Square steel pipe joint and structural design method

Abstract

This invention provides a square steel pipe joint and its structural design method, relating to the field of fastening or fixing components. By determining the structural form of the square steel pipe and its support, and designing the shape and structure of the square pipe joint based on the structural form of the square steel pipe and its support, the structure of the square steel pipe joint is made more reasonable, and it has better standardization in terms of assembly accuracy, structural strength, and versatility, and is also convenient for mass production of the joint. In the design process, by referring to the dimensional parameters of the square steel pipe under the current standards, as well as the mechanical properties of the square steel pipe, the shape, structure, and size of the square pipe joint can be quickly calculated, and an intuitive reference can be provided for the materials used in the joint. This avoids the cumbersome analysis process of modeling, solving, and post-processing, effectively shortening the design and production cycles.

Description

Technical Field

[0001] This invention relates to the field of fastening or fixing components, specifically to square steel pipe joints and structural design methods. Background Technology

[0002] Square steel pipes are a common type of pipe material, typically with a rectangular or square cross-section, hence the names square steel pipes and rectangular steel pipes, respectively. They have a wide range of applications. In the construction industry, square steel pipes are often used as load-bearing and supporting components, with several square steel pipes assembled and connected to form a unified load-bearing support structure. In industrial manufacturing processes, there are also frequent situations where it is necessary to connect two or more square pipes.

[0003] Currently, one of the common methods for connecting square steel pipes is welding, which involves directly welding multiple square pipe beams together. However, welding multiple components together is time-consuming and labor-intensive, and the components are fixedly connected and cannot be disassembled. This makes it difficult to replace the square pipe beams when they are damaged or need to be replaced with other types of square pipe beams. Another method is to use specific square tube connectors for insertion. However, there are many types and specifications of existing square tube connectors, such as "CN113389782A-A square tube connection structure, CN114087265A-square tube connector, CN113513081A-A square tube connector structure and support mechanism, CN109025245A-A square tube scaffolding connector and square tube scaffolding". The connectors disclosed have their own characteristics and are different from each other. However, according to the national standard GB_T 3094-2012, both square steel pipes and rectangular steel pipes have strict dimensional and performance specifications. The overly complicated types of connectors can easily lead to problems such as large fitting gaps, low precision, low strength, and low versatility in actual use. At present, the industry only considers the number of steel pipes that a single square tube connector can accommodate, the convenience and speed of assembly, and the simplicity of the connector structure, which makes it easy to mass-produce.

[0004] Therefore, there is still room for improvement in the structural design of square steel pipe joints. Optimization and improvement are needed, along with the development of reasonable technical solutions and the discovery of a standard joint for square and rectangular steel pipes that conform to national standards, in order to overcome the aforementioned technical problems. Summary of the Invention

[0005] To achieve standardized and large-scale production of square steel pipe joints as specified in existing national standards, this invention provides a square steel pipe joint and structural design method, which makes the structure of the square steel pipe joint more reasonable and has better standardization in terms of assembly accuracy, structural strength, and versatility, and also facilitates the mass production of the joint.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a structural design method for square steel pipe joints, characterized in that the structural form of the square steel pipe and support is determined, and the shape and structure of the square pipe joint are designed according to the structural form of the square steel pipe and support, specifically including the following steps:

[0007] a. Determine the structural form of the square steel pipe, i.e., whether the cross-section is square or rectangular;

[0008] b. Determine that the cross-sectional shape of the joint insertion end corresponding to the square steel pipe in step a is either square or rectangular;

[0009] c. Determine the dimensional parameters of the square steel pipe, namely, the side length of the square cross-section is A1, the length and width of the rectangular cross-section are A2 and B respectively; and the outer bending radius of the four right-angle bends is R, and the wall thickness is S; the value range and corresponding relationship of A1, A2, B, R and S must comply with the provisions of square steel pipe D-1 and rectangular steel pipe D-2 in GB / T3094—2012;

[0010] d. Based on the parameters A1 or A2 and B obtained in step c, determine the dimensions of the insertion port of the square steel pipe joint and the cross-sectional dimensions of the locking section inside the joint;

[0011] ① A steel pipe with a square cross-section, that is, a steel pipe with an outer edge length of A1, whose corresponding insertion port of the connector and the cross-section of the locking section inside the connector are both square with a side length of A1+1.0-1.5mm;

[0012] ② A steel pipe with a rectangular cross-section, i.e., the length and width of the outer edge of the cross-section are A2 and B respectively, and the cross-section of the corresponding insertion port of the connector and the internal locking section of the connector is a rectangle with a length of A2+1.0-1.5mm and a width of B+1.0-1.5mm;

[0013] e. The determination of other auxiliary parameters is as follows:

[0014] ① The inner arc r at the bend of the connector insertion port, where r is a constant value of 3mm;

[0015] ②The locking through hole provided on the front of the connector has a diameter ranging from 10mm to 12mm;

[0016] ③ The wall thickness of the connector is directly proportional to the size of the connector insertion port, and the value ranges from 8.4mm to 10.6mm;

[0017] ④ A closed ring-shaped protrusion is provided at the connector insertion port, with a thickness of 4-5mm and a height of 1.6mm;

[0018] f. Determine the combination form of the square steel pipe support: The conventional combination forms are divided into the following types: single steel pipe through structure J1, two coordinate vertical steel pipe fixed structure J2, two coordinate vertical steel pipe through structure J3, three coordinate vertical steel pipe fixed structure J4, and three coordinate vertical steel pipe through structure J5.

[0019] g. Determine the external shape of the square steel pipe joint based on the parameters obtained in step f, which correspond to two straight sections F14, two openings F10, three openings F26, two vertical seals F15, three vertical seals F25, three vertical openings F35, as well as stacked seals F20 and stacked openings F21, and F62, which is a combination of F14 and the base.

[0020] Applying the above design method and considering the existing standards regarding square steel pipes, the square pipe joint involved includes two straight sections F14, two open sections F10, three open sections F26, two vertical seals F15, three vertical seals F25, three vertical open sections F35, as well as a stacked seal F20, a stacked opening F21, and a bottom support F62, the structures of which are as follows:

[0021] The F14 is a two-section straight cylinder with two vertically connected sections. A circular through hole is provided on the side wall of each connected section, and a locking bolt is installed thereon.

[0022] The F10 is a two-section open type, with a receiving section in the vertical direction and through holes on the left and right side walls in the horizontal direction of the receiving section to accommodate horizontal square steel pipes passing through.

[0023] The F26 is a three-section open type, with two horizontally connected receiving sections that pass through each other to fit the horizontal square steel pipes on the left and right sides. Opposite square through holes are opened at the middle position of the upper and lower side walls of the two horizontal receiving sections to accommodate the vertical square steel pipes. Circular through holes are set in three equal parts on the front side wall, and locking bolts are installed in each of them.

[0024] The F15 includes two mutually perpendicular and connected receiving sections. On the front or back, each receiving section near the port is provided with a circular through hole with a spiral pattern on the inner wall. The outer circumference of the circular through hole is also provided with a raised frustum.

[0025] The F25 is shaped like a triangular plate, comprising two oppositely arranged receiving sections at the bottom and a receiving section vertically connected to the middle of the two lower receiving sections. Each receiving section has a rectangular hole on its end face, and the three rectangular holes are arranged according to the structure of the outer receiving section and are interconnected. In addition, at the same location on the same side of the three receiving sections, that is, near the port of each receiving section, a circular through hole with a spiral pattern on its inner wall is provided, and the outer circumference of the circular through hole is also provided with a raised frustum.

[0026] The F35 is similar in structure to the F25, except that a through hole is provided on the side at the intersection of the three connecting sections to allow a horizontal square steel pipe to pass through.

[0027] The F20 includes three mutually perpendicular and connected receiving sections, located on the positive directions of the X and Y coordinate axes and the opposite direction of the Z coordinate axis, respectively. Each of the three receiving sections has a mutually perpendicular and connected rectangular hole on its end face. According to the orientation in the working state, the lower side of the two receiving sections in the X and Y coordinate axis directions is provided with a circular through hole with a spiral pattern near the port. The inner side of the receiving section in the opposite direction of the Z coordinate axis is provided with the same circular through hole. The vertical projection position of the rectangular hole on the coordinate axis on the side wall of the other two receiving sections is sealed, and the end of the vertical square steel pipe is abutted and fixed in this position.

[0028] F21 is similar to F20, except that the rectangular hole on the Z-axis is set at the vertical projection position on the side wall of the other two receiving sections, and the vertical square steel pipe passes through the rectangular hole and exits from the opening position.

[0029] The F62 includes an elliptical base and a receiving section. The bottom surface of the elliptical base is flat and has anti-slip grooves. The front side has an arc transition and is fixed to the receiving section at the geometric center. A circular through hole is opened on the front or back of the receiving section.

[0030] Beneficial effects:

[0031] The structural design method for square tube joints described in this invention can quickly calculate the shape, structure, and size of square tube joints by using the structural form of square steel pipes and supports, the dimensional parameters of square steel pipes under current standards, and the mechanical properties of square steel pipes. It can also provide an intuitive reference for the materials used in the joints, avoiding cumbersome analysis processes such as modeling, solving, and post-processing, and effectively shortening the design and production cycles. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the support structure in Example 1.

[0033] Figure 2 This is a schematic diagram of the F15 connector in Example 1.

[0034] Figure 3 This is a schematic diagram of the F25 connector in Example 1.

[0035] Figure 4 This is a schematic diagram of the F62 connector in Example 1.

[0036] Figure 5 This is a schematic diagram of the support structure in Example 2.

[0037] Figure 6 This is a schematic diagram of the F20 connector in Example 2.

[0038] Figure 7 This is a schematic diagram of the F21 connector in Example 2.

[0039] Figure 8 This is a schematic diagram of the support structure in Example 3.

[0040] Figure 9 This is a schematic diagram of the F10 connector in Example 3.

[0041] Figure 10 This is a schematic diagram of the F26 connector in Example 3.

[0042] In the diagram, there is a vertical steel pipe 1, a horizontal steel pipe 2, a connecting section 3, a circular through hole 4, and a rectangular hole 5. Detailed Implementation

[0043] The application will be further described below with reference to the accompanying drawings and embodiments.

[0044] Example 1

[0045] like Figure 1-4 As shown, the square steel pipe involved in this embodiment is a square steel pipe with an outer edge length of 25mm, a wall thickness of 2.5mm, and a radius of 6.25mm at the bend, which conforms to the square steel pipe D-1 specification in GB / T3094—2012; the support structure is a rectangular structure, specifically including a single steel pipe through structure J1, a two-coordinate vertical steel pipe fixing structure J2, and a two-coordinate vertical steel pipe through structure J3, which is composed of square steel pipes, including two vertical steel pipes 1, two horizontal steel pipes 2, and three types of square pipe joints.

[0046] The shape and structure design of the square tube joint are based on the structural form of the square steel tube and support, specifically including the following steps:

[0047] ① It is determined that the square steel pipe is a square with an outer edge length of 25mm. Therefore, its corresponding connector insertion port and locking section are squares with an outer edge length of 26.5mm.

[0048] ② The auxiliary parameters are determined as follows:

[0049] The inner radius of the bend at the connector insertion port is 3mm; the locking through hole on the front of the connector has a diameter of 10mm.

[0050] The connector wall thickness is 8.4mm; the closed ring-shaped protrusion at the connector insertion port has a thickness of 4mm and a height of 1.6mm.

[0051] ③ Based on the above parameters, the joint involved in this embodiment includes two vertical seals F15, three vertical seals F25, and a base assembly F62; the specific connection form is as follows: the lower end of the vertical steel pipe 1 is connected to the F62 joint, and the upper end is vertically connected to both ends of the horizontal steel pipe 2 through the F15 joint, while the two ends of the other horizontal steel pipe 2 are vertically connected to the vertical steel pipes 1 on both sides through the F25 joint, and the connection part is above the F62 joint.

[0052] Among them, F15 includes two mutually perpendicular and connected receiving sections 3, and on the front or back, each receiving section 3 near the port is provided with a circular through hole 4 with a spiral pattern on the inner wall, and the outer circumference of the circular through hole 4 is also provided with a raised frustum.

[0053] The F25 is shaped like a triangular plate, consisting of two oppositely arranged receiving sections 3 at the bottom and a receiving section 3 vertically connected to the middle of the two lower receiving sections 3. Each receiving section 3 has a rectangular hole 5 on its end face, and the three rectangular holes 5 are arranged according to the structure of the outer receiving section 3 and are interconnected. In addition, at the same location on the same side of the three receiving sections 3, that is, near the port of each receiving section 3, a circular through hole 4 with a spiral pattern on its inner wall is provided. The outer circumference of the circular through hole 4 is also provided with a raised frustum.

[0054] F62 includes an elliptical base and a receiving section 3. The bottom surface of the elliptical base is flat and has anti-slip grooves. The front side has an arc transition and is fixed to the receiving section 3 at the geometric center. A circular through hole 4 is opened on the front or back of the receiving section 3.

[0055] Example 2

[0056] like Figure 5-7 As shown, the square steel pipe involved in this embodiment is a square steel pipe with an outer edge length of 40mm, a wall thickness of 2.5mm, and a radius of curvature of 6.25mm at the bend, which conforms to the square steel pipe D-1 specification in GB / T3094—2012; the support structure is a quadrangular prism structure, specifically including a single steel pipe through structure J1, a three-coordinate vertical steel pipe fixing structure J4, and a three-coordinate vertical steel pipe through structure J5; it is constructed from square steel pipes, including four vertical steel pipes 1, eight horizontal steel pipes 2, and three types of square pipe joints.

[0057] The shape and structure design of the square tube joint are based on the structural form of the square steel tube and support, specifically including the following steps:

[0058] ① It is determined that the square steel pipe is a square with an outer edge length of 40mm. Therefore, its corresponding connector insertion port and locking section are squares with an outer edge length of 41mm.

[0059] ② The auxiliary parameters are determined as follows:

[0060] The inner radius of the bend at the connector insertion port is 3mm; the locking through hole on the front of the connector has a diameter of 10mm.

[0061] The connector wall thickness is 8.4mm; the closed ring-shaped protrusion at the connector insertion port has a thickness of 4mm and a height of 1.6mm.

[0062] ③ Based on the above parameters, the joints involved in this embodiment include stacked seal F20 and stacked opening F21, as well as base assembly F62; the specific connection form is as follows: the lower ends of the four vertical square steel pipes are respectively connected to the F62 joint, the upper ends are respectively vertically connected to the upper horizontal steel pipe 2 through the F20 joint, and the lower horizontal square steel pipe is respectively vertically connected to the vertical square steel pipe through the F21 joint, with the connection part above F62.

[0063] The F20 includes three mutually perpendicular and connected receiving sections 3, located on the positive directions of the X and Y coordinate axes and the opposite direction of the Z coordinate axis, respectively. Each of the three receiving sections 3 has a mutually perpendicular and connected rectangular hole 5 on its end face. According to the orientation in the working state, the lower side of the two receiving sections 3 in the X and Y coordinate axis directions is provided with a circular through hole 4 with a spiral pattern near the port. The inner side of the receiving section 3 in the opposite direction of the Z coordinate axis is provided with the same circular through hole 4. The vertical projection position of the rectangular hole 5 on the coordinate axis on the side wall of the other two receiving sections 3 is sealed, and the end of the vertical square steel pipe is abutted and fixed in this position.

[0064] F21 is similar to F20, except that the rectangular hole 5 on the Z-axis has an opening at the vertical projection position on the side wall of the other two receiving sections 3, and the vertical square steel pipe passes through the rectangular hole 5 and exits from the opening position.

[0065] F62 includes an elliptical base and a receiving section 3. The bottom surface of the elliptical base is flat and has anti-slip grooves. The front side has an arc transition and is fixed to the receiving section 3 at the geometric center. A circular through hole 4 is opened on the front or back of the receiving section 3.

[0066] Example 3

[0067] like Figure 8-10As shown, the square steel pipe involved in this embodiment is a square steel pipe with an outer edge length of 50mm, a wall thickness of 3.0mm, and a radius of curvature of 7.5mm at the bend, conforming to the square steel pipe D-1 specification in GB / T3094—2012; the support structure is a three-dimensional grid structure, including a single steel pipe through structure J1, a two-coordinate vertical steel pipe fixing structure J2, a two-coordinate vertical steel pipe through structure J3, a three-coordinate vertical steel pipe fixing structure J4, and a three-coordinate vertical steel pipe through structure J5; specifically, it includes at least three layers of rectangular horizontal members, each layer of rectangular horizontal members consisting of at least four The structure consists of horizontal square steel pipes, and also includes a frame composed of four vertical square steel pipes as apex support columns, as well as several vertical square steel pipes as connecting columns; the topmost rectangular horizontal member is connected to the four apex support columns via F20 joints; the lower second and third layer rectangular horizontal members are connected to the four apex support columns via F20 joints; the lower ends of the four apex support columns are connected to F62 joints respectively; in addition, from top to bottom, the first, second, and third layer rectangular horizontal members are connected to the connecting columns via F25 joints, F26 joints, and F10 joints respectively.

[0068] The shape and structure design of the square tube joint are based on the structural form of the square steel tube and support, specifically including the following steps:

[0069] ①The square steel pipe is determined to be a square with an outer edge length of 50mm. Therefore, its corresponding connector insertion port and locking section are squares with an outer edge length of 51.5mm.

[0070] ② The auxiliary parameters are as follows: the inner radius of the bend at the connector insertion port is 3mm; the diameter of the locking through hole on the front of the connector is 10mm; the wall thickness of the connector is 8.4mm; the thickness of the closed ring protrusion at the connector insertion port is 4mm and the height is 1.6mm.

[0071] ③ Based on the above parameters, the connectors involved in this embodiment include F20, F62, F25, F26, and F10.

[0072] The F20 includes three mutually perpendicular and connected receiving sections 3, located on the positive directions of the X and Y coordinate axes and the opposite direction of the Z coordinate axis, respectively. Each of the three receiving sections 3 has a mutually perpendicular and connected rectangular hole 5 on its end face. According to the orientation in the working state, the lower side of the two receiving sections 3 in the X and Y coordinate axis directions is provided with a circular through hole 4 with a spiral pattern near the port. The inner side of the receiving section 3 in the opposite direction of the Z coordinate axis is provided with the same circular through hole 4. The vertical projection position of the rectangular hole 5 on the coordinate axis on the side wall of the other two receiving sections 3 is sealed, and the end of the vertical square steel pipe is abutted and fixed in this position.

[0073] The F10 is a two-section open type, with a receiving section 3 set in the vertical direction, and through holes set on the left and right side walls in the horizontal direction of the receiving section 3 to accommodate the horizontal square steel pipe passing through.

[0074] The F26 is a three-section open type, with two horizontally arranged receiving sections 3 that pass through each other to fit the horizontal square steel pipes on the left and right sides. Opposite square through holes are opened at the middle position of the upper and lower side walls of the two horizontally arranged receiving sections 3 to accommodate the vertical square steel pipes passing through. Circular through holes 4 are arranged in three equal parts on the front side wall, and locking bolts are installed in each of them.

[0075] The F25 is shaped like a triangular plate, comprising two oppositely arranged receiving sections 3 at the bottom and a receiving section 3 vertically connected to the middle of the two lower receiving sections 3. Each receiving section 3 has a rectangular hole 5 on its end face, and the three rectangular holes 5 are arranged according to the structure of the outer receiving section 3 and are interconnected. In addition, at the same location on the same side of the three receiving sections 3, that is, near the port of each receiving section 3, a circular through hole 4 with a spiral pattern on its inner wall is provided. The outer circumference of the circular through hole 4 is also provided with a raised frustum.

[0076] F62 includes an elliptical base and a receiving section 3. The bottom surface of the elliptical base is flat and has anti-slip grooves. The front side has an arc transition and is fixed to the receiving section 3 at the geometric center. A circular through hole 4 is opened on the front or back of the receiving section 3.

Claims

1. A structural design method for square steel pipe joints, characterized in that, The structural form of the square steel pipe and support is determined, and the shape and structure of the square pipe joint are designed according to the structural form of the square steel pipe and support. Specifically, this includes the following steps: The structural form of the square steel pipe is determined, that is, the cross-section is square or rectangular; The cross-sectional shape of the joint insertion end corresponding to the square steel pipe in step a is determined to be either square or rectangular. The dimensional parameters of the square steel pipe are determined as follows: the side length of the square cross-section is A1, and the length and width of the rectangular cross-section are A2 and B, respectively; the outer bending radius of the four right-angle bends is R, and the wall thickness is S; the range of values ​​and corresponding relationships of A1, A2, B, R, and S must comply with the provisions of square steel pipe D-1 and rectangular steel pipe D-2 in GB / T3094—2012. Based on the parameters A1 or A2 and B obtained in step c, determine the dimensions of the insertion port of the square steel pipe joint and the cross-sectional dimensions of the locking section inside the joint. ① A steel pipe with a square cross-section, that is, a steel pipe with an outer edge length of A1, whose corresponding insertion port of the connector and the cross-section of the locking section inside the connector are both squares with a side length of A1+1.0-1.5mm. ② A steel pipe with a rectangular cross-section, i.e., the length and width of the outer edge of the cross-section are A2 and B respectively, and the cross-section of the corresponding insertion port of the connector and the internal locking section of the connector is a rectangle with a length of A2+1.0-1.5mm and a width of B+1.0-1.5mm; e. The determination of other auxiliary parameters is as follows: ① The inner arc r at the bend of the connector insertion port, where r is a constant value of 3mm; ②The diameter of the locking through hole on the front of the connector is between 10mm and 12mm. ③ The wall thickness of the connector is directly proportional to the size of the connector insertion port, and the value ranges from 8.4mm to 10.6mm; ④ A closed ring-shaped protrusion is provided at the connector insertion port, with a thickness of 4-5mm and a height of 1.6mm; f. Determine the combination form of the square steel pipe support: The conventional combination forms are divided into the following types: single steel pipe through structure J1, two coordinate vertical steel pipe fixed structure J2, two coordinate vertical steel pipe through structure J3, three coordinate vertical steel pipe fixed structure J4, and three coordinate vertical steel pipe through structure J5. g. Determine the external shape of the square steel pipe joint based on the parameters obtained in step f, which correspond to two straight sections F14, two openings F10, three openings F26, two vertical seals F15, three vertical seals F25, three vertical openings F35, as well as stacked seals F20 and stacked openings F21, and F62, which is a combination of F14 and the base.

2. The structural design method for the square steel pipe joint according to claim 1, characterized in that, The structure of the square tube joint F10 involved is as follows: F10 is a two-section open type, with a receiving section in the vertical direction and through holes on the left and right side walls in the horizontal direction of the receiving section to accommodate the horizontal square steel pipe passing through.

3. The structural design method for the square steel pipe joint according to claim 1, characterized in that, The structure of the square tube joint F14 involved is as follows: F14 is a two-section straight cylinder with two receiving sections in the vertical direction. A circular through hole is provided on the side wall of each receiving section, and a locking bolt is installed.

4. The structural design method for a square steel pipe joint according to claim 1, characterized in that, The structure of the square tube joint F26 involved is as follows: F26 is a three-section open type. Two horizontal receiving sections are set to pass through each other to fit the horizontal square steel pipes on the left and right sides. Opposite square through holes are opened at the middle position of the upper and lower side walls of the two horizontal receiving sections to accommodate the vertical square steel pipes. Circular through holes are set in three equal parts on the front side wall to install locking bolts.

5. The structural design method for a square steel pipe joint according to claim 1, characterized in that, The structure of the square tube connector F15 involved is as follows: F15 includes two mutually perpendicular and connected receiving sections, and on the front or back, each receiving section near the port is provided with a circular through hole with spiral patterns on the inner wall, and the outer circumference of the circular through hole is also provided with a raised frustum.

6. The structural design method for a square steel pipe joint according to claim 1, characterized in that, The structure of the square tube connector F25 involved is as follows: F25 is generally in the shape of a triangular shape, including two oppositely arranged receiving sections at the bottom and a receiving section vertically connected to the middle part of the two receiving sections at the bottom. Each receiving section has a rectangular hole on its end face. The three rectangular holes are also arranged according to the structure of the outer receiving section and are interconnected. In addition, at the same position on the same side of the three receiving sections, that is, at the position near the port of each receiving section, a circular through hole with a spiral pattern on the inner wall is provided. The outer circumference of the circular through hole is also provided with a raised frustum.

7. The structural design method for a square steel pipe joint according to claim 1 or 6, characterized in that, The structure of the square tube joint F35 involved is as follows: F35 is similar to F25, except that a through hole is provided on the side at the intersection of the three receiving sections to accommodate the horizontal square steel pipe passing through.

8. The structural design method for a square steel pipe joint according to claim 1, characterized in that, The structure of the square tube connector F20 involved is as follows: F20 includes three mutually perpendicular and connected receiving sections, located on the positive direction of the X-axis, the Y-axis and the opposite direction of the Z-axis, respectively. Each of the three receiving sections has a rectangular hole that is perpendicular to each other and connected. According to the orientation in the working state, the lower side of the two receiving sections in the X-axis and Y-axis directions is provided with a circular through hole with a spiral pattern near the port. The inner side of the receiving section in the opposite direction of the Z-axis is provided with the same circular through hole. The vertical projection position of the rectangular hole on the coordinate axis on the side wall of the other two receiving sections is sealed, and the end of the vertical square steel tube is abutted and fixed in this position.

9. The structural design method for a square steel pipe joint according to claim 1 or 8, characterized in that, The structure of the square tube joint F21 involved is as follows: F21 is similar to F20, except that the rectangular hole on the Z coordinate axis is set at the vertical projection position on the side wall of the other two receiving sections. The vertical square steel pipe passes through the rectangular hole and exits from the opening position.

10. The structural design method for a square steel pipe joint according to claim 1, characterized in that, The structure of the square tube connector F62 involved is as follows: F62 includes an elliptical base and a receiving section. The bottom surface of the elliptical base is flat and has anti-slip grooves. The front side has an arc transition and is fixed to the receiving section at the geometric center. A circular through hole is opened on the front or back of the receiving section.

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