Method for calculating unbalanced moment of rotation bridge with arch and application

Abstract

The invention relates to the technical field of swivel control methods, in particular to an unbalanced moment calculation method for a swivel bridge with an arch and application of the unbalanced moment calculation method. Based on bridge design parameters, a three-dimensional finite element model comprising an arch rib, a bridge deck system and a temporary supporting structure is established, and a bridge structure is dispersed into a plurality of mass units; and recording the mass of each unit and the three-dimensional coordinate of each unit in the swivel coordinate system, establishing a bridge overall barycentric coordinate calculation formula, and substituting the recorded mass of each unit and the three-dimensional coordinate of each unit in the swivel coordinate system into the bridge overall barycentric coordinate calculation formula for calculation to obtain the overall barycentric coordinate of the bridge. The method comprises the following steps: calculating a wind load moment, a friction resistance moment and a superposed gravity center offset moment, calculating the superposed gravity center offset moment, the wind load moment and the friction resistance moment, and calculating to obtain a total unbalanced moment. The problems of large model simplification error and dynamic factor deficiency in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of swivel control methods, and particularly relates to a calculation method and application of unbalanced moment of a swivel bridge with an arch. Background Art

[0002] In the field of bridge engineering, swivel bridges have been widely used in various bridge constructions due to their unique structural advantages and construction convenience. However, the calculation of the center of gravity of such bridges has always been a key problem in engineering design and construction. Traditional calculation methods simplify the arch bridge into a two-dimensional plane model to calculate the center of gravity, completely ignoring the complex spatial curve distribution characteristics of the arch rib, and unable to truly reflect the geometric shape and force conditions of the arch rib in space, resulting in a large deviation between the calculation result and the actual center of gravity position.

[0003] At the same time, dynamic factors such as wind load and rotational friction resistance have an undeniable impact on the center of gravity calculation of the swivel bridge with an arch, but traditional methods fail to systematically incorporate these factors into the calculation model. The action of wind load will cause dynamic deformation and vibration of the bridge structure, thereby changing the center of gravity position of the bridge, and the rotational friction resistance will increase the resistance during the rotation of the bridge, having an important impact on the equilibrium state during the swivel process. However, due to the limitations of its model, traditional methods cannot accurately consider these dynamic interference factors, making the calculation results lack accuracy and reliability. Therefore, a calculation method and application of unbalanced moment of a swivel bridge with an arch are proposed. Summary of the Invention

[0004] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides a calculation method and application of unbalanced moment of a swivel bridge with an arch.

[0005] To solve the above technical problems, the present invention provides the following technical solutions: A calculation method of unbalanced moment of a swivel bridge with an arch, comprising the following steps:

[0006] Step S1, based on the bridge design parameters, establish a three-dimensional finite element model including the arch rib, the bridge deck system and the temporary support structure;

[0007] Step S2, discretize the bridge structure into a number of mass units, and record the mass m of each unit i and its three-dimensional coordinates (x i , y i , z i ) in the swivel coordinate system;

[0008] Step S3, establish a calculation formula for the overall center of gravity coordinates of the bridge, and substitute the recorded mass m of each unit i and its three-dimensional coordinates (x i , y i , z i) Substitute into the calculation formula of the overall centroid coordinates of the beam to obtain the overall centroid coordinates of the bridge (X c , Y c , Z c );

[0009] Step S4, calculate the wind load moment M w , the frictional resistance moment M f and the superimposed centroid offset moment M g ;

[0010] Step S5, superimpose the centroid offset moment M g , the wind load moment M w and the frictional resistance moment M f , calculate the total unbalanced moment M total = M g + M w + M f .

[0011] Preferably, in step S1, when establishing the three-dimensional finite element model, a non-uniform mesh division strategy is adopted, and the grid is encrypted at the arch feet and hinge points, and the grid density is 3-5 times that of other areas. The three-dimensional finite element model is established using Midas Civil or ANSYS software, and the model accuracy meets the requirement that the element size is not greater than 1 / 10 of the minimum size of the arch rib section.

[0012] Preferably, in step S3, the calculation formula for the overall centroid coordinates of the bridge is and

[0013] Preferably, the calculation formula for the wind load moment M w in step S4 is:

[0014] M w = 0.5·ρ·v 2 ·C d ·A·R

[0015] Where ρ is the air density, C d is the wind resistance coefficient, A is the windward area of the entire bridge, R is the rotation radius of the entire bridge, and v is the real-time wind speed.

[0016] Preferably, the value of the wind resistance coefficient C d is determined by CFD simulation, and the real-time wind speed v is collected by a wind speed sensor at the bridge construction site.

[0017] Preferably, the calculation formula for the frictional resistance moment M f in step S4 is:

[0018] M f = μ·R·N

[0019] The N is the normal pressure, where θ is the rotation angle of the rotating body, μ is the static friction coefficient, and R is the rotation radius of the overall bridge.

[0020] Preferably, the calculation formula of the normal pressure N is M g = ∑m i ·g·cosθ, where θ is the rotation angle of the rotating body.

[0021] Preferably, in the step S4, the calculation formula of the center of gravity offset moment M g is:

[0022] M g = ∑mi·g·Δdi

[0023] The Δdi is the horizontal distance deviation of the unit from the rotation axis, and g is the acceleration due to gravity.

[0024] Preferably, in S5, M total Equivalent counterweight blocks are arranged on the opposite side of the bridge body, and the mass m of the counterweight blocks satisfies where d is the horizontal distance of the counterweight block from the rotation axis.

[0025] The calculation method of the unbalanced moment of the arch-rotating bridge is applied in the rotation of the arch bridge.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. Based on three-dimensional refined modeling and combined with the unbalanced moment calculation method of multi-factor coupling analysis, the present invention solves the problems of large model simplification error and lack of dynamic factors in the prior art, provides a scientific basis for the counterweight optimization of the rotating bridge, and makes the rotation process more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of the calculation flow of the present invention;

[0029] Figure 2 is a schematic diagram of the three-dimensional finite element model established by the present invention, including the arch rib, the bridge deck system and the temporary support structure. DETAILED DESCRIPTION OF THE INVENTION

[0030] The following further elaborates the present invention in combination with the drawings and embodiments, but the following embodiments are only the preferred embodiments of the present invention, not all.

[0031] Embodiment:

[0032] As Figure 1 - Figure 2 shown, the present invention provides a calculation method for the unbalanced moment of an arch-rotating bridge, including the following steps:

[0033] Based on the bridge design parameters, a three-dimensional finite element model including the arch rib, the bridge deck system and the temporary support structure is established;

[0034] When establishing the three-dimensional finite element model, a non-uniform grid division strategy is adopted, and the grid is encrypted at the arch feet and hinge points, and the grid density is 3-5 times that of other areas. The three-dimensional finite element model is established using Midas Civil or ANSYS software, and the model accuracy meets the requirement that the element size is not greater than 1 / 10 of the minimum size of the arch rib cross-section;

[0035] The bridge structure is discretized into several mass elements, and the mass m of each element is recorded i and its three-dimensional coordinates (x i , y i , z i ) in the rotation coordinate system;

[0036] A calculation formula for the overall center of gravity coordinates of the bridge is established, and the mass m of each recorded element i and its three-dimensional coordinates (x i , y i , z i ) in the rotation coordinate system are substituted into the calculation formula for the overall center of gravity coordinates of the beam to calculate, and the overall center of gravity coordinates (X c , Y c , Z c ) of the bridge are obtained. The calculation formula for the overall center of gravity coordinates of the bridge is

[0037] Calculate the wind load moment M w , the frictional resistance moment M f and the superimposed center of gravity offset moment M g ;

[0038] The calculation formula for the wind load moment M w is:

[0039] M w = 0.5·ρ·v 2 ·C d ·A·R

[0040] where ρ is the air density, C d is the wind resistance coefficient, A is the windward area of the whole bridge, R is the rotation radius of the whole bridge, v is the real-time wind speed, and the value of the wind resistance coefficient C d is determined by CFD simulation, and the real-time wind speed v is collected by the wind speed sensor at the bridge construction site.

[0041] The calculation formula for the frictional resistance moment M f is:

[0042] M f= μ·R·N

[0043] where N is the normal pressure, θ is the rotation inclination angle, μ is the static friction coefficient, R is the rotation radius of the overall bridge, and the calculation formula for the normal pressure N is M g = ∑m i ·g·cosθ, where θ is the rotation inclination angle.

[0044] The calculation formula for the center of gravity offset moment M g is:

[0045] M g = ∑mi·g·Δdi

[0046] where Δdi is the horizontal distance deviation of the unit from the rotating shaft, and g is the acceleration due to gravity.

[0047] The superimposed center of gravity offset moment M g , the wind load moment M w and the frictional resistance moment M f are calculated to obtain the total unbalanced moment M total = M g + M w + M f , in S5, M total Equivalent counterweight blocks are arranged on the opposite side of the bridge body, and the mass m of the counterweight blocks satisfies where d is the horizontal distance of the counterweight block from the rotating shaft;

[0048] After calculating the required weight m of the counterweight, prepare it with an error of ±5% of the calculated weight m, and place the prepared counterweight blocks at a distance d from the rotation center on the bridge deck. The placement position of the counterweight blocks is at the center position of the bridge deck and is arranged in a normal distribution.

[0049] The above are only the preferred embodiments of the present invention, which are illustrative rather than restrictive to the present invention. Those skilled in the art understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, but all will fall within the protection scope of the present invention.

Claims

1. A method for calculating the unbalanced moment of an arched swivel bridge, characterized in that: The following steps are involved: Step S1, based on the bridge design parameters, establish a three-dimensional finite element model including the arch rib, the bridge deck system and the temporary support structure; Step S2: Discretize the bridge structure into several mass units and record the mass m of each unit. i and its three-dimensional coordinates in the rotation coordinate system (x i ,y i ,z i ); Step S3, establish the calculation formula of the overall center of gravity coordinates of the bridge, and record the mass m of each unit i and its three-dimensional coordinates in the rotation coordinate system (x i ,y i ,z i ) into the calculation formula of the overall center of gravity coordinates of the beam, and the overall center of gravity coordinates of the bridge (X c ,Y c ,Z c ); Step S4, calculate the wind load moment M w , friction resistance torque M f and superimposed center of gravity displacement moment M g ; Step S5: superimpose the center of gravity offset moment M g , wind load moment M w and friction resistance torque M f , the total unbalanced moment M is calculated total =M g +M w +M f .

2. A method for calculating unbalanced moment of an arched swivel bridge as claimed in claim 1, characterized in that: In the step S1, a non-uniform grid division strategy is adopted when establishing the three-dimensional finite element model, and the arch foot and the hinge point are meshed, and the mesh density is 3-5 times that of other areas. The three-dimensional finite element model is established using Midas Civil or ANSYS software, and the model accuracy satisfies that the unit size is not greater than 1 / 10 of the minimum size of the arch rib section.

3. The method for calculating the unbalanced moment of an arched rotating bridge according to claim 1, characterized in that: In step S3, the calculation formula of the coordinates of the center of gravity of the bridge is:

4. The method for calculating the unbalanced moment of an arched rotating bridge according to claim 1, characterized in that: In step S4, the wind load moment M w The calculation formula is: M w =0.5·ρ·v 2 ·C d ·A·R ρ is the air density, C d is the drag coefficient, A is the windward area of ​​the entire bridge, R is the rotation radius of the entire bridge, and v is the real-time wind speed.

5. The method for calculating the unbalanced moment of an arched rotating bridge according to claim 4, characterized in that: The drag coefficient C d The value of is determined through CFD simulation, and the real-time wind speed v is collected by a wind speed sensor at the bridge construction site.

6. The method for calculating the unbalanced moment of an arched rotating bridge according to claim 1, characterized in that: In step S4, the friction resistance torque M f The calculation formula is: M f =μ·R·N N is the normal pressure, θ is the rotation inclination angle, μ is the static friction coefficient, and R is the rotation radius of the entire bridge.

7. A method for calculating unbalanced moment of an arched swivel bridge as claimed in claim 6, characterized in that: The calculation formula of the normal pressure N is: g =∑m i ·g·cosθ, where θ is the inclination angle of rotation.

8. The method for calculating the unbalanced moment of an arched rotating bridge according to claim 1, characterized in that: In step S4, the gravity center offset moment M g The calculation formula is: The Δdi is the horizontal distance deviation between the unit and the rotation axis, and g is the gravitational acceleration.

9. The method for calculating the unbalanced moment of an arched rotating bridge according to claim 7, characterized in that: In S5, M total An equivalent counterweight is arranged on the opposite side of the bridge body, and the mass m of the counterweight satisfies Where d is the horizontal distance between the counterweight and the rotating shaft.

10. The method for calculating the unbalanced moment of an arched rotating bridge as claimed in any one of claims 1 to 9 is applied in rotating arched bridges.

Images