Design method of steel structure spiral staircase

Abstract

The invention provides a design method of a steel structure spiral staircase, and relates to the field of building steel structure engineering, and the method comprises the steps: building a spiral staircase space line model through computer software, and discretizing and importing a finite element program; defining a bearing system composed of the internal rotation steel beam, the external rotation steel beam and the step steel beam; applying a handrail load, a step load and a temperature effect; setting boundary conditions of the fixed support; executing deformation, internal force and stress analysis; internal and external rotation steel beams are designed by adopting a box-shaped section according to a stress result, and a rectangular steel pipe step beam is used for providing plane external support; arranging riffled plates and rib plates on the lower flanges of the steel beams based on the deformation data; section steel is pre-embedded in the concrete platform according to the internal force of the support, and rigid connection of the ends of the steel beams is achieved. According to the method, the limitation of a traditional graph set on the size of the spiral staircase is broken through, and the requirements for strength, stability and deformation control are met at the same time through finite element full-process driving design under the condition that intermediate supports are cancelled.

Description

Technical Field

[0001] This invention relates to the field of steel structure engineering, and in particular to a design method for a steel structure spiral staircase. Background Technology

[0002] Spiral staircases, designed with a spiral shape, are aesthetically pleasing, lightweight, and space-saving, making them popular among architects for both interior and exterior applications. However, due to the inherent properties of curved structures, components must consider the combined effects of spatial bending, shear, torsion, and axial forces, resulting in a complex stress state. Currently available reference methods are limited, thus restricting their design and use. The existing steel staircase atlas 15J401 provides two types of steel spiral staircases: a central column type with a maximum height of 6000mm and a width of 750mm; and a slab type type with a maximum height of 6000mm, a width of 1500mm, and an inner radius of 600mm. For staircases exceeding these size limitations, or for architectural designs with arbitrary spatial spiral curves, no design or analysis methods or detailed construction details are provided. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a design method for steel structure spiral staircases, overcoming the shortcomings of existing structural analysis and design techniques for steel structure spiral staircases. Specifically, it includes:

[0004] A design method for a steel structure spiral staircase includes:

[0005] S1. Draw the spatial lines of the spiral staircase according to the requirements, and generate a 3D wireframe model of the spiral staircase;

[0006] S2. Based on the three-dimensional wireframe model, define the components in the finite element analysis program to obtain the defined component model;

[0007] S3. Apply a load to the component model with reference to the ambient temperature;

[0008] S4. Apply boundary constraints to the component model to which the load is applied;

[0009] S5. Perform finite element calculation to obtain stress analysis results, which include structural deformation data, component internal force distribution and stress state;

[0010] S6. Based on the stress analysis results, a step steel beam is set between the inner and outer rotating steel beams to provide out-of-plane support;

[0011] S7. Based on the stress analysis results, patterned steel plates and ribs are installed at the lower flange of the inner and outer rotating steel beams to control local deformation.

[0012] S8. Based on the stress analysis results, steel sections are pre-embedded in the concrete of the platform support area, and the ends of the inner and outer rotating steel beams are rigidly connected to the pre-embedded steel sections respectively.

[0013] Optionally, S1, which involves drawing the spatial lines of the spiral staircase as needed and generating a 3D wireframe model of the spiral staircase, includes:

[0014] Use computer-aided design software to draw the spatial lines of the spiral staircase;

[0015] After dividing the curved lines and straight line segments into equal intervals at specific intervals, import them into the finite element analysis program to generate a three-dimensional wireframe model of the spiral staircase.

[0016] Optionally, defining the components in the finite element analysis program includes:

[0017] In the finite element program, an inner spiral steel beam, an outer spiral steel beam, and a stair tread steel beam are defined respectively, and the stair tread steel beam connects the inner spiral steel beam and the outer spiral steel beam.

[0018] Optionally, the reference ambient temperature of S3, applying loads to the component model includes:

[0019] Within the finite element analysis program, define the loads on the inner and outer rotating steel beams:

[0020] The loads on the inner and outer rotating steel beams include: railing load, dead load on the stair tread steel beams, and live load on the stair tread steel beams.

[0021] The dead load borne by the steel beam of the stair tread: The application method is either uniform line load or concentrated load. The amount of resin for the dead load is calculated based on the self-weight of the stair tread plate, the weight of the surface material, the weight of the leveling layer, the material density, and the material size of the steel beam of the stair tread.

[0022] The live load borne by the steel beams of the stair treads is 3.5 kN / m².

[0023] Railing load: Acting on the top node of the main beam of the inner rotating steel beam and the top node of the main beam of the inner rotating steel beam, the railing load is used to simulate the service load of the railing handrail.

[0024] Optionally, the boundary constraints applied to the component model under load in step S4 include:

[0025] In the general finite element analysis program, the inner-rotation steel beam support and the outer-rotation steel beam support are defined as fixed supports, and the fixed supports are the model boundaries.

[0026] Optionally, the finite element calculation performed in S5 to obtain stress analysis results includes structural deformation data, component internal force distribution, and stress state, including:

[0027] When analyzing structural deformation data, obtain the maximum vertical and maximum horizontal displacements of each component in the three-dimensional wireframe model under various load conditions and combinations.

[0028] When performing component internal force distribution analysis, extract the distribution cloud map and maximum value of bending moment, torque, shear force and axial force of key components in the three-dimensional wireframe model;

[0029] When performing stress state analysis, the comprehensive stress ratio of components within the three-dimensional wireframe model is calculated based on the fourth strength theory.

[0030] Optionally, S6, based on the stress analysis results, includes setting a step steel beam between the inner and outer rotating steel beams to provide out-of-plane support, including:

[0031] The inner-rotation steel beam and the outer-rotation steel beam are defined as box-section beams;

[0032] A step steel beam is provided between the stair treads of the inner rotating steel beam and the stair treads of the outer rotating steel beam;

[0033] The step beams are rectangular steel pipes.

[0034] Optionally, in step S8, based on the stress analysis results, pre-embedding steel sections in the concrete of the platform support portion and rigidly connecting the ends of the inner and outer rotating steel beams to the pre-embedded steel sections includes:

[0035] Before pouring concrete for adjacent upper and lower rest platforms or floor beams, pre-embed steel sections:

[0036] The steel section includes a first part and a second part. The first part is an exposed steel beam with a box-shaped cross section. The second part is a steel column embedded in concrete with a cross-shaped cross section.

[0037] When the ends of the inner and outer spiral box-shaped beams of the spiral staircase are welded to the first part on site, ultrasonic flaw detection is carried out. After the pouring is completed, fine stone concrete is poured to make it dense.

[0038] The above technical solution has at least the following advantages compared with the existing technology:

[0039] This invention patent can meet the requirements for strength, stability and displacement when using steel structure spiral staircases. When spiral staircases appear in projects that are not applicable to the steel staircase design drawings, the method provided by this invention can be used.

[0040] The spiral staircase of this invention does not have supporting walls or columns between the starting and ending sections, resulting in a lightweight design and minimal building space occupation. It utilizes the inner and outer spiral steel beams installed at the railings on both sides of the staircase as the main load-bearing components, and the step steel beams installed based on the height difference of the stair treads as the out-of-plane support components for the inner and outer spiral steel beams. This achieves both functional use and structural load-bearing requirements, thus unifying functional use and structural load-bearing capacity.

[0041] By installing steel sections inside the concrete components of the platform support and connecting the inner and outer rotating steel beams with the built-in steel sections, a rigid connection between the inner and outer rotating steel beams and the platform support is achieved. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0043] Figure 1 This is a schematic diagram of the overall process of one embodiment of the present invention;

[0044] Figure 2 A spiral staircase spatial line drawn by computer-aided design software according to one embodiment of the present invention;

[0045] Figure 3 This invention provides an embodiment of an internally rotating steel beam, an externally rotating steel beam, and a stair tread steel beam within a general finite element analysis program.

[0046] Figure 4 This is a simplified diagram illustrating a variation analysis of one embodiment of the present invention;

[0047] Figure 5 This is a simplified diagram of the internal forces in one embodiment of the present invention;

[0048] Figure 6 This is a simplified diagram of stress analysis according to one embodiment of the present invention;

[0049] Figure 7 This is a schematic diagram illustrating an embodiment of the present invention in which a step steel beam is installed at the stair tread between inner and outer spiral steel beams.

[0050] Figure 8 In one embodiment of the present invention, a patterned steel plate and its ribs are provided at the lower flange between the inner and outer spiral steel beams;

[0051] Figure 9 This is a schematic diagram illustrating the reliable connection between the inner and outer rotating steel beams and the concrete-embedded steel profiles according to one embodiment of the present invention.

[0052] Figure 10 This is a detailed description of the first floor of a spiral staircase according to one embodiment of the present invention;

[0053] Figure 11 This is a plan view at elevation 7.450 of a spiral staircase according to one embodiment of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0055] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising,” “including,” or “including,” and similar terms mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or “connected,” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0056] Steel spiral staircases are frequently used by architects for both interior and exterior building applications due to their aesthetic appeal, lightweight design, and minimal space requirements. For spiral staircases meeting the requirements of the steel staircase atlas 15J401, the steel beam sections and joint details can be directly found in the atlas. However, for spiral staircases outside the applicable conditions of the atlas, there are no reference methods. Some designs using U-shaped steel beams as load-bearing components are rarely implemented due to their high cost and construction difficulty. Furthermore, the inherent properties of curved structures require consideration of the combined effects of spatial bending, shear, torsion, and axial forces, resulting in a complex stress state. Therefore, the use of spiral staircases is often limited. The purpose of this invention is to overcome the shortcomings of existing spiral staircase structural technologies by providing a design and analysis method for steel spiral staircases. This method can meet the strength, stability, and displacement requirements of steel spiral staircases during use. Specifically, this invention includes:

[0057] like Figures 1 to 11 As shown, a design method for a steel structure spiral staircase includes:

[0058] S1. Draw the spatial lines of the spiral staircase according to the requirements, and generate a 3D wireframe model of the spiral staircase;

[0059] like Figure 2 As shown, the spatial lines of the spiral staircase are drawn using computer-aided design software; the curved lines and straight line segments are divided into equal parts at specific intervals and then imported into the finite element analysis program to generate a three-dimensional wireframe model of the spiral staircase.

[0060] One specific implementation involves automatically generating the central reference spatial curve of the spiral staircase using parametrically driven parameters based on architectural design parameters (such as center radius R, total rotation angle θ, floor height H, and starting point coordinates). This is achieved through the application programming interface (API) of computer-aided design (CAD) software (such as AutoCAD or Rhino) or building information modeling (BIM) software (such as Revit). Then, using this central reference curve as a reference, spatial positioning curves for the inner and outer spiral beams are generated according to the radii of the inner and outer spiral beams determined in the design drawings, employing an offset algorithm. Finally, the spatial curves undergo discretization preprocessing. A specific interval (i.e., element division length) is used to equally divide the continuous curves; this interval is preferably between 100mm and 500mm and can be adjusted according to computational accuracy and efficiency requirements. After division, the generated series of key node coordinates and their connection relationships are exported in a common data format (such as IGES, STEP, or a text-formatted list of node coordinates) to provide the geometric basis for subsequent precise finite element mesh generation.

[0061] S2. Based on the three-dimensional wireframe model, define the components in the finite element analysis program to obtain the defined component model;

[0062] like Figure 3 As shown, an inner rotating steel beam, an outer rotating steel beam, and a stair tread steel beam are defined in the finite element program, and the stair tread steel beam connects the inner rotating steel beam and the outer rotating steel beam.

[0063] One specific implementation involves constructing a finite element model of the spiral staircase in a general-purpose finite element analysis program (such as ANSYS, ABAQUS, SAP2000, or MIDAS).

[0064] Import the geometric data exported in step S1 into the finite element program. Define beam elements to simulate all major load-bearing components according to steel structure design specifications:

[0065] The inner-rotation main steel beam and the outer-rotation main steel beam are simulated using spatial beam elements. When defining the element properties, their cross-sectional characteristics must be specified, including but not limited to the cross-sectional type (such as box section, H-beam, circular tube), cross-sectional area (A), moments of inertia in two directions (Iy, Iz), and torsional constant (J). These cross-sectional parameters can be predetermined based on mechanical calculations and architectural design.

[0066] Staircase tread steel beams: These are also simulated using spatial beam elements. Both ends are connected to the corresponding nodes of the inner and outer rotating main beams via rigid connections or coupled degrees of freedom to accurately simulate the mechanical transmission relationship between the treads and the main beams. The spacing of the tread beams is completely consistent with the distribution of the staircase treads.

[0067] The core of this step lies in transforming the complex spatial steel structure into a discretized mathematical model capable of numerical calculation through precise unit definition and connection methods.

[0068] S3. Apply a load to the component model with reference to the ambient temperature;

[0069] Within the finite element analysis program, define the loads on the inner and outer rotating steel beams:

[0070] The loads on the inner and outer rotating steel beams include: railing load, dead load on the stair tread steel beams, and live load on the stair tread steel beams.

[0071] The dead load borne by the steel beam of the stair tread: The application method is either uniform line load or concentrated load. The amount of resin for the dead load is calculated based on the self-weight of the stair tread plate, the weight of the surface material, the weight of the leveling layer, the material density, and the material size of the steel beam of the stair tread.

[0072] The live load borne by the steel beams of the stair treads is 3.5 kN / m².

[0073] Railing load: Acting on the top node of the main beam of the inner rotating steel beam and the top node of the main beam of the inner rotating steel beam, the railing load is used to simulate the service load of the railing handrail.

[0074] This step mainly involves defining the railing loads borne on the inner and outer spiral steel beams, the dead loads and live loads borne on the step beams in a general finite element analysis program; and considering the temperature effect of the steel spiral staircase.

[0075] One specific implementation method involves a dead load, applied to the stair beam element as a uniformly distributed line load (kN / m) or a concentrated load (kN). The load value includes the self-weight of the stair tread, the weight of the surface material (such as stone or wood), the weight of the leveling layer, etc., and is calculated based on the material density and dimensions.

[0076] Live load: Acting on the stair tread beam element, according to the requirements of the "Code for Design of Building Structures" GB50009, the standard value of the live load of stairs is usually taken as 3.5 kN / m². This surface load is converted into an equivalent line load or concentrated load acting on the stair tread beam.

[0077] Railing load: Acting on the top nodes of the inner and outer rotating main beams, simulating the service load of the railing handrail. Horizontal thrust (e.g., 0.5 kN / m or 1.0 kN / m) and vertical force are typically considered, and their magnitudes should comply with relevant specifications.

[0078] Temperature Effects: Considering the sensitivity of steel structures to temperature changes, an overall temperature variation needs to be defined. Based on the local climate conditions, a positive temperature rise (e.g., +30℃) and a negative temperature rise (e.g., -30℃) condition should be set. The program will then apply this to the coefficient of thermal expansion of steel (typically 1.2 × 10⁻⁶). -5 The system automatically calculates the resulting temperature stress ( / ℃).

[0079] Load combinations: Based on structural design codes, basic load combinations and standard combinations are defined, such as: 1.3 dead load + 1.5 live load; 1.0 dead load + 1.0 live load + 0.6 temperature effect, etc., for subsequent ultimate limit state and serviceability limit state verification.

[0080] like Figures 4 to 6 S4. Apply boundary constraints to the component model to which the load is applied;

[0081] In the general finite element analysis program, the inner-rotation steel beam support and the outer-rotation steel beam support are defined as fixed supports, and the fixed supports are the model boundaries.

[0082] One specific implementation method involves accurately simulating the supports in a finite element model based on the actual connection method between the spiral staircase and the main structure (such as a concrete platform beam or floor slab).

[0083] The most common connection method is a fixed hinge support, which fully constrains the nodes at both ends of the inner and outer rotating beams in all translational degrees of freedom (UX, UY, UZ) and rotational degrees of freedom (RX, RY, RZ). This simulation method is suitable for scenarios where the two ends of the staircase are rigidly connected to the main structure, effectively transferring bending moment and shear force, and the calculation results tend to be conservative.

[0084] The present invention preferably adopts a scheme with fixed constraints at both ends, because it can most effectively control the vibration and displacement of the spiral staircase under load, ensuring comfort and safety in use.

[0085] S5. Perform finite element calculation to obtain stress analysis results, which include structural deformation data, component internal force distribution and stress state;

[0086] When analyzing structural deformation data, the maximum vertical and horizontal displacements of each component within the 3D wireframe model are obtained under various load conditions and combinations. Specifically, the maximum vertical and horizontal displacements of the structure under various load conditions and combinations are obtained. These are then compared with the limits specified in the "Steel Structure Design Standard" GB50017 (usually 1 / 400 of the staircase span) to verify the serviceability limit state.

[0087] When performing component internal force distribution analysis, the distribution cloud maps and maximum values ​​of bending moment, torque, shear force, and axial force of key components within the 3D wireframe model are extracted. Specifically, the distribution cloud maps and maximum values ​​of bending moment (My, Mz), torque (Tx), shear force (Fy, Fz), and axial force (Fx) of key components (inner and outer rotating main beams) are extracted. These internal forces form the basis for subsequent section strength verification and node design.

[0088] When performing stress state analysis, the comprehensive stress ratio of the components within the 3D wireframe model is calculated based on the fourth strength theory (Von Mises stress). The comprehensive stress ratio of the components is calculated based on the fourth strength theory (Von Mises stress). It is ensured that the maximum stress of each component satisfies: σ under all load combinations. max / f y ≤1.0 (where f) y (This refers to the yield strength of the steel), thereby verifying the ultimate limit state of the structure's bearing capacity.

[0089] Based on the above analysis results, if displacement or stress exceeds the limits, it is supported to return to step S2 and iteratively optimize the steel beam cross-sectional dimensions (such as increasing the cross-sectional height and wall thickness) until all verifications meet the specification requirements. Finally, the optimized and confirmed cross-sectional model, internal force diagram, and displacement diagram are output as the basis for processing, manufacturing, and construction.

[0090] S6. Based on the stress analysis results, a step steel beam is set between the inner and outer rotating steel beams to provide out-of-plane support;

[0091] The inner and outer spiral steel beams of the spiral staircase have box-shaped sections. To ensure the stability of the inner and outer spiral steel beams and to meet the requirements for the stair treads, step steel beams are installed at the stair treads between the inner and outer spiral steel beams. The step steel beams are rectangular steel pipes.

[0092] like Figure 7 As shown in Figure S7, based on the stress analysis results, patterned steel plates and ribs are installed at the lower flanges of the inner and outer spiral steel beams to control local deformation; patterned steel plates and ribs are installed at the lower flanges between the inner and outer spiral steel beams.

[0093] The inner and outer spiral steel beams adopt closed box-sections, preferably rectangular box-sections. Box-sections have the characteristics of high torsional stiffness and good bidirectional bending performance, which can effectively resist the bending moment, torque and shear force generated by the spiral staircase under complex spatial loads, effectively control structural deformation, and its superior torsional performance is crucial for curved structures.

[0094] The aforementioned step beams are made of rectangular steel tubing. Their two flat surfaces facilitate connection to the step treads and their supporting structure, and also allow for intersecting welding to the inner and outer spiral main beams. Each step beam is arranged parallel to the main beams at equal intervals along the ascending direction of the staircase, and its ends are reliably connected to the webs of the inner and outer spiral box beams via high-strength welds, collectively transferring the step load to the main beams. This structure combines the dispersed step beams with the main beams into a highly statically indeterminate spatial beam system, greatly enhancing the overall and local stability of the entire staircase system.

[0095] Furthermore, the stair treads are constructed as follows: A patterned steel plate is laid as the base plate of the treads at the lower flange between the inner and outer spiral steel beams. The patterned steel plate serves both load-bearing and anti-slip functions. To enhance the rigidity of the base plate and reduce vibration, and to prevent excessive elastic deformation during use, stiffening ribs are welded above the patterned steel plate, i.e., between the inner and outer spiral steel beams. The ribs can be arranged parallel to the tread span direction, with equal spacing. The rib thickness is preferably 8mm to 12mm, the height is 100mm, and they are installed at 700mm intervals. This structure ensures that the stair treads have sufficient rigidity and comfort when bearing live loads such as pedestrian traffic, avoiding flutter.

[0096] S8. Based on the stress analysis results, steel sections are pre-embedded in the concrete of the platform support area, and the ends of the inner and outer rotating steel beams are rigidly connected to the pre-embedded steel sections respectively.

[0097] Before pouring concrete for the upper and lower rest platforms (or floor beams), steel embedded parts are pre-installed. These embedded parts are not simply pre-embedded steel plates, but consist of two parts: one part is an exposed steel beam (whose cross section can match the main beam of the staircase, such as a box section), and the other part is a steel column embedded in the concrete (whose cross section is designed to connect with the steel beam, such as a cross section). A sufficient number of studs or shear keys must be welded to ensure reliable anchorage with the concrete and shear force transfer.

[0098] During construction, the ends of the inner and outer spiral box-shaped beams of the spiral staircase will be butt-welded to the exposed steel embedded parts on site. The weld grade is Class I, and ultrasonic testing (UT) is required to ensure that the weld quality fully meets the mechanical performance requirements of rigid connections. After the column concrete is poured, the steel beams within 600 mm of the column edge will be filled with fine aggregate concrete to ensure the strength and stability of the ends of the inner and outer spiral steel beams.

[0099] This node construction achieves a true rigid connection between steel and concrete, reliably transmitting bending moment, axial force, and shear force. This is completely consistent with the fixed constraint boundary conditions of the finite element model in step S4, ensuring a high degree of consistency between the calculation model and the actual situation, thus making the analysis results realistic and reliable. This connection method greatly improves the overall stiffness and stability of the staircase.

[0100] The inner and outer rotating steel beams are connected to the platform support in a rigid manner. Since the support is a concrete structure, in order to ensure the rigid connection between the inner and outer rotating steel beams and the platform support, this invention uses steel sections inside the concrete of the support to reliably connect the inner and outer rotating steel beams with the steel sections inside the concrete.

[0101] This invention patent can meet the requirements for strength, stability and displacement when using steel structure spiral staircases. When spiral staircases appear in projects that are not applicable to the steel staircase design drawings, the method provided by this invention can be used.

[0102] The spiral staircase of this invention does not have supporting walls or columns between the starting and ending sections, resulting in a lightweight design and minimal building space occupation. It utilizes the inner and outer spiral steel beams installed at the railings on both sides of the staircase as the main load-bearing components, and the step steel beams installed based on the height difference of the stair treads as the out-of-plane support components for the inner and outer spiral steel beams. This achieves both functional use and structural load-bearing requirements, thus unifying functional use and structural load-bearing capacity.

[0103] By installing steel sections inside the concrete components of the platform support and connecting the inner and outer rotating steel beams with the built-in steel sections, a rigid connection between the inner and outer rotating steel beams and the platform support is achieved.

[0104] The following points need to be explained:

[0105] (1) The accompanying drawings of the embodiments of the present invention only involve the structures involved in the embodiments of the present invention. Other structures can refer to the general design.

[0106] (2) For clarity, the thickness of layers or regions is enlarged or reduced in the drawings used to describe embodiments of the invention, i.e., these drawings are not drawn to scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being “above” or “below” another element, the element may be “directly” located “above” or “below” the other element or there may be intermediate elements.

[0107] (3) Where there is no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to obtain new embodiments.

[0108] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A design method for a steel structure spiral staircase, characterized in that, include: S1. Draw the spatial lines of the spiral staircase according to the requirements, and generate a 3D wireframe model of the spiral staircase; S2. Based on the three-dimensional wireframe model, define the components in the finite element analysis program to obtain the defined component model; S3. Apply a load to the component model with reference to the ambient temperature; S4. Apply boundary constraints to the component model to which the load is applied; S5. Perform finite element calculation to obtain stress analysis results, which include structural deformation data, component internal force distribution and stress state; S6. Based on the stress analysis results, a step steel beam is set between the inner and outer rotating steel beams to provide out-of-plane support; S7. Based on the stress analysis results, patterned steel plates and ribs are installed at the lower flange of the inner and outer rotating steel beams to control local deformation. S8. Based on the stress analysis results, steel sections are pre-embedded in the concrete of the platform support area, and the ends of the inner and outer rotating steel beams are rigidly connected to the pre-embedded steel sections respectively.

2. The design method for a steel structure spiral staircase according to claim 1, characterized in that, The step S1, which involves drawing the spatial lines of the spiral staircase as required and generating a 3D wireframe model of the spiral staircase, includes: Use computer-aided design software to draw the spatial lines of the spiral staircase; After dividing the curved lines and straight line segments into equal intervals at specific intervals, import them into the finite element analysis program to generate a three-dimensional wireframe model of the spiral staircase.

3. The design method for a steel structure spiral staircase according to claim 2, characterized in that, The component definition in the finite element analysis program includes: In the finite element program, an inner spiral steel beam, an outer spiral steel beam, and a stair tread steel beam are defined respectively, and the stair tread steel beam connects the inner spiral steel beam and the outer spiral steel beam.

4. The design method for a steel structure spiral staircase according to claim 2, characterized in that, The reference ambient temperature of S3, and the load applied to the component model include: Within the finite element analysis program, define the loads on the inner and outer rotating steel beams: The loads on the inner and outer rotating steel beams include: railing load, dead load on the stair tread steel beams, and live load on the stair tread steel beams. The dead load borne by the steel beam of the stair tread: The application method is either uniform line load or concentrated load. The amount of resin for the dead load is calculated based on the self-weight of the stair tread plate, the weight of the surface material, the weight of the leveling layer, the material density, and the material size of the steel beam of the stair tread. The live load borne by the steel beams of the stair treads is 3.5 kN / m². Railing load: Acting on the top node of the main beam of the inner rotating steel beam and the top node of the main beam of the inner rotating steel beam, the railing load is used to simulate the service load of the railing handrail.

5. The design method for a steel structure spiral staircase according to claim 4, characterized in that, The boundary constraints applied to the component model under load in S4 include: In the general finite element analysis program, the inner-rotation steel beam support and the outer-rotation steel beam support are defined as fixed supports, and the fixed supports are the model boundaries.

6. The design method for a steel structure spiral staircase according to claim 5, characterized in that, The finite element calculation performed in S5 to obtain stress analysis results includes structural deformation data, component internal force distribution, and stress state, including: When analyzing structural deformation data, obtain the maximum vertical and maximum horizontal displacements of each component in the three-dimensional wireframe model under various load conditions and combinations. When performing component internal force distribution analysis, extract the distribution cloud map and maximum value of bending moment, torque, shear force and axial force of key components in the three-dimensional wireframe model; When performing stress state analysis, the comprehensive stress ratio of components within the three-dimensional wireframe model is calculated based on the fourth strength theory.

7. The design method for a steel structure spiral staircase according to claim 6, characterized in that, Based on the stress analysis results, S6 includes setting a step steel beam between the inner and outer rotating steel beams to provide out-of-plane support, including: The inner-rotation steel beam and the outer-rotation steel beam are defined as box-section beams; A step steel beam is provided between the stair treads of the inner rotating steel beam and the stair treads of the outer rotating steel beam; The step beams are rectangular steel pipes.

8. The design method for a steel structure spiral staircase according to claim 7, characterized in that, Based on the stress analysis results, S8 involves pre-embedding steel sections within the concrete of the platform support area and rigidly connecting the ends of the inner and outer rotating steel beams to the pre-embedded steel sections, respectively. Before pouring concrete for adjacent upper and lower rest platforms or floor beams, pre-embed steel sections: The steel section includes a first part and a second part. The first part is an exposed steel beam with a box-shaped cross section. The second part is a steel column embedded in concrete with a cross-shaped cross section. When the ends of the inner and outer spiral box-shaped beams of the spiral staircase are welded to the first part on site, ultrasonic flaw detection is carried out. After the pouring is completed, fine stone concrete is poured to make it dense.

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