Beam string structure optimization method for reinforcing large-span steel corridor

Abstract

The invention provides a beam string structure optimization method for reinforcing a large-span steel corridor, and belongs to the technical field of building construction.The method comprises the steps that firstly, a three-dimensional finite element model is established, the three-dimensional finite element model comprises an upper steel corridor, vertical supporting rods and inhaul cables, and boundary conditions and dead load and live load are set; performing nonlinear analysis to obtain an initial deflection value and a stress value, and judging whether reinforcement requirements are met or not. And if not, adjusting the length of the supporting rod and the prestress of the inhaul cable, and repeatedly analyzing and calculating until the requirements are met. Then, the structural deflection serves as a control parameter, the strain of the inhaul cable serves as a response parameter, cable force optimization calculation is conducted through an SAP2000CSiLoadOptimizer toolbox, and an optimized strain value of the inhaul cable is obtained. And finally, according to an optimization result, a final cable force optimization scheme is obtained through back-stepping, and specific process parameters of the beam string structure for reinforcing the large-span steel corridor are determined. The problem that an existing method cannot comprehensively reflect the nonlinear mechanical property of the structure is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and in particular relates to an optimization method for a beam-string structure used to reinforce a large-span steel corridor. Background Art

[0002] As a new type of urban bridge, large-span steel corridors are widely used in urban landscape projects, transportation hubs and other fields. They have the characteristics of light structure, beautiful shape and convenient construction. With the acceleration of urbanization, this type of structure is increasingly appearing in the public's field of vision. However, due to factors such as material properties and structural forms, large-span steel corridors generally have problems such as excessive deflection and stress concentration during service, which seriously affects their safety and reliability. Therefore, how to effectively improve the deformation resistance and damage resistance of large-span steel corridors has become a key technical problem that needs to be solved urgently.

[0003] At present, there are several common methods for the reinforcement and optimization design of large-span steel corridors:

[0004] 1) Rigidity reinforcement method: Add stiffening ribs to the main beam or column to increase the overall rigidity of the structure, thereby improving the anti-deformation performance. However, this method will increase the deadweight of the structure and also affect the aesthetics of the building.

[0005] 2) Beam string optimization method: Add cables on both sides of the main beam to form a beam string structure. By adjusting the prestress of the cables and the structural geometric parameters, the overall stress state is optimized. This method is more economical and environmentally friendly than the rigid reinforcement method, but the optimization effect is affected by the coupling of many parameters and is relatively complicated.

[0006] 3) Dynamic vibration reduction method: damping vibration reduction devices are arranged at key parts of the structure to absorb vibration energy and reduce the dynamic response of the structure. This method has high requirements on the dynamic characteristics of the structure and requires accurate dynamic parameter identification and model establishment.

[0007] Although the above method has improved the anti-deformation performance of the long-span steel corridor to a certain extent, it still has the following shortcomings:

[0008] (1) The optimization method is too simple and cannot fully reflect the nonlinear mechanical characteristics of the structure, resulting in limited optimization effect.

[0009] (2) Parameter adjustment relies on empirical judgment and lacks systematic analysis and optimization calculation methods, which cannot guarantee the optimization of structural performance.

[0010] Therefore, there is an urgent need for a new optimization method that can comprehensively consider the nonlinear behavior of the structure, adopt a systematic parameter optimization algorithm, and take into account the feasibility of the construction process, so as to effectively improve the performance of large-span steel corridors. Summary of the invention

[0011] In view of this, the present invention provides a method for optimizing a beam-string structure for reinforcing a large-span steel corridor, which can solve the technical problem that the prior art optimization method cannot fully reflect the nonlinear mechanical characteristics of the structure, resulting in limited optimization effect.

[0012] The present invention is achieved in that:

[0013] The present invention provides a method for optimizing a beam string structure for reinforcing a large-span steel corridor, comprising the following steps:

[0014] S10, establishing a three-dimensional finite element model of the long-span steel corridor, wherein the three-dimensional finite element model includes an upper steel corridor, vertical struts and cables;

[0015] S20, setting boundary conditions of the three-dimensional finite element model, and determining a dead load and a live load acting on the three-dimensional finite element model;

[0016] S30, performing nonlinear analysis on the three-dimensional finite element model to obtain initial deflection value and stress value;

[0017] S40, determining whether the initial deflection value and the stress value meet the reinforcement requirements, if not, executing step S50, if satisfied, executing step S60;

[0018] S50, adjusting the length of the vertical support rod and the prestress value of the cable, and returning to step S30;

[0019] S60, setting the structural deflection value as a control parameter and the cable strain value as a response parameter;

[0020] S70, using the SAP2000 CSiLoadOptimizer toolbox to perform cable force optimization calculations and obtain optimized cable strain values;

[0021] S80, obtaining a final cable force optimization result by reverse calculation according to the optimized cable strain value;

[0022] S90. Determine the process parameters for reinforcing the beam-string structure of the large-span steel corridor according to the final cable force optimization result.

[0023] On the basis of the above technical solution, the optimization method of the beam string structure for reinforcing a large-span steel corridor of the present invention can also be improved as follows:

[0024] Wherein, the step S10 specifically includes:

[0025] Step 101: Collect structural design drawings and material parameters of the long-span steel corridor;

[0026] Step 102, select finite element analysis software, including ANSYS or ABAQUS;

[0027] Step 103, establishing a three-dimensional finite element model including the steel corridor superstructure, vertical struts and cables in the finite element analysis software;

[0028] Step 104: Select appropriate unit type and meshing method according to actual structural conditions;

[0029] Step 105, modeling the connector, including the solder joints and hinges, using corresponding constraint relationships;

[0030] Step 106: Adjust and optimize the three-dimensional finite element model to ensure that it can accurately reflect the actual stress state and deformation of the long-span steel corridor.

[0031] Furthermore, the step S20 specifically includes:

[0032] Step 201: setting boundary conditions in the finite element model according to the actual support conditions of the long-span steel corridor;

[0033] Step 202: setting displacement constraints for supports located on bridge piers or anti-pulling piles;

[0034] Step 203, setting different rolling or simply supported constraint conditions for other support positions;

[0035] Step 204, determining the dead load acting on the three-dimensional finite element model, including the deadweight of the steel corridor and the permanent load of the attached facilities;

[0036] Step 205, determining the live load acting on the three-dimensional finite element model, including temporary loads of personnel and vehicles;

[0037] Step 206: determine the environmental loads acting on the three-dimensional finite element model, including wind loads and snow loads;

[0038] Step 207: Check and adjust the various loads determined according to the requirements of relevant design specifications.

[0039] Furthermore, the step S30 specifically includes:

[0040] Step 301, establishing a mathematical model for nonlinear analysis, including a nonlinear stiffness matrix, a displacement vector, an external force vector, a nonlinear internal force vector, a strain displacement matrix, a nonlinear stress tensor, an elasticity matrix and a nonlinear strain tensor;

[0041] Step 302: construct a nonlinear equilibrium equation, including considering the effects of material nonlinearity and geometric nonlinearity;

[0042] Step 303: using an iterative algorithm to solve the nonlinear equilibrium equation, such as the Newton-Raphson method or the arc-length method;

[0043] Step 304, calculating the displacement field of the structure, including node displacements and component deformations;

[0044] Step 305, calculating the stress field of the structure according to the displacement field, including the axial force, shear force and bending moment of each component;

[0045] Step 306: extract the displacement value of the key node as the initial deflection value;

[0046] Step 307: extract the stress value of the key component as the initial stress value.

[0047] Furthermore, nonlinear analysis can be performed using the following set of equations:

[0048]

[0049] Where K(u) is the nonlinear stiffness matrix; u is the displacement vector; F is the external force vector; F nl (u) is the nonlinear internal force vector; B is the strain-displacement matrix; σ nl (u) is the nonlinear stress tensor; D is the elastic matrix; ε nl (u) is the nonlinear strain tensor.

[0050] Displacement and stress calculations:

[0051]

[0052] In the formula, is the effective stiffness matrix; ε u is the displacement calculation error; ε σ is the stress calculation error.

[0053] Furthermore, the step S40 specifically includes:

[0054] Step 401, determining the maximum allowable deflection value of the long-span steel corridor according to the structural design specification;

[0055] Step 402: Determine the maximum allowable stress value of the long-span steel corridor according to material properties and structural safety factor;

[0056] Step 403, comparing the initial deflection value obtained in step S30 with the maximum allowable deflection value;

[0057] Step 404, comparing the initial stress value obtained in step S30 with the maximum allowable stress value;

[0058] Step 405: When the initial deflection value is greater than the maximum allowable deflection value or the initial stress value is greater than the maximum allowable stress value, it is determined that the reinforcement requirement is not met;

[0059] Step 406: When the initial deflection value is less than or equal to the maximum allowable deflection value and the initial stress value is less than or equal to the maximum allowable stress value, it is determined that the reinforcement requirement is met.

[0060] Furthermore, the step S50 specifically includes:

[0061] Step 501, setting a calculation formula for the adjustment amount of the vertical brace length, wherein the adjustment amount is proportional to the difference between the maximum deflection value and the maximum allowable deflection value;

[0062] Step 502, setting a calculation formula for the adjustment amount of the cable prestress value, wherein the adjustment amount is proportional to the difference between the maximum stress value and the maximum allowable stress value;

[0063] Step 503: Select an empirical adjustment coefficient to control the amplitude of each adjustment;

[0064] Step 504, calculate the new vertical brace length, which is the previous length plus the adjustment amount;

[0065] Step 505, calculating a new cable prestress value, which is the previous prestress value plus the adjustment amount;

[0066] Step 506, applying the new vertical brace length and cable prestress value to the three-dimensional finite element model;

[0067] Step 507: Repeat the nonlinear analysis of step S30 until the reinforcement requirements are met.

[0068] Furthermore, the length of the vertical struts and the prestressing force of the cables are adjusted:

[0069]

[0070] Where, L i and P i are the length of the vertical strut and the prestress of the cable after the i-th adjustment; ΔL i and ΔP i is the adjustment amount; α L and α P is the adjustment coefficient; u max and σ max are the maximum displacement and stress respectively; u allow and σ allow are the maximum allowable displacement and stress, respectively.

[0071] Furthermore, the step S60 specifically includes:

[0072] Step 601: Determine the target structural deflection value of the long-span steel corridor according to the structural design requirements;

[0073] Step 602: Select key control points to monitor the actual deflection value of the structure;

[0074] Step 603, setting the target structure deflection value as a control parameter;

[0075] Step 604, selecting the actual strain value of the cable as the response parameter;

[0076] Step 605: Establish a relationship model between control parameters and response parameters;

[0077] Step 606, setting an optimization target to make the actual deflection value as close to the target deflection value as possible;

[0078] Step 607: Set constraint conditions to ensure that the cable strain value meets the structural design requirements.

[0079] Furthermore, the step S70 specifically includes:

[0080] Step 701: construct a multi-objective optimization model, including a deflection objective function and a cable force uniformity objective function;

[0081] Step 702: setting optimization variables, including the cable force value of each cable;

[0082] Step 703, determining constraint conditions, including upper and lower limits of cable force, maximum deflection limit and maximum stress limit;

[0083] Step 704: Set optimization parameters in the SAP2000 CSiLoadOptimizer toolbox;

[0084] Step 705: Select a suitable multi-objective optimization algorithm, such as NSGA2 or MOEA / D;

[0085] Step 706: Run the optimization program to obtain a series of non-dominated solutions;

[0086] Step 707: Select the optimal cable strain value solution from the non-dominated solutions.

[0087] Furthermore, the cable force optimization calculation adopts a multi-objective optimization model:

[0088]

[0089] In the formula, f 1 (T) is the deflection objective function; f 2 (T) is the cable force uniformity objective function; T is the cable force vector; δ i and are the actual and target deflections respectively; Tj and are the actual and target cable forces respectively; n is the number of control points; m is the number of cables; T min and T max are the lower and upper limits of the cable force, respectively; δ allow is the maximum allowable deflection; σ k is the stress at the kth key point; σ allow is the maximum allowable stress; p is the number of key points.

[0090] Furthermore, the step S80 specifically includes:

[0091] Step 801, establishing a nonlinear relationship equation between cable force and strain, taking into account the effects of material nonlinearity and geometric nonlinearity;

[0092] Step 802: Collect the initial state data of the cable, including the initial length, initial cable force and endpoint coordinates;

[0093] Step 803, obtaining the elastic modulus, cross-sectional area and temperature influence coefficient of the cable material;

[0094] Step 804, determining the nonlinear coefficient of the cable, obtained through material testing or empirical formula;

[0095] Step 805, constructing a nonlinear equation group including all cables;

[0096] Step 806: Select a suitable numerical solution method, such as Newton iteration method or quasi-Newton method;

[0097] Step 807: Solve the nonlinear equation group to obtain the optimized cable force value.

[0098] Furthermore, the cable force back-calculation adopts the nonlinear equation system:

[0099]

[0100] Where, T j is the cable force of the jth cable; E j is the elastic modulus; A j is the cross-sectional area; ε j is strain; j and γ j is the nonlinear coefficient; is the cable force calculation error; L j and are the current and initial lengths respectively; α T is the temperature influence coefficient; is the initial cable force; (x j ,y j ,z j )and are the current and initial endpoint coordinates respectively.

[0101] Furthermore, the step S90 specifically includes:

[0102] Step 901, calculating the length adjustment amount of each cable according to the optimized cable force value;

[0103] Step 902, taking into account the nonlinear characteristics of the cable material, correcting the calculation result of the length adjustment amount;

[0104] Step 903, calculating the height adjustment amount of each vertical support rod, taking into account the coupling effect with the change of the length of the adjacent cable;

[0105] Step 904, calculating the angle adjustment of the key nodes based on the geometric relationship between the vertical struts and the cables;

[0106] Step 905: Evaluate the calculation errors of various adjustment amounts and make necessary corrections;

[0107] Step 906, compile a detailed process parameter table, including the tension of each cable, the lifting height of each vertical support rod, and the angle adjustment value of each node;

[0108] Step 907: Develop construction procedures and quality control plans to ensure accurate implementation of process parameters.

[0109] Further, the process parameters are determined using the following equations:

[0110]

[0111] In the formula, ΔL j is the length adjustment of the jth cable; ΔH k is the height adjustment of the kth vertical support rod; Δθ l is the angle adjustment of the lth node; k is the coupling coefficient between the height of the vertical strut and the length of the adjacent cables; N k is the set of cables connected to the kth vertical strut; H l and L l are the initial height and horizontal distance of the node respectively; and Adjust the errors for length, height, and angle separately.

[0112] Related parameter acquisition method:

[0113] 1.K(u) and B: generated by finite element analysis software;

[0114] 2.F: Determined based on structural load analysis, taking into account dead load, live load, wind load, etc.;

[0115] 3.D: Determined according to the mechanical properties of the material, the influence of temperature and stress level can be considered;

[0116] 4. and Determined according to structural design requirements and the principle of uniform force;

[0117] 5.T min and T max : Determined according to cable material properties, fatigue life and design specifications;

[0118] 6. Delta allow and σ allow : Determined according to structural design specifications and usage requirements;

[0119] 7.E j and A j : Determined according to the cable material properties and design selection, taking into account the temperature effect;

[0120] 8. Beta j and γ j : Obtained through nonlinear test of cable materials;

[0121] 9. and Obtained through field measurements;

[0122] 10. alpha T : Obtained through cable material thermal performance test;

[0123] 11. Lambda k : Determined by structural analysis and numerical simulation;

[0124] 12. H l and L l : Obtained through on-site measurements and structural drawings.

[0125] Among them, SAP2000 CSiLoadOptimizer is a toolbox developed by Computers and Structures, Inc. (CSI) for SAP2000 structural analysis software. The main functions are as follows:

[0126] Load Optimization: This tool can help users automatically generate suitable load combinations to optimize structural design. It can consider various load conditions, such as dead load, live load, wind load, earthquake load, etc., and generate different load combinations according to relevant specifications.

[0127] Component Design: By analyzing the structural response under different load combinations, CSiLoadOptimizer can automatically select the appropriate component size and reinforcement configuration to optimize the overall structural design.

[0128] Report generation: This tool can generate detailed design reports, including load analysis, component design and other information, for user reference and archiving.

[0129] Integration with SAP2000: CSiLoadOptimizer is directly integrated into SAP2000, and users can operate within the SAP2000 interface without switching between the two software.

[0130] Compared with the prior art, the beneficial effects of the optimization method for strengthening the beam string structure of a large-span steel corridor provided by the present invention are:

[0131] 1. A three-dimensional finite element model including the upper steel corridor, vertical struts and cables was established, which fully considered the material nonlinearity and geometric nonlinearity of the structure and could more accurately simulate the actual stress and deformation state of the large-span steel corridor.

[0132] 2. A systematic parameter optimization algorithm is adopted, including structural parameter adjustment, cable force optimization calculation and other steps, which can effectively control the structural deflection and stress and achieve the optimal design of structural performance.

[0133] 3. Taking into account the construction process factors of reinforcement and reconstruction, specific parameters such as the adjustment amount of cable length, vertical support rod height adjustment amount and node angle adjustment amount were determined, providing reliable guidance for on-site construction.

[0134] Compared with the prior art, the method of the present invention not only fully considers the nonlinear characteristics of the structure, but also adopts a systematic optimization algorithm to further optimize the overall stress state and deformation characteristics of the structure while meeting the safety requirements. At the same time, the construction process factors are incorporated into the optimization process to ensure the operability of the optimization scheme. Therefore, this method can effectively improve the deformation resistance and reliability of the long-span steel corridor, and solves the technical problem that the prior art optimization method cannot fully reflect the nonlinear mechanical characteristics of the structure, resulting in limited optimization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0135] Figure 1 This is the working principle diagram of the beam string structure;

[0136] Figure 2 A flow chart of the method provided by the present invention;

[0137] Figure 3 Partial design drawing of the node for strengthening the long-span steel corridor with beam string;

[0138] Figure 4 Schematic diagram of the detailed design of the connection nodes of the long-span steel corridor reinforced with beam string;

[0139] Figure 5 It is the curve diagram of deflection change during the structural optimization process;

[0140] Figure 6 This is the thermal diagram of cable force distribution after optimization;

[0141] Figure 7 This is a stress comparison diagram of key locations of the structure;

[0142] Figure 8 Statistical box plot of process parameter adjustment. DETAILED DESCRIPTION

[0143] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0144] like Figure 6 As shown in the figure, the beam string is a self-balancing system formed by connecting bending and compression members and tension members with struts. The structural system includes an upper beam, an intermediate strut and a lower cable. The prestress applied to the lower cable of the beam string causes the middle strut to produce an upward component force, which in turn produces a negative bending moment in the upper beam, thereby changing the force performance of the upper beam and improving its stiffness and bearing capacity. In the reinforcement process of the large-span steel corridor, the existing corridor is used as the upper beam structure, and vertical supports are set at the bottom of the steel corridor. Cables are used to connect the vertical supports and the upper steel corridor. When pre-tension is applied to the cables, the upper steel corridor will deform upward due to the action of the vertical struts, thereby restoring the initial deflection deformation and achieving the purpose of reinforcement.

[0145] like Figure 1 As shown, it is a flow chart of a method for optimizing a beam string structure for reinforcing a large-span steel corridor provided by the present invention. The method comprises the following steps:

[0146] S10, establishing a three-dimensional finite element model of the long-span steel corridor, wherein the three-dimensional finite element model includes an upper steel corridor, vertical struts and cables;

[0147] S20, setting boundary conditions of the three-dimensional finite element model, and determining the dead load and live load acting on the three-dimensional finite element model;

[0148] S30, performing nonlinear analysis on the three-dimensional finite element model to obtain initial deflection value and stress value;

[0149] S40, determining whether the initial deflection value and the stress value meet the reinforcement requirements, if not, executing step S50, if satisfied, executing step S60;

[0150] S50, adjusting the length of the vertical support rod and the prestress value of the cable, and returning to step S30;

[0151] S60, setting the structural deflection value as a control parameter and the cable strain value as a response parameter;

[0152] S70, using the SAP2000 CSiLoadOptimizer toolbox to perform cable force optimization calculations and obtain optimized cable strain values;

[0153] S80, reversely calculating the optimized cable strain value to obtain the final cable force optimization result;

[0154] S90. Determine the process parameters of the beam string structure for reinforcing the large-span steel corridor based on the final cable force optimization results.

[0155] The specific implementation methods of the above steps are described in detail below:

[0156] Step S10: Establish a three-dimensional finite element model of the long-span steel corridor

[0157] The specific implementation method of step S10 is: first, collect the structural design drawings, material parameters and other relevant data of the long-span steel corridor. Then, use finite element analysis software such as ANSYS, ABAQUS, etc. to establish a three-dimensional finite element model including the upper structure of the steel corridor, vertical struts and cables. In the modeling process, it is necessary to select appropriate unit types, meshing methods and other parameters according to the actual structural conditions. For connectors such as welds, hinges, etc., corresponding constraint relationships should be used for modeling. The establishment of the entire three-dimensional finite element model aims to reflect the actual stress state and deformation of the long-span steel corridor as accurately as possible.

[0158] Step S20: Set boundary conditions and determine the loads acting on the model

[0159] The specific implementation method of step S20 is: first, according to the actual support conditions of the long-span steel corridor, reasonable boundary conditions are set in the finite element model. For example, for the supports located on the piers or anti-pulling piles, displacement constraints can be set; for other support positions, different constraints such as rolling or simple support can be set.

[0160] Secondly, determine the various loads acting on the three-dimensional finite element model. Mainly including:

[0161] 1) Dead load: permanent loads such as the deadweight of the steel corridor and attached facilities. It can be calculated based on the structural drawings and material parameters.

[0162] 2) Live load: temporary loads such as personnel and vehicles. It can be determined according to the use function and design specifications.

[0163] 3) Environmental loads: such as wind loads, snow loads, etc. They can be calculated based on meteorological data and design specifications.

[0164] The determination of the above-mentioned loads should comply with the requirements of relevant design specifications to ensure that the finite element model can accurately simulate the stress state of the large-span steel corridor under actual use conditions.

[0165] Step S30: Perform nonlinear analysis on the three-dimensional finite element model

[0166] The specific implementation of step S30 is: for the established three-dimensional finite element model, a nonlinear analysis method is used to perform mechanical calculations on it. The main feature of nonlinear analysis is that it can take into account the nonlinear effects of structural materials, geometry, etc., so as to more accurately reflect the actual stress and deformation state of the structure.

[0167] Specifically, the nonlinear analysis process can be expressed using the following set of mathematical equations:

[0168]

[0169] Where K(u) is the nonlinear stiffness matrix, u is the displacement vector, F is the external force vector, and F nl (u) is the nonlinear internal force vector, B is the strain-displacement matrix, σ nl (u) is the nonlinear stress tensor, D is the elastic matrix, ε nl (u) is the nonlinear strain tensor.

[0170] By solving this set of equations, the initial deflection and stress values ​​of the structure can be obtained, providing the necessary basic data for structural optimization in subsequent steps.

[0171] Step S40: Determine whether the initial deflection value and stress value meet the reinforcement requirements

[0172] The specific implementation method of step S40 is: first, according to the structural design specifications and actual use requirements, determine the maximum allowable deflection value u of the long-span steel corridor allow and the maximum allowable stress value σ allow .

[0173] Then, compare the initial deflection value u obtained in step S30 max and stress value σ max Compare with the above allowable values ​​to determine whether the reinforcement requirements are met:

[0174]

[0175] If the above requirements are not met, step S50 is executed to adjust the structural parameters; if the requirements are met, step S60 is executed to start the structural optimization calculation.

[0176] Through this step, it can be ensured that the initial structure meets the basic safety requirements for use and lay the foundation for subsequent optimization calculations.

[0177] Step S50: Adjust the length of the vertical support rod and the prestress value of the cable

[0178] The specific implementation of step S50 is: for the deflection or stress exceeding the standard found in step S40, it is necessary to adjust the length of the vertical support rod and the prestress value of the cable to achieve the goal of meeting the reinforcement requirements. The specific implementation process is as follows:

[0179]

[0180] Among them, L i and P i are the length of the vertical strut and the prestress of the cable after the i-th adjustment; ΔL i and ΔP i is the adjustment amount; α L and α P It is the empirical adjustment coefficient, and its value can be 0.1~0.3.

[0181] By adjusting the length of the vertical struts and the prestress of the cables one by one, the maximum deflection and maximum stress of the structure meet the reinforcement requirements, namely:

[0182]

[0183] After the adjustment is completed, return to step S30 to re-perform nonlinear analysis calculation until the reinforcement requirements are met.

[0184] Step S60: Set the structural deflection value as the control parameter and the cable strain value as the response parameter

[0185] The specific implementation of step S60 is: after completing the structural adjustment of the aforementioned steps S40 and S50, further optimizing the beam string structure of the large-span steel corridor, wherein the structural deflection value is used as a control parameter and the cable strain value is used as a response parameter for subsequent optimization calculation.

[0186] Specifically, the target structural deflection value is set to The actual strain value of the cable is ε i Through optimization calculation, the actual deflection value δ i As close to the target value as possible At the same time, the cable strain value ε i It can also meet the structural design requirements.

[0187] This step aims to ensure that the overall deformation of the structure meets the usage standards, and at the same time the force on the cables can be uniform and controllable, laying the foundation for subsequent cable force optimization calculations.

[0188] Step S70: Use SAP2000CSiLoadOptimizer toolbox to perform cable force optimization calculation

[0189] The specific implementation method of step S70 is: adopting a multi-objective optimization model and using the SAP2000CSiLoadOptimizer toolbox to optimize the cable force to obtain the optimized cable strain value.

[0190] The specific optimization model is as follows:

[0191]

[0192] Among them, f 1 (T) is the deflection objective function, f 2 (T) is the cable force uniformity objective function, T is the cable force vector, δ i and are the actual and target deflections, T j and are the actual and target cable forces, n is the number of control points, m is the number of cables, T min and T max are the lower and upper limits of the cable force, δ allow is the maximum allowable deflection, σ k is the stress at the kth key point, σ allow is the maximum allowable stress, and p is the number of critical points.

[0193] By solving this multi-objective optimization problem, the optimal cable strain value that meets the requirements of structural deflection control and cable force uniformity can be obtained, which lays the foundation for the subsequent cable force back-calculation.

[0194] Step S80: Obtain the final cable force optimization result by reverse calculation based on the optimized cable strain value

[0195] The specific implementation method of step S80 is: using a nonlinear equation group to inversely deduce the optimized cable force value, and the specific equation group is as follows:

[0196]

[0197] Among them, T j is the cable force of the jth cable, E j is the elastic modulus, A j is the cross-sectional area, ε j is strain, β j and γ j is the nonlinear coefficient, is the cable force calculation error, L j and are the current and initial lengths, α T is the temperature influence coefficient, is the initial cable force, (x j ,y j ,z j)and are the current and initial endpoint coordinates respectively.

[0198] By solving the nonlinear equations, the optimized cable force value T can be inferred. j This provides the necessary data support for the subsequent determination of process parameters.

[0199] Step S90: Determine the process parameters for reinforcing the large-span steel corridor according to the cable force optimization results

[0200] The specific implementation of step S90 is: according to the cable force optimization result obtained in the above step S80, combined with the on-site measurement data, the specific process parameters for the reinforcement of the long-span steel corridor are determined, including the cable length adjustment, the vertical support rod height adjustment, and the node angle adjustment. The specific calculation process is as follows:

[0201]

[0202] Among them, ΔL j is the length adjustment of the jth cable, ΔH k is the height adjustment of the kth vertical support rod, Δθ l is the angle adjustment of the lth node, λ k is the coupling coefficient between the height of the vertical strut and the length of the adjacent cables, N k is the set of cables connected to the kth vertical strut, H l and L l are the initial height and horizontal distance of the node respectively, and Adjust the errors for length, height, and angle separately.

[0203] Through the above calculations, the specific process parameters for the reinforcement and reconstruction of the long-span steel corridor can be determined, providing guidance for subsequent on-site construction. In order to facilitate installation and ensure a reasonable stress state of the structure, the vertical support rods and the upper steel corridor are connected through pin lugs, and the cables are connected to the vertical support rods and the upper steel corridor through cable clamps and cable heads. Stiffening plates are set at the connection positions. The stiffening plates of the vertical support and the steel corridor are welded to the flange plates of the steel corridor and corner braces are added. The node design of the long-span steel corridor reinforced with a string beam is as follows: Figure 7-8 shown.

[0204] In summary, the present invention proposes a method for optimizing the tension-string structure for reinforcing large-span steel corridors, which ultimately determines the specific process parameters for reinforcement and transformation through steps such as establishing a three-dimensional finite element model, performing nonlinear analysis, adjusting structural parameters, and optimizing cable force.

[0205] Specifically, the principle of the present invention is:

[0206] Firstly, a three-dimensional finite element model including the upper steel corridor, vertical struts and cables was established, and nonlinear analysis and calculation were performed to obtain the initial structural deflection and stress state. Then, in case of excessive deflection or stress, the structural parameters were optimized by adjusting the length of the vertical struts and the prestress of the cables to meet the reinforcement requirements.

[0207] Furthermore, the present invention adopts a multi-objective optimization algorithm, takes the structural deflection value as the control parameter, and the cable strain value as the response parameter to optimize the cable force of the structure. This step is to ensure that the overall deformation of the structure is controlled within the allowable range, and the cable force can also reach a uniform and controllable state.

[0208] After completing the above parameter optimization calculation, the present invention also infers the final cable force value based on the optimization result, and determines the specific process parameters of the reinforcement and transformation based on this, such as the cable length adjustment amount, the vertical support rod height adjustment amount and the node angle adjustment amount, etc. This not only meets the optimization requirements of the structural performance, but also ensures the operability of the optimization scheme in actual construction.

[0209] The above optimization effects can be achieved mainly due to the following key technologies:

[0210] 1. Use a three-dimensional finite element model to fully describe the structural form and stress characteristics. Compared with a simplified two-dimensional model or one-dimensional beam element, the three-dimensional model can more accurately reflect the actual stress state of the long-span steel corridor, laying the foundation for subsequent nonlinear analysis and parameter optimization.

[0211] 2. Use nonlinear analysis methods to consider the coupling effect of materials and geometry. By solving nonlinear equations involving strain-stress relationship, displacement-strain relationship, etc., the initial deflection and stress state of the structure can be obtained, providing a basis for determining the reinforcement requirements.

[0212] 3. Use a systematic parameter optimization algorithm to achieve the optimization of structural performance. The multi-objective optimization model involved in the present invention can simultaneously meet the target requirements such as structural deflection control and cable strain uniformity, and determine the specific process parameters through cable force back calculation. Compared with empirical parameter adjustment, this system optimization method can better improve structural performance.

[0213] 4. Incorporate construction process factors into the optimization process. In addition to meeting the structural use requirements, the present invention also infers actual process parameters such as the cable length adjustment, vertical strut height adjustment, and node angle adjustment based on the optimization results to ensure the operability of the optimization solution in on-site construction.

[0214] In summary, the large-span steel corridor reinforcement optimization method proposed in the present invention fully considers the nonlinear characteristics of the structure, adopts a systematic parameter optimization algorithm, and takes into account the construction process requirements, thereby effectively improving the structure's anti-deformation performance and reliability.

[0215] In order to better understand and implement the present invention, an embodiment of a specific application scenario of the present invention is provided below: A large-span steel corridor with a span of 120 meters is built in a certain area. As an important transportation hub in the city, the steel corridor bears a large amount of people and vehicles. During long-term use, serious problems such as excessive deflection and local stress concentration have occurred, and reinforcement and reconstruction are urgently needed.

[0216] According to the optimization method proposed in this invention, the long-span steel corridor is analyzed and optimized in detail. The specific process is as follows:

[0217] 1. Establish a 3D finite element model

[0218] Firstly, the design drawings and material parameters of the long-span steel corridor were collected, and a three-dimensional finite element model including the upper steel corridor, vertical struts and cables was established using ANSYS software. In the modeling process, appropriate unit types and meshing methods were selected according to the actual structural conditions, and corresponding constraint relationships were adopted for connectors such as welds and pins. The establishment of the entire three-dimensional model aims to reflect the actual stress and deformation state of the long-span steel corridor as accurately as possible.

[0219] Table 1 Parameters of the three-dimensional finite element model of the long-span steel corridor

[0220] Parameter name Parameter Value Total number of nodes 23456 Total number of units 18345 Elastic modulus of steel 210GPa Poisson's ratio of steel 0.3 Steel material yield strength 345MPa Steel material tensile strength 490MPa

[0221] 2. Determine the applied load

[0222] After establishing the 3D finite element model, various loads acting on the long-span steel corridor were determined according to the requirements of the site investigation and design specifications, mainly including:

[0223] (1) Dead load: It is composed of permanent loads such as the dead weight of the steel corridor and ancillary facilities. The total dead load is calculated to be 35.6 kN / m.

[0224] (2) Live load: including personnel load and vehicle load. The total live load is calculated to be 45.2 kN / m according to the functional requirements and relevant specifications.

[0225] (3) Environmental load: According to local meteorological data, the wind load value is 0.65 kN / m 2 , the snow load value is 0.35kN / m 2 .

[0226] The determination of the above-mentioned loads complies with the requirements of relevant design specifications and provides accurate external load input for subsequent nonlinear analysis.

[0227] 3. Nonlinear analysis calculation

[0228] After completing the establishment of the finite element model and determining the load, the nonlinear analysis and calculation of the long-span steel corridor was carried out. The specific mathematical equations used are as follows:

[0229]

[0230] By solving the above nonlinear equations, the initial deflection and stress values ​​of the long-span steel corridor under the current load are obtained. The specific results are shown in Table 2:

[0231] Table 2 Initial analysis results of long-span steel corridors

[0232]

[0233]

[0234] As can be seen from Table 2, the maximum deflection of the long-span steel corridor exceeds the allowable value, and the local stress is close to the yield strength of the material, which poses a certain safety hazard. Therefore, it is necessary to further optimize and adjust the structural parameters to meet the reinforcement requirements.

[0235] 4. Structural parameter adjustment

[0236] In response to the problems of excessive deflection and excessive stress found in step 3, the vertical support rod length and cable prestress were first adjusted and optimized. The specific adjustment process is as follows:

[0237]

[0238] Among them, α L =0.2,α P =0.15. After three iterations of calculation, the length of the vertical brace was adjusted from the original 12m to 15.12m, and the prestress of the cable was adjusted from the original 45kN to 41.55kN. After the adjustment, the maximum deflection of the long-span steel corridor was reduced to 116.8mm, and the maximum stress was reduced to 301MPa, both meeting the reinforcement requirements.

[0239] 5. Cable force optimization calculation

[0240] After completing the preliminary adjustment of the structural parameters, the multi-objective optimization model was further used to optimize the cable force in order to achieve coordinated control of the structural deflection and cable strain. The specific optimization model is as follows:

[0241]

[0242] Among them, δ i and are the actual and target deflections (100 mm), T j and are the actual and target cable forces, n=25 is the number of deflection control points, m=32 is the number of cables, T min =30kN,T max =120kN is the cable force limit, δ allow =120mm is the maximum allowable deflection, σ k is the stress at the kth key point, σ allow =310MPa is the maximum allowable stress, and p=45 is the number of critical stress points.

[0243] By using the SAP2000CSiLoadOptimizer toolbox for optimization calculation, the optimization results that meet the requirements of structural deflection control and cable force uniformity are obtained. The key parameters are shown in Table 3:

[0244] Table 3 Cable force optimization calculation results

[0245] parameter value Maximum deflection 99.6mm Average cable tension 74.2kN Standard deviation of cable force 8.6kN

[0246] It can be seen from Table 3 that after the cable force optimization calculation, the maximum deflection of the large-span steel corridor is controlled within 100 mm, and the cable force has reached a relatively uniform state, meeting the design requirements.

[0247] 6. Cable force reverse calculation and process parameter determination

[0248] With the above optimization calculation results, the cable force was reversely calculated and the specific process parameters of the reinforcement and transformation were determined, including the cable length adjustment, vertical support rod height adjustment and node angle adjustment, as follows:

[0249]

[0250] Based on the above calculations, the specific process parameters for the reinforcement and reconstruction of the large-span steel corridor were determined:

[0251] 1) Cable length adjustment ΔL j Between 0.12 and 0.48 m;

[0252] 2) Vertical support rod height adjustment ΔH k Between 0.15 and 0.42 m;

[0253] 3) Node angle adjustment Δθ l Between 0.4 and 1.2 degrees.

[0254] These specific process parameters provide a reliable guide for subsequent on-site construction. The following data charts intuitively demonstrate the optimization effect of the present invention in this embodiment:

[0255] Figure 2 The deflection change curve during the structural optimization process is depicted. The horizontal axis represents the number of optimization iterations, and the vertical axis represents the maximum deflection value (unit: mm). It can be seen from the figure that the initial deflection is 135.6 mm. After multiple iterations of optimization, the deflection is finally reduced to 99.6 mm, which is much lower than the allowable value of 120 mm shown by the red dotted line.

[0256] Figure 3 This is the optimized cable force distribution heat map. This map uses different shades of color to represent the cable force of each cable, and annotates the specific value in each grid. The figure shows the cable force distribution of 32 cables in 4 layers, with an average cable force of 74.2kN and a standard deviation of 8.6kN. Through this heat map, the uniformity of cable force distribution can be intuitively judged, providing a reference for construction cable adjustment.

[0257] Figure 4 The stress comparison of key positions of the structure is shown. The figure contains the stress values ​​of four key positions: mid-span, 1 / 4 span, support and connection node. Different colored bar graphs are used to represent the initial stress, optimized stress and allowable stress. It can be seen from the figure that although the stress after optimization has increased slightly, it is still controlled within the allowable stress range, ensuring the safety of the structure.

[0258] Figure 5 It is a statistical box plot of process parameter adjustment. This chart shows the adjustment range of three key process parameters: cable length adjustment, vertical support rod height adjustment and node angle adjustment. Through the form of box plot, we can clearly see the median, quartile range and extreme value of each parameter adjustment, providing a specific reference for on-site construction.

[0259] In summary, the optimization method proposed in this invention was used to carry out a detailed reinforcement design for a large-span steel corridor with a span of 120 meters. First, a three-dimensional finite element model was established, and the initial deflection and stress state were determined by nonlinear analysis; then, the length of the vertical struts and the prestress of the cables were adjusted to make the structural performance meet the reinforcement requirements; further, a multi-objective optimization algorithm was used to optimize the cable force and achieve coordinated control of the structural deflection and cable strain. Finally, specific process parameters were inferred based on the optimization results to ensure the operability of the optimization scheme in on-site construction. The entire optimization design process fully considered the nonlinear characteristics of the structure, adopted a systematic parameter optimization algorithm, and took into account the construction process factors, providing a scientific and effective solution for the reinforcement and reconstruction of the large-span steel corridor.

[0260] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for optimizing the beam string structure for strengthening a long-span steel corridor, characterized in that , including the following steps: S10, establishing a three-dimensional finite element model of the long-span steel corridor, wherein the three-dimensional finite element model includes an upper steel corridor, vertical struts and cables; S20, setting boundary conditions of the three-dimensional finite element model, and determining a dead load and a live load acting on the three-dimensional finite element model; S30, performing nonlinear analysis on the three-dimensional finite element model to obtain initial deflection value and stress value; S40, determining whether the initial deflection value and the stress value meet the reinforcement requirements, if not, executing step S50, if satisfied, executing step S60; S50, adjusting the length of the vertical support rod and the prestress value of the cable, and returning to step S30; S60, setting the structural deflection value as a control parameter and the cable strain value as a response parameter; S70, using the SAP2000 CSiLoadOptimizer toolbox to perform cable force optimization calculations and obtain optimized cable strain values; S80, obtaining a final cable force optimization result by reverse calculation according to the optimized cable strain value; S90. Determine the process parameters for reinforcing the beam-string structure of the large-span steel corridor according to the final cable force optimization result.

2. The optimization method for strengthening a beam string structure of a large-span steel corridor according to claim 1 is characterized in that: The step S10 specifically includes: Step 101: Collect structural design drawings and material parameters of the long-span steel corridor; Step 102, select finite element analysis software, including ANSYS or ABAQUS; Step 103, establishing a three-dimensional finite element model including the steel corridor superstructure, vertical struts and cables in the finite element analysis software; Step 104: Select appropriate unit type and meshing method according to actual structural conditions; Step 105, modeling the connector, including the solder joints and hinges, using corresponding constraint relationships; Step 106: Adjust and optimize the three-dimensional finite element model to ensure that it can accurately reflect the actual stress state and deformation of the long-span steel corridor.

3. The optimization method for strengthening the beam string structure of a large-span steel corridor according to claim 2 is characterized in that: The step S20 specifically includes: Step 201: setting boundary conditions in the finite element model according to the actual support conditions of the long-span steel corridor; Step 202: setting displacement constraints for supports located on bridge piers or anti-pulling piles; Step 203, setting different rolling or simply supported constraint conditions for other support positions; Step 204, determining the dead load acting on the three-dimensional finite element model, including the deadweight of the steel corridor and the permanent load of the attached facilities; Step 205, determining the live load acting on the three-dimensional finite element model, including temporary loads of personnel and vehicles; Step 206: determine the environmental loads acting on the three-dimensional finite element model, including wind loads and snow loads; Step 207: Check and adjust the various loads determined according to the requirements of relevant design specifications.

4. The optimization method for strengthening a beam string structure of a large-span steel corridor according to claim 3 is characterized in that: The step S30 specifically includes: Step 301, establishing a mathematical model for nonlinear analysis, including a nonlinear stiffness matrix, a displacement vector, an external force vector, a nonlinear internal force vector, a strain displacement matrix, a nonlinear stress tensor, an elasticity matrix and a nonlinear strain tensor; Step 302: construct a nonlinear equilibrium equation, including considering the effects of material nonlinearity and geometric nonlinearity; Step 303: using an iterative algorithm to solve the nonlinear equilibrium equation, such as the Newton-Raphson method or the arc-length method; Step 304, calculating the displacement field of the structure, including node displacements and component deformations; Step 305, calculating the stress field of the structure according to the displacement field, including the axial force, shear force and bending moment of each component; Step 306: extract the displacement value of the key node as the initial deflection value; Step 307: extract the stress value of the key component as the initial stress value.

5. The optimization method for strengthening a beam string structure of a large-span steel corridor according to claim 4 is characterized in that: The step S40 specifically includes: Step 401, determining the maximum allowable deflection value of the long-span steel corridor according to the structural design specification; Step 402: Determine the maximum allowable stress value of the long-span steel corridor according to material properties and structural safety factor; Step 403, comparing the initial deflection value obtained in step S30 with the maximum allowable deflection value; Step 404, comparing the initial stress value obtained in step S30 with the maximum allowable stress value; Step 405: When the initial deflection value is greater than the maximum allowable deflection value or the initial stress value is greater than the maximum allowable stress value, it is determined that the reinforcement requirement is not met; Step 406: When the initial deflection value is less than or equal to the maximum allowable deflection value and the initial stress value is less than or equal to the maximum allowable stress value, it is determined that the reinforcement requirement is met.

6. The optimization method for strengthening a beam string structure of a large-span steel corridor according to claim 5, characterized in that: The step S50 specifically includes: Step 501, setting a calculation formula for the adjustment amount of the vertical brace length, wherein the adjustment amount is proportional to the difference between the maximum deflection value and the maximum allowable deflection value; Step 502, setting a calculation formula for the adjustment amount of the cable prestress value, wherein the adjustment amount is proportional to the difference between the maximum stress value and the maximum allowable stress value; Step 503: Select an empirical adjustment coefficient to control the amplitude of each adjustment; Step 504, calculate the new vertical brace length, which is the previous length plus the adjustment amount; Step 505, calculating a new cable prestress value, which is the previous prestress value plus the adjustment amount; Step 506, applying the new vertical brace length and cable prestress value to the three-dimensional finite element model; Step 507: Repeat the nonlinear analysis of step S30 until the reinforcement requirements are met.

7. The optimization method for strengthening a beam string structure of a large-span steel corridor according to claim 6, characterized in that: The step S60 specifically includes: Step 601: Determine the target structural deflection value of the long-span steel corridor according to the structural design requirements; Step 602: Select key control points to monitor the actual deflection value of the structure; Step 603, setting the target structure deflection value as a control parameter; Step 604, selecting the actual strain value of the cable as the response parameter; Step 605: Establish a relationship model between control parameters and response parameters; Step 606, setting an optimization target to make the actual deflection value as close to the target deflection value as possible; Step 607: Set constraint conditions to ensure that the cable strain value meets the structural design requirements.

8. The optimization method for strengthening a beam string structure of a large-span steel corridor according to claim 7, characterized in that: The step S70 specifically includes: Step 701: construct a multi-objective optimization model, including a deflection objective function and a cable force uniformity objective function; Step 702: setting optimization variables, including the cable force value of each cable; Step 703, determining constraint conditions, including upper and lower limits of cable force, maximum deflection limit and maximum stress limit; Step 704: Set optimization parameters in the SAP2000 CSiLoadOptimizer toolbox; Step 705: Select a suitable multi-objective optimization algorithm, such as NSGA2 or MOEA / D; Step 706: Run the optimization program to obtain a series of non-dominated solutions; Step 707: Select the optimal cable strain value solution from the non-dominated solutions.

9. The optimization method for strengthening a beam string structure of a large-span steel corridor according to claim 8, characterized in that: The step S80 specifically includes: Step 801, establishing a nonlinear relationship equation between cable force and strain, taking into account the effects of material nonlinearity and geometric nonlinearity; Step 802: Collect the initial state data of the cable, including the initial length, initial cable force and endpoint coordinates; Step 803, obtaining the elastic modulus, cross-sectional area and temperature influence coefficient of the cable material; Step 804, determining the nonlinear coefficient of the cable, obtained through material testing or empirical formula; Step 805, constructing a nonlinear equation group including all cables; Step 806: Select a suitable numerical solution method, such as Newton iteration method or quasi-Newton method; Step 807: Solve the nonlinear equation group to obtain the optimized cable force value.

10. The optimization method for strengthening the beam string structure of a large-span steel corridor according to claim 9, characterized in that: The step S90 specifically includes: Step 901, calculating the length adjustment amount of each cable according to the optimized cable force value; Step 902, taking into account the nonlinear characteristics of the cable material, correcting the calculation result of the length adjustment amount; Step 903, calculating the height adjustment amount of each vertical support rod, taking into account the coupling effect with the change of the length of the adjacent cable; Step 904, calculating the angle adjustment of the key nodes based on the geometric relationship between the vertical struts and the cables; Step 905: Evaluate the calculation errors of various adjustment amounts and make necessary corrections; Step 906, compile a detailed process parameter table, including the tension of each cable, the lifting height of each vertical support rod, and the angle adjustment value of each node; Step 907: Develop construction procedures and quality control plans to ensure accurate implementation of process parameters.

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