BIM (Building Information Modeling)-based elastic sling of high-speed rail overhead line system and electric connection prefabrication processing method

Abstract

The invention discloses a BIM-based high-speed rail overhead line system elastic sling and electric connection prefabrication processing method, and relates to the field of elastic sling processing, and the method comprises the steps: building a knowledge base, and building an initial elastic sling BIM model of a target project through parametric modeling; establishing an initial finite element analysis model of the target project through grid division and material attribute mapping; calculating the internal force and deformation of the elastic sling under the action of the static load by adopting an incremental iteration method; carrying out dynamic time-history analysis by adopting a direct integration method to obtain time-history curves of the elastic sling under different seismic waves; according to static and dynamic analysis results, stress-strain response of the elastic sling is extracted, and the initial elastic sling BIM model is optimized by adopting a topological optimization method with the minimum strain of the elastic sling as the target and the stress constraint of the elastic sling as the condition; and updating the finite element analysis model by using the optimized elastic sling BIM model. According to the method, the parameterized design degree of the elastic sling is improved.

Description

Technical Field

[0001] The present application relates to the field of elastic sling processing, and in particular to a BIM-based high-speed railway contact network elastic sling and electrical connection prefabrication processing method. Background Art

[0002] The rapid development of high-speed railways has put forward higher requirements on the reliability and stability of the contact network. As a key component of the high-speed railway power supply system, the performance of the contact network directly affects the safe operation and operational efficiency of the train. In order to adapt to complex working conditions such as high speed, heavy load, and high density, the contact network needs to continuously improve the scientific and refined level of design, construction, and operation and maintenance. However, the traditional contact network design and production methods have problems such as experience dependence, information islands, and insufficient analysis, which can no longer meet the technical requirements of the new era. It is urgent to introduce advanced information and intelligent technologies to promote the transformation and upgrading of the contact network design and production mode.

[0003] BIM (Building Information Modeling), as a representative technology of informatization in the construction industry, has been widely used in the field of engineering construction in recent years. BIM uses digital models as a carrier to integrate information such as geometry, attributes, and status throughout the life cycle of the project, and significantly improves the efficiency and quality of project implementation through visualization, collaboration, and optimization. Introducing BIM into contact network design and production is expected to break the current technical bottleneck, achieve the integration of design, construction, and operation and maintenance, and improve the level of contact network construction. This is not only an inevitable choice to comply with the development trend of informatization, but also an important measure to promote high-speed rail technology progress and industrial upgrading.

[0004] Elastic slings are one of the key components of the contact network and are crucial to ensuring the geometric shape and dynamic performance of the contact network. The design of traditional elastic slings mainly relies on experience, lacks theoretical guidance and information support, and is difficult to cope with the increasingly high technical requirements. The design lacks a unified information expression standard, and the attribute data such as geometry, materials, and processes are scattered and incomplete, making it difficult to establish professional associations, and the level of parameterization and intelligence needs to be improved urgently. Elastic slings need to withstand a variety of loads such as wind loads, ice loads, and earthquakes. The existing design lacks a systematic static and dynamic performance analysis, and it is difficult to fully evaluate the force characteristics and safety margins. The layout of elastic slings has a significant impact on the performance of the contact network, but currently it is mainly optimized by empirical methods or parameter methods. There is a lack of advanced topological optimization and intelligent optimization methods, and the scientificity and efficiency of the optimization need to be strengthened. Summary of the invention

[0005] In response to the problem of low degree of parametric design of elastic slings in the prior art, the present application provides a BIM-based method for prefabrication of high-speed railway contact network elastic slings and electrical connections. Static and dynamic analysis are used to evaluate the response of elastic slings under complex loads, and a topological optimization algorithm is introduced to optimize the layout of the elastic slings. This improves the degree of parametric design while ensuring the safety of the elastic slings.

[0006] The purpose of this application is achieved through the following technical solutions.

[0007] The present application provides a BIM-based high-speed railway contact network elastic sling and electrical connection prefabrication processing method, including: collecting design parameters and processing data of different types of high-speed railway contact network elastic slings, and establishing a knowledge base including geometric parameters, material properties and processing technology; according to the knowledge base, through parametric modeling, establishing an initial elastic sling BIM model of the target project; the initial elastic sling BIM model includes the spatial position, size and material property parameters of the elastic sling; according to the initial elastic sling BIM model, through meshing and material property mapping, establishing an initial finite element analysis model of the target project; in the initial finite element analysis model, applying a static load condition, and using an incremental iteration method to calculate the internal load of the elastic sling under the static load. force and deformation; static loads include dead loads and live loads; in the initial finite element analysis model, simulated seismic waves are input, and the direct integration method is used for dynamic time history analysis to obtain the displacement, velocity, acceleration and internal force time history curves of the elastic sling under different seismic waves; according to the results of static and dynamic analysis, the stress-strain response of the elastic sling is extracted, and the topological optimization method is used to optimize the initial elastic sling BIM model with the goal of minimizing the strain of the elastic sling and the stress constraint of the elastic sling as the condition; the finite element analysis model is updated using the optimized elastic sling BIM model until the performance of the elastic sling meets the design requirements and the final elastic sling BIM model is obtained; according to the final elastic sling BIM model, the elastic sling processing parameters are derived.

[0008] Furthermore, in the initial finite element analysis model, a static load condition is applied, and an incremental iteration method is used to calculate the internal force and deformation of the elastic sling under the static load, including: mapping the constant load information and live load information in the initial elastic sling BIM model into constant load data and live load data respectively; linearly superimposing the constant load data and live load data as static load data applied to the initial finite element model; discretizing the static load data into multiple incremental step data according to the arc length method; obtaining the nonlinear state index of the elastic sling response, and when the nonlinear state index exceeds the threshold, adjusting the step size of the incremental step; when the nonlinear state index exceeds the preset extreme value, using the secant method to interpolate the incremental step data; wherein the nonlinear state index includes deflection; For each incremental step data, the Newton-Raphson iteration format is used. In the first iteration, the displacement increment data is extracted and substituted into the tangent stiffness matrix to form the tangent stiffness equation; in subsequent iterations, the displacement increment data is extracted and substituted into the secant stiffness matrix to form the secant stiffness equation; at the same time, the energy criterion is used to correct the direction of the displacement increment data to generate optimized displacement increment data; after all incremental step calculations are completed, the characteristic point data reflecting the deformation and failure mode of the elastic sling are extracted from the displacement field, stress field and strain field data, and the characteristic points include the maximum deflection points; the characteristic point data are statistically analyzed to obtain the weak parts of the elastic sling, and the elastic sling response data under static load is formed.

[0009] Furthermore, a secant stiffness equation is formed, including: extracting unit stress data and unit strain data of the initial finite element analysis model, inputting the unit stress data and unit strain data into the tangent stiffness matrix, and obtaining the tangent stiffness matrix data of the elastic sling in the current incremental step; in the first iteration, extracting displacement increment component data from the arc length increment data of the current incremental step, substituting the displacement increment component data and the tangent stiffness matrix data into the tangent stiffness equation, and solving the node displacement data of the first iteration; using the node displacement data of the first iteration to update the unit stress data and unit strain data; inputting the updated unit stress data and unit strain data into the secant stiffness matrix, and obtaining the secant stiffness matrix data of the second iteration; from the current incremental step The displacement increment component data is extracted from the arc length increment data of the step, and the displacement increment component data and the secant stiffness matrix data are substituted into the secant stiffness matrix to solve the node displacement data of the second iteration; based on the node displacement data of the first iteration and the node displacement data of the second iteration, the displacement difference data of the two iterations are calculated; if the displacement difference data is less than the convergence threshold, the node displacement data of the second iteration is used as the converged displacement data of the current increment step, and the iterative calculation is stopped, otherwise, the next iterative calculation is entered; the node displacement data of the second iteration is used to update the unit stress data and the unit strain data, and the updated unit stress data and the unit strain data are input into the secant stiffness matrix to obtain the secant stiffness matrix of the next iteration.

[0010] Furthermore, the optimized displacement increment data is generated, including: taking the arc length increment data of the current increment step and the node displacement data of the previous iteration as input, solving the displacement increment direction correction coefficient of the current iteration through the minimum potential energy; multiplying the displacement increment direction correction coefficient with the displacement increment component data of the current increment step to obtain the corrected displacement increment component data; substituting the corrected displacement increment component into the secant stiffness matrix, solving the node displacement data of the current iteration, and returning to the displacement convergence judgment step until the node displacement data of the current increment step converges.

[0011] Furthermore, the displacement, velocity, acceleration and internal force time history curves of the elastic sling under different seismic waves are obtained, including: according to the intensity and site category of the project area, a set of representative seismic waves are selected from the seismic wave database as input seismic wave data; the input seismic wave data are baseline corrected and the amplitude adjusted using the vibration mode decomposition response spectrum method to obtain simulated seismic wave data; the simulated seismic wave data are converted into node load time history data, applied to the basic node degrees of freedom of the initial finite element analysis model, and the dynamic balance equation considering the seismic effect is established, and the dynamic balance equation is directly integrated and solved using the Newmark-β method to obtain each The node displacement, node velocity and node acceleration data of one time step; according to the node displacement data of each time step, the unit strain data is calculated using the strain-displacement relationship, and the unit stress data is updated using the constitutive relationship; the unit stress data is multiplied and integrated with the unit volume to obtain the unit node equivalent force data; the unit node equivalent force data is assembled into the overall node load data, and substituted into the dynamic balance equation for the next step of integral calculation; after completing the dynamic integral calculation of the entire time series, the node displacement, node velocity, node acceleration and unit stress data of each time step are extracted to form the displacement, velocity, acceleration and internal force time history curve data of the elastic sling under earthquake action.

[0012] Furthermore, the node displacement, node velocity and node acceleration data of each time step are obtained, including: multiplying the simulated seismic wave data with the elastic cable mass matrix to convert it into node load time history data, and applying it to the basic nodes of the initial finite element analysis model; introducing the Rayleigh damping matrix in the initial finite element analysis model, establishing a dynamic equilibrium equation including the elastic cable stiffness, mass and damping terms, and obtaining a differential equation describing the elastic cable response under earthquake action; discretizing the node displacement, node velocity and node acceleration in the dynamic equilibrium equation using the central difference format, selecting the integration step according to the earthquake duration and the elastic cable period, and discretizing the time interval into multiple time steps; integrating the dynamic equilibrium equation through Newmark parameters β and γ, and establishing an iterative format between the node displacement, velocity and acceleration of the current time step; setting the node displacement, node velocity and node acceleration of the elastic cable at the initial moment to zero, and in the first time step, using the node load data as input, and using the Newmark iterative format to explicitly solve the node displacement, node velocity and node acceleration of the first time step; in the second time step, according to The node displacement data obtained in the previous time step are used to calculate the unit strain increment of the current time step using the strain-displacement relationship, and the unit stress is updated using the constitutive relationship. The unit stress is multiplied by the unit stress and the unit volume and integrated to obtain the node equivalent force increment of the current time step; the node velocity obtained in the previous step is substituted into the damping force expression to calculate the damping force increment of the current time step; the node load increment, damping force increment and node equivalent force increment of the current time step are introduced into the dynamic equilibrium equation to establish an algebraic equation group reflecting the force equilibrium state of the node at the current moment; the algebraic equation group is solved to obtain the node displacement increment of the second time step, and the node velocity increment and node acceleration increment of the second time step are updated using the Newmark iteration relationship; the node displacement increment, node velocity increment and node acceleration increment are respectively added to the calculation results of the previous time step to obtain the node displacement, node velocity and node acceleration of the current time step; the time step iteration update is repeated until the full time course dynamic response calculation is completed, and the node displacement, node velocity and node acceleration data of each time step are extracted to form the dynamic response time history curve of the elastic sling under earthquake action.

[0013] Furthermore, the initial elastic cable BIM model is optimized, including: according to the elastic cable response data under static load conditions and the elastic cable response data under earthquake conditions, by combining the displacement field, stress field and strain field data under different conditions, the envelope surface data reflecting the response characteristics of the elastic cable under the combined load is calculated; the envelope surface data is used to update the stress-strain properties of the elastic cable unit in the initial elastic cable BIM model; taking the strain energy density distribution of the elastic cable as the optimization target, the strain energy density attribute parameters of the elastic cable unit are input into the SIMP interpolation model, and the nonlinear mapping relationship between the strain energy of the elastic cable and the arrangement density of the elastic cable is established through the interpolation equation in the form of a power function; taking the Mises stress distribution of the elastic cable as the constraint condition; the Mises stress attribute parameters of the elastic cable unit are input into the KS aggregation function, and the local stress constraint is converted into the global stress constraint through the aggregation equation in the form of the P norm. force constraint equation; use the MMA optimization criterion to perform sensitivity analysis on the elastic cable layout density of the elastic sling, and establish a linearized optimization sub-problem based on the first-order derivatives of the objective function and the constraint conditions; use the dual method to solve the optimization sub-problem and obtain the optimal elastic cable layout scheme for the current iteration step; use the optimal elastic cable layout scheme to update the strain energy density data and Mises stress attribute parameters of the elastic cable unit, and substitute the updated attribute parameters into the optimization criterion function to calculate the objective function value and constraint function value of the current iteration step; determine whether the difference between the objective function value of the current iteration step and the objective function value of the previous step is less than the convergence threshold. If so, stop the iteration and output the final elastic cable layout scheme; discretize the final elastic cable layout scheme into the geometric information of the elastic cable, use the set geometric information to perform parameter correction on the initial elastic cable BIM model, and generate the optimized elastic cable layout BIM model.

[0014] Furthermore, the strain energy density distribution of the elastic sling is taken as the optimization target, including: inputting the strain energy density attribute parameters of the updated elastic sling unit into the SIMP interpolation model, establishing a nonlinear relationship between the strain energy of the elastic sling and the elastic sling arrangement density by performing interpolation mapping formed by a power function on the strain energy density attribute parameters, and obtaining the strain energy expression of the elastic sling as the optimization objective function; inputting the Mises stress attribute parameters of the updated elastic sling unit into the KS aggregation function, and converting the stress constraint reflecting the local stress level of the elastic sling into a global stress constraint equation reflecting the overall stress level of the elastic sling by performing an aggregation operation in the form of a P norm on the Mises stress attribute parameters, and obtaining a violation function as the optimization constraint function; according to the optimization objective function and the optimization constraint function, taking the elastic sling arrangement density as the design variable, establishing a mathematical model with minimizing the strain energy of the elastic sling as the optimization target and with the overall stress of the elastic sling meeting the strength requirement as the optimization constraint; and using a heuristic optimization algorithm to iteratively solve the established mathematical model to obtain the elastic sling arrangement scheme of the current iteration step.

[0015] Furthermore, the optimization objective function expression is as follows: ,in is the total strain energy expression of the elastic sling, i is the unit number in the finite element model of the elastic sling, is the volume of the ith unit, is the relative density of the i-th unit, i.e., the elastic sling arrangement density, ranging from 0 to 1. is the initial strain energy density of the i-th unit; It is the penalty factor of SIMP interpolation model, which is used to suppress the elastic sling arrangement density from taking the middle value and promote the optimization of elastic sling arrangement scheme towards the discretization direction. It is usually set to 3. is the corrected element strain energy density; , where is the initial strain energy density of the element.

[0016] Furthermore, the optimization constraint function expression is as follows: ,in, To optimize the constraint function, namely the violation function, when When , it means that the optimized design satisfies the stress constraint condition; is the Mises equivalent stress of the ith unit, which is related to the relative density of the unit The function can be obtained by finite element analysis; is the allowable stress limit of Mises equivalent stress, which is usually taken as the yield strength of the material; is the aggregation factor of the KS aggregation function, which is used to adjust the contribution of the local stress constraint to the global violation function. The larger the value, the more sensitive the violation function is to the maximum stress value. When the value is infinite, Equivalent to mini stress constraint; 〈 〉 is Macaulay bracket. hour, ,otherwise , that is, only the contribution of stress values ​​exceeding the allowable stress limit to the violation function is considered.

[0017] Compared with the prior art, the advantages of this application are:

[0018] By collecting the design and processing data of different types of elastic slings, establishing a knowledge base containing geometric parameters, material properties and process attributes, and performing parametric modeling based on the knowledge base, an initial elastic sling BIM model with associative association can be quickly generated. The model contains rich semantic information, which facilitates subsequent performance analysis and topology optimization, and realizes the parametric expression of elastic slings from design to processing.

[0019] In the static analysis, the incremental iteration method and the secant method are introduced to overcome the convergence difficulties caused by material and geometric nonlinearity; the direction of the displacement increment is corrected through the energy criterion, which improves the calculation efficiency and stability. The Newmark integral format and Rayleigh damping model are used in the dynamic analysis to simulate the dynamic response of the elastic sling under seismic loads with high accuracy. The displacement field and stress-strain field obtained through static and dynamic analysis provide a reliable basis for the topological optimization of the elastic sling.

[0020] Taking the minimization of strain energy of elastic slings as optimization objective and the satisfaction of strength requirements of Mises stress as optimization constraint, a topology optimization mathematical model with elastic sling arrangement density as design variable was constructed. The continuous expression of objective function and constraint function was realized by SIMP interpolation and KS aggregation function respectively. The sensitivity analysis of design variables was performed by MMA optimization criterion, and the optimal elastic sling arrangement scheme was obtained. Topology optimization makes the material distribution of elastic slings match with the stress characteristics, and minimizes the amount of materials while ensuring safety performance.

[0021] The elastic sling layout scheme obtained by topology optimization is fed back into the BIM model, and the geometric information of the elastic sling is updated through parameter drive to obtain a BIM model of the elastic sling with optimized performance. Based on this model, the NC code required for the processing of the elastic sling can be directly derived, realizing the seamless connection of design, optimization and processing, and improving the manufacturing efficiency of the elastic sling. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1It is an exemplary flow chart of a BIM-based high-speed railway contact network elastic sling and electrical connection prefabrication processing method according to the present application;

[0023] Figure 2 is an exemplary flow chart for obtaining statically loaded elastic sling response data according to the present application;

[0024] Figure 3 is an exemplary flow chart of obtaining a time history curve under earthquake action according to the present application;

[0025] Figure 4 is an exemplary flow chart for obtaining an optimized elastic sling arrangement BIM model according to the present application. DETAILED DESCRIPTION

[0026] The method and system provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0027] Figure 1 This is an exemplary flow chart of a BIM-based high-speed railway contact network elastic sling and electrical connection prefabrication processing method according to the present application, including: collecting reinforcement data of different types of elastic slings and establishing a reinforcement knowledge base; the reinforcement knowledge base contains elastic sling geometric parameters, load conditions, material properties and reinforcement rules; according to the reinforcement knowledge base, an initial elastic sling BIM model of the target project is established through parametric modeling; the initial elastic sling BIM model contains the spatial position, size and material property parameters of the elastic sling; according to the initial elastic sling BIM model, an initial finite element analysis model of the target project is established through meshing and material property mapping; in the initial finite element analysis model, a static load condition is applied, and an incremental iteration method is used to calculate the elastic sling in static Internal forces and deformations under the action of static loads; static loads include dead loads and live loads; in the initial finite element analysis model, simulated seismic waves are input, and the direct integration method is used for dynamic time history analysis to obtain the displacement, velocity, acceleration and internal force time history curves of the elastic sling under different seismic waves; based on the static and dynamic analysis results, the stress-strain response of the elastic sling is extracted, and the topological optimization method is used to optimize the initial elastic sling BIM model with the goal of minimizing the strain of the elastic sling and the stress constraint of the elastic sling as the condition; using the optimized elastic sling BIM model, the finite element analysis model is updated, and the process is repeated until the performance of the elastic sling meets the design requirements to obtain the final elastic sling BIM model; based on the final elastic sling BIM model, the elastic sling processing parameters are derived.

[0028] Collect the design parameters and processing data of different types of high-speed rail contact network elastic slings, establish a knowledge base including geometric parameters, material properties and processing technology, collect design drawings, product samples, technical standards and other documents of high-speed rail contact network elastic slings and electrical connections, extract key design parameters, such as length, cross-sectional dimensions, taper, weight and other geometric parameters, material grades, mechanical performance indicators, conductivity, corrosion resistance and other material parameters. Collect the production and processing records, process documents, operating procedures, quality inspection reports, etc. of elastic slings and electrical connection products, and extract key processing parameters, such as forging process parameters, heat treatment process parameters, surface treatment process parameters, assembly process parameters, geometric tolerances and surface roughness. Classify and organize the collected data and standardize them. Use text mining, pattern recognition and other technologies to convert unstructured design and production data into structured parametric data; perform pre-processing operations such as screening, denoising and normalization on the original data.

[0029] The ontology construction method is used to define the core concepts, attributes, relationships, etc. in the field of high-speed rail contact network elastic slings and electrical connection design and manufacturing, forming a domain ontology model. For example, "elastic slings" and "electrical connections" are defined as core concepts, "geometric parameters", "material properties" and "processing technology" are defined as attribute concepts, and "used materials" and "processing methods" are defined as relationships. The processed structured parameter data is mapped to the ontology model to establish parameter associations at the semantic level. At the same time, the coupling relationship and constraints between parameters are considered to construct a parameter association matrix. For example, by associating the mechanical properties parameters of the material with the processing technology parameters, the mapping relationship between material selection and heat treatment process is established. The ontology-based design and manufacturing knowledge is formally represented as a knowledge base. Knowledge representation methods such as framework representation, production representation, and semantic network can be used to realize the logical organization and storage of the knowledge base. Index links are established between the collected original document materials and the knowledge base entries to form a document knowledge base.

[0030] According to the established knowledge base of elastic slings and electrical connections, the initial elastic sling BIM model of the target project can be quickly generated through parametric modeling technology, and the parametric main model of the elastic sling is constructed using parametric 3D modeling software (such as Catia, UG, Solidworks, etc.). The geometric parameters of the elastic sling in the knowledge base (such as length, cross-sectional size, taper, etc.) are used as the driving parameters of the main model, and the 3D model of the elastic sling is quickly generated through the constraint relationship between the parameters. On the basis of the main model, the matching model of the elastic sling and the electrical connection is constructed through parametric assembly technology. According to the assembly relationship parameters of the two (such as flange size, number and distribution of bolt holes, etc.), assembly constraints are automatically generated to achieve rapid definition of the matching model. Using parametric feature library technology, a series of detail feature models of the elastic sling are predefined, such as end tapered holes, anti-vibration hammer mounting holes, anti-vibration hammer mounting plates, etc. The detail feature model is implanted into the main model through parameter transfer to improve modeling efficiency.

[0031] BIM model attribute definition, import the 3D parametric model of the elastic sling into the BIM software (such as Revit, Tekla, etc.). Using the parametric attribute definition function of the BIM software, assign the material brand, mechanical performance parameters, appearance color number, etc. in the knowledge base to the material attribute parameters of the model. Using the spatial positioning function of the BIM software, accurately define the spatial installation position and elevation of the elastic sling model in the contact network through measurement and lofting. Consider the avoidance relationship with the surrounding components and adjust the spatial position parameters reasonably. Based on the assembly relationship of the elastic sling, define its logical association relationship with adjacent components such as electrical connections and anchoring devices in the BIM model. Through the transfer of associated parameters, when the parameters such as the position and angle of the elastic sling change, the coordinated changes of adjacent components are automatically triggered.

[0032] According to the established initial elastic sling BIM model, the finite element analysis method can be used to realize the digital simulation analysis of the mechanical properties of the elastic sling. The initial elastic sling BIM model is exported through a neutral format (such as STEP, IGES, etc.), opened in the finite element pre-processing software (such as Hypermesh, ANSA, etc.) for model conversion. The BIM model is appropriately simplified to remove the detailed features that have little effect on the structural force, such as chamfers, small round holes, etc. Key features such as the end cone hole and the anti-vibration hammer installation hole are retained. The simplified model is topologically checked to repair geometric defects such as small gaps and intersections between the surfaces to ensure the integrity and continuity of the model. The material properties of the elastic sling are defined in the finite element software. The mechanical parameters such as elastic modulus, Poisson's ratio, density, etc. of the material are extracted from the knowledge base and assigned to the finite element material grade. The material properties are mapped to different areas of the geometric model. Using the topological structure and naming rules of the model, different parts such as the sling body, cone head, and anti-vibration hammer installation plate are automatically identified and the corresponding material properties are assigned. Considering the anisotropic mechanical properties of the material, material parameters in different directions are defined, such as the difference in elastic modulus between the transverse and longitudinal directions.

[0033] According to the purpose and accuracy requirements of the simulation analysis, select the appropriate finite element unit type, such as solid unit, beam unit, shell unit, etc. Mesh the simplified geometric model. Use automatic meshing algorithms (such as Delaunay algorithm, Advancing Front algorithm, etc.) to generate structured triangular or quadrilateral mesh units on the surface model. Encrypt the mesh of key parts (such as the transition zone of the cone head, around the mounting hole of the anti-vibration hammer, etc.) to improve the accuracy of stress and strain calculations. Evaluate the mesh quality, check quality indicators such as unit size and distortion, and adjust or re-divide the distorted units. Define the properties of the mesh unit, such as unit thickness, cross-sectional area, moment of inertia, etc. Extract the corresponding section parameters from the knowledge base and automatically assign them to the mesh unit.

[0034] Define boundary conditions according to the stress state of the elastic sling in the contact network. Apply displacement constraints or hinge constraints to the end nodes of the sling to simulate its connection relationship with the anchoring device. According to the design specifications, calculate the forces on the elastic sling under conditions such as icing and wind vibration. Apply loads to the corresponding nodes or unit surfaces of the finite element model to simulate the actual stress state. Consider the influence of temperature loads, define the thermal expansion coefficient of the model, and apply a temperature field. Perform a visual check on the divided finite element mesh model to confirm the correctness of the mesh quality and material property mapping. Output a finite element model file in a neutral format (such as Nastran, Abaqus format) for subsequent finite element solution analysis.

[0035] Figure 2This is an exemplary flow chart for obtaining the response data of the static load elastic sling according to the present application. The load information in the initial elastic sling BIM model is mapped to the static load data of the finite element model, and the arc length method and the secant method are used for incremental step control to extract the dead load information of the elastic sling in the BIM model, mainly including the dead weight of the sling and its accessories. The dead weight of each component is calculated using the material property parameters (density) and geometric parameters (volume) in the BIM model, and the dead weight value is assigned to the corresponding node of the component to form the node load. The live load information applied to the elastic sling, such as wind load, ice load, etc., is extracted in the BIM model. The wind load can be calculated based on the wind pressure and wind direction data of the geographical location of the sling, and the wind load acting on the projection surface of the sling; the ice load can be calculated based on the meteorological parameters. The ice thickness and ice density on the surface of the sling are calculated and converted into additional mass. The load combination coefficient is used to linearly combine the dead load data and the live load data. The combination coefficient under different working conditions can refer to the design specifications. The combined load data is applied to the corresponding nodes or element surfaces of the finite element model to form static load data.

[0036] According to the nonlinear characteristics of the elastic sling, the arc length method is used to discretize the static load data in increments. The arc length method can capture complex nonlinear paths by limiting the length of the load-displacement curve (i.e., arc length) of each increment and adaptively adjusting the load increment and displacement increment. Before solving each increment, the index value reflecting the nonlinear state of the elastic sling, such as the maximum deflection of the sling, is obtained. The deflection value of the current increment is compared with the preset threshold (such as the ratio of deflection / span). When the deflection exceeds the threshold, the arc length of the current increment is reduced, the load increment is reduced, and the calculation accuracy is improved. At the same time, the nonlinear state index of the sling is monitored to see if it exceeds the preset extreme value (such as the maximum allowable deflection). When the index exceeds the extreme value, the secant method is used to interpolate the current increment, and an intermediate point is added to the load-displacement curve to avoid non-convergence of the calculation. The secant method forms a secant by connecting two points on the curve, and replaces the tangent stiffness with the secant slope, which can cross the local stiffness degradation area.

[0037] Deflection is an important indicator for evaluating the nonlinear state of elastic slings. By extracting the displacement field data of the sling in the current incremental step, the maximum deflection value of the sling is calculated. Usually, the vertical displacement of the mid-span point of the sling is focused. Crack width can also be used as a nonlinear state indicator. Through the stress field data, the principal tensile stress on the surface of the sling is calculated and compared with the tensile strength of the material to determine whether it is cracked. According to the strain field data, the cracking displacement of the crack area is calculated to estimate the crack width. Other nonlinear state indicators include the stress level and plastic strain of the sling. By extracting the stress-strain data of the sling, calculating the equivalent stress, equivalent plastic strain, etc., the nonlinear degree of the sling is evaluated.

[0038] In each increment, the nonlinear equations of the elastic sling are solved using the Newton-Raphson iteration scheme to extract element stress data from the initial finite element analysis model. and unit strain data Assume that the elastic sling is discretized using a four-node quadrilateral plane stress unit, the unit number is e, and the node numbers are i, j = 1, 2, 3, 4. For unit e, its stress data is , , , the strain data is , , Based on the material constitutive relations, such as elastic modulus E and Poisson's ratio ν, the tangent stiffness matrix coefficients of the element are calculated For example, for an isotropic elastic material, The expression is: ; ; ;the remaining ; Use 2x2 Gaussian integral to calculate the tangent stiffness matrix of element e . Let the unit node coordinates be , the shape function is , the coordinates of the Gaussian integration point are , the weight coefficient is , k=1,2,3,4. Then The expression is: ;in, is the strain-displacement matrix at Gaussian point k, is the tangent stiffness coefficient matrix at Gaussian point k, is the Jacobian matrix at Gaussian point k. For example, and The expression is: ; ; Using the unit set operation, the tangent stiffness matrices of all units are assembled into the tangent stiffness matrix K_T of the overall structure. Assume that the degrees of freedom of the overall structure are numbered I, J, then The assembly process is: , is the total number of units; i=1, 2, 3, 4; , ID is the overall degree of freedom number of the i-th node of element e; j = 1, 2, 3, 4; ; , add the unit tangent stiffness matrix to the corresponding position of the overall tangent stiffness matrix; introduce displacement boundary conditions, and adjust the tangent stiffness matrix Perform singular processing. Assuming that the degree of freedom of the constraint node is IC, modify The diagonal elements of : , α is the penalty factor, which takes a large positive number, such as ; So far, the tangent stiffness matrix data of the elastic sling in the current increment step is obtained .

[0039] First iteration solution: Let the arc length increment of the current incremental step be , which contains the load increment and displacement increment Two components. By constraining the arc length equation, determine and Relationship: ;in, is the reference length, usually the initial arc length. and , the above nonlinear equation is solved by Newton iteration method to obtain the displacement increment component . The displacement increment component and the tangent stiffness matrix Substituting into the tangent stiffness equation, we get the displacement increment of the node: The linear equations are: ; Where P is the reference load vector. The LU decomposition method is used to solve the above equations to obtain the node displacement increment of the first iteration . Using the node displacement increment , update the unit strain increment through the displacement-strain relationship : ;in, is the element strain-displacement matrix. The stress increment of the element is updated through the elastic-plastic constitutive equations, such as the Mises yield criterion and related flow laws. : ;in, is the elastic-plastic tangent stiffness matrix. The element stress and strain are updated as: ; .

[0040] Subsequent iterative solutions: Updated element stresses and strain Substitute the expression of the secant stiffness matrix K_S^e to calculate the unit secant stiffness matrix: ; Where D_s is the secant stiffness coefficient matrix. Using unit set operation, assemble it into the secant stiffness matrix of the overall structure : ; Introduce boundary conditions, perform singular processing on the secant stiffness matrix, and obtain the secant stiffness matrix of the second iteration Extract the displacement increment component from the arc length increment data of the current increment step , and compare it with the secant stiffness matrix Substitute into the secant stiffness equation to form a new set of node displacement increment equations: ; Solve the above equations to obtain the node displacement increment of the second iteration . Based on the node displacement increments of the first iteration and the node displacement increments of the second iteration , calculate the displacement difference between two iterations : ; Using the Euclidean norm , and compare it with the preset convergence threshold ε. , then the calculation is considered to have converged, let , stop the iteration. Otherwise, proceed to the next iteration. Use the node displacement increment of the second iteration , update the element stress-strain increments, and recalculate the secant stiffness matrix , prepare for the next iteration. Repeat the iteration process until the displacement difference converges.

[0041] Based on the Newton-Raphson iteration format, the energy criterion is introduced to correct the direction of the displacement increment to speed up the iterative convergence. The correction process is nested in the iteration loop of each incremental step until the displacement of the current incremental step converges. and the node displacement data of the previous iteration As input, we substitute the potential energy function Π of the elastic sling: , where [K] is the secant stiffness matrix of the elastic sling, is the current load, is the load increment corresponding to the unit arc length increment. The potential energy function Π is minimized to obtain the displacement increment direction correction coefficient α: ,in, is the initial displacement increment of the current iteration. Solve the above equation to get the correction coefficient α: , the displacement increment direction correction coefficient α and the displacement increment component data of the current increment step Multiply to get the corrected displacement increment component data : , the corrected displacement increment component Substitute the secant stiffness matrix [K] to solve the node displacement data of the current iteration : , determine the node displacement If converged, the current incremental step calculation is completed, otherwise it returns to the next iteration until the node displacement data of the current incremental step converges. By correcting the displacement increment direction by the energy criterion, the displacement direction with the minimum potential energy can be searched in each iteration, thereby accelerating the convergence speed of the Newton-Raphson iteration and reducing the number of iterations. At the same time, since only the displacement increment direction needs to be corrected without changing the modulus of the displacement increment, the control effect of the arc length increment is not affected.

[0042] After all incremental calculations are completed, the characteristic points of the deformation and failure mode of the elastic sling are extracted and the response data is formed. The total number of nodes of the elastic sling is assumed to be The total number of units is After all incremental steps are calculated, the following data fields are obtained: Displacement field data: , , j = 1, 2, 3, represents the displacement component of the i-th node in the j-th direction. Stress field data: , , , , represents the stress component of the e-th unit. Strain field data: , , , , represents the strain component of the e-th unit. From the above data field, extract the characteristic point data reflecting the deformation and failure mode of the elastic sling: Maximum deflection point: In the displacement field data, search for the maximum displacement component in the j=2 direction (i.e., the y direction) , determine the corresponding node number The coordinates of the maximum deflection point are ,in, . For the Initial coordinates of nodes. Stress and strain extreme points: Search for , , , , , The maximum and minimum values ​​of and The coordinates of the stress and strain extreme points are in units of and The center coordinates of and Buckling instability point: For a compression rod element, if its axial compressive stress Exceeding critical buckling stress , then the unit is determined to be a buckling instability point. It can be calculated according to Euler buckling formula: , where E is the elastic modulus of the material, I is the moment of inertia of the unit cross section, A is the unit cross section area, and l is the unit length. The coordinates of the buckling instability point are the center coordinates of the unit e Strength failure point: For each unit, calculate the equivalent stress according to its stress state , such as Mises equivalent stress: ,Will and material allowable stress For comparison, if , then the unit is determined to be a strength failure point. The coordinates of the strength failure point are the center coordinates of unit e .

[0043] Perform statistical analysis on the above feature point data: calculate the number of each type of feature points , , , , get the weak point distribution of the elastic sling. Calculate the mean value of the coordinates of various feature points and standard deviation , and obtain the spatial distribution characteristics of the weak parts. The feature point data and the geometric parameters of the elastic sling (span , sagittal height f), material parameters (elastic modulus E, allowable stress [σ]), load parameters (vertical uniform load q), etc. are analyzed to establish the elastic sling response function under static load, such as: ; ;in, is the cross-sectional area of ​​the sling, is the maximum stress of the sling.

[0044] Figure 3 This is an exemplary flow chart for obtaining the time history curve under the action of an earthquake according to the present application. According to the site conditions, the input seismic waves are selected and converted into node load time history data, and the dynamic balance equation is established. According to the design intensity I and site category S of the project area, a group of representative seismic waves are selected from the seismic wave database (such as PEER). The design intensity is 6, 7, 8, and 9 degrees, and the site category is I, II, III, and IV. Each group of seismic waves contains two horizontal (x and y) and one vertical (z) acceleration time history curves, and the sample size is not less than 10 groups. The peak acceleration PGA and duration of the seismic wave , non-zero time points Parameters such as the above should meet the requirements of the fortification intensity. For example, select the following set of seismic wave data:

[0045]

[0046] The above seismic wave data are baseline corrected and amplitude adjusted using the modal decomposition response spectrum method. Suppose the original acceleration time history curve of the i-th group of seismic waves is , where i=1, 2, ..., 10, j=x, y, z, . Perform the following processing: Calculate the vibration mode decomposition response spectrum of the seismic wave ,in, is the natural vibration period, ξ is the damping ratio, which is 5%. According to the design response spectrum of the project site , calculate the target adjustment coefficient : ; Perform baseline correction on the original seismic wave to obtain the corrected acceleration time history : ;in, The corrected seismic wave Multiply by the adjustment factor , and get the simulated seismic wave : ; Convert the simulated seismic waves into node load time history data. Assume that the number of nodes in the initial finite element model of the elastic sling is , the earthquake action direction is j direction (j=x, y, z), and the displacement time history of node i in j direction is . From the dynamic balance equation: ; Where M, C, K are the mass, damping and stiffness matrices of the structure respectively, I is the unit column vector, To simulate the acceleration time history of the earthquake wave in the j direction. The node load time history is: ;in, is the mass of node i. Applied to the j-direction degree of freedom of node i, the dynamic equilibrium equation considering the earthquake effect is established: ;in, is the node load time history array.

[0047] Introducing the Rayleigh damping matrix into the initial finite element analysis model, the dynamic equilibrium equation including the elastic cable stiffness, mass and damping terms is established, and the differential equation describing the elastic cable response under earthquake action is obtained. Introducing the elastic cable damping into the dynamic equilibrium equation, the Rayleigh damping model can be used, that is, the damping matrix [C] is a linear combination of the mass matrix [M] and the stiffness matrix [K]: , where α and β are Rayleigh damping coefficients, which can be calculated based on the first two vibration modes of the elastic sling: and And the corresponding damping ratio and Find: , the damping ratio ξ is generally taken as 3% to 5% to consider the energy dissipation of the elastic cable under earthquake action. Substituting the mass matrix [M], stiffness matrix [K] and Rayleigh damping matrix [C] into the dynamic equilibrium equation, the second-order ordinary differential equation describing the response of the elastic cable under earthquake action is obtained: .

[0048] The central difference format is used to discretize the node displacement, node velocity and node acceleration in the dynamic equilibrium equation. The integration step size is selected according to the earthquake duration and the elastic cable period, and the time interval is discretized into multiple time steps. is the unknown quantity, and the time on both sides of the dynamic equilibrium equation is Perform Taylor expansion at and take the second-order term to obtain: , where , , They are The node acceleration, velocity and displacement at the time, , , is the time step The increments of the internal node acceleration, velocity and displacement. Using the central difference format, we have: , , ,in, , , , For the next time step The node displacement, velocity and acceleration of . Substituting the differential relationship into the dynamic equilibrium equation, we get: , time step The selection of must satisfy the integral stability and convergence conditions, and is generally taken as the elastic sling period 1 / 10~1 / 20, that is: .cycle The first-order natural frequency of the elastic sling Estimate: , The characteristic value of the initial finite element analysis model can be obtained by solving the Rayleigh quotient iteration method. For high-rise buildings, generally In the 1s to 5s range, take The total earthquake duration is 0.02s to 0.1s. Divide by , the number of integration steps N can be determined: , the time interval Discretized into N time steps, the time sequence is: , , ,......, .

[0049] The dynamic equilibrium equation is integrated through the Newmark parameters β and γ to establish the iterative format between the node displacement, velocity and acceleration of the current time step. The Newmark-β method is an implicit direct integration algorithm that uses two parameters β and γ to control the integration format. β reflects the contribution of the time-averaged acceleration to the displacement, and γ reflects the contribution of the time-averaged acceleration to the velocity. Order: , When β=1 / 4, γ=1 / 2, it is the constant acceleration method, which has second-order accuracy and unconditional stability; when β=1 / 6, γ=1 / 2, it is the linear acceleration method, which has third-order accuracy and conditional stability. Substituting the Newmark iteration relationship into the dynamic balance equation, we get: ,in, , , [A] is called the Newmark effective stiffness matrix, is the Newmark payload vector.

[0050] The node displacement, node velocity and node acceleration of the elastic sling are set to zero at the initial moment. In the first time step, the node load data is used as input, and the node displacement, node velocity and node acceleration of the first time step are explicitly solved using the Newmark iteration format. The initial conditions are: , , ; At the first time step , the earthquake load is , substitute into the Newmark payload vector : ; Substitute into Newmark effective stiffness equation and solve Node acceleration at time : ; Then update the Newmark iteration relationship Node speed at time and node displacement : , In the second time step, according to the node displacement data obtained in the previous time step, the unit strain increment of the current time step is calculated using the strain-displacement relationship, the unit stress is updated using the constitutive relationship, and the unit stress is multiplied by the unit volume and integrated to obtain the node equivalent force increment of the current time step. Interpolated unit displacement field , and then from the strain displacement relationship matrix Convert to unit strain : ; According to the material constitutive relations, such as elastic, elastoplastic or damage constitutive relations, the unit strain Update Element Stresses Taking elasticity as an example, let the elasticity matrix be ,but: ; The unit stress Decomposition into equivalent nodal forces ,have: ; is the spatial domain of unit e. The equivalent node forces of all units are grouped to obtain the overall elastic sling The node equivalent force increment at time : Substitute the node velocity obtained in the previous step into the damping force expression to calculate the damping force increment for the current time step. The damping force at time is: ,Will and Damping force at the moment Make a difference and get the damping force increment : The node load increment, damping force increment and node equivalent force increment of the current time step are introduced into the dynamic equilibrium equation to establish a group of algebraic equations reflecting the node force equilibrium state at the current moment. The earthquake load increment at time , Damping force increment and node equivalent force increment Substituting into the dynamic balance equation, we get: .

[0051] Further substituting into the Newmark effective stiffness equation and the effective load vector, we obtain: ,in, , , , [A] is the same as the first time step. Solve the algebraic equations to obtain the node acceleration increments of the second time step, and use the Newmark iteration relationship to update the node velocity increments and node displacement increments of the second time step. For the Newmark effective stiffness equation Solve it and get Node acceleration at time . Direct or iterative methods can be used to solve, such as LU decomposition, Pardiso solver, etc. Then, according to the Newmark iteration relationship, update Node speed at time and node displacement : ; The node acceleration, node velocity and node displacement are respectively added to the calculation results of the previous time step to obtain the node acceleration, node velocity and node displacement of the current time step. , , Repeat the time step iteration update until the full-time dynamic response calculation is completed, extract the node displacement, node velocity and node acceleration data of each time step, and form the dynamic response time history curve of the elastic sling under earthquake action. , calculate successively Extract the node response data for each time step. By plotting the acceleration, velocity and displacement time history curves for the nodes of interest, the dynamic response characteristics of the elastic sling during the entire earthquake process can be fully analyzed and the seismic performance of the elastic sling can be evaluated.

[0052] According to the node displacement data of each time step, the unit strain data is calculated using the strain-displacement relationship, and the unit stress data is updated using the constitutive relationship; the unit stress data is multiplied and integrated with the unit volume to obtain the unit node equivalent force data; the unit node equivalent force data is assembled into the overall node load data and substituted into the dynamic balance equation for the next step of integral calculation. The unit strain data is calculated according to the node displacement data, assuming that the elastic sling is The node displacement vector at time , for each element e, the element displacement field is interpolated from the node displacement : , where [N^e] is the unit shape function matrix, is the unit node displacement vector, which is the overall node displacement vector The unit node degrees of freedom are extracted from Through the strain displacement relationship matrix Convert to unit strain : , There are standard expressions for common elements such as beam elements, shell elements, etc., depending on the element type and the degree of the shape function.

[0053] According to the material constitutive relation, the unit strain Update Element Stresses . It is divided into two cases: elastic and inelastic. For elastic materials, stress and strain are linearly related: ,in, is the elastic matrix, which is related to the elastic modulus and Poisson's ratio of the material. For non-elastic materials, such as elastic-plastic and damage-plastic materials, it is necessary to use incremental theory and implicit iterative algorithm to update the unit stress. Taking ideal elastic-plastic as an example, according to the last time step The unit stress and the element strain increment , updated by elastic-plastic return mapping algorithm : (elastic forecast), (Yield function). If f > 0, then: (Plastic correction), , where f is the Mises yield function, is the second deviatoric invariant of stress, is the yield strength, is the normal direction of the yield surface, is the plasticity multiplier. For nonlinear hardening and damaged materials, the strength parameter needs to be considered in the stress update Calculate the unit node equivalent force data and convert the unit stress Decompose into equivalent nodes ,have: , is the spatial domain of unit e, which can be calculated by numerical integration such as Gauss integration. This step is called stress equilibrium solution.

[0054] Assemble the overall node load data, perform unit equivalent node force grouping on all units, and obtain the overall elastic sling Node equivalence at time : The assembly process is similar to the total rigid assembly in finite element static analysis. Substitute into the dynamic balance equation for the next step of integral calculation, and As the next time step The internal force terms, together with the external load, damping force, and inertia force, constitute the load terms of the dynamic equilibrium equation: ,in, , They are The increment of seismic load and damping force at time . [K] is the tangent stiffness matrix, which takes into account the stiffness degradation caused by material nonlinearity. Repeating the Newmark-β method to solve the integral of the dynamic equilibrium equation, we can get The node acceleration, velocity, and displacement response at the moment of earthquake are realized, realizing the bidirectional coupling analysis of material nonlinearity and elastic cable dynamics. After completing the dynamic integral calculation of the whole time history, the node displacement, node velocity, node acceleration, and unit stress data of each time step are extracted to form the displacement, velocity, acceleration, and internal force time history curve data of the elastic cable under earthquake action. (n=0, 1, 2, ..., N), read the node acceleration vector respectively , node velocity vector , node displacement vector , and organized into a matrix form according to the node number: , , , the number of rows in the matrix is ​​the total number of nodes, and the number of columns is the total number of time steps. These matrices are called nodal response time history matrices. Similarly, for each element e, the stress time history (n=0, 1, ..., N) are organized into matrices by columns: ,in, for The stress component vectors at each integration point of element e at time instant. It is called the element stress time history matrix. From the node response time history matrix , , Extract the acceleration, velocity, and displacement components of the node of interest and draw the response time history curve. The ordinate is the response amount and the abscissa is time. For example, for the displacement time history of node i in the x direction : , , , similarly, from the element stress time history matrix Extract the Mises equivalent stress time history of key elements such as supports, node areas, opening edges, etc. , The response time history curves at key locations can be used to intuitively evaluate the dynamic characteristics of elastic cables in earthquakes, such as the peak values ​​of displacement, velocity and acceleration and their occurrence times, residual displacement, displacement after unloading and stress recovery, etc. , , The unit stress time history matrix is ​​output to an external file in a certain format for post-processing analysis. Common data formats include .txt (text file), .mat (Matlab data file), .xls (Excel spreadsheet file), etc.

[0055] Figure 4This is an exemplary flow chart for obtaining an optimized elastic cable arrangement BIM model according to the present application. Based on the results of static and dynamic analysis, the stress-strain response of the elastic cable is extracted. The topology optimization method is used to minimize the strain of the elastic cable and to optimize the initial elastic cable BIM model based on the stress constraint of the elastic cable, including: S61. Based on the response data of the elastic cable under static load conditions and the response data of the elastic cable under earthquake action, the envelope surface data reflecting the response characteristics of the elastic cable under the combined action of loads is calculated by combining the displacement field, stress field and strain field data under different working conditions; the envelope surface data is used to update the stress-strain properties of the elastic cable unit in the initial elastic cable BIM model. Linear elastic finite element analysis is performed on static working conditions such as permanent load (D), variable load (L), and wind load (W) to obtain the node displacement of the elastic cable under each working condition. , unit stress and unit strain Taking permanent load as an example, the node displacement under its action is , the unit stress is , the unit strain is Variable loads and wind loads are represented by subscripts L and W. Nonlinear dynamic time history analysis is used to simulate the dynamic response of elastic cables under different earthquake levels (frequent, fortified, rare), and obtain the node displacement time history reflecting material nonlinearity and geometric nonlinearity. , unit stress history and unit strain history Taking the frequent earthquake (E1) as an example, the node displacement time history under its action is , the unit stress time history is , the unit strain history is . Design earthquakes (E2) and rare earthquakes (E3) are indicated by subscripts E2 and E3.

[0056] According to the rules of load combination, the displacement, stress and strain responses of static and seismic conditions are combined to obtain the envelope data reflecting the response characteristics of the elastic sling under the action of load combination. ,have: ,in, It represents the modulus of the orientation quantity, and max represents the maximum value of the displacement modulus of all nodes. represents the node displacement under permanent load, represents the node displacement under variable load; represents the node displacement under wind load; They represent the node displacement time histories under frequent, fortified and rare earthquakes respectively.

[0057] Stress envelope of the element ,have: Element strain envelope Calculation and Similarly, just change the equivalent stress to equivalent strain. Envelope surface data , , It reflects the upper limit of the displacement, stress and strain response of the elastic sling under the combined action of loads and can be used to evaluate the overall performance of the elastic sling and the stress state of the elastic sling. represents the element stress under permanent load, represents the element stress under variable load; represents the element stress under wind load; They represent the unit stress time history under frequent, defense and rare earthquakes respectively.

[0058] Use the envelope surface data to update the elastic sling properties of the BIM model. In the initial elastic sling BIM model, the cada elastic sling unit has its material properties and geometric properties. The material properties include the initial elastic modulus, Poisson's ratio, yield strength, etc. The geometric properties include the cross-sectional size, elastic sling diameter and spacing, etc. These properties determine the stress-strain relationship of the elastic sling unit. , , which updates the yield strength of the elastic sling element : (maximum value of the element stress envelope), for elastic slings, Take its tensile yield strength, for concrete, Take the standard value of its compressive strength. At the same time, the stress-strain time history [σ] and [ε] of the unit obtained by nonlinear dynamic analysis can be used to fit the hysteresis curve of the elastic sling unit, and thus determine the degraded secant stiffness : (Take the slope of the line connecting the peak points of the stress-strain time history), the above yield strength and secant stiffness The update enables the stress-strain relationship of the elastic sling unit in the BIM model to reflect the strength degradation and stiffness degradation of the material under the combined action of loads, thereby improving the accuracy of the BIM model.

[0059] A mathematical model is established with the goal of minimizing the strain energy of the elastic sling and the constraint that the stress of the elastic sling meets the strength requirements, and the initial strain energy density of each unit in the finite element model of the elastic sling is extracted. and volume . Initial strain energy density By element stress and strain calculate: ,in, and The envelope data of S61 , Get. Unit volume It can be directly extracted from the unit attribute table of the finite element model. ρᵢ reflects the volume proportion of the elastic sling arrangement in the i-th unit. It is a continuous variable with a domain of [0, 1]. When , it means that there is no elastic sling in unit i; when When , it means that solid elastic slings are arranged in unit i. The SIMP (Solid Isotropic Material with Penalization) interpolation model is used to establish the nonlinear mapping relationship between unit strain energy density and elastic sling arrangement density: , where is the corrected element strain energy density, is the initial strain energy density of the element, is the relative density of the unit elastic sling arrangement, is the penalty factor, which is 3. This power function interpolation is Correction coefficient when it is 0 or 1 is also 0 or 1, corresponding to the two extreme cases of no elastic sling or solid elastic sling. When taking an intermediate value such as 0.5, the correction coefficient Will be much smaller than , so that the unit strain energy density It is too small, thus suppressing the tendency of the elastic sling arrangement density to take an intermediate value and promoting the optimization of the elastic sling arrangement towards the direction of solidification.

[0060] Establish the optimization objective function of minimizing the total strain energy of the elastic sling: ,in, is the total strain energy of the elastic sling, and the strain energy corrected by each unit Multiply by the unit volume Accumulated. is the relative density of the i-th unit elastic sling arrangement, there are n As the design variable, n is the total number of units in the finite element model of the elastic sling. Based on the KS function, the optimization constraint function is established to extract the Mises stress function of each unit in the finite element model of the elastic sling. Element Mises stress It is also the density of elastic sling arrangement. Function. Substitute the envelope surface data {σ}_env into the three-dimensional Mises stress formula: ,in, , , is the unit principal stress, which can be obtained from The principal stress extraction is done by introducing the KS (Kreisselmeier-Steinhauser) aggregation function to convert the element stress function Aggregation as violation function : , where σ is the allowable stress, which is the smaller value of the tensile strength of the elastic sling and the compressive strength of the concrete. For Macaulay brackets, when hour is a positive value, otherwise it is 0. p is the aggregation parameter, the larger p is, The closer The introduction of Macaulay brackets allows the violation function to consider only the overstressed area without paying attention to the low stress area. When the stress level of the fully elastic sling is lower than the allowable value, ;on the contrary, Therefore, select As an optimization constraint, it can ensure that the elastic sling meets the strength requirements under load.

[0061] Establish the optimization constraint function of the overall stress constraint of the elastic sling: The mathematical model of topological optimization of elastic slings for concrete is established. The optimization goal is to minimize the total strain energy of the elastic slings, the optimization constraint is that the overall stress of the elastic slings meets the strength requirements, and the relative density of the unit elastic sling arrangement is used as the design variable. The following mathematical model is established: , constraints: , ,in, is the lower limit of the elastic sling arrangement density, which is generally taken as 0.001 to avoid singularity of the unit stiffness matrix. Under the premise that the elastic sling meets the overall strength requirements, the elastic sling arrangement scheme with the minimum total strain energy is sought. The minimum total strain energy means that the internal force of the elastic sling is optimal and the mechanical properties of the material are fully utilized. By solving the mathematical model, the optimal topological configuration of the elastic sling concrete elastic sling, that is, the optimal elastic sling arrangement scheme, can be obtained. Under this configuration, the force on the elastic sling is more reasonable, the utilization rate of the elastic sling is higher, and the mechanical properties are improved. Substitute the envelope surface data , , , the displacement field, stress field and strain field under the optimized configuration can be obtained.

[0062] Based on the MMA optimization criterion, a linear optimization sub-problem is established. The mathematical model established by S62 is used to analyze the objective function. and constraint functions Find the design variables The first derivative of . The objective function right The partial derivative of is: , where p is the penalty factor of the SIMP interpolation model, which is 3; is the relative density of the i-th unit elastic sling arrangement; is the initial strain energy density of the i-th unit; is the volume of the ith unit. Constraint function right The partial derivative of is: , where p is the aggregation parameter of the KS aggregation function; is the Mises stress function of the ith unit; is the allowable stress.

[0063] Mises stress function right The partial derivative of It can be obtained by the implicit function derivation rule: ,in, is the principal stress of the i-th unit; The principal stress and The nonlinear relationship of the material needs to be determined by numerical differentiation of the material constitutive equation. , at the current design point The objective function and constraint functions Perform a first-order Taylor expansion to obtain the linearized optimization subproblem: , constraints: , ; In the formula, and are the partial derivatives of the objective function and constraint function with respect to the i-th design variable respectively; is the improvement of the i-th design variable; is the lower limit of the elastic sling density, which is 0.001. The linear optimization subproblem constructs a linear approximation of the original problem near the current design point. The direction of steepest descent is indicated to guide the optimization of design variables.

[0064] The dual method is used to solve the linearized optimization subproblem. The Lagrangian multiplier λ and KKT conditions are introduced to transform the linearized optimization subproblem into the following unconstrained optimization problem of the Lagrangian function: , constraints: , . Respectively right The partial derivative of and λ is equal to 0, and we get:

[0065] , .

[0066] Combining the above optimality conditions and complementary slackness conditions, we get the linear complementarity problem (LCP) with respect to λ: , , , , where is the Lagrangian function The second-order partial derivative with respect to λ is Corresponding to the linearized constraint function. Using the Lemke complementary pivoting method to solve the above LCP, we get the optimal multiplier Substituting λ into , solve for the optimal design variable improvement : It should be pointed out that since the linearized optimization subproblem is a local approximation of the original problem at the current design point, its solution It can only be used as a reference for design improvement. To ensure global convergence, strategies such as trust region and moving limit should be combined in the iteration process. Make corrections to obtain practical and feasible design variable improvements .

[0067] Update the design variables, calculate the objective function value and constraint function value, and use For the current design variable To update: . The updated Substitute into SIMP interpolation model and calculate the unit strain energy density : . The updated Substitute the Mises stress function and calculate the unit Mises stress : . and Substitute into the objective function and constraint functions , get the objective function value and constraint function value of the current iteration step: , . This completes one optimization iteration. and The changing trend of will determine the direction of the next optimization iteration until the algorithm converges.

[0068] Calculate the change in the objective function value, determine whether the convergence conditions are met, and define the convergence control parameters, including the objective function threshold and the maximum number of iterations N. Control the change range of the objective function value, generally take ; N controls the upper limit of the number of optimization iterations, which is generally 200. After completing the optimization of the current iteration, extract the objective function value of the previous step And the objective function value of this step , calculate the change of the two: ,like , or the number of iterations has reached N, the optimization process is considered to have converged, and the current elastic sling arrangement scheme is output. As the final optimization result; otherwise, it is considered that the optimization process has not converged, and the current The optimal density distribution is used as the basis to continue the next optimization iteration. Transformed into discrete elastic sling arrangement parameters, assuming that the initial parameters of an elastic sling in the BIM model are as follows: concrete section size b×h, longitudinal elastic sling diameter d, number of elastic sling layers n, number of elastic slings per layer m, tensile elastic sling area , elastic sling yield strength f, concrete compressive strength Optimal elastic sling layout Each cell in is divided into two groups according to its density value. Multiply by the unit volume , the volume of the elastic sling actually arranged in the unit after optimization is obtained: ,Will Divide by the unit length , and the unit elastic sling area is obtained : ,in, is the cross-sectional area of ​​the unit. Assume By diameter The elastic sling is configured as follows: ,in The number of elastic slings actually arranged for the unit. , and we get: ,visible, Follow is monotonically increasing. Therefore, The larger the actual required elastic sling diameter The thicker, the worse. Similarly, in the total cross-sectional area Under certain circumstances, the number of unit elastic sling layers can be determined And the number of elastic slings per layer : ,Will , , , Substitute into the specification and calculate the spacing of elastic slings , protective layer thickness , elastic sling reinforcement ratio Wait to see whether the construction requirements are met.

[0069] Using the optimized elastic sling BIM model, the static and dynamic analysis of the elastic sling is carried out to obtain its displacement field, stress field and strain field response, evaluate its bearing capacity, stiffness, stability and seismic performance, and compare them with the design requirements, namely: displacement response: maximum deflection , where [d] is the deflection limit; stress response: maximum equivalent stress , where [σ] is the strength limit; Stability: critical buckling load ,in is the design load, K is the stability safety factor; seismic performance: maximum displacement response , maximum stress response ,in and are the displacement and stress limits under earthquake conditions respectively. According to the final elastic sling BIM model , export elastic sling processing parameters, including: sling length , i=1,2,..., ,in is the total number of slings; sling cross-section type (round, square or flat), cross-sectional dimensions (diameter or Width ,high ); Sling material type (wire rope, threaded steel rod or high-strength hinge), material grade; sling end structure type (fork, anchor or rope loop), end geometry; sling installation elevation and horizontal offset ; Prestress or initial strain The above parameters can be exported as processing drawings to guide the cutting, processing, transportation and installation of elastic slings.

Claims

1. A BIM-based high-speed railway contact network elastic sling and electrical connection prefabrication processing method, characterized in that: include: Collect design parameters and processing data of different types of high-speed rail contact network elastic slings, and establish a knowledge base including geometric parameters, material properties and processing technology; According to the knowledge base, an initial elastic sling BIM model of the target project is established through parametric modeling; the initial elastic sling BIM model includes the spatial position, size and material property parameters of the elastic sling; According to the initial elastic sling BIM model, the initial finite element analysis model of the target project is established through meshing and material property mapping; In the initial finite element analysis model, static load conditions are applied, and the internal forces and deformations of the elastic slings under static loads are calculated using the incremental iteration method; static loads include dead loads and live loads; In the initial finite element analysis model, simulated seismic waves were input, and the direct integration method was used to perform dynamic time history analysis to obtain the displacement, velocity, acceleration and internal force time history curves of the elastic sling under different seismic waves; According to the results of static and dynamic analysis, the stress-strain response of the elastic sling is extracted, and the topology optimization method is used to optimize the initial elastic sling BIM model with the goal of minimizing the strain of the elastic sling and the stress constraint of the elastic sling as the condition; Using the optimized elastic sling BIM model, the finite element analysis model is updated until the performance of the elastic sling meets the design requirements, and the final elastic sling BIM model is obtained; According to the final elastic sling BIM model, the elastic sling processing parameters are derived.

2. The method for prefabrication of elastic slings and electrical connections for high-speed railway overhead contact network based on BIM according to claim 1 is characterized in that: Calculate the internal forces and deformations of elastic slings under static loads, including: The dead load information and live load information in the initial elastic sling BIM model are mapped into dead load data and live load data respectively; the dead load data and live load data are linearly superimposed as static load data applied to the initial finite element model; The static load data is discretized into multiple incremental step data according to the arc length method; the nonlinear state index of the elastic sling response is obtained, and when the nonlinear state index exceeds the threshold, the step size of the incremental step is adjusted; when the nonlinear state index exceeds the preset extreme value, the incremental step data is interpolated by the secant method; wherein the nonlinear state index includes deflection; For each incremental step data, the Newton-Raphson iteration format is used. In the first iteration, the displacement increment data is extracted and substituted into the tangent stiffness matrix to form the tangent stiffness equation; in the subsequent iterations, the displacement increment data is extracted and substituted into the secant stiffness matrix to form the secant stiffness equation; at the same time, the energy criterion is used to correct the direction of the displacement increment data to generate optimized displacement increment data; After all incremental calculations are completed, characteristic point data reflecting the deformation and failure mode of the elastic sling are extracted from the displacement field, stress field and strain field data. The characteristic points include the maximum deflection points. Statistical analysis is performed on the characteristic point data to obtain the weak parts of the elastic sling and form the response data of the elastic sling under static load.

3. The method for prefabrication of elastic slings and electrical connections for high-speed railway contact network based on BIM according to claim 2 is characterized in that: The secant stiffness equation is formed, including: Extract the unit stress data and unit strain data of the initial finite element analysis model, input the unit stress data and unit strain data into the tangent stiffness matrix, and obtain the tangent stiffness matrix data of the elastic sling in the current incremental step; in the first iteration, extract the displacement increment component data from the arc length increment data of the current incremental step, substitute the displacement increment component data and the tangent stiffness matrix data into the tangent stiffness equation, and solve the node displacement data of the first iteration; Use the node displacement data of the first iteration to update the unit stress data and unit strain data; input the updated unit stress data and unit strain data into the secant stiffness matrix to obtain the secant stiffness matrix data of the second iteration; extract the displacement increment component data from the arc length increment data of the current increment step, substitute the displacement increment component data and the secant stiffness matrix data into the secant stiffness matrix, and solve the node displacement data of the second iteration; Based on the node displacement data of the first iteration and the node displacement data of the second iteration, the displacement difference data of the two iterations are calculated; if the displacement difference data is less than the convergence threshold, the node displacement data of the second iteration is used as the converged displacement data of the current incremental step and the iterative calculation is stopped, otherwise the next iterative calculation is entered; The node displacement data of the second iteration is used to update the unit stress data and the unit strain data, and the updated unit stress data and the unit strain data are input into the secant stiffness matrix to obtain the secant stiffness matrix of the next iteration.

4. The method for prefabrication of elastic slings and electrical connections for high-speed railway overhead contact network based on BIM according to claim 3 is characterized in that: Generate optimized displacement increment data, including: The arc length increment data of the current incremental step and the node displacement data of the previous iteration are used as input, and the displacement increment direction correction coefficient of the current iteration is solved through the minimum potential energy; Multiply the displacement increment direction correction coefficient by the displacement increment component data of the current increment step to obtain the corrected displacement increment component data; Substitute the corrected displacement increment component into the secant stiffness matrix, solve the node displacement data of the current iteration, and return to the displacement convergence judgment step until the node displacement data of the current increment step converges.

5. The method for prefabrication of elastic slings and electrical connections for high-speed railway contact network based on BIM according to claim 2, characterized in that: Obtain the displacement, velocity, acceleration and internal force time history curves of the elastic cable under different seismic waves, including: According to the intensity and site category of the project area, a group of representative seismic waves are selected from the seismic wave database as input seismic wave data; the input seismic wave data are baseline corrected and amplitude adjusted using the vibration mode decomposition response spectrum method to obtain simulated seismic wave data; The simulated seismic wave data is converted into node load time history data, applied to the basic node degrees of freedom of the initial finite element analysis model, and the dynamic equilibrium equation considering the seismic effect is established; The Newmark-β method is used to directly integrate and solve the dynamic equilibrium equation to obtain the node displacement, node velocity and node acceleration data at each time step; According to the node displacement data of each time step, the unit strain data is calculated using the strain-displacement relationship, and the unit stress data is updated using the constitutive relationship; the unit stress data is multiplied and integrated with the unit volume to obtain the unit node equivalent force data; the unit node equivalent force data is assembled into the overall node load data and substituted into the dynamic balance equation for the next step of integral calculation; After completing the dynamic integral calculation of the entire time course, the node displacement, node velocity, node acceleration and unit stress data of each time step are extracted to form the displacement, velocity, acceleration and internal force time history curve data of the elastic cable under earthquake action.

6. The method for prefabrication of elastic slings and electrical connections for high-speed railway overhead contact network based on BIM according to claim 5, characterized in that: Get the node displacement, node velocity and node acceleration data for each time step, including: The simulated seismic wave data is multiplied by the elastic sling mass matrix to be converted into node load time history data, and then applied to the foundation nodes of the initial finite element analysis model; The Rayleigh damping matrix is ​​introduced into the initial finite element analysis model, and the dynamic equilibrium equation including the elastic cable stiffness, mass and damping terms is established, and the differential equation describing the elastic cable response under earthquake action is obtained; The central difference format is used to discretize the node displacement, node velocity and node acceleration in the dynamic equilibrium equation. The integration step is selected according to the earthquake duration and the elastic cable period, and the time interval is discretized into multiple time steps. The dynamic equilibrium equation is integrated through Newmark parameters β and γ to establish the iterative format between the node displacement, velocity and acceleration of the current time step; The node displacement, node velocity and node acceleration of the elastic sling are set to zero at the initial moment. In the first time step, the node load data is used as input, and the node displacement, node velocity and node acceleration of the first time step are explicitly solved using the Newmark iteration format; In the second time step, according to the node displacement data obtained in the previous time step, the unit strain increment of the current time step is calculated using the strain-displacement relationship, the unit stress is updated using the constitutive relationship, and the unit stress is multiplied by the unit volume and integrated to obtain the node equivalent force increment of the current time step; Substitute the node velocity obtained in the previous step into the damping force expression to calculate the damping force increment of the current time step; introduce the node load increment, damping force increment and node equivalent force increment of the current time step into the dynamic equilibrium equation to establish an algebraic equation group reflecting the node force equilibrium state at the current moment; Solve the algebraic equations to obtain the node displacement increment of the second time step, and use the Newmark iteration relationship to update the node velocity increment and node acceleration increment of the second time step; add the node displacement increment, node velocity increment and node acceleration increment to the calculation results of the previous time step, respectively, to obtain the node displacement, node velocity and node acceleration of the current time step; Repeat the iterative update of the time step until the dynamic response calculation of the entire time history is completed, extract the node displacement, node velocity and node acceleration data of each time step, and form the dynamic response time history curve of the elastic cable under earthquake action.

7. The method for prefabrication of elastic slings and electrical connections for high-speed railway overhead contact network based on BIM according to claim 6, characterized in that: Optimize the initial elastic sling BIM model, including: Based on the response data of the elastic sling under static load conditions and the response data of the elastic sling under earthquake action, the envelope surface data reflecting the response characteristics of the elastic sling under the combined action of loads are calculated by combining the displacement field, stress field and strain field data under different working conditions; the envelope surface data is used to update the stress and strain properties of the elastic sling unit in the initial elastic sling BIM model; Taking the strain energy density distribution of the elastic sling as the optimization target, the strain energy density attribute parameters of the elastic sling unit are input into the SIMP interpolation model, and the nonlinear mapping relationship between the strain energy of the elastic sling and the elastic sling arrangement density is established through the interpolation equation in the form of a power function; the Mises stress distribution of the elastic sling is taken as the constraint condition; the Mises stress attribute parameters of the elastic sling unit are input into the KS aggregation function, and the local stress constraint is converted into a global stress constraint equation through the aggregation equation in the form of a P norm; The MMA optimization criterion is used to conduct sensitivity analysis on the elastic sling arrangement density of the elastic sling. Based on the first-order derivatives of the objective function and the constraints, a linearized optimization sub-problem is established. The dual method is used to solve the optimization sub-problem and the optimal elastic sling arrangement scheme of the current iteration step is obtained. The strain energy density data and Mises stress attribute parameters of the elastic sling unit are updated using the optimal elastic sling arrangement scheme, and the updated attribute parameters are substituted into the optimization criterion function to calculate the objective function value and constraint function value of the current iteration step; Determine whether the difference between the objective function value of the current iteration step and the objective function value of the previous step is less than the convergence threshold. If so, stop the iteration and output the final elastic sling arrangement plan; The final elastic sling arrangement scheme is discretized into the geometric information of the elastic sling, and the geometric information is used to modify the parameters of the initial elastic sling BIM model to generate the optimized elastic sling arrangement BIM model.

8. The method for prefabrication of elastic slings and electrical connections for high-speed railway contact network based on BIM according to claim 7, characterized in that: Taking the strain energy density distribution of the elastic sling as the optimization target, the strain energy density attribute parameters of the elastic sling unit are input into the SIMP interpolation model, and the nonlinear mapping relationship between the strain energy of the elastic sling and the elastic sling arrangement density is established through the interpolation equation in the form of a power function, including: The updated strain energy density attribute parameters of the elastic sling unit are input into the SIMP interpolation model, and the nonlinear relationship between the strain energy of the elastic sling and the density of the elastic sling arrangement is established by performing interpolation mapping formed by a power function on the strain energy density attribute parameters, and the strain energy expression of the elastic sling is obtained as the optimization objective function; The updated Mises stress attribute parameters of the elastic sling unit are input into the KS aggregation function. By performing a P-norm aggregation operation on the Mises stress attribute parameters, the stress constraint reflecting the local stress level of the elastic sling is transformed into a global stress constraint equation reflecting the overall stress level of the elastic sling, and a violation function is obtained as an optimization constraint function. According to the optimization objective function and optimization constraint function, the elastic sling arrangement density is taken as the design variable, and a mathematical model is established with the elastic sling strain energy being minimized as the optimization objective and the elastic sling overall stress meeting the strength requirement as the optimization constraint. The heuristic optimization algorithm is used to iteratively solve the established mathematical model and obtain the elastic sling arrangement scheme for the current iteration step.

9. The method for prefabrication of elastic slings and electrical connections for high-speed railway overhead contact network based on BIM according to claim 8, characterized in that: The optimization objective function expression is as follows: ; in, is the total strain energy expression of the elastic sling, i is the unit number in the finite element model of the elastic sling, is the volume of the ith unit, is the relative density of the i-th unit, i.e., the elastic sling arrangement density, ranging from 0 to 1. is the initial strain energy density of the i-th unit; is the penalty factor of the SIMP interpolation model.

10. The method for prefabrication of elastic slings and electrical connections for high-speed railway overhead contact network based on BIM according to claim 9, characterized in that: The optimization constraint function expression is as follows: ; in, represents the constraint function; represents the stress of the ith element as a function of relative density; is a given stress threshold.

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