Extension of IFC Standard and Model Conversion Method for Railway Suspension Bridge Structure Analysis

Abstract

The application provides an IFC standard extension and model conversion method for railway suspension bridge structure analysis, belongs to the technical field of IFC standard extension and application, and comprises the following steps: step 1, IFC physical element entity extension and spatial geometric expression; step 2, IFC structure analysis entity extension and physical property expression; step 3, STEP format IFC model construction; step 4, design of multi-level semantic rules covering spatial geometry and physical property information; and step 5, establishment of a railway suspension bridge structure analysis model. Through the directional extension of the IFC standard and the establishment of the semantic model conversion method, the application realizes the standardized integration and lossless transmission of full-factor information of suspension bridge structure analysis, efficiently completes the automatic conversion from a BIM model to a computable structure analysis model, and finally provides technical support for core applications such as simulation analysis, performance prediction and intelligent management in the whole life cycle of the suspension bridge digital twin.

Description

Technical Field

[0001] This invention relates to the field of IFC standard extension and application technology, and in particular to IFC standard extension and model conversion methods for railway suspension bridge structural analysis. Background Technology

[0002] The construction and operation of railway suspension bridges in complex environments face multiple safety risks. Digital twin bridges are the core support for realizing intelligent monitoring, fault diagnosis, life prediction and full life cycle management of bridges. Structural simulation analysis capability is the key to the implementation of digital twin functions, which is highly dependent on the integration and complete transmission of bridge geometric model and physical property information such as material mechanical properties, loads, and boundary conditions.

[0003] While traditional BIM (Building Information Modeling) technology has significant advantages in information integration and collaboration throughout the entire lifecycle of suspension bridge projects, existing BIM models mostly focus on three-dimensional modeling of structural geometric features, primarily serving design collaboration, construction organization, schedule and cost management. They are severely lacking in semantic expression of structural analysis units, loads, boundary conditions, and detailed physical and mechanical parameters of components, and related key information is not explicitly associated with the component entities.

[0004] Existing methods for converting BIM models to structural analysis models largely rely on geometric format conversion and third-party software mesh generation. While these methods reduce errors in manual modeling and improve basic modeling efficiency to some extent, they have significant technical limitations: at the geometric level, a large number of non-load-bearing auxiliary components are easily retained, and structural analysis unit nodes are prone to positioning deviations, making it impossible to directly generate a calculable mechanical model; at the physical property level, due to the semantic deficiencies of BIM models, key mechanical parameters, loads, and boundary conditions are easily lost, still requiring structural analysis engineers to manually remodel, and the existing information in the BIM model cannot be effectively reused.

[0005] As a standardized carrier for cross-platform information sharing in BIM, the IFC (Industry Foundation Classes) standard possesses comprehensive object-oriented entity definition and semantic association capabilities, serving as the foundation for the complete expression of bridge lifecycle information. However, the latest IFC standard lacks standard definitions for core components of suspension bridges. Furthermore, due to issues such as the lack of semantics in structural analysis of BIM source models and limitations in the interactive functions of professional software IFC, directly generated IFC files cannot serve as an intermediate format to support the direct conversion from BIM models to structural analysis models. Therefore, there is an urgent need to establish an IFC semantic extension system and supporting model conversion methods for suspension bridge structural analysis. Summary of the Invention

[0006] This invention provides an IFC standard extension and model conversion method for railway suspension bridge structural analysis. The aim is to address industry pain points during the conversion from traditional BIM models to railway suspension bridge structural analysis models, such as redundancy of non-load-bearing auxiliary components, positioning deviations of structural analysis unit nodes, missing semantic representations of physical attributes required for structural analysis, and incomplete information transmission. It also fills the technical gaps in the current IFC standard, which lacks standard definitions for core suspension bridge components and the inability of native IFC models to directly support the automated construction of structural analysis models. Through the establishment of a targeted extension and semantic model conversion method for the IFC standard, the invention achieves standardized integration and lossless transmission of all elements of suspension bridge structural analysis information, efficiently completing the automated conversion from BIM models to computable structural analysis models. Ultimately, it provides technical support for core applications such as simulation analysis, performance prediction, and intelligent lifecycle management of suspension bridge digital twins.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The IFC standard extension and model conversion method for railway suspension bridge structural analysis includes: Step 1: Define physical element entities using the industrial base class standard extension method for new entities to describe the load-bearing components of the railway suspension bridge. Combine the existing definitions of the industrial base class standard and use attribute association to express spatial coordinates and geometric information to construct a spatial geometric expression framework for the railway suspension bridge. Step 2: Define entities in the structural analysis domain using the industrial foundation class standard extension method for newly added entities to describe the load action of the railway suspension bridge. Combine the existing definitions of the industrial foundation class standard to describe the component material parameters and structural units, nodes, load action and boundary conditions required for structural analysis, and construct a framework for expressing the physical properties of the railway suspension bridge. Step 3: Based on the spatial geometric expression framework and physical property expression framework of railway suspension bridges, select the Product Model Data Exchange Standard (STEP) format as the example modeling object, integrate multi-source engineering data, and construct an industrial basic standard model oriented towards structural analysis. Step 4: Based on the industrial foundation standard model, and according to the information expression hierarchy and characteristics of the industrial foundation standard model, design multi-level semantic rules covering spatial geometry and physical attribute information to constrain and guide the conversion process of the industrial foundation standard model to the structural analysis model. Step 5: Select Midas Civil as the structural analysis platform, use the standard industrial basic model for structural analysis as the conversion object, complete information extraction and conversion under the constraints of multi-level semantic rules, and establish the railway suspension bridge structural analysis model according to the Midas Command Flow (MCT) syntax rules.

[0008] In this instruction manual, step 1 includes: The physical element entity class is extended to include bridge physical element entities, and the subclasses of the bridge physical element entities cover the load-bearing components of railway suspension bridges, including stiffening girders, bridge towers, and main cables. Spatial geometric information is described using attribute association. Spatial positioning is directly defined through object placement attributes. Geometric information is defined using existing standard extrusion region entities and swept disk entities, including geometric information such as component cross-sectional profile, length, and cross-sectional radius.

[0009] In this instruction manual, step 2 includes: Material types are described using standard, existing material entities, and the material parameters required for structural analysis are described by a predefined set of properties. The standard existing structural component entities are introduced to describe the simplified element type of the components in structural analysis, structural connection entities are introduced to represent structural nodes, and boundary condition entities are associated to describe boundary constraint information. To address the load effects on railway suspension bridge structures, a new entity representing the structural load effects is developed, characterizing the effects of structural self-weight and environmental physical fields. The subclasses of this entity cover load types including structural self-weight, environmental wind effects, and temperature effects.

[0010] In this manual, step 3, the specific process of constructing a standard industrial foundation model for structural analysis by integrating multi-source engineering data, includes: A building information model of a railway suspension bridge project is established using building information modeling software, and the building information model of the railway suspension bridge project is exported as an original industrial basic standard model using supporting plugins. The heterogeneous engineering data of the structural design scheme and material parameter table, as well as the original industrial basic class standard model, are analyzed. The spatial hierarchy of the model is analyzed from top to bottom by traversing the relational entities. Based on the component category attribute or the component unique identifier, the set of physical element entities representing the load-bearing components is identified and filtered. The name or type attribute of the physical element entities is modified or defined to complete the entity type update. The system retrieves project entity attributes, defines global units, constructs a list of material parameters based on structural analysis requirements, sequentially creates structural units, nodes, boundary conditions, and load entities, and establishes explicit associations between physical attribute information and load-bearing component entities through relational entities. Finally, it generates a standard industrial basic model for structural analysis in a standard format for product model data exchange.

[0011] This manual describes the specific process of establishing a Building Information Modeling (BIM) model for a railway suspension bridge project using BIM modeling software, and then exporting the original industrial basic standard model using the accompanying plugin: In the building information modeling software, a three-dimensional parametric model including stiffening girders, bridge towers, suspension cables and main cables is created according to the design drawings of the railway suspension bridge. Configure the export parameters of the supporting plugin to export the three-dimensional parametric model as an original industrial basic class standard model.

[0012] In this specification, step 4 involves multi-level semantic rules, including global unit extraction rules, load-bearing component screening rules, node coordinate extraction rules, cross-sectional information extraction rules, and local-global coordinate transformation rules, which are applied sequentially to the geometric information processing stage of model transformation.

[0013] In this specification, step 4, the multi-level semantic rules also include material parameter mapping rules, structural unit type matching rules, load information mapping rules, and boundary condition mapping rules, which are applied sequentially to the physical information processing stage of model transformation.

[0014] In this specification, step 5, the geometric processing for information extraction and transformation under multi-level semantic rule constraints, includes: According to the load-bearing component screening rules, semantic filtering is performed on the components in the standard industrial foundation class model for structural analysis, and non-load-bearing auxiliary components are eliminated. The global unit definition of the model is clarified according to the global unit extraction rules. The node coordinates and section information of the load-bearing components are extracted according to the node coordinate extraction rules, section information extraction rules and local-global coordinate transformation rules, and the physical components are mapped to the corresponding structural analysis units. Setting a distance threshold removes redundant nodes and ensures the uniqueness of nodes in the structural analysis unit.

[0015] In this specification, step 5, the physical attribute processing for information extraction and transformation under multi-level semantic rule constraints, includes: According to the material parameter mapping rules and structural unit type matching rules, the corresponding material parameters and unit types are extracted from the industrial basic standard model for structural analysis and associated with the mapped structural analysis units. According to the load information mapping rules and boundary condition mapping rules, the corresponding load parameters and boundary constraint parameters are extracted from the model and associated with the corresponding structural analysis units and nodes.

[0016] In this manual, step 5, the specific process of establishing the railway suspension bridge structural analysis model according to the Midas command flow syntax rules, is as follows: The extracted geometric and physical property information is converted into a format according to the command flow syntax rules of the Midas civil structural design software to generate a command flow file containing element definitions, node definitions, material definitions, load definitions, and boundary condition definitions. Import the command stream file into Midas Civil Structural Design software to generate a railway suspension bridge structural analysis model for calculation.

[0017] In summary, the present invention has at least the following beneficial effects: it fills the gap in the definition of suspension bridge components in the current IFC standard, realizes the standardized and normalized expression of the classification, hierarchical relationship and structural analysis of suspension bridge components, and lays the core model framework foundation for cross-platform interoperability applications of bridge engineering based on the IFC standard.

[0018] It realizes the transformation of static design BIM model into semantic IFC model with complete mechanical properties, and constructs standardized IFC model for structural analysis through the fusion of multi-source engineering data, providing a unified and standardized intermediate data source for the generation of structural analysis models on different platforms.

[0019] It effectively solves industry pain points such as semantic alignment difficulties, easy information loss, and easy geometric topology deviations during the conversion of BIM models to structural analysis models. It ensures the correctness of geometric topology and the integrity of semantic information during cross-platform model conversion, greatly improves the iterative efficiency of suspension bridge structural analysis modeling, and reduces human error caused by manual modeling.

[0020] It provides key model support and technical assurance for the performance prediction, situation simulation, engineering decision-making, and intelligent application of digital twins throughout the entire life cycle of suspension bridge engineering. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the IFC standard extension and model conversion method for railway suspension bridge structural analysis involved in this invention.

[0023] Figure 2 This is the spatial geometric representation framework of the IFC suspension bridge in this embodiment of the invention.

[0024] Figure 3 This is the framework for expressing the physical properties of the suspension bridge IFC in this embodiment of the invention.

[0025] Figure 4 This is the process for constructing an IFC model based on the STEP format in this embodiment of the invention.

[0026] Figure 5 This is the structural analysis model conversion process in the embodiments of the present invention. Detailed Implementation

[0027] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the embodiments of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0028] The following disclosure provides many different implementations or examples for carrying out different structures of the embodiments of the present invention. To simplify the disclosure of the embodiments of the present invention, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the embodiments of the present invention. Furthermore, reference numerals and / or reference letters may be repeated in different examples of the embodiments of the present invention; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed.

[0029] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0030] like Figure 1 As shown, this embodiment provides an IFC standard extension and model conversion method for railway suspension bridge structural analysis, including: Step 1: Define physical element entities using the industrial base class standard extension method for new entities to describe the load-bearing components of the railway suspension bridge. Combine the existing definitions of the industrial base class standard and use attribute association to express spatial coordinates and geometric information to construct a spatial geometric expression framework for the railway suspension bridge. Step 2: Define entities in the structural analysis domain using the industrial foundation class standard extension method for newly added entities to describe the load action of the railway suspension bridge. Combine the existing definitions of the industrial foundation class standard to describe the component material parameters and structural units, nodes, load action and boundary conditions required for structural analysis, and construct a framework for expressing the physical properties of the railway suspension bridge. Step 3: Based on the spatial geometric expression framework and physical property expression framework of railway suspension bridges, select the Product Model Data Exchange Standard (STEP) format as the example modeling object, integrate multi-source engineering data, and construct an industrial basic standard model oriented towards structural analysis. Step 4: Based on the industrial foundation standard model, and according to the information expression hierarchy and characteristics of the industrial foundation standard model, design multi-level semantic rules covering spatial geometry and physical attribute information to constrain and guide the conversion process of the industrial foundation standard model to the structural analysis model. Step 5: Select Midas Civil as the structural analysis platform, use the standard industrial basic model for structural analysis as the conversion object, complete information extraction and conversion under the constraints of multi-level semantic rules, and establish the railway suspension bridge structural analysis model according to the Midas Command Flow (MCT) syntax rules.

[0031] In some embodiments, step 1 includes: The physical element entity class is extended to include bridge physical element entities, and the subclasses of the bridge physical element entities cover the load-bearing components of railway suspension bridges, including stiffening girders, bridge towers, and main cables. Spatial geometric information is described using attribute association. Spatial positioning is directly defined through object placement attributes. Geometric information is defined using existing standard extrusion region entities and swept disk entities, including geometric information such as component cross-sectional profile, length, and cross-sectional radius.

[0032] In some embodiments, step 2 includes: Material types are described using standard, existing material entities, and the material parameters required for structural analysis are described by a predefined set of properties. The standard existing structural component entities are introduced to describe the simplified element type of the components in structural analysis, structural connection entities are introduced to represent structural nodes, and boundary condition entities are associated to describe boundary constraint information. To address the load effects on railway suspension bridge structures, a new entity representing the structural load effects is developed, characterizing the effects of structural self-weight and environmental physical fields. The subclasses of this entity cover load types including structural self-weight, environmental wind effects, and temperature effects.

[0033] In some embodiments, step 3, the specific process of constructing an industrial foundation-based standard model for structural analysis by integrating multi-source engineering data, includes: A building information model of a railway suspension bridge project is established using building information modeling software, and the building information model of the railway suspension bridge project is exported as an original industrial basic standard model using supporting plugins. The heterogeneous engineering data of the structural design scheme and material parameter table, as well as the original industrial basic class standard model, are analyzed. The spatial hierarchy of the model is analyzed from top to bottom by traversing the relational entities. Based on the component category attribute or the component unique identifier, the set of physical element entities representing the load-bearing components is identified and filtered. The name or type attribute of the physical element entities is modified or defined to complete the entity type update. The system retrieves project entity attributes, defines global units, constructs a list of material parameters based on structural analysis requirements, sequentially creates structural units, nodes, boundary conditions, and load entities, and establishes explicit associations between physical attribute information and load-bearing component entities through relational entities. Finally, it generates a standard industrial basic model for structural analysis in a standard format for product model data exchange.

[0034] In some embodiments, the specific process of establishing a building information model of a railway suspension bridge project using building information modeling software and exporting the original industrial basic class standard model using a supporting plugin is as follows: In the building information modeling software, a three-dimensional parametric model including stiffening girder, suspension cable, bridge tower and main cable is created according to the design drawings of the railway suspension bridge; Configure the export parameters of the supporting plugin to export the three-dimensional parametric model as an original industrial basic class standard model.

[0035] In some embodiments, in step 4, the multi-level semantic rules include global unit extraction rules, load-bearing component screening rules, node coordinate extraction rules, cross-section information extraction rules, and local-global coordinate transformation rules, which are applied sequentially to the geometric information processing stage of model transformation.

[0036] In some embodiments, in step 4, the multi-level semantic rules also include material parameter mapping rules, structural unit type matching rules, load information mapping rules, and boundary condition mapping rules, which are applied sequentially to the physical information processing stage of model transformation.

[0037] In some embodiments, step 5, the geometric processing for information extraction and transformation under multi-level semantic rule constraints, includes: According to the load-bearing component screening rules, semantic filtering is performed on the components in the standard industrial foundation class model for structural analysis, and non-load-bearing auxiliary components are eliminated. The global unit definition of the model is clarified according to the global unit extraction rules. The node coordinates and section information of the load-bearing components are extracted according to the node coordinate extraction rules, section information extraction rules and local-global coordinate transformation rules, and the physical components are mapped to the corresponding structural analysis units. Setting a distance threshold removes redundant nodes and ensures the uniqueness of nodes in the structural analysis unit.

[0038] In some embodiments, step 5, the physical attribute processing for information extraction and transformation under multi-level semantic rule constraints, includes: According to the material parameter mapping rules and structural unit type matching rules, the corresponding material parameters and unit types are extracted from the industrial basic standard model for structural analysis and associated with the mapped structural analysis units. According to the load information mapping rules and boundary condition mapping rules, the corresponding load parameters and boundary constraint parameters are extracted from the model and associated with the corresponding structural analysis units and nodes.

[0039] In some embodiments, the specific process of establishing the railway suspension bridge structural analysis model according to the Midas command flow syntax rules in step 5 is as follows: The extracted geometric and physical property information is converted into a format according to the command flow syntax rules of the Midas civil structural design software to generate a command flow file containing element definitions, node definitions, material definitions, load definitions, and boundary condition definitions. Import the command stream file into Midas Civil Structural Design software to generate a railway suspension bridge structural analysis model for calculation.

[0040] In some embodiments, for the force transmission coupling characteristics of the "main cable-suspender-stiffening girder-bridge tower" of railway suspension bridges, a new suspension bridge coupling force association entity IfcBridgeForceCoupling is added based on the already extended bridge component entity IfcBridgeElement subclass entity. This entity is used to explicitly define the mechanical coupling relationship between load-bearing components. This entity inherits from the existing relation entity IfcRelConnects in the IFC standard. The predefined attribute set includes three core attributes: coupling type, coupling constraint stiffness, and global ID of associated components. The coupling type includes four types of railway suspension bridge-specific coupling forms: "main cable-suspender articulated coupling", "suspender-stiffening girder rigid coupling", "stiffening girder-bridge tower fixed coupling", and "main cable-bridge tower saddle sliding coupling".

[0041] In practice, upstream force transmission components (such as the main cable) are associated through the RelatingElement attribute of the coupled force-related entity of the suspension bridge, and downstream force-bearing components (such as suspenders) are associated through the RelatedElements attribute of the associated component. The coupling mechanical rules between the two are defined through a predefined set of attributes. At the same time, in the spatial geometric expression framework, a new spatial coordinate linkage rule for the coupled nodes is added: when the spatial coordinates of any component of the main cable, suspenders, or stiffening girder change, the coordinates of the coupled nodes of the associated components are automatically updated synchronously through the coupled associated entity.

[0042] In some embodiments, for the specific train moving live load requirements of railway suspension bridges, a new railway time-series moving load subclass entity IfcActionRailwayMovingLoad is added under the already extended bridge structural action entity IfcBridgeStructuralAction, filling the gap in the IFC standard's lack of standardized definitions for railway train moving live loads. The predefined attribute set of this entity fully matches the load requirements of railway bridge and culvert design specifications, including seven core attributes: train type, load formation, moving speed, number of loading lanes, impact coefficient, time-series loading step size, and ID of the component associated with the loading path. Among them, the train type covers three types of railway standard live loads: ZK live load, medium-load live load, and passenger dedicated line live load.

[0043] In practice, the railway time-series moving load subclass entity is associated with the stiffening beam corresponding structural unit entity IfcStructuralMember through the structural activity association entity IfcRelConnectsStructuralActivity. The action path of the live load is clarified by the component ID associated with the loading path. The continuous moving live load is decomposed into a multi-condition static load sequence that can be identified by the structural analysis software by the time-series loading step size attribute. At the same time, an automatic mapping rule between moving live load and structural unit is added to the physical attribute expression framework: according to the segment division of the stiffening beam, the time-series load sequence is automatically assigned to the structural unit of the corresponding segment without the need for manual secondary decomposition of load conditions.

[0044] In some embodiments, for the core of suspension bridge structural analysis—the stress-free form-finding parameters of the main cable—a new attribute set Pset_CableFormFinding is added to the predefined attribute set of the bridge main cable entity IfcBridgeCable. This attribute set includes five core parameters: stress-free cable length, initial tension, mid-span sag, saddle pre-offset, and completed bridge state coordinates. This attribute set is strongly bound to the geometric expression attributes of the bridge main cable entity. When the spatial coordinates of the main cable in the geometric expression change, the matching between the stress-free cable length and the completed bridge coordinates is automatically checked. If the deviation exceeds a preset threshold, an early warning is triggered.

[0045] In some embodiments, when constructing a STEP format IFC model by integrating multi-source engineering data, a new full-link parameter traceability mechanism is added: for each structural analysis parameter (material parameter, load parameter, boundary condition, form-finding parameter) written into the IFC model, a new exclusive traceability attribute set Pset_ParameterTraceability is added, which includes five core attributes: parameter source document number, data version number, generation time, verifier, and original data hash value; at the same time, global traceability metadata is added to the header of the STEP format file to record the original BIM model version, the storage path of multi-source engineering data, and the data fusion operation log, so as to realize full-link traceability from the original design data to the IFC model parameters.

[0046] In practice, when creating parameter entities based on the IfcOpenShell library (an open-source software parsing library based on industrial basic standards), a hash algorithm is synchronously called to generate a unique hash value for the original engineering data (such as material parameter table PDF files and structural design scheme documents), and write it into a dedicated traceability attribute set. When it is necessary to verify the authenticity of the parameters later, it is only necessary to recalculate the hash value of the original data and compare it with the hash value stored in the IFC model to confirm whether the parameters have been tampered with.

[0047] In some embodiments, an adaptive semantic rule optimization mechanism is added based on the designed multi-level semantic rules, specifically as follows: 1. A preset rule accuracy evaluation index system, including four core indicators: node coordinate deviation rate, component mapping integrity rate, parameter transfer accuracy rate, and model calculation convergence rate. 2. After each model transformation is completed, the evaluation index values ​​of the transformation results are automatically extracted. If any index fails to reach the preset threshold, rule adaptive optimization is triggered. 3. For geometric processing rules, the node deduplication distance threshold is adaptively adjusted according to the component type: for cable-type components such as main cables and suspenders, the threshold is automatically reduced to 2mm; for rigid components such as bridge towers and stiffening girders, the threshold is automatically adjusted to 10mm; for coordinate transformation rules, a coordinate transformation accuracy control strategy combining absolute tolerance and relative tolerance is adopted.

[0048] 4. Based on the convergence results of the structural analysis model, the load mapping step size is automatically optimized according to the physical property mapping rules: if the model does not converge, the time-series loading step size of the train moving live load is automatically reduced, the number of load cases is increased, and the solution stability is improved.

[0049] In some embodiments, after generating the Midas Civil structural analysis model according to the MCT syntax rules, a geometric-mechanical consistency closed-loop verification step is added, specifically: 1. Extract the main cable bridge-completed state node coordinates, initial tension, element type, material parameters, and boundary conditions from the generated Midas Civil model, and perform a full comparison with the corresponding parameters in the original IFC model; 2. For components such as main cables and suspension cables, perform form-finding consistency verification: Using the suspension bridge form-finding module of Midas Civil, perform form-finding calculations based on the converted model in the completed bridge state, and compare the calculated stress-free cable length and mid-span sag with the parameters stored in the dedicated attribute set of suspension bridge form-finding parameters in the IFC model. If the relative deviation exceeds 0.5%, the cable length parameters of the structural analysis model will be automatically corrected.

[0050] 3. For train moving live loads, perform load mapping consistency verification: automatically extract the moving load cases generated in Midas Civil and compare them with the attributes of the railway time-series moving load subclass entities in the IFC model to confirm that the load grouping, loading path and impact coefficient are completely matched. 4. After all verification items pass, a consistency verification report is generated. The hash value of the report is written into the custom attribute set of the IFC model project level, completing the full closed loop of transformation-verification-correction.

[0051] The technical concept of this invention is as follows: This invention adopts a core technical approach that combines IFC standard entity extension with existing entity reuse, and constructs an IFC standard extension system and a fully automated model conversion method for railway suspension bridge structural analysis. The core implementation process is as follows: IFC Physical Element Entity Expansion and Spatial Geometric Representation: By adding new entities through the IFC extension method, exclusive physical element entities are defined to describe the main load-bearing components of the suspension bridge. Combined with the existing definitions in the IFC standard, the spatial coordinates and geometric information are standardized through attribute association, thus constructing a spatial geometric representation framework for suspension bridges.

[0052] IFC Structural Analysis Entity Extension and Physical Property Representation: By adding new entities using the IFC extension method, we define entities in the structural analysis domain to describe the loads specific to suspension bridges. Combining existing definitions in the IFC standard, we complete the standardized expression of core physical properties of structural analysis, such as component material parameters, structural units, nodes, loads, and boundary conditions, and construct a framework for expressing the physical properties of suspension bridges.

[0053] STEP Format IFC Model Construction: Based on the aforementioned spatial geometry and physical attribute expression framework, the STEP format was selected as the instance modeling carrier. Using the original IFC model generated by BIM software as a basis, multi-source heterogeneous engineering data was integrated using Python's IfcOpenShell library to complete the construction of an instanced IFC model for structural analysis.

[0054] Multi-level semantic rule design: In response to the core differences between the IFC model and the structural analysis model in terms of geometric simplification and information expression logic, multi-level semantic rules covering two dimensions, spatial geometry and physical properties, are designed to provide standardized constraints and guidance for the conversion process from the IFC model to the structural analysis model.

[0055] Automated conversion of structural analysis models: Midas Civil was selected as the structural analysis platform. Under the constraints of multi-level semantic rules, the extraction, mapping and conversion of all elements of the IFC model were completed. Finally, a suspension bridge structural analysis model that can be directly used for calculation was generated according to the MCT syntax rules.

[0056] By extending the IFC standard entity definition of suspension bridge load-bearing components and load parameters, and combining it with the existing IFC architecture, a framework for expressing the spatial geometry and physical properties of suspension bridges is constructed. This fills the gap in the IFC standard suspension bridge entity definition, realizes the standardized expression of component classification, hierarchical relationships and structural analysis information, and lays the foundation for a model framework for cross-platform interoperability applications based on the IFC standard.

[0057] Based on the IFC (Information Capacity) representation framework for suspension bridges, this paper utilizes Python's IfcOpenShell library to integrate multi-source engineering data to establish an IFC model oriented towards structural analysis. This transforms the static BIM model into a semantic model with mechanical attributes, providing a standardized intermediate data source for generating structural analysis models in specific formats.

[0058] By comparing and analyzing the structure and characteristics of the IFC model and the structural analysis model, multi-level semantic rules covering spatial geometry and physical attribute information are designed. Model transformation is achieved under the constraints of semantic rules, and an MCT structural analysis model suitable for Midas Civil software is constructed to ensure the integrity and effectiveness of information transmission and improve the iterative efficiency of structural analysis modeling.

[0059] In one specific embodiment: Step 1: IFC Physical Element Entity Expansion and Spatial Geometric Representation: The IFC expansion method for adding new entities is used to define physical element entities to describe the main load-bearing components of the suspension bridge. Combined with existing IFC standard definitions, spatial coordinates and geometric information are expressed using attribute association, constructing a spatial geometric representation framework for the suspension bridge, such as... Figure 2 As shown, the detailed sub-steps are as follows: Step 1.1: Extend the bridge physical element entities, with subclasses covering load-bearing components such as stiffening girders (IfcStiffeningRib), bridge towers (IfcBridgePylon), and main cables. The extended entities inherit the basic attributes of the root entity IfcRoot, including globally unique identifiers (GlobalId), component names (Name), and descriptions. The physical element entities establish spatial dependencies with spatial element entities through the spatial structure containment relationship entity IfcRelContainedInSpatialStructure. Step 1.2: Spatial positioning is directly defined through the ObjectPlacement property. In terms of geometric representation, the modeling method corresponding to the SweptAreaSolid entity can be used to describe regular cross-section components such as bridge towers and stiffening girders, including attributes such as the two-dimensional cross-sectional profile SweptArea, extrusion depth Depth, and extrusion direction ExtrudedDirection. The SweptDiskSolid entity IfcSweptDiskSolid can achieve parametric geometric representation of cable-type components such as main cables and suspension cables by defining the scan trajectory Directrix and the disk radius Radius.

[0060] Step 2: IFC Structural Analysis Entity Expansion and Physical Property Representation: The IFC expansion method for adding new entities is used to define entities in the structural analysis domain to describe the loads acting on the suspension bridge. Combined with existing IFC standard definitions, the material parameters of components and the structural elements, nodes, loads, and boundary conditions necessary for structural analysis are described, constructing a framework for representing the physical properties of the suspension bridge, such as... Figure 3 As shown, the detailed sub-steps are as follows: Step 2.1: The material type (e.g., C50 concrete) is described by the material entity IfcMaterial, and the material parameters required for structural analysis are described by a predefined property set. For example, mechanical parameters are defined by the material mechanical parameter property set Pset_MaterialMechanical, including parameters such as elastic modulus, Poisson's ratio, and coefficient of thermal expansion. Based on the good extensibility of the IFC property set, the property set can be flexibly expanded to supplement parameters according to specific analysis conditions. Step 2.2: Introduce structural element entities to describe the simplified element types of components in structural analysis. For example, stiffening beams and cable towers are mapped to beam elements. The physical element entities are associated with their corresponding structural element entities through the product assignment relationship entity IfcRelAssignsToProduct. Based on this, the IfcStructuralConnection entity is introduced to represent structural nodes and associated with boundary conditions. Step 2.3: Extend the entity for the load action of the suspension bridge structure to represent the structural self-weight and the action of the environmental physical field. Its subclasses can cover types such as structural self-weight, environmental wind and temperature action. For example, the gravity action entity IfcActionSelfWeight properties include gravity vector and acceleration, etc., and the data type is defined by the IFC simple data type specification.

[0061] Step 3: Constructing an IFC model based on the STEP format: Based on the spatial geometric and physical property expression framework established in Step 2, the STEP format is selected as the instance modeling object. Multi-source engineering data is integrated to construct an IFC model oriented towards structural analysis, such as... Figure 4 As shown, the detailed sub-steps are as follows: Step 3.1: Create a BIM model of the bridge project using Revit software, and export the model as an original IFC model using the IFC for Revit plugin; Step 3.2: Analyze the heterogeneous engineering data such as structural design schemes and material parameter tables, and the original IFC model established in Step 3.1. Traverse the relational entities and parse the spatial hierarchy structure of the IFC model from top to bottom. Based on the component category attributes or component IDs of the BIM model, identify and filter the set of IFC physical element entities representing load-bearing components. Call the ifcopenshell.api.attribute.edit_attributes() function to modify or define their name or type attributes to update the entity type. Step 3.3: Retrieve the IfcProject entity attribute to clarify the global unit definition. Based on the structural analysis requirements, construct a material parameter list and call the model.create_entity() function to instantiate the material attributes. Then, create structural elements, nodes, boundary conditions, and load entities in sequence. Establish an explicit association between the above physical attributes and the load-bearing component IFC entity through relational entities. Step 4: Based on the hierarchical structure and characteristics of the information representation in the IFC model, design multi-level semantic rules covering spatial geometry and physical attribute information to constrain and guide the conversion process from the IFC model to the structural analysis model. Detailed sub-steps are as follows: Step 4.1: Extract global units and filter load-bearing components. Obtain the global unit definition by retrieving the global unit attribute UnitsInContext of the project entity, and filter the load-bearing core components, filtering out non-load-bearing or redundant components whose mechanical effects can be ignored. Step 4.2: Extract node coordinates and sections. Extract the linear beam element sections and node coordinates corresponding to components such as bridge towers and stiffening girders from the swept region entity. The coordinates of each corner point and section type of the initial section can be obtained from the section profile attributes. The coordinates of the center point of the section are the node coordinates of the element. The calculation method is shown in the formula: ; In the formula, and These are the coordinates of the first and second nodes, respectively, and n is the number of corner points in the stretching region. These are the coordinates of the i-th corner point of the stretched region. It is a unit vector in the stretching direction, and L is the stretching length.

[0062] Extract the cable element sections and node coordinates corresponding to components such as the main cable and suspenders from the swept disk entity. Obtain the reference radius of the swept section through the disk radius attribute. The node coordinate calculation method is shown in the equation: ; In the formula, and These are the coordinates of the first and second nodes, respectively. D is a function determined by the properties of the scan curve, s represents the source / starting point, and e represents the sink / end point.

[0063] Furthermore, to ensure continuity between structural analysis units, a distance threshold can be set to remove redundant nodes, thereby guaranteeing node uniqueness. This paper considers factors such as model accuracy and detail, setting the distance threshold to 10mm. Step 4.3: Perform local-to-global coordinate transformation. IFC physical element entities are typically defined based on a local coordinate system. The node coordinates extracted using the method in the previous section are located in the component's relative coordinate system. Therefore, coordinate transformation rules need to be established to obtain the global coordinates of the component nodes. Taking the entity representing a bridge tower component as an example, the 4×4 homogeneous transformation matrix for converting from the child coordinate system to the parent coordinate system is... As shown in the formula: ; In the formula: u, v, w represent the X, Y, Z axis direction vectors of the parent coordinate system, and p represents the position of the origin of the child coordinate system in the parent coordinate system; The three coordinate components of the X-axis unit vector of the target coordinate system in the original coordinate system describe the X-axis direction transformation from the original coordinate system to the target coordinate system. The three coordinate components of the Y-axis unit vector of the target coordinate system in the original coordinate system describe the Y-axis direction transformation from the original coordinate system to the target coordinate system. The three coordinate components of the Z-axis unit vector of the target coordinate system in the original coordinate system describe the transformation of the Z-axis direction from the original coordinate system to the target coordinate system. The three positional coordinate components of the origin of the target coordinate system in the original coordinate system describe the displacement vector from the origin of the original coordinate system to the origin of the target coordinate system.

[0064] By sequentially accessing the entire bridge IfcBridge, the bridge section IfcBridgePart, and the site IfcSite, and by layering the transformation matrices of the parent coordinate system, the coordinate values ​​of the component entity in the global coordinate system can be obtained, as shown in the equation: ; In the formula: Represents the global coordinates of the target vertex. Represents the local coordinates of the target vertex; : Component-Bridge homogeneous transformation matrix, a 4×4 homogeneous transformation matrix, used to transform the local coordinates of bridge components to the global coordinate system of the bridge, describing the pose (rotation + translation) of the component relative to the whole bridge. : Bridge-Bridge Site Homogeneous Transformation Matrix, a 4×4 homogeneous transformation matrix, used to transform the overall coordinates of the bridge to the coordinate system of the bridge site (such as the coordinate system for on-site engineering surveys), describing the pose of the bridge relative to the bridge site; Bridge site - Global homogeneous transformation matrix, a 4×4 homogeneous transformation matrix, is used to transform the bridge site coordinates to a global coordinate system (such as the national geodetic coordinate system or the project's overall coordinate system), describing the bridge site's pose relative to the global scene.

[0065] Step 4.4: Perform physical property mapping. Extract material parameters by retrieving the material mechanical parameter attribute set of load-bearing components. Determine the structural unit type corresponding to each load-bearing component using product allocation relationship entities. For example, the bridge tower component corresponds to the line element entity IfcStructuralCurveMember with the predefined type attribute value RIGID_JOINED_MEMBER for rigid connection rods. Finally, obtain the load and boundary conditions of the component sequentially through various relationship entities.

[0066] Step 5: Select Midas Civil software as the structural analysis platform. Transform the IFC model built in Step 3 under the semantic rule constraints of Step 4, and establish a structural analysis model according to the MCT syntax rules, such as... Figure 5 As shown, the bridge tower structure is converted into beam elements, the material parameters are matched with the corresponding parameters in the software's built-in material database, the gravity load direction is the opposite direction of the Z-axis, and the coefficient is -1.

[0067] This invention extends the IFC standard entity definition of suspension bridge load-bearing components and load parameters, and constructs a framework for expressing the spatial geometry and physical properties of suspension bridges by combining it with the existing IFC architecture. This fills the gap in the IFC standard's entity definition of suspension bridges, and achieves standardized expression of component classification, hierarchical relationships, and structural analysis information, laying the foundation for cross-platform interoperability applications based on the IFC standard. Based on the IFC expression framework for suspension bridges, the invention utilizes Python's IfcOpenShell library to integrate multi-source engineering data to establish an IFC model oriented towards structural analysis, transforming the static BIM model into a semantic model with mechanical properties, providing a standardized intermediate data source for generating structural analysis models in specific formats. By comparing and analyzing the structure and characteristics of the IFC model and the structural analysis model, multi-level semantic rules covering spatial geometry and physical property information are designed. Model conversion is achieved under the constraints of semantic rules, and an MCT structural analysis model suitable for Midas Civil software is constructed, ensuring the integrity and effectiveness of information transmission and improving the iterative efficiency of structural analysis modeling.

[0068] The embodiments described above are for illustrative purposes only and are not intended to limit the invention. Therefore, any changes in numerical values ​​or substitutions of equivalent elements should still fall within the scope of this invention.

[0069] The above detailed description will enable those skilled in the art to understand that the present invention can indeed achieve the aforementioned objectives and has complied with the provisions of the Patent Law.

[0070] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention. The above descriptions are merely preferred embodiments of the invention and are not intended to limit the invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

[0071] It should be noted that the above description of the process is for illustrative purposes only and does not limit the scope of this specification. Those skilled in the art can make various modifications and changes to the process under the guidance of this specification. However, these modifications and changes remain within the scope of this specification.

[0072] The basic concepts have been described above. Obviously, for those skilled in the art who have read this application, the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore, such modifications, improvements, and corrections still fall within the spirit and scope of the exemplary embodiments of this application.

[0073] Furthermore, this application uses specific terms to describe its embodiments. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different positions in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0074] Furthermore, those skilled in the art will understand that aspects of this application can be described and illustrated through several patentable types or situations, including any new and useful combination of processes, machines, products, or substances, or any new and useful improvements thereof. Therefore, aspects of this application can be implemented entirely in hardware, entirely in software (including firmware, resident software, microcode, etc.), or a combination of hardware and software. All of the above hardware or software can be referred to as a “unit,” “module,” or “system.” Furthermore, aspects of this application can take the form of a computer program product embodied in one or more computer-readable media, wherein computer-readable program code is contained therein.

[0075] The computer program code required for the operation of each part of this application can be written in any one or more programming languages, including object-oriented programming languages ​​such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, and Python; general programming languages ​​such as C; Visual Basic, Fortran2103, Perl, COBOL2102, PHP, and ABAP; dynamic programming languages ​​such as Python, Ruby, and Groovy; or other programming languages. This program code can run entirely on the user's computer, or as a standalone software package on the user's computer, or partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer can be connected to the user's computer via any network, such as a local area network (LAN) or wide area network (WAN), or connected to an external computer (e.g., via the Internet), or in a cloud computing environment, or used as a service such as Software as a Service (SaaS).

[0076] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this application are not intended to limit the order of the processes and methods of this application. Although some currently considered useful embodiments of the invention have been discussed in the foregoing disclosure by way of various examples, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments; rather, the claims are intended to cover all modifications and equivalent combinations that conform to the substance and scope of the embodiments of this application. For example, although the implementation of the various components described above can be embodied in a hardware device, it can also be implemented as a purely software solution, such as an installation on an existing server or mobile device.

[0077] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this approach of the present application should not be construed as reflecting an intention that the claimed subject matter requires more features than expressly recited in each claim. Rather, the subject of the invention should possess fewer features than in any single embodiment described above.

Claims

1. An IFC standard extension and model conversion method for railway suspension bridge structural analysis, characterized in that, include: Step 1: Define physical element entities using the industrial base class standard extension method for new entities to describe the load-bearing components of the railway suspension bridge. Combine the existing definitions of the industrial base class standard and use attribute association to express spatial coordinates and geometric information to construct a spatial geometric expression framework for the railway suspension bridge. Step 2: Define entities in the structural analysis domain using the industrial foundation class standard extension method for newly added entities to describe the load action of the railway suspension bridge. Combine the existing definitions of the industrial foundation class standard to describe the component material parameters and structural units, nodes, load action and boundary conditions required for structural analysis, and construct a framework for expressing the physical properties of the railway suspension bridge. Step 3: Based on the spatial geometric expression framework and physical property expression framework of railway suspension bridges, select the standard format for product model data exchange as the example modeling object, integrate multi-source engineering data, and construct an industrial basic standard model oriented towards structural analysis. Step 4: Based on the industrial foundation standard model, and according to the information expression hierarchy and characteristics of the industrial foundation standard model, design multi-level semantic rules covering spatial geometry and physical attribute information to constrain and guide the conversion process of the industrial foundation standard model to the structural analysis model. Step 5: Select Midas Civil Structural Design Software as the structural analysis platform, take the industrial basic standard model for structural analysis as the conversion object, complete information extraction and conversion under the constraints of multi-level semantic rules, and establish a railway suspension bridge structural analysis model according to the Midas command flow syntax rules. In step 4, the multi-level semantic rules include global unit extraction rules, load-bearing component screening rules, node coordinate extraction rules, cross-section information extraction rules, and local-global coordinate transformation rules, which are applied sequentially to the geometric information processing stage of model transformation. In step 4, the multi-level semantic rules also include material parameter mapping rules, structural unit type matching rules, load information mapping rules, and boundary condition mapping rules, which are applied sequentially to the physical information processing stage of model transformation.

2. The IFC standard extension and model conversion method for railway suspension bridge structural analysis according to claim 1, characterized in that, Step 1 includes: The physical element entity class is extended to include bridge physical element entities, and the subclasses of the bridge physical element entities cover the load-bearing components of railway suspension bridges, including stiffening girders, bridge towers, and main cables. Spatial geometric information is described using attribute association. Spatial positioning is directly defined through object placement attributes. Geometric information is defined using existing standard extrusion region entities and swept disk entities, including geometric information such as component cross-sectional profile, length, and cross-sectional radius.

3. The IFC standard extension and model conversion method for railway suspension bridge structural analysis according to claim 1, characterized in that, Step 2 includes: Material types are described using standard, existing material entities, and the material parameters required for structural analysis are described by a predefined set of properties. The standard existing structural component entities are introduced to describe the simplified element type of the components in structural analysis, structural connection entities are introduced to represent structural nodes, and boundary condition entities are associated to describe boundary constraint information. To address the load effects on railway suspension bridge structures, a new entity representing the structural load effects is developed, characterizing the effects of structural self-weight and environmental physical fields. The subclasses of this entity cover load types including structural self-weight, environmental wind effects, and temperature effects.

4. The IFC standard extension and model conversion method for railway suspension bridge structural analysis according to claim 1, characterized in that, Step 3, the specific process of constructing a standard industrial foundation model for structural analysis by integrating multi-source engineering data, includes: A building information model of a railway suspension bridge project is established using building information modeling software, and the building information model of the railway suspension bridge project is exported as an original industrial basic standard model using supporting plugins. The heterogeneous engineering data of the structural design scheme and material parameter table, as well as the original industrial basic class standard model, are analyzed. The spatial hierarchy of the model is analyzed from top to bottom by traversing the relational entities. Based on the component category attribute or the component unique identifier, the set of physical element entities representing the load-bearing components is identified and filtered. The name or type attribute of the physical element entities is modified or defined to complete the entity type update. The system retrieves project entity attributes, defines global units, constructs a list of material parameters based on structural analysis requirements, sequentially creates structural units, nodes, boundary conditions, and load entities, and establishes explicit associations between physical attribute information and load-bearing component entities through relational entities. Finally, it generates a standard industrial basic model for structural analysis in a standard format for product model data exchange.

5. The IFC standard extension and model conversion method for railway suspension bridge structural analysis according to claim 4, characterized in that, The specific process of establishing a building information model for a railway suspension bridge project using building information modeling software, and then exporting the original industrial basic standard model using the supporting plugins, is as follows: In the building information modeling software, a three-dimensional parametric model including stiffening girders, bridge towers, suspension cables and main cables is created according to the design drawings of the railway suspension bridge. Configure the export parameters of the supporting plugin to export the three-dimensional parametric model as an original industrial basic class standard model.

6. The IFC standard extension and model conversion method for railway suspension bridge structural analysis according to claim 1, characterized in that, Step 5, the geometric processing for information extraction and transformation under the constraints of multi-level semantic rules, includes: According to the load-bearing component screening rules, semantic filtering is performed on the components in the standard industrial foundation class model for structural analysis, and non-load-bearing auxiliary components are eliminated. The global unit definition of the model is clarified according to the global unit extraction rules. The node coordinates and section information of the load-bearing components are extracted according to the node coordinate extraction rules, section information extraction rules and local-global coordinate transformation rules, and the physical components are mapped to the corresponding structural analysis units. Setting a distance threshold removes redundant nodes and ensures the uniqueness of nodes in the structural analysis unit.

7. The IFC standard extension and model conversion method for railway suspension bridge structural analysis according to claim 1, characterized in that, Step 5, the physical attribute processing for information extraction and transformation under multi-level semantic rule constraints, includes: According to the material parameter mapping rules and structural unit type matching rules, the corresponding material parameters and unit types are extracted from the industrial basic standard model for structural analysis and associated with the mapped structural analysis units. According to the load information mapping rules and boundary condition mapping rules, the corresponding load parameters and boundary constraint parameters are extracted from the model and associated with the corresponding structural analysis units and nodes.

8. The IFC standard extension and model conversion method for railway suspension bridge structural analysis according to claim 1, characterized in that, In step 5, the specific process of establishing the railway suspension bridge structural analysis model according to the Midas command flow syntax rules is as follows: The extracted geometric and physical property information is converted into a format according to the command flow syntax rules of the Midas civil structural design software to generate a command flow file containing element definitions, node definitions, material definitions, load definitions, and boundary condition definitions. Import the command stream file into Midas Civil Structural Design software to generate a railway suspension bridge structural analysis model for calculation.

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