A method, device and storage medium for inverse lofting using a yarn unit

Abstract

The application discloses a method and device for inverse form-finding of cable elements, and a storage medium, which projects a building space curved surface to an xoy plane to obtain a building outer contour projection line; an initial net shell structure model is designed according to the building outer contour projection line and combined with building modeling needs; real boundary conditions are set for the net shell structure model, real loads are applied, all beam elements in the net shell structure model are replaced by cable elements, initial stiffness is set, and an initial cable structure model is obtained; a finite element analysis software is used to obtain deformation forms and deformation data of the cable structure model under real loads and real boundary conditions; the obtained deformation data is scaled and inverted in combination with actual building sizes to obtain an optimal structure form matched with an actual building form. The form-finding calculation process of the application does not need multiple iterative calculations, effectively saves time cost, greatly improves structure form-finding efficiency, is simple to operate, low in design difficulty and high in design efficiency.

Description

Technical Field

[0001] This invention relates to the field of digital design technology in structural engineering, and in particular to a structural form-finding method, device and storage medium for determining structural morphology. Background Technology

[0002] In structural engineering, inverse suspension form finding is a commonly used technique for determining the optimal shape of a structure under external loads. "Inverse" corresponds to the reverse process of "forward suspension analysis"; it is not the opposite of gravity, but rather reverses the causal relationship between "shape" and "lofting," determining the original geometry of the cable (or membrane) in a stress-free state through reverse calculation. Traditional inverse suspension form finding methods typically involve the creation and testing of physical models, resulting in high time and material costs and low form finding efficiency.

[0003] With the development of computer technology, numerical simulation has become an effective alternative to traditional physical model-based shape finding methods. However, traditional numerical simulation methods are prone to problems such as a large number of iterations when dealing with complex structures, resulting in poor computational convergence and low computational efficiency.

[0004] Meanwhile, existing numerical simulation methods require replacing the elements in the model after shape finding, and then rebuilding the structural model to obtain the structural design model. This makes relay design impossible and results in a waste of manpower and time.

[0005] Finally, existing numerical simulation methods are usually based on complex mechanical concepts. Designers need to have a thorough understanding of the model before they can design, which is complicated to operate, difficult to design, and not conducive to improving design efficiency. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a method, device and storage medium for reverse hoisting form finding using cable elements, which addresses the defects and shortcomings of existing reverse hoisting form finding and numerical simulation technologies. This method has a clear mechanical concept, simple design and high computational efficiency.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for reverse lifting form finding using cable elements includes the following steps: S1 projects the architectural space surface onto the xoy plane to obtain the architectural outline projection line; S2 designs an initial grid shell structure model based on the building's outer contour projection lines and the building's shape requirements. S3 sets realistic boundary conditions for the reticulated shell structure model, applies realistic loads, replaces all beam elements in the reticulated shell structure model with cable elements, and sets initial stiffness to obtain the initial cable structure model. S4 uses finite element analysis software to obtain the deformation morphology and deformation data of the cable structure model under real load and real boundary conditions; S5 scales and inverts the obtained deformation data in conjunction with the actual dimensions of the building to obtain the optimal structural form that matches the actual shape of the building.

[0008] Specifically, step S1 projects the curved surface of the building space onto the xoy plane using relevant software to obtain the projection line of the building's outer contour line on the xoy plane.

[0009] Specifically, step S1 involves using 3D design software to read the 3D model of the architectural space surface and obtain the architectural space surface.

[0010] Specifically, step S2 involves dividing the building into grids based on the building's outer contour projection lines and the building's design requirements, and designing an initial grid shell structure model.

[0011] Specifically, in step S3, real boundary conditions are set for the outer contour nodes of the reticulated shell structure model, and real loads are applied to the internal nodes.

[0012] Specifically, in step S3, all beam elements in the reticulated shell structure model are replaced with cable elements, and the initial stiffness is set to obtain the initial cable structure model.

[0013] Specifically, step S4 involves performing finite element analysis on the cable structure model to obtain the deformation morphology of the cable structure under geometric nonlinearity and large displacement conditions.

[0014] Specifically, step S5 extracts the displacement results of each node in the cable structure model, and then performs scaling and inversion processing in conjunction with the actual building dimensions to obtain the optimal structural form that matches the actual building shape.

[0015] Specifically, in step S5, the cable elements in the inverted model are replaced with beam elements, and the cross-sectional properties of the members are assigned. The cross-sectional properties can be the height, width and wall thickness of a box section, and the diameter and wall thickness of a circular tube section, thus obtaining the final structural design model.

[0016] Since the cable element can only withstand tensile stress, when it first reaches equilibrium under external load, the optimal structural form with only tensile stress in the internal forces can be obtained. Therefore, this method effectively saves time and greatly improves the efficiency of structural form finding.

[0017] Based on the above method, the present invention also provides an electronic device or system for implementing the above-described method of reverse hoisting and shape finding using cable units.

[0018] Meanwhile, based on the widespread adoption of digital design, this invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed, is used to implement the above-mentioned method of reverse hoisting and form finding using cable units.

[0019] The innovation of this invention lies in the application of cables in structural form finding, which can effectively simulate the inverse deformation of the structure under real boundary and real grid division conditions. The building form after form finding is obtained by inverted deformation. At the same time, this method can utilize the mechanical properties of cables only being under tension to achieve successful form finding in one attempt, effectively saving time and costs, greatly improving form finding efficiency. Furthermore, this method has a clear mechanical concept, is simple to operate, and can effectively reduce design difficulty.

[0020] This invention first uses cable elements to perform a 'straight-up' test under actual load and boundary conditions, then reverses the displacement results, and finally replaces the cable elements back with beam elements in one go, thus obtaining a design model that can be directly used in construction drawings. It directly addresses the two pain points of "reconstructing the model after element replacement" and "complex concepts and difficult operation."

[0021] Compared with the prior art, the beneficial effects of this invention are: 1) It greatly reduces the dependence on physical models, reduces material consumption, and saves costs; 2) Fully utilize the mechanical property that cable elements can only withstand tension to ensure that the optimal structural form with only tensile stress in the internal forces of the cable structure can be obtained when the cable structure first reaches the equilibrium state, thus ensuring the accuracy of the form-finding results; 3) The form-finding calculation process does not require multiple iterations, which effectively saves time and greatly improves the efficiency of structural form-finding; 4) The mesh was realistically divided, and the boundary conditions and loads were realistically set. After replacing the elements in the model after form finding, the structural design model can be obtained. It can be used for relay design without having to rebuild the structural model. After completing the shape finding in step S5, the cable element is switched back to the beam element and a real cross section is assigned. In the software, this is done with just two commands: "Change element type" and "Change cross section properties". This achieves a "relay" design with almost no human intervention.

[0022] Cell replacement "zero reconstruction": "Cable" on the same mesh Switching between "beam" and "cable" in step S3, only the "beam → cable" batch replacement is performed on the original shell mesh. Node numbers, loads, boundaries, and section libraries are all retained, and there is no need to remodel.

[0023] 5) Clear mechanical concepts and simple operation greatly reduce design difficulty. The main purpose of this invention is to provide a design for rectangular steel-concrete composite beams that is convenient to construct, cost-effective, and has stable performance. It only utilizes the mechanical concept that "cables cannot withstand compression." Traditional reverse-hanging methods require calculating abstract quantities such as stress-free length, prestress distribution, and geometric stiffness; this method simply lets the cable "hang" itself, and designers only need to know how to apply loads and observe displacements to complete the entire process. Since the cable stops working once it is under compression, the first equilibrium state automatically filters out the optimal shape "only under tension," eliminating the need for iterative adjustments to prestress, achieving 100% success rate in finding the optimal shape. The operational threshold is reduced to three steps: "apply load - run nonlinear calculations - obtain the inverse displacement," simplifying the operation and greatly reducing design difficulty. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a flowchart of the method for reverse lifting and shape finding using cable units according to the present invention.

[0025] Figure 2 This is the initial cable structure model of an embodiment of the method for reverse lifting and form finding using cable units according to the present invention.

[0026] Figure 3 The deformation results of the cable structure are shown in the embodiment of the method of reverse lifting and forming by cable unit according to the present invention.

[0027] Figure 4 This is a structural model after form finding in an embodiment of the method of reverse lifting using cable units according to the present invention.

[0028] The corresponding labels in the attached drawings are as follows: 1-Architectural spatial curved surface, 2-Architectural outer contour projection line, 3-Cable unit, 4-Cable structure deformation form, 5-Structural model after reverse lifting and form finding. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] Example 1 Reference Figures 1-4 This preferred embodiment demonstrates a method for reverse-lifting shape finding using cable units, including 1-architectural space curved surface, 2-architectural outer contour projection line, 3-cable unit, 4-cable structure deformation form, and 5-structural model after reverse-lifting shape finding.

[0031] Reference Figures 1-2 In this embodiment, the three-dimensional model of the building surface is first read using the three-dimensional design software Rhino to obtain the building space surface 1; The architectural space surface 1 is then projected onto the xoy plane using the relevant software Rhino to obtain the projection line of the building's outer contour on the xoy plane.

[0032] refer to Figures 1-2 The above-mentioned building outline 2 is combined with the building shape requirements to design the initial grid shell model.

[0033] refer to Figures 1-2 Boundary conditions are set for the nodes on the outer contour 2 of the reticulated shell model, while real loads are applied to the internal nodes. All element types in the reticulated shell model are set to cable elements 3 to obtain the initial cable structure model.

[0034] refer to Figures 1-3 Using finite element analysis software, the initial cable structure model was analyzed using finite element methods. Considering geometric nonlinearity and large displacement conditions, the deformation morphology of the cable structure was obtained (see Figure 4). Figure 3 As shown.

[0035] Large displacement conditions can be achieved by applying initial loads, large displacements, and geometric stiffness loads to the cables using structural calculation software. Geometric nonlinearity can be achieved by selecting geometric nonlinearity in the analysis menu of the structural calculation software. The calculation method is the Newton-Raphson method.

[0036] When performing analysis of "cable structure + geometric nonlinearity + large displacement", the "structural calculation software" often referred to mainly refers to the following general-purpose finite element programs. They all have the function of directly selecting "geometric nonlinearity" in the menu and using the Newton-Raphson method for iteration, such as ANSYS, ABAQUS / Standard, MIDAS series (Gen, Civil, NFX), etc.

[0037] refer to Figure 1 and Figure 4 The displacement of each node in the cable structure is extracted and scaled and inverted according to the actual building dimensions to obtain the optimal structural form that adapts to the curved surface of the building space. The cable elements are then replaced with beam elements and given actual member cross-sections to obtain the final structural model 5, as shown in Figure 5. Figure 4 As shown, Figure 4 The cross-section of the member is a box-shaped section B400x200x8x8.

[0038] Example 2 Based on Embodiment 1, this embodiment provides an electronic device or system for implementing the above-described method of reverse hoisting and shape finding using cable units.

[0039] Meanwhile, based on the widespread adoption of digital design, this invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed, is used to implement the above-mentioned method of reverse hoisting and form finding using cable units.

[0040] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for reverse lifting and form finding using cable units, characterized in that... Includes the following steps: S1 projects the architectural space curved surface onto the xoy plane to obtain the architectural outline projection line; S2 designs an initial grid shell structure model based on the building's outer contour projection lines and the building's shape requirements. S3 sets realistic boundary conditions for the reticulated shell structure model, applies realistic loads, replaces all beam elements in the reticulated shell structure model with cable elements, and sets initial stiffness to obtain the initial cable structure model. S4 uses finite element analysis software to obtain the deformation morphology and deformation data of the cable structure model under real load and real boundary conditions; S5 scales and inverts the obtained deformation data in conjunction with the actual dimensions of the building to obtain the optimal structural form that matches the actual shape of the building.

2. The method for reverse hoisting and shape finding using cable units according to claim 1, characterized in that... Step S1 involves using 3D design software to read the 3D model of the architectural space surface and obtain the architectural space surface.

3. The method for reverse hoisting and shape finding using cable units according to claim 1, characterized in that... Step S2 involves dividing the building into grids based on the building's outer contour projection lines and the building's shape requirements, and designing the initial grid shell structure model.

4. The method for reverse hoisting and shape finding using cable units according to claim 1, characterized in that... Step S3 sets realistic boundary conditions for the outer contour nodes of the reticulated shell structure model and applies realistic loads to the internal nodes.

5. The method for reverse hoisting and shape finding using cable units according to claim 1, characterized in that... Step S3 replaces all beam elements in the reticulated shell structure model with cable elements and sets the initial stiffness to obtain the initial cable structure model.

6. The method for reverse hoisting and shape finding using cable units according to claim 1, characterized in that... Step S4 involves performing finite element analysis on the cable structure model to obtain the deformation morphology of the cable structure under geometric nonlinearity and large displacement conditions.

7. The method for reverse hoisting and shape finding using cable units according to claim 1, characterized in that... Step S5 extracts the displacement results of each node in the cable structure model, and then performs scaling and inversion processing based on the actual building dimensions to obtain the optimal structural form that matches the actual building shape.

8. The method for reverse hoisting and shape finding using cable units according to claim 1, characterized in that... Step S5 replaces the cable elements in the inverted model with beam elements and assigns section properties to the members to obtain the final structural design model.

9. An electronic device for implementing the method of reverse lifting and form finding using a cable unit as described in any one of claims 1-9.

10. A computer-readable storage medium having a computer program stored thereon, which, when executed, implements the method of reverse lifting and form finding using cable units according to any one of claims 1-9.

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