Adaptive parametric lofting and modeling method for spatial special-shaped variable cross-section structure beam

Abstract

The application discloses a self-adaptive parameterized lofting and modeling method for a spatial special-shaped variable cross-section structure beam steel bar, and belongs to the technical field of building information modeling. In view of the fact that existing special-shaped beam steel bar modeling relies on preset cross-section profiles and cannot automatically adapt to cross-section gradual changes, based on a parameterized design platform, a two-dimensional drawing steel bar line is extruded through a curved surface and intersected with a skin model to construct a longitudinal steel bar three-dimensional space line, a stirrup working plane is adaptively generated along the skin normal direction, and then a longitudinal steel bar space position and a normal working plane are geometrically intersected to adaptively construct a stirrup and a tension bar solid model, and steel bar engineering quantity is automatically extracted. The method solves the defect that the spatial special-shaped variable cross-section structure beam steel bar modeling needs to define profile parameters section by section, realizes a full-process closed loop of self-adaptive fitting of a steel bar shape to a variable cross-section curved surface form and lofting and modeling of blanking, and improves the deepening design efficiency and precision of the complex spatial structure steel bar.

Description

Technical Field

[0001] This invention belongs to the field of building information modeling technology, specifically relating to an adaptive parametric lofting and modeling method for steel reinforcement of spatial irregular cross-section structural beams, applicable to the detailed design, three-dimensional modeling and quantity calculation of steel reinforcement in complex spatial curved concrete structures. Background Technology

[0002] In the construction field, conventional rebar layout software has significant limitations in handling the reinforcement of variable cross-section concrete beams with spatial irregularities. Manual calculations have low accuracy and are time-consuming and labor-intensive due to repeated calculations. Most existing rebar layout software focuses on handling variable cross-section beams with conventional shapes, and often fails to accurately generate rebar models and cutting data for complex spatial irregular variable cross-section beams. These software programs typically rely on simple geometries and fixed rules to arrange the rebar, making it difficult to adapt to the diverse and irregular geometric characteristics of spatial irregular variable cross-section beams.

[0003] Chinese invention patent application CN110119516A discloses a method for rebar detailing based on BIM technology. This method receives design drawings within the Revit platform and creates a BIM 3D model. Rebar is then placed in the model manually or through imported drawings, and the rebar settings are optimized and parameters are exported for fabrication. However, this method relies entirely on manual placement or importing drawings to create the rebar model. It lacks a parametric lofting algorithm for spatially irregular cross-section beams. For beams with complex curved surfaces, significant manual intervention is still required for boundary correction and rebar positioning, resulting in low efficiency and a high risk of errors.

[0004] Chinese invention patent application CN109918760A discloses a rebar modeling method based on Revit interoperability. This method involves manually drawing the rebar centerlines (excluding hooks and bends) in CATIA software, saving it as a DWG file, importing it into Revit, and then generating the rebar solid using Dynamo's Rebar.ByCurves module. However, this method essentially still relies on manually drawing the rebar centerlines in CATIA, failing to achieve parametric automatic lofting; furthermore, its technical solution does not involve surface adaptation algorithms for irregularly shaped variable cross-section beams, making it unable to handle the complex geometry of spatially variable cross-section beams.

[0005] Chinese invention patent application CN121412240A, filed by Shanghai Baoye Group Co., Ltd., discloses a BIM-based method for three-dimensional parametric modeling and cutting of reinforcing bars in irregularly shaped beams. This method also uses the Rhino / Grasshopper platform, coupling the structural skin with the two-dimensional beam centerline to generate a three-dimensional spatial path. The path is segmented at variable intervals, and working planes perpendicular to the skin normal are automatically created. The cross-sectional contours of longitudinal bars, stirrups, and tie bars are then parametrically mapped to each target working plane. Three-dimensional reinforcing bar entities are generated through lofting, and finally, the length, quantity, and weight of each bar are automatically extracted and a CNC cutting table is output. However, claim 1 of this application explicitly limits the method to "irregularly shaped spatial beams with uniform cross-sections," and its technical solution adopts a path of "extracting the detailed cross-sectional contour of the reinforcing bars - setting an initial working plane - mapping to the target working planes of all segment points - lofting to generate reinforcing bar entities based on the cross-sectional contour lines on the target working planes." For beams with variable cross-sections, the cross-sectional profile parameters need to be redefined and changed segment by segment along the beam length, and the beam cannot automatically adapt to the gradual change in cross-section. Furthermore, the shape of the stirrups is determined by the preset cross-sectional profile mapping and cannot be adaptively adjusted according to the changes in stirrup width caused by the variable cross-section. Therefore, although the existing technology solves the problem of parametric modeling of irregularly shaped spatial beams with uniform cross-sections, it still has shortcomings for the reinforcement layout and modeling of irregularly shaped spatial beams with variable cross-sections, such as the inability to automatically adapt to the gradual change in cross-section and the cumbersome operation of the preset profile.

[0006] As is well known to those skilled in the art, the Rhino / Grasshopper platform has advantages in NURBS surface fitting and complex geometric algorithm processing. Its functions such as extrusion, intersection, offset, pullback, normal calculation, and geometric intersection are all standard geometric functions of the platform. However, the specific combination and parameter connection of the above-mentioned standard functions in the reinforcement layout of spatial irregular cross-section structural beams, and the resulting alternative technical path that differs from the "preset cross-section contour mapping" route, have not yet been disclosed in the prior art. Summary of the Invention

[0007] To address the aforementioned deficiencies in existing technologies, this invention provides an adaptive parametric lofting and modeling method for steel reinforcement in spatial irregular cross-section structural beams. Based on a parametric design platform, the steel reinforcement lines in the two-dimensional drawings are extruded through curved surfaces and intersected with the outer skin model of the structural beam to directly construct the three-dimensional spatial lines of the longitudinal reinforcement. The working plane of the stirrups is adaptively generated along the normal direction of the outer skin. Then, the three-dimensional solid model of the stirrups and tie bars is adaptively constructed by the geometric intersection of the spatial position of the longitudinal reinforcement and the normal working plane, and the steel reinforcement quantity is automatically extracted.

[0008] Specifically, the method of the present invention includes five interconnected steps: generating and solidifying the three-dimensional spatial line of longitudinal reinforcement, generating the working plane of stirrup normal, generating the stirrup line and tie center line, generating the solid model of reinforcement, and extracting the quantity of reinforcement.

[0009] In the stage of generating and solidifying the three-dimensional spatial lines of longitudinal reinforcement, the planar drawing containing information on the top longitudinal reinforcement and additional reinforcement lines of the beam is imported into the parametric design platform and horizontally aligned with the outer skin model of the structural beam. The reinforcement line data is read and extruded vertically to generate a curved surface. The three-dimensional spatial lines of the beam's longitudinal reinforcement are extracted through the intersection calculation between the curved surface and the outer skin model of the structural beam. The outer skin model of the structural beam is offset according to the layer spacing of the longitudinal reinforcement to obtain the offset surfaces of each layer. The three-dimensional spatial lines are then pulled back to the corresponding offset surfaces to obtain the centerlines of the longitudinal reinforcement in each layer. The longitudinal reinforcement diameter parameters are input to generate the solid model of the longitudinal reinforcement. It is worth noting that the above steps are not simply a matter of calling and stacking Grasshopper nodes: using the method of extruding reinforcement lines vertically to generate a curved surface and then intersecting it with the outer skin model is to ensure that the three-dimensional spatial lines of the longitudinal reinforcement can cover the spatial position of the entire beam length and accurately fit the complex curved surface shape; using the method of offsetting the outer skin model according to the layer spacing of the longitudinal reinforcement and then pulling it back to the spatial lines is to ensure that the longitudinal reinforcement in each layer automatically fits the gradual change of the curved surface of the variable cross-section beam. If a two-dimensional cross-section contour mapping is directly used, it cannot adapt to the continuous change of the cross-section along the beam length.

[0010] In the stage of generating the stirrup normal working plane, the centerline of the variable cross-section beam is extracted and segmented according to the stirrup spacing to obtain segment points. A vertical working plane is generated at the segment points. The UV coordinate parameter values ​​of each segment point on the outer skin model of the structural beam are analyzed. Based on the UV coordinate values, the surface normal direction at the segment point is calculated. The vertical working plane is rotated to align with the surface normal direction to generate a stirrup normal working plane perpendicular to the outer skin surface. The generation of the above-mentioned normal working plane is also not a conventional plane operation: the working plane is generated by obtaining the UV coordinates of the segment points and calculating the surface normal in order to make the working plane accurately perpendicular to the local curved surface tangent plane of the irregular variable cross-section beam. If a vertical plane or a horizontal plane is directly used as the stirrup reference, the angle between the stirrup and the outer skin surface will deviate from the design angle as the cross-section changes, resulting in uncontrolled reinforcement cover thickness.

[0011] In the generation stage of stirrup lines and tie center lines, the intersection of the corner longitudinal reinforcement line located in the stirrup arrangement area with the stirrup normal working plane is obtained to obtain the stirrup vertex; the upper vertex and the lower vertex are connected respectively, and the two ends of the line segment are extended by the sum of the longitudinal reinforcement radius and the stirrup radius, the extended endpoints are extracted and connected to close the line, generating the stirrup center line; the two sides of the stirrup are extracted and segmented according to the tie spacing, and the segment points are combined one by one to generate the tie center line. The construction of the stirrup line also reflects a specific technical purpose: the use of intersecting the longitudinal reinforcement line with the normal working plane to determine the vertex, rather than pre-setting a fixed cross-sectional profile mapping, is to make the stirrup opening width adapt to the actual cross-sectional dimensions of the variable cross-section beam; the use of extending the two ends of the line by a specific distance of the sum of the longitudinal reinforcement radius and the stirrup radius is to accurately reserve the radial lap space between the longitudinal reinforcement and the stirrup while closing the stirrup, and this extension parameter needs to be dynamically calculated according to the actual reinforcement diameter, not a fixed empirical value.

[0012] During the reinforcement solid model generation stage, the stirrup diameter parameters and tie rod diameter parameters are input, and a stirrup solid model is generated based on the stirrup centerline. A tie rod solid model is also generated based on the tie rod centerline. Together with the already generated longitudinal reinforcement solid model, a complete three-dimensional model of the reinforcement of the spatial irregular cross-section structural beam is formed.

[0013] During the steel reinforcement quantity extraction stage, based on the aforementioned longitudinal reinforcement solid model, stirrup solid model, and tie bar solid model, the quantity, single length, and volume of each type of steel reinforcement are automatically counted, and steel reinforcement cutting parameters are output. The model automatically counts the quantity of each type of steel reinforcement, calculates and counts the length of each steel reinforcement, and calculates the volume of each steel reinforcement. Then, based on the steel reinforcement weight formula, the weight of each steel reinforcement is calculated and accumulated to form the total weight. The steel reinforcement is then numbered and exported to form a steel reinforcement cutting table.

[0014] It should be further explained that the above steps are not simply a collection of conventional geometric functions of the parametric design platform, but rather an alternative technical path that differs from the existing "preset cross-section contour mapping" approach by specifically combining and connecting functions such as extrusion, intersection, offset, pull-back, normal calculation, and geometric intersection with parameters. This specific combination enables the conventional geometric functions of the parametric design platform to work collaboratively on complex objects such as spatial irregular cross-section beams, achieving direct construction from two-dimensional drawing information to three-dimensional steel reinforcement entities, as well as adaptive fitting of steel reinforcement shapes to the variable cross-section surface morphology. Its overall technical effect is greater than the sum of the individual functions.

[0015] The beneficial effects of this invention are as follows: By replacing the preset cross-sectional contour mapping and layout with the intersection calculation and pull-back operation of the rebar lines and the outer skin model of the structural beam, the problem of having to define contour parameters segment by segment and being unable to automatically adapt to the gradual change of the cross-section in the modeling of the rebar of spatial irregular cross-section structural beams is solved, realizing the direct parametric construction from two-dimensional drawings to three-dimensional rebar models; by replacing the fixed cross-sectional contour mapping with the geometric intersection of the working plane based on the surface normal direction and the longitudinal reinforcement lines, the shape of the stirrups and tie bars is adaptively determined according to the actual cross-sectional size of the variable cross-section beam, avoiding the tedious operation of manually adjusting the stirrup contour segment by segment; through the collaborative parametric generation of longitudinal reinforcement, stirrups, and tie bars and the automatic statistics of engineering quantities, a fully adaptive closed loop of layout, modeling, and material cutting is formed, which significantly improves the efficiency and accuracy of the detailed design of the rebar of complex spatial variable cross-section structural beams. Attached Figure Description

[0016] Figure 1 This is a model of a large-scale spatial concrete roof beam rib, showing the combined form of a spatial irregular cross-section structural beam and a hyperboloid roof.

[0017] Figure 2This is a flowchart of the parametric modeling of the present invention, showing the connection relationship between the four modules: longitudinal reinforcement generation, normal working plane generation, stirrup and tie bar generation, and quantity statistics.

[0018] Figure 3 This is a plan view of a variable cross-section beam on a large-scale spatial concrete roof, showing the plan layout of the longitudinal reinforcement and additional reinforcement lines at the top of the beam.

[0019] Figure 4 This is a schematic diagram of the logical method of the present invention where the segmentation point position is perpendicular to the working plane of the surface, showing the connection relationship and data flow of nodes such as PerpFrame, Surface Closest Point, Evaluate Surface, and Align Plane.

[0020] Figure 5 This is a schematic diagram of the logical method of the stirrup model formed by the present invention, showing the node chain of the entity formed by the intersection of Curve Plane, the extension of ExtendCurve, the extraction of End Points, the closure of Line, and the generation of Pipe.

[0021] Figure 6 This is a schematic diagram of the logical method for forming a List of project rebar lengths and a List of rebar weights, showing the node flow for Length statistics, Mass Add accumulation, and weight formula calculation.

[0022] Figure 7 This is a schematic diagram of the material preparation for the three-dimensional spatial beam reinforcement formed by the present invention, showing the material preparation table format of reinforcement number, model, single length, number of reinforcements, total length and total weight.

[0023] Figure 8 This invention provides a spatial three-dimensional beam reinforcement model, demonstrating the arrangement of longitudinal bars, stirrups, and tie bars on a complex spatial curved surface. Detailed Implementation

[0024] The invention will be described in detail below using a large-scale spatial concrete roof project as an example. This project includes multiple spatial irregular cross-section structural beams. The beam cross-sections gradually change in height along the length direction, the beam axis is a spatial curve, and the beams intersect with the hyperboloid skin. It is necessary to perform parametric layout of reinforcement, 3D modeling, and quantity calculation for all beam components.

[0025] I. Generation and solidification of three-dimensional spatial lines of longitudinal reinforcement Import the plan view containing information on the top longitudinal reinforcement and additional reinforcement lines of the beam into the Rhino parametric design platform and align it horizontally with the outer skin model of the structural beam. Use the Grasshopper plugin to read the reinforcement line data from the drawing and accurately locate the spatial position of the reinforcement lines. Use the Extrude command to extrude the acquired reinforcement lines vertically, generating the corresponding surface model. Through the Intersect operation between the surface and the outer skin model of the structural beam, accurately extract the precise position lines of the beam's longitudinal reinforcement in three-dimensional space, completing the conversion from two-dimensional drawing to three-dimensional model.

[0026] Offset the outer surface model of the structural beam according to the longitudinal reinforcement layer spacing using the Offset Surface command, offsetting it to the location of the longitudinal reinforcement in each layer to obtain the offset surface for each layer. Use the Pull Curve command to pull the 3D spatial lines back to the offset surfaces to obtain the centerline of the longitudinal reinforcement in each layer. Input the longitudinal reinforcement diameter parameters, use the Pipe command to connect the spatial longitudinal reinforcement centerline and dimensions, and generate a 3D solid longitudinal reinforcement model.

[0027] It should be noted that for the spatial irregular cross-section structural beam in this embodiment, if the existing method of "extracting the detailed cross-sectional profile of the reinforcing bars and mapping it to the target working plane before lofting" is used, the cross-sectional profile parameters need to be redefined at certain intervals along the beam's length to adapt to the gradual change in cross-sectional height. When the beam cross-section changes non-linearly along its length or the beam axis is a spatial curve, the number of preset cross-sectional profiles will increase dramatically, and the transition area between adjacent profiles will be difficult to connect smoothly, leading to a decrease in model accuracy or a significant extension of the modeling cycle. However, this application, through the direct intersection and pull-back operation of the reinforcing bar lines and the outer skin model, eliminates the need to preset any cross-sectional profiles, allowing the longitudinal reinforcement to automatically conform to the curved surface of the variable cross-section beam, significantly improving modeling efficiency and geometric accuracy.

[0028] II. Generation of the working plane for the stirrup normal line The Offset Surface command is used to offset the outer surface model of the structural beam to the top and bottom positions of the stirrups. The PullCurve command is then used to pull the corner longitudinal reinforcement lines back to the top and bottom offset surfaces, obtaining the longitudinal reinforcement positioning lines for the stirrup arrangement area. The centerline of the variable cross-section beam is extracted, and the Divide Length command is used to segment the beam centerline according to the stirrup spacing, obtaining the segmentation points. The Perp Frame command is then used to generate a vertical working plane at the segmentation points.

[0029] The Surface Closest Point command is used to analyze the UV coordinate parameters of each segment point on the outer skin model of the structural beam. Then, the Evaluate Surface command is used to calculate the normal direction of the segment point on the surface based on the UV coordinate values. Finally, the Align Plane command is used to align the vertical working plane with the normal direction and rotate it to become a working plane perpendicular to the stirrup normal direction on the outer skin surface of the structural beam. This completes the accurate conversion from two-dimensional to three-dimensional space, ensuring the accuracy of subsequent reinforcement model generation.

[0030] III. Generation of Stirrup Lines and Tie Center Lines The Curve Plane command is used to intersect the top and bottom longitudinal reinforcement lines with the working plane of the stirrup normal, obtaining the stirrup vertices. The Line command is used to connect the two top and two bottom intersection points, forming a preliminary stirrup outline. The Extend Curve command is used to extend both ends of the connecting line by the sum of the longitudinal reinforcement radius and the stirrup radius (0.025 meters in this embodiment). The endpoints of the extended line segment are extracted using End Points, and then the Line command is used to connect the start and end points of the line segment, completing the stirrup line closure. The Pipe command is used to access the spatial stirrup centerline and stirrup dimension parameters, generating a three-dimensional solid stirrup model.

[0031] For the stirrup construction of variable cross-section beams, if a preset cross-section profile mapping method is used, the cross-sectional shape and size of the stirrups need to be defined separately for each segment. When the beam cross-section gradually changes, the stirrup opening widths at each segment are different, and the preset profile cannot adapt automatically, requiring manual adjustment segment by segment. In contrast, this application determines the stirrup apex by the actual intersection of the longitudinal reinforcement line and the normal working plane, and the stirrup opening width adaptively determines the actual cross-sectional dimensions of the variable cross-section beam without manual intervention.

[0032] The List Item command is used to extract the lines on both sides of the stirrup. Then, the Divide Length command is used to segment the center line of the stirrup according to the stirrup spacing. Next, the Line command is used to connect the corresponding segment points to obtain the center line of the stirrup. The Pipe command is used to input the center line and dimension parameters of the spatial stirrup to generate a three-dimensional solid stirrup model.

[0033] IV. Integration of Reinforcing Steel Entity Model Based on the longitudinal reinforcement solid model, stirrup solid model, and tie rod solid model generated in the aforementioned steps, a complete three-dimensional model of the reinforcement of a spatial irregular cross-section structural beam is formed. (Attached) Figure 8 The invention presents a spatial three-dimensional beam reinforcement model, in which longitudinal bars, stirrups, and tie bars are arranged according to their actual spatial positions. Problems of bar insertion and arrangement collisions can be detected and resolved in advance in the model.

[0034] V. Extraction of Reinforcing Steel Quantities and Export of Cutting Sheets The Length command is used to statistically analyze the length of each rebar, creating a Rebar Length Statistics List. The simplified calculation formula for rebar weight (kg) is used: Rebar weight (kg) = 0.00617 × Rebar diameter (mm) × Rebar diameter (mm) × Rebar length (m). The weight of each rebar is then calculated, creating a Rebar Weight List. Finally, the Mass Add command is used to sum the results, resulting in the total weight (kg). The rebars are then numbered, and their information is exported to create a rebar cutting table, including rebar number, rebar type, single length, number of rebars, total length, and total weight.

[0035] Through the above process, the reinforcement of all spatial irregular cross-section structural beams in this project was parametrically laid out, 3D modeled and the quantity of work was calculated in a short period of time. The generated 3D reinforcement model was in high-precision fit with the outer surface of the structural beam, and the cutting table could be directly used for material preparation and processing guidance during the construction phase.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An adaptive parametric lofting and modeling method for reinforcement of spatial irregular cross-section structural beams, characterized in that, Based on a parametric design platform, the steel reinforcement lines in the two-dimensional drawings are extruded through curved surfaces and intersected with the outer skin model of the structural beam to directly construct the three-dimensional spatial lines of the longitudinal reinforcement. Then, a working plane for the stirrups is adaptively generated along the normal direction of the outer skin. Finally, the geometric intersection of the spatial position of the longitudinal reinforcement with the normal working plane is used to adaptively construct a three-dimensional solid model of the stirrups and tie bars, automatically extracting the steel reinforcement quantities. The method includes the following steps: S1. Generation and solidification of longitudinal reinforcement 3D spatial lines: Import the plan drawing containing the longitudinal reinforcement and additional reinforcement information of the top of the beam into the parametric design platform and align it horizontally with the outer skin model of the structural beam. Read the reinforcement line data and extrude it along the vertical direction to generate a curved surface. Extract the 3D spatial lines of the longitudinal reinforcement of the beam through the intersection calculation of the curved surface and the outer skin model of the structural beam. Offset the outer skin model of the structural beam according to the layer spacing of the longitudinal reinforcement to obtain the offset surface of each layer. Pull the 3D spatial lines back to the corresponding offset surface to obtain the centerline of the longitudinal reinforcement of each layer. Input the longitudinal reinforcement diameter parameters to generate the longitudinal reinforcement solid model. S2. Generation of the stirrup normal working plane: Extract the centerline of the variable cross-section beam and divide it into segments according to the stirrup spacing to obtain segment points. Generate a vertical working plane at the segment points. Analyze the UV coordinate parameter values ​​of each segment point on the outer skin model of the structural beam. Calculate the skin normal direction at the segment points based on the UV coordinate values. Align the vertical working plane with the skin normal direction and rotate it to generate a stirrup normal working plane perpendicular to the outer skin surface. S3. Generation of stirrup lines and tie center lines: Intersect the corner longitudinal reinforcement lines located in the stirrup arrangement area with the stirrup normal working plane to obtain the stirrup vertices; connect the upper and lower vertices respectively, and extend the two ends of the line segment by the sum of the longitudinal reinforcement radius and the stirrup radius, extract the extended endpoints and connect them to close the line to generate the stirrup center line; extract the lines on both sides of the stirrup and divide them into segments according to the tie spacing, and combine the segment points one by one to generate the tie center line; S4. Reinforcing bar solid model generation: Input stirrup diameter parameters and tie bar diameter parameters, generate stirrup solid model based on the stirrup centerline, and generate tie bar solid model based on the tie bar centerline; S5. Reinforcing steel quantity extraction: Based on the aforementioned longitudinal reinforcement solid model, stirrup solid model, and tie bar solid model, automatically calculate the quantity, single length, and volume of each type of reinforcing steel, and output the reinforcing steel cutting parameters.

2. The adaptive parametric lofting and modeling method for reinforcement of spatial irregular cross-section structural beams according to claim 1, characterized in that, In S1, the parametric design platform is Rhino software, which reads the rebar data and performs the extrusion, intersection, offset and pullback operations through the Grasshopper plugin.

3. The adaptive parametric lofting and modeling method for reinforcement of spatial irregular cross-section structural beams according to claim 1, characterized in that, In S2, the vertical working plane is generated at the segment point using the Perp Frame command, the surface normal direction is obtained by calculating the UV coordinates after obtaining the Surface Closest Point, and the rotation is achieved using the Align Plane command.

4. The adaptive parametric lofting and modeling method for reinforcement of spatial irregular cross-section structural beams according to claim 1, characterized in that, In S2, the step of pulling the corner longitudinal reinforcement line located in the stirrup arrangement area back to the stirrup working plane specifically includes: calling Offset Surface to offset the outer skin model of the structural beam to the top and bottom positions of the stirrups, and pulling the corner longitudinal reinforcement line back to the top and bottom offset surfaces through PullCurve.

5. The adaptive parametric lofting and modeling method for reinforcement of spatial irregular cross-section structural beams according to claim 1, characterized in that, In S3, generating the stirrup centerline specifically includes: calling Curve Plane to intersect the top and bottom longitudinal reinforcement lines with the stirrup normal working plane to obtain intersection points; connecting the two top intersection points and the two bottom intersection points through the Line command to form a preliminary outline; calling Extend Curve to extend the connecting line by the sum of the longitudinal reinforcement radius and the stirrup radius; extracting the extended endpoint and closing it through the Line command to complete the stirrup line construction.

6. The adaptive parametric lofting and modeling method for reinforcement of spatial irregular cross-section structural beams according to claim 1, characterized in that, In S3, generating the center line of the stirrup specifically includes: calling List Item to extract the lines on both sides of the stirrup, calling Divide Length to segment according to the stirrup spacing, and connecting the corresponding segment points with the Line command to obtain the center line of the stirrup.

7. The adaptive parametric lofting and modeling method for reinforcement of spatial irregular cross-section structural beams according to claim 1, characterized in that, In S4, the center lines of the stirrups, tie bars, and longitudinal bars are connected via the Pipe command, and the corresponding bar diameter parameters are also connected to generate a three-dimensional solid bar model.

8. The adaptive parametric lofting and modeling method for reinforcement of spatial irregular cross-section structural beams according to claim 1, characterized in that, The method is applicable to spatial irregular cross-section beams, including complex shapes where the beam cross-section gradually changes in height or width along the length direction, the beam axis is a spatial curve, and the beam intersects with a hyperboloid skin.

9. The adaptive parametric lofting and modeling method for reinforcement of spatial irregular cross-section structural beams according to claim 1, characterized in that, The method achieves adaptive updates through a parameterized driving mechanism: when any parameter among the structural beam outer skin model shape, rebar diameter, and rebar spacing changes, the longitudinal reinforcement three-dimensional space line, stirrup normal working plane, rebar solid model, and engineering quantity statistics results are updated synchronously and automatically.

10. The adaptive parametric lofting and modeling method for reinforcement of spatial irregular cross-section structural beams according to claim 1, characterized in that, The parametric design platform mentioned in S1 is Rhino / Grasshopper.

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