Construction method of suspension pipe rack based on midas civil software structural analysis

Abstract

The application discloses a suspension pipe rack construction method based on midas Civil software structure analysis, and relates to the technical field of pipeline crossing structure design. By establishing a main cable model, an initial linear shape is generated by using a built-in suspension bridge modeling assistant function of the software; a wind-resistant cable model is established, and the spatial linear shape of the wind-resistant cable is determined through independent modeling and iterative analysis; the main cable model and the wind-resistant cable model are combined to form a whole bridge integral model; material properties, section parameters, boundary conditions and construction stages are defined to perform structure balanced state analysis; operation load, maintenance load, wind load, temperature action and earthquake action are applied to perform load combination and structure response analysis. The application solves the problem that the mutual influence between the wind-resistant cable and the main cable is difficult to simulate in the traditional method, is suitable for complex suspension pipe rack structures such as large-span, wind-resistant cable and tower top cable disconnection, provides a standardized and reusable modeling method for pipeline crossing engineering design, and has good engineering application value.

Description

Technical Field

[0001] This invention relates to the field of pipeline crossing structure design technology, and in particular to a method for constructing suspension pipe racks based on structural analysis using midas Civil software. This method is applicable to structural modeling, alignment determination, stress analysis, and seismic verification of long-span suspension pipeline crossing projects. Background Technology

[0002] Suspension pipe racks are pipeline support structures that span long distances across obstacles such as rivers, canyons, and highways, and are widely used in long-distance oil and gas pipeline projects. Compared with traditional beam bridges and arch bridges, suspension structures have significant advantages such as strong spanning capacity, less material consumption, and convenient construction. Especially in conditions where it is not suitable to set up piers in the riverbed, navigation requirements are high, and terrain is complex, suspension pipe racks have become the preferred solution.

[0003] A typical cable-stayed pipe bridge structure mainly includes components such as the main cable (back cable), wind cable system, towers, anchor piers, bridge deck structure, hangers, and saddles. The main cable is the primary load-bearing component, supporting the pipe's own weight, maintenance loads, and environmental loads. The wind cable system enhances the structure's lateral stiffness and resists wind loads. The bridge deck structure provides a support platform for the pipe. Compared to highway suspension bridges, cable-stayed pipe bridges are characterized by lighter loads, narrower bridge decks, smaller width-to-span ratios, and lower structural stiffness, resulting in more pronounced nonlinear structural behavior.

[0004] Currently, structural analysis of cable-stayed pipe structures primarily relies on finite element analysis software. Among these, Midas Civil is widely used in the design of such structures due to its powerful nonlinear analysis capabilities and dedicated functions for suspension bridges. However, the following technical problems still exist in practical engineering applications:

[0005] (1) Difficulty in co-modeling the main cable and the wind-resistant cable

[0006] Existing modeling methods often treat the main cable and wind-resistant cable separately, failing to fully consider their mutual influence. The tension of the wind-resistant cable alters the vertical stress on the main cable, while changes in the main cable's alignment affect the spatial morphology of the wind-resistant cable. Traditional iterative methods lack a systematic collaborative modeling process, making it difficult to obtain accurate bridge equilibrium states.

[0007] (2) Insufficient simulation of the cable disconnection pattern at the top of the tower

[0008] In cable-stayed pipeline crossings, the main cable and backstay cable are often disconnected at the top of the tower via a connecting plate, unlike the continuous saddle design of highway suspension bridges. Existing modeling methods are not accurate enough in simulating the boundary conditions of this disconnected form, leading to biases in the stress analysis at the top of the tower.

[0009] (3) Lack of standardized procedures for determining the linear shape and solving the equilibrium state

[0010] Suspension structures are highly sensitive to their alignment and height; the selection of parameters such as the sag-to-span ratio of the main cable, the side-to-mid span ratio, and the length of the hangers directly affects the structural performance. Existing methods mostly rely on empirical values ​​and lack systematic parameter sensitivity analysis and standardized iterative processes.

[0011] (4) Inconsistent seismic and buckling analysis methods

[0012] For long-span flexible structures, seismic response and overall stability are key control indicators. In existing designs, the selection criteria for response spectrum analysis and time history analysis are inconsistent, and there is controversy over the treatment of cable elements in buckling analysis, resulting in poor comparability of analysis results.

[0013] To address this, a method for constructing cable-stayed pipe racks based on structural analysis using midas Civil software is proposed. Summary of the Invention

[0014] To address the shortcomings of existing technologies, this invention provides a method for constructing cable-stayed pipe racks based on structural analysis using midas Civil software. The aim is to achieve accurate modeling, reasonable alignment determination, comprehensive stress analysis, and stability verification of cable-stayed pipe rack structures.

[0015] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0016] A method for constructing a cable-stayed pipe rack based on structural analysis using midas Civil software includes the following steps:

[0017] Step S1: Establish the main cable model, use the built-in suspension bridge modeling assistant function of midas Civil software to generate the initial alignment, and solve the precise equilibrium state through the suspension bridge modeling analysis and control function, and define the equilibrium state to verify the construction stage.

[0018] Step S2: Establish a wind-resistant cable model. Determine the spatial shape of the wind-resistant cable through independent modeling and iterative analysis. Specifically, this includes: using the modeling assistant to establish a single-sided wind-resistant cable main cable, rotating it to the design angle, manually connecting the transverse wind-resistant cable cables and performing mirror processing, using the precise balance analysis function to define the balance load and perform a re-shape finding analysis to obtain the spatial equilibrium model of the wind-resistant cable.

[0019] Step S3: Merge the main cable model and the wind-resistant cable model to form the overall bridge model. During the merging process, verify the consistency between the unit number and the initial internal force load.

[0020] Step S4: Define material properties, section parameters, boundary conditions and construction stages, and perform structural equilibrium analysis. The cable section uses the effective diameter, and the unit weight calculation includes the sheath thickness.

[0021] Step S5: Apply operating loads, maintenance loads, wind loads, temperature effects, and seismic effects, perform load combination and structural response analysis, and conduct eigenvalue analysis, time history analysis, and buckling analysis to verify structural stability. The combination coefficients are determined according to the "Design Standard for Oil and Gas Pipeline Crossing Engineering" GB / T 50459-2017.

[0022] Furthermore, in the overall model of the entire bridge, the bridge deck structure is established according to the actual coordinates, the tower top connecting plate rotation angle adopts the offset modeling overall translation method, the suspender spacing is input according to the actual arrangement, and the bridge deck arch height is set to 1 / 100 to 1 / 300 of the main span.

[0023] Furthermore, the seismic action analysis includes response spectrum modal decomposition method and time history analysis method. In the time history analysis method, time-varying static load is used to apply the dead load in the form of dynamic load, and horizontal and vertical seismic wave functions are defined respectively.

[0024] Furthermore, in the buckling analysis, the cable elements in the full bridge model are manually modified into truss elements, the overall structural stability coefficient is calculated, and a stability coefficient greater than 4 is used as the control index.

[0025] The present invention has the following beneficial effects:

[0026] Compared with existing technologies, this solution achieves collaborative modeling and precise alignment iteration of the main cable and the wind-resistant cable, solving the problem that it is difficult to simulate the mutual influence between the wind-resistant cable and the main cable in traditional methods.

[0027] Compared with existing technologies, this solution establishes a complete modeling-analysis-verification process for cable-stayed pipe racks, covering key aspects such as material definition, equilibrium solution, load combination, eigenvalue analysis, time history analysis, and buckling analysis.

[0028] Compared with existing technologies, this solution is applicable to complex suspension pipe rack structures such as long spans, wind-resistant cables, and tower top cable breaks, significantly improving design accuracy and analysis efficiency;

[0029] Compared with existing technologies, this solution provides a standardized and reusable finite element modeling method for pipeline crossing engineering design, and has good engineering application value. Attached Figure Description

[0030] Figure 1 This is a flowchart of the overall modeling and calculation process for the cable-stayed pipe frame of the present invention;

[0031] Figure 2 A model drawing of the entire Midas Civil bridge with a suspension pipe frame and wind-resistant cables;

[0032] Figure 3 This is a schematic diagram of the input interface for calculating the dead load of the bridge deck system in an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of the main cable parameter input interface for the modeling assistant in an embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of generating a parabolic wind-resistant cable in a plane using a modeling assistant in an embodiment of the present invention;

[0035] Figure 6 This is a schematic diagram illustrating the "tree menu - rotate" function in an embodiment of the present invention;

[0036] Figure 7 This is a schematic diagram comparing the model before and after rotation in an embodiment of the present invention;

[0037] Figure 8 This is a schematic diagram of mirroring a single-sided wind-resistant cable model to generate the other side in an embodiment of the present invention;

[0038] Figure 9 This is a schematic diagram illustrating the modification of the unit weight of the stiffening beam material in an embodiment of the present invention;

[0039] Figure 10 This is a schematic diagram illustrating the setting of the precise equilibrium state pre-boundary conditions in an embodiment of the present invention;

[0040] Figure 11 This is a schematic diagram of the load on the front beam unit in precise equilibrium state in an embodiment of the present invention;

[0041] Figure 12 This is a schematic diagram of the precise balance analysis and control settings in an embodiment of the present invention. Figure 1 ;

[0042] Figure 13 This is a schematic diagram of the precise balance analysis and control settings in an embodiment of the present invention. Figure 2 ;

[0043] Figure 14 This is a schematic diagram of the wind-resistant cable extraction model in an embodiment of the present invention;

[0044] Figure 15 This is a schematic diagram of the full-bridge model in an embodiment of the present invention;

[0045] Figure 16 This is a schematic diagram of the load conversion to mass interface in an embodiment of the present invention;

[0046] Figure 17 This is a schematic diagram of the feature value analysis control interface in an embodiment of the present invention;

[0047] Figure 18 This is a schematic diagram of the first mode shape and period in an embodiment of the present invention;

[0048] Figure 19 This is a schematic diagram of the second mode shape and period in an embodiment of the present invention;

[0049] Figure 20 This is a schematic diagram of the third mode shape and period in an embodiment of the present invention;

[0050] Figure 21 This is a schematic diagram of the design response spectrum function definition in an embodiment of the present invention. Figure 1 ;

[0051] Figure 22 This is a schematic diagram of the design response spectrum function definition in an embodiment of the present invention. Figure 2 ;

[0052] Figure 23 This is a schematic diagram of the definition of the response spectrum load case in an embodiment of the present invention. Figure 1 ;

[0053] Figure 24 This is a schematic diagram of the definition of the response spectrum load case in an embodiment of the present invention. Figure 2 ;

[0054] Figure 25 This is a schematic diagram of the longitudinal bending moment output under an E2 earthquake in an embodiment of the present invention;

[0055] Figure 26 This is a schematic diagram of the transverse bending moment output of the bridge under earthquake E2 in an embodiment of the present invention;

[0056] Figure 27 This is a schematic diagram of adding a time history function - constant load in an embodiment of the present invention;

[0057] Figure 28 This is a schematic diagram of the time-varying static load setting in an embodiment of the present invention;

[0058] Figure 29 A schematic diagram of the first horizontal seismic wave function is added to this embodiment of the invention;

[0059] Figure 30 A schematic diagram of the first vertical seismic wave function is added to this embodiment of the invention;

[0060] Figure 31 This is a schematic diagram of the time-history load condition settings in an embodiment of the present invention;

[0061] Figure 32 This is a schematic diagram of the ground acceleration setting in an embodiment of the present invention;

[0062] Figure 33 This is a schematic diagram of the buckling analysis control interface in an embodiment of the present invention;

[0063] Figure 34 This is a schematic diagram of the stability coefficient output results in an embodiment of the present invention. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0065] Example 1

[0066] like Figure 1 The flowchart shown below illustrates the overall modeling and calculation process for the cable-stayed pipe frame, which includes the following steps:

[0067] Main cable model establishment

[0068] In Midas Civil, the initial alignment of the main cable is generated by inputting parameters such as the main span, side spans, sag-to-span ratio, hanger spacing, and bridge deck slope using the "Suspension Bridge Modeling Assistant." The "Suspension Bridge Modeling Analysis and Control" function is then used to define dead load conditions and perform iterative calculations to obtain the precise equilibrium state. Construction phase analysis verifies that the completed bridge alignment matches the design objectives.

[0069] Wind-resistant cable model establishment

[0070] A separate wind-resistant cable model was created, and a parabolic wind cable was generated using a modeling assistant, with parameters such as the cable's sag-to-span ratio and the unit weight of the bridge deck input. The generated wind cable model was rotated around the bridge deck axis to the design angle (e.g., 15°), and transverse cable elements were manually created. The double-sided wind cable system was then mirrored to generate the model. Using the "Precise Balance Analysis" function, the design load of the wind-resistant cable was defined, and the model was re-formed to obtain a spatial equilibrium model.

[0071] Model merging and parameter setting

[0072] The main cable model and the wind-resistant cable model were integrated using the "Merge Data Files" function, and the correspondence between unit numbers and loads was verified. In the cable material definition, the wire bundle area and sheath thickness were entered according to the product specification table, and the converted unit weight was calculated. The corner position of the tower top connection plate was modeled using an overall translation method to ensure that the stress-free cable length remained unchanged.

[0073] Load application and combination

[0074] The following loads are applied: operating load (pipeline self-weight, water weight, friction), maintenance load (0.8 kN / m²), wind load (2.34 kN / m), temperature effect, and seismic effect. Four load combinations are defined according to GB / T 50459-2017: maintenance control combination, wind load control combination, temperature control combination, and seismic effect combination.

[0075] Eigenvalue, time history and buckling analysis

[0076] The self-weight and secondary load were converted into mass, and eigenvalue analysis was performed using the multiple Rizt vector method to extract the first five periods and mode shapes. In the time history analysis, three seismic waves were selected, and horizontal and vertical time history functions were defined respectively. Dynamic analysis was then performed after applying a time-varying static load with a dead load. In the buckling analysis, the cable elements were replaced with truss elements, and a stability coefficient of 5.2 was calculated, which is greater than the code limit of 4, indicating that the overall stability meets the requirements.

[0077] Using the above methods, high-precision modeling and comprehensive stress analysis of the suspension pipe rack structure were achieved, verifying the safety and stability of the structure under various working conditions.

[0078] The following detailed description of this solution uses a specific embodiment as an example.

[0079] Project Overview: Main span: 300m; Side span: 90m; Main cable sag-to-span ratio: 1 / 10; Wind-resistant cable sag-to-span ratio: 1 / 15; Wind-resistant cable inclination angle: 15°; Bridge deck width: 5m; Hanger spacing: 5m; Design load: DN800 steam pipe (including insulation layer, water weight, and maintenance load); A double-tower ground anchorage structure is adopted, with a double-sided wind-resistant cable system.

[0080] The specific process includes:

[0081] Step 1: Modeling Preparation and Material Parameter Definition

[0082] 1.1) Material property definitions, see the table below:

[0083] Main cable High-strength galvanized steel wire <![CDATA[1.95×10 5 ]]> 78.5 Conversion of density into protective layer Wind-resistant cable High-strength galvanized steel wire <![CDATA[1.95×10 5 ]]> 78.5 Same as above Sota C50 concrete <![CDATA[3.45×10 4 ]]> 25.0 Bridge deck beam Q355B steel <![CDATA[2.06×10 5 ]]> 78.5 boom High-strength steel wire <![CDATA[1.95×10 5 ]]> 78.5

[0084] 1.2) Calculation of converted unit weight of cable cross section

[0085] Taking the main cable as an example:

[0086] Nominal area of ​​the wire bundle: A = 0.003845 m² 2

[0087] Cable unit weight: w cable = 0.302 kN / m

[0088] Protective layer thickness: t = 0.005 m

[0089] Effective diameter: D = 2 × √(A / π) = 0.07 m

[0090] Converted bulk density: γ = w_cable / A = 0.302 / 0.003845 = 78.5 kN / m 3

[0091] Key points of operation: In midas Civil, define the material according to the above data in “Properties - Material Characteristic Values”, and use the converted value for cable unit weight to ensure accurate self-weight calculation.

[0092] Step 2: Main Cable Model Establishment

[0093] 2.1) Modeling assistant parameter input, see the table below:

[0094] Main span 300 m Left span 90 m right span 90 m Distance from left backstay anchor point to left tower 85 m Distance from right backstay anchor point to right tower 85 m Main cable sag ratio 1 / 10 30m vertical Rod spacing 5 m Number of spanning rods on the left 0 Backsling without boom Number of right spanning rods 0 Backsling without boom Distance from stiffening girder end to tower pier centerline 2.5 m Half the distance from the outermost auger to the tower column Bridge deck slope 0% Input according to actual coordinates

[0095] 2.2) Treatment of tower top connection plate

[0096] Since this project uses a method where the main cable and back cable are disconnected at the top of the tower, the following operations are performed after the modeling assistant generates the model:

[0097] The tower top node is moved as a whole according to the actual position of the connecting plate;

[0098] Ensure that the stress-free cable length Lu remains unchanged before and after translation;

[0099] The angular constraint of the connecting plate is simulated by using a rigid connection.

[0100] Operation screenshots as follows Figure 3 Bridge deck system dead load calculation data input interface and Figure 4 The main cable parameter input interface of the modeling assistant is shown.

[0101] Step 3: Establishment of wind-resistant cable model

[0102] 3.1) Parameters for the wind-resistant cable modeling assistant are shown in the table below:

[0103] Main span 300 m Consistent with the main cable sag-to-span ratio 1 / 15 Verticality 20m Bridge deck unit weight 12.5 kN / m Total vertical load (force of both sides of the hangers × 2) Number of booms 58 Spacing 5m Distance from stiffening girder end to tower 2.5 m

[0104] 3.2) Wind-resistant cable rotation and connection

[0105] Operating procedures:

[0106] Generate the initial model: Use a modeling assistant to generate a parabolic wind-resistant cable in the plane, such as... Figure 5 As shown;

[0107] Rotation transformation: via the "Tree menu - Rotate" function, such as... Figure 6 As shown;

[0108] Rotate 15° around the bridge deck axis to the designed inclination angle;

[0109] Comparison of the model before and after rotation, such as Figure 7 As shown;

[0110] Lateral cable connection: Manually establish lateral cable units, connect the wind-resistant cable to the bridge deck structure, and ensure that the cable spacing is consistent with the suspender spacing (5m).

[0111] Mirroring: Mirror the single-sided wind-resistant cable model to generate the other side, such as... Figure 8 As shown.

[0112] 3.3) Precise balance analysis of wind-resistant cable, see the table below:

[0113] Balanced load Total vertical force of double-sided wind-resistant cables Determined based on the design tension. Number of iterations 20 times Convergence tolerance 1e-6

[0114] Key points of operation:

[0115] In the wind-resistant cable modeling assistant, input the total vertical load on one side in the "Unit weight of bridge deck system" field.

[0116] The vertical force applied during precise balance analysis is the total vertical force of the wind-resistant cables on both sides;

[0117] The density of the stiffening beam material has been revised to 1e-4 to avoid double counting of its self-weight. Figure 9 As shown.

[0118] The user interface for this step is shown in Figure 10- Figure 14 As shown.

[0119] Step 4: Merging the full bridge model and applying loads

[0120] 4.1) Model merging

[0121] Export the main cable model data file (in .mcb format);

[0122] Export the wind-resistant cable model data file;

[0123] Import the main cable model into the wind-resistant cable model via "File - Merge Data Files";

[0124] Verify the element number to ensure that the initial internal force load matches the number of elements;

[0125] Check the boundary conditions and connectivity of the merged model.

[0126] 4.2 Load definitions, see the table below:

[0127] Pipeline self-weight 8.5 kN / m Including insulation layer Water weight (operating conditions) 10% water weight Steam pipes Pipeline dynamic coefficient 1.3 Considering the impact Pipeline horizontal friction 1.2 kN / m Axial constraint Lateral thrust of the pipeline 0.8 kN / m Lateral constraints Maintenance load <![CDATA[0.8 kN / m 2 ]]> Arranged according to a mid-span length ≥ 30m Snow load <![CDATA[0.5 kN / m 2 ]]> Local basic snow pressure Ice load <![CDATA[0.3 kN / m 2 ]]> Values ​​should be taken according to specifications. Wind load (cross-bridge direction) 2.34 kN / m <![CDATA[Basic wind pressure 0.5kN / m 2 > Temperature effect ±30℃ Overall temperature rise and fall, and gradient temperature

[0128] 4.3) Load combinations, see the table below:

[0129] Combination 1 Maintenance load control 1.3 Dead Load + 1.69 Operating Load + 1.5 Maintenance Load + 0.9 Wind Load + 1.05 Snow Load + 1.05 Icing Load + 0.9 Temperature Effect Combination 2 Wind load control 1.3 Dead Load + 1.69 Running Load + 1.5 Wind Load + 1.05 Snow Load + 1.05 Icing Load + 0.9 Temperature Effect Combination 3 Temperature control 1.3 Dead Load + 1.69 Operating Load + 1.05 Maintenance Load + 0.9 Wind Load + 1.05 Snow Load + 1.5 Temperature Effect Combination 4 Earthquake action 1.3 Dead Load + 1.69 Running Load + 0.2 Wind Load + 0.5 Snow Load + 0.5 Icing Load + 0.6 Temperature Effect + 1.4 Seismic Effect

[0130] Full bridge model as Figure 15 As shown.

[0131] Step 5: Eigenvalue Analysis

[0132] 5.1) Load converted into mass

[0133] Operation path: Load - Static Load - Convert to Mass, see the table below:

[0134] Change direction X, Y, Z directions Combination coefficient 1.0 Including self-weight yes

[0135] 5.2) Eigenvalue analysis control, see the table below:

[0136] Analysis type Multiple Rizt vector method Suitable for large structures Initial load vector Ground acceleration X, ground acceleration Y Number of initial vectors 20 Number of vibration modes 10

[0137] The analysis results are shown in the table below:

[0138] 1 3.85 Main span symmetrical vertical curve 2 2.96 Main span antisymmetric vertical bend 3 2.21 Main span side bend (with wind-resistant cable involved) 4 1.78 Side Span Vertical Bend 5 1.52 Twist

[0139] User interface as follows Figures 16 to 20 As shown.

[0140] Step 6: Reaction spectrum analysis

[0141] 6.1) Definition of reaction spectrum function

[0142] According to the "Design Standard for Oil and Gas Pipeline Crossing Projects" GB / T 50459-2017, the site category is Class II, the design seismic group is Group 2, and the fortification intensity is 7 degrees (0.10g).

[0143] Design acceleration peak 0.10g Characteristic Periodicity 0.40s Damping ratio 0.05 Response spectral function type Standard reaction spectrum

[0144] 6.2) Response spectrum load cases, see the table below:

[0145] SPEC-X Along the bridge (X) 1.0 SPEC-Y Cross-bridge direction (Y) 1.0 SPEC-Z Vertical (Z) 0.65

[0146] User interface as follows Figures 21 to 26 As shown.

[0147] Step 7: Time History Analysis

[0148] 7.1) Seismic wave selection

[0149] No seismic safety assessment was conducted for this project; three seismic waves matching the design response spectrum were selected:

[0150] Wave-1 El Centro 6.9 0.10 30.0 Wave-2 Taft 7.4 0.10 30.0 Wave-3 Artificial wave - 0.10 30.0

[0151] 7.2) Definition of Time History Function

[0152] Horizontal seismic waves:

[0153] Function type: dimensionless acceleration g

[0154] Magnification factor: 1.0 (corresponding to 0.10g);

[0155] Vertical seismic waves:

[0156] Function type: dimensionless acceleration g

[0157] Magnification factor: 0.65.

[0158] 7.3) Time-varying static loads (dead load application), see the table below:

[0159] Application time 1.0 s Load type Dead load (DL) Load combination factor 1.0

[0160] 7.4) Time-history load cases, see the table below:

[0161] Analysis time 30 s Time step 0.02 s Integration methods Newmark-β method

[0162] User interface as follows Figures 27 to 32 As shown.

[0163] Step 8: Buckling Analysis

[0164] 8.1) Cable unit processing

[0165] Key operations:

[0166] Before the overall bridge stability calculation, all tension-only truss elements (cable elements) were manually changed to truss elements.

[0167] Operation path: Model - Element - Modify Element Type;

[0168] Unit type: changed from "cable" to "truss".

[0169] 8.2) Buckling analysis control, see the table below:

[0170] Analysis type Linear buckling buckling mode number 10 Load Combination Dead load + Operating load + Maintenance load + Wind load

[0171] 8.3) The analysis results are shown in the table below:

[0172] 1 5.2 Main span antisymmetric lateral bending 2 6.8 Main span symmetrical lateral curve 3 8.1 Main tower side bend

[0173] Conclusion: The stability coefficient is 5.2 > 4.0, and the overall stability meets the requirements of the "Design Standard for Crossing Engineering of Oil and Gas Transmission Pipelines".

[0174] User interface as follows Figures 33 to 34 As shown.

[0175] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for constructing cable-stayed pipe racks based on structural analysis using Midas Civil software, characterized in that: Includes the following steps: Step 1: Establish the main cable model and use the built-in suspension bridge modeling assistant function of midas Civil software to generate the initial alignment; Step 2: Establish a wind-resistant cable model and determine the spatial shape of the wind-resistant cable through independent modeling and iterative analysis; Step 3: Merge the main cable model and the wind-resistant cable model to form a complete bridge model; Step 4: Define material properties, section parameters, boundary conditions, and construction stages, and perform structural equilibrium analysis; Step 5: Apply operating loads, maintenance loads, wind loads, temperature effects, and seismic effects, and perform load combination and structural response analysis.

2. The method for constructing a cable-stayed pipe rack based on structural analysis using Midas Civil software according to claim 1, characterized in that, During the establishment of the main cable model, the suspension bridge modeling analysis and control function is used to solve for the precise equilibrium state, and the equilibrium state is verified by defining the construction stage.

3. The method for constructing a cable-stayed pipe rack based on structural analysis using Midas Civil software according to claim 1, characterized in that, The establishment of the wind-resistant cable model includes the following sub-steps: Sub-step 1: Use midas Civil modeling assistant to create a single-sided wind-resistant cable main cable; Sub-step 2: Rotate the wind-resistant cable to the designed angle, manually connect the horizontal wind-resistant cable cable and mirror it; Sub-step 3: Using the precise balance analysis function, define the balance load and perform a new shape-finding analysis to obtain the spatial equilibrium model of the wind-resistant cable.

4. The method for constructing a cable-stayed pipe rack based on structural analysis using Midas Civil software according to claim 1, characterized in that, During the merging process of the main cable and wind-resistant cable models, the data files of the wind-resistant cable model and the main cable model need to be merged, and the unit numbers need to be checked and unified to ensure that the initial internal force load and the number of units are consistent.

5. The method for constructing a cable-stayed pipe rack based on structural analysis using Midas Civil software according to claim 1, characterized in that, In the definition of the material properties, the cable cross-section diameter is the effective diameter, the unit weight calculation must include the sheath thickness, and the unit weight value is determined by dividing the cable weight by the area of ​​the wire bundle.

6. The method for constructing a cable-stayed pipe rack based on structural analysis using Midas Civil software according to claim 1, characterized in that, After the overall model of the bridge is established, eigenvalue analysis is performed. The multiple Rizt vector method is used to convert the self-weight and secondary load into mass, and the ground acceleration direction is set as the initial load vector to extract the natural vibration period and mode shape of the structure.

7. The method for constructing a cable-stayed pipe rack based on structural analysis using Midas Civil software according to claim 1, characterized in that, The seismic action analysis includes response spectrum modal decomposition and time history analysis. In the time history analysis, a time-varying static load is used to apply the dead load as a dynamic load in a short period of time, and horizontal and vertical seismic wave functions are defined respectively.

8. The method for constructing a cable-stayed pipe rack based on structural analysis using Midas Civil software according to claim 1, characterized in that, In the buckling analysis, the cable elements in the full bridge model are manually modified to truss elements. The effects of dead load and variable load are considered, the overall stability coefficient of the structure is calculated, and a stability coefficient greater than 4 is used as the control index.

9. The method for constructing a cable-stayed pipe rack based on structural analysis using Midas Civil software according to claim 1, characterized in that, The load combinations include maintenance load control combinations, wind load control combinations, temperature control combinations, and seismic action combinations.

10. The method for constructing a cable-stayed pipe rack based on structural analysis using Midas Civil software according to claim 1, characterized in that, In the overall model of the entire bridge, the bridge deck structure is established according to the actual coordinates, the tower top connecting plate rotation is modeled by offset and translated as a whole, the suspender spacing is input according to the actual arrangement, and the bridge deck arch height is set to 1 / 100 to 1 / 300 of the main span.

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