5 The Froude number influence coefficient of the moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, K p5 The influence coefficient of the moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, K a5 The aspect ratio influence coefficient of the moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, F 5 (·) represents the inundation function of the moment coefficient of the equivalent model of flood load for the superstructure of highway simply supported beam bridge, h * represents the degree of submergence, Pr represents the approach ratio, Fr represents the Froude number, and Ar represents the aspect ratio;

[0050] The moment coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge satisfies the following formula:

[0051] C M6 =K s6 K f6 K p6 K a 6.F 6 (h * )

[0052]

[0053] K f6 =-0.694Fr+1.295,0<Fr<1

[0054]

[0055]

[0056] Among them, C M6The moment coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge, K s6 The cross-sectional shape factor, K, represents the moment coefficient of the equivalent model of flood loads for the superstructure of a railway simply supported beam bridge. f6 The Froude number influence coefficient of the moment coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K p6 The influence coefficient of the approach ratio of the moment coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K a6 The aspect ratio influence coefficient of the moment coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge, F 6 (·) represents the inundation function of the moment coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge. The present invention further improves the calculation efficiency of the present invention by formulating the component coefficients of the equivalent model of the flood load of the superstructure of the simply supported beam bridge of the highway and the railway. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A schematic flow chart of a method for calculating flood loads on superstructures of highway and railway simply supported beam bridges according to an embodiment of the present invention;

[0058] Figure 2 It is a schematic diagram of dimensional influencing factors of the flood load equivalent model of the superstructure of a simply supported beam bridge according to an embodiment of the present invention. DETAILED DESCRIPTION

[0059] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details do not need to be adopted to implement the present invention. In other examples, in order to avoid confusing the present invention, known circuits, software or methods are not specifically described.

[0060] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "in one embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or subcombination. In addition, it should be understood by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale.

[0061] See also Figure 1, in order to solve the problem of fast calculation of flood loads on the superstructure of highway and railway simply supported beam bridges, such as Figure 1 As shown, the present invention provides a method for calculating flood loads on the superstructure of highway and railway simply supported beam bridges, comprising the following steps:

[0062] S1. Construct an equivalent model of flood load for the superstructure of a simply supported beam bridge.

[0063] Specifically, the flood load equivalent model of the superstructure of the simply supported beam bridge constructed in step S1 includes a flood load equivalent model of the superstructure of the highway simply supported beam bridge and a flood load equivalent model of the superstructure of the railway simply supported beam bridge.

[0064] Furthermore, the flood load equivalent model of the simply supported beam bridge superstructure satisfies the following formula:

[0065]

[0066] Among them, F D The horizontal thrust represented by the concentrated load in the direction of the water flow, C D represents the thrust coefficient, ρ represents the flood density, and the unit of measurement is kg / m 3 , V represents the flow velocity, the unit of measurement is m / s, L 0 It indicates the length of the simply supported beam, measured in m, H indicates the water blocking height, when the flooding degree is h * ≥1, take H=S, when the flooding degree h * When <1, take H=Sh * , measurement units: m, h * =(h u -h b ) / S, S represents the height of the simply supported beam, h u Indicates the depth of incoming water, h b Indicates the distance between the bottom of the simply supported beam and the riverbed, measured in m, F L Represents the vertical upward force perpendicular to the direction of water flow, C L Indicates lift coefficient, W indicates simply supported beam width, unit of measurement, M 0 is the overturning moment at the centroid of the cross section, C M Represents the torque coefficient.

[0067] Furthermore, the thrust coefficient, lift coefficient and moment coefficient include the thrust coefficient, lift coefficient and moment coefficient of the equivalent model of the flood load of the superstructure of a highway simply supported beam bridge and the thrust coefficient, lift coefficient and moment coefficient of the equivalent model of the flood load of the superstructure of a railway simply supported beam bridge.

[0068] S2. Obtaining the dimensional influencing factors of the flood load equivalent model of the superstructure of the simply supported beam bridge, and obtaining the dimensionless influencing factors according to the dimensional influencing factors.

[0069] See also Figure 2 In the embodiment, Figure 2 As shown, the dimensioned influencing factors include hydraulic factors and structural factors; the hydraulic factors include incoming flow velocity, incoming water depth, water density, gravitational acceleration and water kinematic viscosity coefficient; the structural factors include cross-sectional form, simply supported beam height, simply supported beam width and the distance between the simply supported beam bottom and the riverbed.

[0070] Furthermore, obtaining dimensionless influencing factors according to the dimensional influencing factors includes the following steps: setting basic variables, performing dimensional analysis on the dimensional influencing factors using the basic variables, and obtaining the dimensionless influencing factors.

[0071] Specifically, the force component coefficient is expressed as C = F (V, h u ,h b ,ρ,g,v,S,W,K s ), set V, S, and ρ as basic variables, and combine the remaining independent variables into 6 dimensionless numbers as follows: in, and Can be further combined into It is an index for evaluating the flooding degree of the bridge superstructure. * express; is the aspect ratio, denoted by Ar; and Can be combined into That is, the incoming flow Froude number, expressed as Fr; is the flow Reynolds number; It indicates the degree of obstruction of the beam to the incoming flow, which is defined as the blocking ratio Br; It indicates the relative height of the clearance under the bridge, which is defined as the approach ratio Pr. The flow pattern of water in natural rivers is turbulent, so the influence of Reynolds number Re can be ignored. The blockage ratio Br can be calculated by the approach ratio Pr and the flooding degree h * Expressed as Br = 1 / (h * +Pr), no longer considered separately, in summary, the dimensionless expression of the component force coefficient is: C = F (h * ,Pr,Fr,Ar,K s ), that is, the dimensionless influencing factor of the flood load on the superstructure of the beam bridge under flooding conditions is the flooding degree h * , Froude number Fr, proximity ratio Pr, aspect ratio Ar and cross-sectional shape factor K s .

[0072] Furthermore, the dimensionless influencing factor satisfies the following formula:

[0073]

[0074] Among them, h * Indicates the degree of flooding, h u Indicates the depth of incoming water, h b It represents the distance between the bottom of the simply supported beam and the riverbed, S represents the height of the simply supported beam, Pr represents the approach ratio, Fr represents the Froude number, g represents the gravitational acceleration, Ar represents the aspect ratio, and W represents the width of the simply supported beam.

[0075] S3. Utilize the dimensionless influencing factors to obtain the component force coefficients of the equivalent model of flood load of the superstructure of the simply supported beam bridge, substitute the component force coefficients into the equivalent model of flood load of the superstructure of the simply supported beam bridge, and obtain the flood load of the superstructure of highway and railway simply supported beam bridges.

[0076] By using the dimensionless influencing factors, the component force coefficients of the flood load equivalent model of the superstructure of the simply supported beam bridge, including the thrust coefficients of the flood load equivalent model of the superstructure of the highway simply supported beam bridge, are obtained, which satisfy the following formula:

[0077] C D1 =K s1 K f1 K p1 K a1 ·F 1 (h * )

[0078]

[0079] K f1 =-0.464Fr+1.197

[0080] K p1 =0.742+2.404e -0.544Pr

[0081]

[0082] Among them, C D1 The thrust coefficient of the equivalent model of flood load on the superstructure of a highway simply supported beam bridge, K s1 The cross-sectional shape factor, K, represents the thrust coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge. f1 The Froude number influence coefficient of the thrust coefficient of the equivalent model of flood load on the superstructure of a highway simply supported beam bridge, K p1 The influence coefficient of the approach ratio of the thrust coefficient of the equivalent model of the flood load of the superstructure of the highway simply supported beam bridge, K a1 The aspect ratio influence coefficient of the equivalent model of the flood load of the superstructure of a highway simply supported beam bridge, F 1 (·) represents the inundation function of the thrust coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, h *represents the degree of submergence, Pr represents the approach ratio, Fr represents the Froude number, and Ar represents the aspect ratio;

[0083] The thrust coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge satisfies the following formula:

[0084] C D2 =K s2 K f2 K p2 K a2 ·F 2 (h * )

[0085]

[0086] K f2 =-0.606Fr+1.258,0<Fr<1

[0087] K p2 =0.873+3.188e -0.786Pr

[0088]

[0089] Among them, C D2 The thrust coefficient of the equivalent model of flood load for the superstructure of railway simply supported beam bridge, K s2 The cross-sectional shape factor, K, represents the thrust coefficient of the equivalent model of flood loads for the superstructure of a railway simply supported beam bridge. f2 The Froude number influence coefficient of the thrust coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K p2 The influence coefficient of the approach ratio of the thrust coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K a2 The aspect ratio influence coefficient of the thrust coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge, F 2 (·) represents the inundation function of the thrust coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge;

[0090] The lift coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge satisfies the following formula:

[0091] C L3 =K s3 K f3 K p3 K a3 ·F 3 (h * )

[0092]

[0093] K p3=0.605+2.69e -0.468Pr

[0094]

[0095] Among them, C D3 The lift coefficient of the equivalent model of flood load on the superstructure of a highway simply supported beam bridge, K s3 The cross-sectional shape factor, K, represents the lift coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge. f3 The influence coefficient of the incoming Froude number, K, represents the lift coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge. p3 The influence coefficient of the lift coefficient of the equivalent model of flood load on the superstructure of a highway simply supported beam bridge, K a3 The aspect ratio influence coefficient of the lift coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, F 3 (·) represents the inundation function of the lift coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, h * represents the degree of submergence, Pr represents the approach ratio, Fr represents the Froude number, and Ar represents the aspect ratio;

[0096] The lift coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge satisfies the following formula:

[0097] C L 4=K s4 K f4 K p4 K a 4.F 4 (h * )

[0098]

[0099] K f4 =-2.407Fr+2.023,0≤Fr<1

[0100]

[0101] Among them, C D4 The lift coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge, K s4 The cross-sectional shape factor, K, represents the lift coefficient of the equivalent model of the flood load of the superstructure of a railway simply supported beam bridge. f4 The Froude number influence coefficient of the lift coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K p4 The influence coefficient of the lift coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K a4The aspect ratio influence coefficient of the lift coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, F 4 (·) represents the inundation function of the lift coefficient of the equivalent model of flood load for the superstructure of railway simply supported beam bridge, ST represents a single-track T beam, and RT represents a double-track T beam;

[0102] The moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge satisfies the following formula:

[0103] C M5 =K s5 K f5 K p5 K a5 ·F 5 (h * )

[0104]

[0105] K f5 =-1.564Fr+1.513

[0106] K p5 =1+76.226e -3.694Pr

[0107]

[0108] Among them, C M5 The moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, K s5 The cross-sectional shape factor, K, represents the moment coefficient of the equivalent model of flood loads for the superstructure of a highway simply supported beam bridge. f5 The Froude number influence coefficient of the moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, K p5 The influence coefficient of the moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, K a5 The aspect ratio influence coefficient of the moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, F 5 (·) represents the inundation function of the moment coefficient of the equivalent model of flood load for the superstructure of highway simply supported beam bridge, h * represents the degree of submergence, Pr represents the approach ratio, Fr represents the Froude number, and Ar represents the aspect ratio;

[0109] The moment coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge satisfies the following formula:

[0110] C M6 =K s6 K f6 K p6 K a 6.F6 (h * )

[0111]

[0112] K f6 =-0.694Fr+1.295,0<Fr<1

[0113]

[0114] Among them, C M6 The moment coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge, K s6 The cross-sectional shape factor, K, represents the moment coefficient of the equivalent model of flood loads for the superstructure of a railway simply supported beam bridge. f6 The Froude number influence coefficient of the moment coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K p6 The influence coefficient of the approach ratio of the moment coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K a6 The aspect ratio influence coefficient of the moment coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge, F 6 (·) represents the inundation function of the moment coefficient of the equivalent model of flood load for the superstructure of railway simply supported beam bridge.

[0115] In a specific embodiment, according to the floods that have occurred in actual highway projects and the parameters of bridge structures, the parameters used for calculation are that the flow velocity V is 2.10 m / s and the density ρ is 1000 kg / m 3 , the beam length L is 1m, the beam width W is 8.51m, the beam height S is 3m, and the incoming water depth h u Take 35.7m, the distance h between the bottom of the beam and the riverbed b Take 21.7m, the water blocking height is H = S, take 3m. The main beam section of the highway simply supported bridge is T beam, take K s =1, and the obtained parameters are calculated to obtain dimensionless influencing factors, where the aspect ratio Ar is 2.84, the approach ratio Pr is 7.23, and the submergence h * is 4.67, and the Froude number Fr is 0.10. Furthermore, the horizontal thrust coefficient C of the highway simply supported bridge is obtained based on the dimensionless influencing factors. D is 2.047, the vertical lift coefficient C L is 0.586, and the overturning moment coefficient C M =0.235, and then substitute it into the equivalent model of flood load on the superstructure of highway simply supported beam bridge to obtain the horizontal thrust F on the superstructure of simply supported beam bridge at this time. D is 13527.7N, vertical lift F LIt is 11240.0N, and the overturning moment M is 37845.7N·m.

[0116] In summary, the present invention effectively solves the problem of fast calculation of flood load partial safety of superstructure of highway and railway simply supported beam bridges. Therefore, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for calculating flood loads on the superstructure of highway and railway simply supported beam bridges, characterized in that: The method for calculating flood loads on the superstructure of highway and railway simply supported beam bridges comprises the following steps: Construct an equivalent model of flood loads on the superstructure of a simply supported beam bridge; Obtaining dimensional influencing factors of the flood load equivalent model of the superstructure of the simply supported beam bridge, and obtaining dimensionless influencing factors according to the dimensional influencing factors; Using the dimensionless influencing factors, the force component coefficients of the flood load equivalent model of the superstructure of the simply supported beam bridge are obtained, and the force component coefficients are substituted into the flood load equivalent model of the superstructure of the simply supported beam bridge to obtain the flood load of the superstructure of the highway and railway simply supported beam bridges; The component force coefficients include thrust coefficient, lift coefficient and moment coefficient; The flood load equivalent model of the simply supported beam bridge superstructure satisfies the following formula: Among them, F D The horizontal thrust represented by the concentrated load in the direction of the water flow, C D represents the thrust coefficient, ρ represents the flood density, V represents the incoming flow velocity, L0 represents the simply supported beam length, H represents the water blocking height, F L represents the vertical upward force perpendicular to the direction of water flow, C L represents the lift coefficient, W represents the width of the simply supported beam, M0 represents the overturning moment at the centroid of the cross section, C M represents the moment coefficient; The flood load equivalent model of the superstructure of the simply supported beam bridge includes the flood load equivalent model of the superstructure of the highway simply supported beam bridge and the flood load equivalent model of the superstructure of the railway simply supported beam bridge; The thrust coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge satisfies the following formula: C D1 =K s1 K f1 K p1 K a1 ·F1(h * ) K f1 =-0.464Fr+1.197 K p1 =0.742+2.404e -0.544Pr Among them, C D1 The thrust coefficient of the equivalent model of flood load on the superstructure of a highway simply supported beam bridge, K s1 The cross-sectional shape factor, K, represents the thrust coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge. f1 The Froude number influence coefficient of the thrust coefficient of the equivalent model of flood load on the superstructure of a highway simply supported beam bridge, K p1 The influence coefficient of the approach ratio of the thrust coefficient of the equivalent model of the flood load of the superstructure of the highway simply supported beam bridge, K a1 represents the aspect ratio influence coefficient of the thrust coefficient of the equivalent model of the flood load of the superstructure of the highway simply supported beam bridge, F1(·) represents the inundation function of the thrust coefficient of the equivalent model of the flood load of the superstructure of the highway simply supported beam bridge, h * represents the degree of submergence, Pr represents the approach ratio, Fr represents the Froude number, and Ar represents the aspect ratio; The thrust coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge satisfies the following formula: C D2 =K s2 K f2 F p2 K a2 ·F2(h * ) K f2 =-0.606Fr+1.258,0<Fr<1 K p2 =0.873+3.188e -0.786Pr Among them, C D2 The thrust coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge, K s2 The cross-sectional shape factor, K, represents the thrust coefficient of the equivalent model of flood loads for the superstructure of a railway simply supported beam bridge. f2 The Froude number influence coefficient of the thrust coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K p2 The influence coefficient of the approach ratio of the thrust coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K a2 represents the aspect ratio influence coefficient of the thrust coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, and F2(·) represents the submergence function of the thrust coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge; The lift coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge satisfies the following formula: C L3 =K s3 K f3 K p3 K a3 ·F3(h * ) K p3 =0.605+2.69e -0.468Pr Among them, C L3 The lift coefficient of the equivalent model of flood load on the superstructure of a highway simply supported beam bridge, K s3 The cross-sectional shape factor, K, represents the lift coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge. f3 The influence coefficient of the incoming Froude number, K, represents the lift coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge. p3 The influence coefficient of the lift coefficient of the equivalent model of flood load on the superstructure of a highway simply supported beam bridge, K a3 represents the aspect ratio influence coefficient of the lift coefficient of the equivalent model of the flood load of the superstructure of the highway simply supported beam bridge, F3(·) represents the inundation function of the lift coefficient of the equivalent model of the flood load of the superstructure of the highway simply supported beam bridge, h * represents the degree of submergence, Pr represents the approach ratio, Fr represents the Froude number, and Ar represents the aspect ratio; The lift coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge satisfies the following formula: C L4 =K s4 K f4 K p4 K a4 ·F4(h * ) K f4 =-2.407Fr+2.023,0≤Fr<1 Among them, C L4 The lift coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge, K s4 The cross-sectional shape factor, K, represents the lift coefficient of the equivalent model of the flood load of the superstructure of a railway simply supported beam bridge. f4 The Froude number influence coefficient of the lift coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K p4 The influence coefficient of the lift coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K a4 represents the influence coefficient of the aspect ratio of the lift coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, F4(·) represents the submergence function of the lift coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, ST represents a single-line T beam, and RT represents a double-line T beam; The moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge satisfies the following formula: C M5 =K s5 K f5 K p5 K a5 ·F5(h * ) K f5 =-1.564Fr+1.513 K p5 =1+76.226e -3.694Pr Among them, C M5 The moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, K s5 The cross-sectional shape factor, K, represents the moment coefficient of the equivalent model of flood loads for the superstructure of a highway simply supported beam bridge. f5 The Froude number influence coefficient of the moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, K p5 The influence coefficient of the moment coefficient of the equivalent model of flood load for the superstructure of a highway simply supported beam bridge, K a5 represents the aspect ratio influence coefficient of the moment coefficient of the equivalent model of flood load for the superstructure of highway simply supported beam bridge, F5(·) represents the inundation function of the moment coefficient of the equivalent model of flood load for the superstructure of highway simply supported beam bridge, h * represents the degree of submergence, Pr represents the approach ratio, Fr represents the Froude number, and Ar represents the aspect ratio; The moment coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge satisfies the following formula: C M6 =K s6 K f6 K p6 K a6 ·F6(h * ) K f6 =-0.694Fr+1.295,0<Fr<1 Among them, C M6 The moment coefficient of the equivalent model of flood load for the superstructure of a railway simply supported beam bridge, K s6 The cross-sectional shape factor, K, represents the moment coefficient of the equivalent model of flood loads for the superstructure of a railway simply supported beam bridge. f6 The Froude number influence coefficient of the moment coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K p6 The influence coefficient of the approach ratio of the moment coefficient of the equivalent model of the flood load of the superstructure of the railway simply supported beam bridge, K a6 represents the aspect ratio influence coefficient of the moment coefficient of the equivalent model of flood load for the superstructure of railway simply supported beam bridge, and F6(·) represents the submergence function of the moment coefficient of the equivalent model of flood load for the superstructure of railway simply supported beam bridge.

2. The method for calculating flood loads on superstructures of highway and railway simply supported beam bridges according to claim 1 is characterized in that: The dimensionally influential factors include hydraulic factors and structural factors; The hydraulic factors include the flow velocity, the water depth, the water density, the gravitational acceleration and the kinematic viscosity coefficient of the water; The structural factors include cross-sectional form, simply supported beam height, simply supported beam width and the distance between the bottom of the simply supported beam and the riverbed.

3. The method for calculating flood loads on superstructures of highway and railway simply supported beam bridges according to claim 1 is characterized in that: The step of obtaining the dimensionless influencing factors according to the dimensioned influencing factors comprises the following steps: Set basic variables; The dimensionless influencing factors are obtained by performing a dimension analysis on the dimensioned influencing factors using the basic variables.

4. The method for calculating flood loads on superstructures of highway and railway simply supported beam bridges according to claim 3 is characterized in that: The dimensionless influencing factors satisfy the following formula: Among them, h * Indicates the degree of flooding, h u Indicates the depth of incoming water, h b It represents the distance between the bottom of the simply supported beam and the riverbed, S represents the height of the simply supported beam, Pr represents the approach ratio, Fr represents the Froude number, g represents the gravitational acceleration, Ar represents the aspect ratio, and W represents the width of the simply supported beam.

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