An off-shore photovoltaic floating support structure of a truss with unequal lengths and different stiffnesses and a floating body fulcrum

Abstract

The present invention discloses a floating photovoltaic floating support structure of a truss with unequal lengths and different stiffnesses at the fulcrum. Four edge beams arranged around and four corner support beams form a square frame of the truss beam system support structure. Inside the square frame, a longitudinal support beam and two transverse support beams are cross-placed. The two transverse support beams and the longitudinal support beam are arranged in a "cross" shape. The "cross" intersection point is located at the midpoint of the square frame. A middle floating body is connected below the "cross" intersection point. Four surrounding floating bodies are respectively arranged at the four corners of the floating photovoltaic unit. The cross-sectional area of the middle floating body at the water surface is larger than that of the surrounding floating bodies to provide greater hydrostatic restoring stiffness, but the length is shorter than that of the surrounding floating bodies to reduce wave forces and save costs. The present invention not only saves steel consumption and reduces manufacturing costs, but also sets a middle floating body at the middle fulcrum of the floating photovoltaic floating support structure, providing a high-stiffness support point for the weakest part of the overall structure, effectively reducing the stress and deformation of the beam system structure, and significantly improving the bending resistance of the beam system structure.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore photovoltaic power generation, and particularly relates to an unequal-length and different-stiffness floating body fulcrum type truss offshore photovoltaic floating support structure. Background Art

[0002] The marine environment is relatively more severe than that in the inland. Ocean waves will be several times or even dozens of times that of inland water waves. Floating photovoltaic power stations will be directly exposed to the harsh marine environment, and the conventional floating body types in inland waters are no longer applicable. It is necessary to specifically develop floating photovoltaic floats suitable for the marine environment.

[0003] Patent CN106347596A discloses an annular floating tube type water surface photovoltaic power generation system and an installation method thereof, which uses a rigid support to support components to resist deformation caused by wave loads, adopts a multi-layer circular tube design, and has uniform buoyancy distribution; however, due to the transverse arrangement of the floating body parallel to the water surface in this design, the ultimate wave load is relatively large, and the waterplane area of the outer floating body is small. The restoring moment is mainly provided by the outermost annular floating tube, and the anti-overturning performance is lacking; Patent CN106411233A discloses an expandable water surface floating photovoltaic power generation device and an installation method adaptable to wind and wave environments, which is designed as an offshore photovoltaic rigid unit and adopts a rigid beam support. The floating body also extends horizontally parallel to the water surface, so the ultimate wave load it receives will also be relatively large; Therefore, it is necessary to propose an offshore photovoltaic floating support system that can reduce wave loading, reasonably conduct wave bending moments, has excellent stability, and is applicable to the harsh marine environment of large waves. Summary of the Invention

[0004] To solve the above problems, the present invention proposes an unequal-length and different-stiffness floating body fulcrum type truss offshore photovoltaic floating support structure, which has the advantages of significantly improving the bending resistance of the beam system structure by the large-stiffness floating body fulcrum in the middle, reducing wave loads and saving costs by the unequal-length design of the middle floating body and the surrounding floating bodies, small wave force when the floating body is placed vertically, reasonable force conduction of the truss beam system structure and better bending resistance, and better stability when arranged at the edge of the floating body.

[0005] The technical solution of the present invention is as follows: an unequal-length and different-stiffness floating body fulcrum type truss offshore photovoltaic floating support structure, which includes a truss beam system support structure, peripheral floating bodies and an intermediate floating body; four edge beams arranged around and four corner support beams arranged at the four corners form a square frame of the truss beam system support structure. The four peripheral floating bodies adopt vertically arranged strip-shaped structures, and the cross-section can be square, circular or any other shape. Compartments or ballasts can be considered according to actual situations inside, and they are respectively arranged at the four corners of the floating photovoltaic unit; a longitudinal support beam and two transverse support beams are arranged inside the square frame; the two transverse support beams are respectively located on both sides of the longitudinal support beam, and the three of the two transverse support beams and one longitudinal support beam are arranged in a "cross" shape. The "cross" intersection point is located at the midpoint of the square frame. An intermediate floating body is arranged below the "cross" intersection point. The cross-sectional area of the intermediate floating body at the water surface is larger than that of the peripheral floating bodies to provide greater hydrostatic restoring stiffness. The height value of the intermediate floating body is less than the height value of the peripheral floating bodies, but it needs to have sufficient height to ensure that the intermediate floating body cannot emerge from the water under any motion state.

[0006] Further, both ends of the longitudinal support beam are respectively connected to two opposite edge beams of the square frame, and the longitudinal support beam is parallel to the other two opposite edge beams.

[0007] Further, the longitudinal support beam includes four longitudinal support beam longitudinal bars, namely two left longitudinal support beam longitudinal bars and two right longitudinal support beam longitudinal bars. The two left longitudinal support beam longitudinal bars are arranged vertically, and the two right longitudinal support beam longitudinal bars are arranged vertically. The longitudinal support beam longitudinal bars are parallel to each other in pairs. The upper left longitudinal support beam longitudinal bar and the upper right longitudinal support beam longitudinal bar are on the same horizontal plane, and the lower left longitudinal support beam longitudinal bar and the lower right longitudinal support beam longitudinal bar are on the same horizontal plane.

[0008] Further, several longitudinal support beam planar diagonal bars are bent and connected between the two left longitudinal support beam longitudinal bars, and each two longitudinal support beam planar diagonal bars and the upper left or lower left longitudinal support beam longitudinal bar form a triangle; several longitudinal support beam planar diagonal bars are also bent and connected between the two right longitudinal support beam longitudinal bars, and each two longitudinal support beam planar diagonal bars and the upper right or lower right longitudinal support beam longitudinal bar form a triangle.

[0009] Further, several longitudinal support beam space diagonal bars are bent and connected between the upper left longitudinal support beam longitudinal bar and the lower right longitudinal support beam longitudinal bar, and several longitudinal support beam space diagonal bars are also bent and connected between the lower left longitudinal support beam longitudinal bar and the upper right longitudinal support beam longitudinal bar.

[0010] Further, one end of the transverse support beam is connected to the longitudinal support beam, and the other end is connected to an edge beam parallel to the longitudinal support beam.

[0011] Further, the edge beam and the transverse support beam have exactly the same structure as the longitudinal support beam.

[0012] Further, the corner support beam includes eight horizontal corner support beam rods and four vertical corner support beam rods; the eight horizontal corner support beam rods form two square frames, one above the other, and the four vertical corner support beam rods connect the two square frames.

[0013] Further, the middle floating body is a vertically arranged strip-shaped structure, and its cross-section can be square or circular.

[0014] The beneficial effects of the present invention are as follows:

[0015] (1) Only one longitudinal support beam and two transverse support beams are used inside the square frame of the beam system structure, and a simple and hollow symmetric design is adopted, which saves materials while the structure can meet the force requirements under large waves; the force is more balanced at each wave direction angle, and it is applicable to the marine environment with relatively balanced wave directions.

[0016] (2) The middle floating body of the beam system adopts a design with a shorter length than the surrounding floating bodies, that is, the middle floating body is shorter than the surrounding floating bodies; on the one hand, by reducing the length of the floating body in the longitudinal direction, the acting length of the wave load is reduced, thereby reducing the wave force, and on the other hand, the amount of floating body used can be reduced, thus reducing the cost.

[0017] (3) The floating body has a restoring stiffness in six degrees of freedom in water, similar to the function of a spring; in the present invention, due to the reduction of the number of longitudinal support beams and transverse support beams inside the square frame, the stiffness of the support structure will also be reduced at the same time; since the support structure is the weakest at the middle point, the present invention arranges a middle floating body in the middle of the truss beam system structure, which is equivalent to adding a spring fulcrum at the weakest part of the beam system bending, that is, the middle of the beam system; in addition, according to the hydrodynamics theory, the heaving restoring stiffness of the floating body depends on its waterplane area; the middle floating body of the beam system adopts a larger waterplane area than the surrounding floating bodies, providing greater stiffness at the middle fulcrum of the beam system structure, effectively reducing the force and deformation of the beam system structure, and significantly improving the bending resistance of the beam system structure while simplifying the beam system structure and reducing the steel consumption.

[0018] (4) Among the internal threats to offshore floating PV in the marine environment, the most significant one is the swell, and the most important impact of waves on offshore PV is the wave bending moment in the extreme state of midship sag and hogging. According to wave theory, wave loads are proportional to the waterplane area of the floating body. To reduce the wave forces acting on the floating body and then transmitted to the entire structure, the present invention designs a vertically placed floating body in the floating PV, which is different from the horizontal placement of the floating body parallel to the water surface in traditional inland water floating PV. The vertically placed floating body reduces the waterplane area of the floating body, thus having the advantage of small wave load.

[0019] (5) To apply floating PV in the marine environment where the number of waves is several times or even dozens of times that of inland waters and to withstand the action of the extreme bending moment under large waves, the present invention uses a truss beam system structure that can better resist bending moments, changing the pure bending force mode of the beam with weaker bending resistance into a tension and compression force mode of the member with stronger bending resistance, greatly enhancing the bending resistance of the beam system structure and improving the structural safety.

[0020] (6) The floating bodies are arranged at the four corners of the floating PV unit. When the floating PV tilts, the lever arm generated by the restoring force of the floating body is the longest, which can provide the maximum restoring moment to provide the maximum stability for the floating unit. Description of the Drawings

[0021] Figure 1 It is a side view of the overall schematic diagram of the offshore PV.

[0022] Figure 2 It is a front view of the overall schematic diagram of the offshore PV.

[0023] Figure 3 It is a schematic diagram of the floating body and truss beam system support structure of the offshore PV.

[0024] Figure 4 It is a schematic diagram of the structure of the longitudinal support beam, transverse support beam and edge beam.

[0025] Figure 5 It is a schematic diagram of the structure of the corner support beam.

[0026] Figure 6 It is a schematic diagram for comparing the optimized design.

[0027] Figure 7 It is the structural stress condition before the design optimization under the wave height of 8.4m.

[0028] Figure 8 It is the structural stress condition of the present invention under the wave height of 8.4m.

[0029] Reference numerals: Photovoltaic module Z, truss beam system support structure 1, longitudinal support beam 1.1, longitudinal support beam longitudinal rod 1.11, longitudinal support beam planar diagonal rod 1.12, longitudinal support beam space diagonal rod 1.13, transverse support beam 1.2, edge beam 1.3, corner support beam 1.4, corner support beam horizontal rod 1.41, corner support beam vertical rod 1.42, peripheral floating body 2, intermediate floating body 3. Detailed implementation mode

[0030] In order to make the purpose, technical solution and advantages of the invention clearer, the present invention will be further described below with reference to the accompanying drawings.

[0031] As Figure 1 and Figure 2 shown, the unequal-length and different-stiffness floating body fulcrum type truss offshore photovoltaic floating support structure includes a photovoltaic module Z, a truss beam system support structure 1, a peripheral floating body 2 and an intermediate floating body 3; the truss beam system support structure 1 is used to install the photovoltaic module Z.

[0032] As Figure 3 shown, the truss beam system support structure 1 is composed of a longitudinal support beam 1.1, two transverse support beams 1.2, four edge beams 1.3 and four corner support beams 1.4. The four edge beams 1.3 arranged around and the four corner support beams 1.4 arranged at the four corners form a square frame of the truss beam system support structure 1. Both ends of the edge beam 1.3 are respectively connected to two corner support beams 1.4, and one corner support beam 1.4 is respectively connected to two adjacent edge beams 1.3; as Figure 5 shown, the corner support beam 1.4 is a cuboid or a cube.

[0033] Inside the square frame of the truss beam system support structure 1, a longitudinal support beam 1.1 and two transverse support beams 1.2 are cross-placed. The two transverse support beams 1.2 are respectively located on both sides of the longitudinal support beam 1.1. The two transverse support beams 1.2 and the longitudinal support beam 1.1 are arranged in a "cross" shape. An intermediate floating body 3 is connected below the "cross" intersection point. The intermediate floating body 3 is connected to the longitudinal support beam 1.1 and is located below the midpoint of the longitudinal support beam 1.1. The "cross" intersection point is located at the midpoint of the square frame.

[0034] Both ends of the longitudinal support beam 1.1 are respectively connected to two opposite edge beams 1.3 of the square frame, and the longitudinal support beam 1.1 is parallel to the other two opposite edge beams 1.3.

[0035] One end of the transverse support beam 1.2 is connected to the longitudinal support beam 1.1, and the other end is connected to an edge beam 1.3 parallel to the longitudinal support beam 1.1.

[0036] As Figure 4As shown in the figure, the longitudinal support beam 1.1 includes four longitudinal support beam longitudinal bars 1.11, namely two left longitudinal support beam longitudinal bars 1.11 and two right longitudinal support beam longitudinal bars 1.11. The two left longitudinal support beam longitudinal bars 1.11 are arranged vertically, and the two right longitudinal support beam longitudinal bars 1.11 are arranged vertically. The longitudinal support beam longitudinal bars 1.11 are parallel to each other in pairs. The upper left longitudinal support beam longitudinal bar 1.11 and the upper right longitudinal support beam longitudinal bar are on the same horizontal plane, and the lower left longitudinal support beam longitudinal bar 1.11 and the lower right longitudinal support beam longitudinal bar 1.11 are on the same horizontal plane. Between the two left longitudinal support beam longitudinal bars 1.11, several longitudinal support beam planar diagonal bars 1.12 are bent and connected. Every two longitudinal support beam planar diagonal bars 1.12 and the upper left or lower left longitudinal support beam longitudinal bar 1.11 form a triangle. Between the two right longitudinal support beam longitudinal bars 1.11, several longitudinal support beam planar diagonal bars 1.12 are also bent and connected. Every two longitudinal support beam planar diagonal bars 1.12 and the upper right or lower right longitudinal support beam longitudinal bar 1.11 form a triangle. The two left longitudinal support beam longitudinal bars 1.11 and the longitudinal support beam planar diagonal bars 1.12 form an independent planar truss structure, and the two right longitudinal support beam longitudinal bars 1.11 and the longitudinal support beam planar diagonal bars 1.12 also form an independent planar truss structure.

[0037] Between the upper left longitudinal support beam longitudinal bar 1.11 and the lower right longitudinal support beam longitudinal bar 1.11, several longitudinal support beam space diagonal bars 1.13 are bent and connected. Between the lower left longitudinal support beam longitudinal bar 1.11 and the upper right longitudinal support beam longitudinal bar 1.11, several longitudinal support beam space diagonal bars 1.13 are also bent and connected.

[0038] The four longitudinal support beam longitudinal bars 1.11, several longitudinal support beam planar diagonal bars 1.12 and several longitudinal support beam space diagonal bars 1.13 are integrally formed to form an integral space truss structure, namely the longitudinal support beam 1.1.

[0039] The transverse support beam 1.2 and the edge beam 1.3 have exactly the same structure as the longitudinal support beam 1.1; however, the length of the transverse support beam 1.2 is shorter than the length of the longitudinal support beam 1.1, and the length of the transverse support beam 1.2 is shorter than the length of the edge beam 1.3.

[0040] As Figure 5 shown, the corner support beam 1.4 is composed of eight corner support beam horizontal bars 1.41 to form upper and lower square frames, and then the corner support beam vertical bars 1.42 are used to connect the upper and lower square frames to form the overall structure of the corner support beam 1.4.

[0041] As Figure 1 and Figure 3As shown in the figure, a floating body fulcrum type truss offshore photovoltaic floating support structure with unequal lengths and different stiffnesses of the present invention includes four peripheral floating bodies 2; the peripheral floating bodies 2 are strip-shaped structures arranged vertically, and the cross-section can be square, circular or any other shape; the peripheral floating bodies 2 can be, for example, cuboid structures, with a length and width of 0.9 m each and a height of 4 m, and the wall thickness is taken as 5 mm. Compartments or ballasts can be considered inside according to the actual situation; the four peripheral floating bodies 2 are arranged vertically perpendicular to the water surface and are connected to the seabed through mooring cables.

[0042] The floating bodies are arranged at the four corners of the floating photovoltaic unit. When the floating photovoltaic tilts, the restoring forces received by the four peripheral floating bodies 2 can provide the maximum restoring moment to provide the maximum stability for the floating unit.

[0043] The middle floating body 3 is a strip-shaped structure arranged vertically, and the cross-section can be square, circular or any other shape.

[0044] In this embodiment, the heights of the four peripheral floating bodies 2 are the same; the middle floating body 3 can adopt a design with a length different from that of the peripheral floating bodies 2, and the middle floating body 3 can be shorter than the peripheral floating bodies 2, for example. The middle floating body 3 adopts an unequal length design. On the one hand, by reducing the length of the floating body in the longitudinal direction, the acting length of the wave load is reduced, thereby reducing the wave force. On the other hand, the amount of floating body used can be reduced, thus reducing the cost; however, the middle floating body 3 needs to have enough length to ensure that it cannot emerge from the water under any motion state; the middle floating body 3 can be, for example, a cuboid structure, with a length and width of 1.5 m each and a height of 2 m, and the wall thickness is taken as 5 mm. Compartments or ballasts can be considered inside according to the actual situation.

[0045] As Figure 6 shown, the present invention only sets one longitudinal support beam 1.1 and two transverse support beams 1.2 in the square frame of the offshore photovoltaic floating support structure. Compared with setting multiple longitudinal support beams and multiple transverse support beams in the square frame, the steel consumption is reduced by about 9%, saving costs.

[0046] In addition, since the support beams in the square frame are symmetrically arranged, the beam system structure is more balanced in force under each wave direction angle and is suitable for an ocean environment with relatively balanced wave directions.

[0047] In the present invention, there is only one longitudinal support beam 1.1 and two transverse support beams 1.2 in the square frame. Although the steel consumption is reduced and the cost is saved, the stiffness of the offshore photovoltaic floating support structure will also be reduced accordingly; considering that reducing the longitudinal support beams and transverse support beams in the square frame will reduce the structural stiffness, and in the case of surges, the center of the square frame is most likely to bend. To increase the stiffness of the center of the square frame, the middle floating body 3 is arranged below the center of the square frame.

[0048] The middle floating body 3 has a large waterplane area, which can provide greater stiffness. The middle part of the truss beam system support structure 1 is the weakest point under bending force. A support point with great stiffness is added at this point, significantly improving the bending burden of the truss beam system support structure 1 and having a better anti-bending effect.

[0049] The middle floating body 3 and the four surrounding floating bodies 2 each have a clear division of labor. The four surrounding floating bodies 2 are mainly responsible for providing stability, and the middle floating body 3 is mainly responsible for providing large-stiffness support.

[0050] As Figure 7 and Figure 8 shown, the truss steel pipe has a diameter of 7 cm and a wall thickness of 5 mm. Under the action of waves with a wave height of 8.4 m, the maximum stress of the design with multiple longitudinal support beams and multiple transverse support beams arranged in the square frame is 212 Mpa, while the maximum stress of the present invention is 180 Mpa. Therefore, compared with arranging multiple longitudinal support beams and multiple transverse support beams in the square frame, the optimized design of the present invention reduces the steel consumption by about 9% while reducing the maximum stress by 15%.

[0051] Finally, it should be noted that the content not described in detail in this specification belongs to the prior art well-known to those skilled in the art. The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0052] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "width", "thickness", "upper", "lower", "left", "right", "inner", "outer", "height", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

Claims

1. An offshore photovoltaic floating support structure with unequal-length and different-stiffness floating body fulcrum type truss, comprising a truss beam system support structure (1), peripheral floating bodies (2) and an intermediate floating body (3); four edge beams (1.3) arranged around and four corner support beams (1.4) arranged at four corners form a square frame of the truss beam system support structure (1). It is characterized in that: The four peripheral floating bodies (2) adopt vertically arranged strip-shaped structures with square cross-sections and are respectively arranged at four corners of the floating photovoltaic unit; a longitudinal support beam (1.1) and two transverse support beams (1.2) are arranged within the square frame; the two transverse support beams (1.2) are respectively located on both sides of the longitudinal support beam (1.1), and the two transverse support beams (1.2) and a longitudinal support beam (1.1) are arranged in a "cross" shape, the "cross" intersection point is located at the midpoint of the square frame, and an intermediate floating body (3) is arranged below the "cross" intersection point. The intermediate floating body (3) is a vertically arranged strip-shaped structure with a square cross-section, and the cross-sectional area of the intermediate floating body (3) at the water surface is larger than that of the peripheral floating bodies (2) to provide greater hydrostatic restoring stiffness. The two ends of the edge beam (1.3) are respectively connected to two corner support beams (1.4), and one corner support beam (1.4) is respectively connected to two adjacent edge beams (1.3); the height value of the intermediate floating body (3) is less than the height value of the peripheral floating bodies (2); the length and width of the peripheral floating bodies (2) are both 0.9 m, the height is 4 m, and the wall thickness is 5 mm; the length and width of the intermediate floating body (3) are both 1.5 m, the height is 2 m, and the wall thickness is 5 mm; the truss steel pipe has a diameter of 7 cm and a wall thickness of 5 mm.

2. An offshore photovoltaic floating support structure with unequal-length and different-stiffness floating body fulcrum type truss according to claim 1, It is characterized in that The two ends of the longitudinal support beam (1.1) are respectively connected to two opposite edge beams (1.3) of the square frame, and the longitudinal support beam (1.1) is parallel to the other two opposite edge beams (1.3).

3. An offshore photovoltaic floating support structure with unequal-length and different-stiffness floating body fulcrum type truss according to claim 1 or 2, It is characterized in that The longitudinal support beam (1.1) comprises four longitudinal support beam longitudinal bars (1.11), namely two left longitudinal support beam longitudinal bars (1.11) and two right longitudinal support beam longitudinal bars (1.11). The two left longitudinal support beam longitudinal bars (1.11) are arranged vertically, and the two right longitudinal support beam longitudinal bars (1.11) are arranged vertically. The longitudinal support beam longitudinal bars (1.11) are parallel to each other in pairs. The upper left longitudinal support beam longitudinal bar (1.11) and the upper right longitudinal support beam longitudinal bar are on the same horizontal plane, and the lower left longitudinal support beam longitudinal bar (1.11) and the lower right longitudinal support beam longitudinal bar (1.11) are on the same horizontal plane.

4. An offshore photovoltaic floating support structure with unequal-length and different-stiffness floating body fulcrum type truss according to claim 3, It is characterized in that Between the two longitudinal support beam longitudinal rods (1.11) on the left side, several longitudinal support beam planar diagonal rods (1.12) are bent and connected, and each two longitudinal support beam planar diagonal rods (1.12) form a triangle with the longitudinal support beam longitudinal rod (1.11) above or below the left side; between the two longitudinal support beam longitudinal rods (1.11) on the right side, several longitudinal support beam planar diagonal rods (1.12) are also bent and connected, and each two longitudinal support beam planar diagonal rods (1.12) form a triangle with the longitudinal support beam longitudinal rod (1.11) above or below the right side.

5. The unequal-length and differential-stiffness floating body fulcrum type truss offshore photovoltaic floating support structure according to claim 3, characterized in that Between the longitudinal support beam longitudinal rod (1.11) above the left side and the longitudinal support beam longitudinal rod (1.11) below the right side, several longitudinal support beam space diagonal rods (1.13) are bent and connected, and between the longitudinal support beam longitudinal rod (1.11) below the left side and the longitudinal support beam longitudinal rod (1.11) above the right side, the longitudinal support beam space diagonal rods (1.13) are also bent and connected.

6. The unequal-length and differential-stiffness floating body fulcrum type truss offshore photovoltaic floating support structure according to claim 1, characterized in that One end of the transverse support beam (1.2) is connected to the longitudinal support beam (1.1), and the other end is connected to an edge beam (1.3) parallel to the longitudinal support beam (1.1).

7. The unequal-length and differential-stiffness floating body fulcrum type truss offshore photovoltaic floating support structure according to claim 1, characterized in that The edge beam (1.3) and the transverse support beam (1.2) have exactly the same structure as the longitudinal support beam (1.1).

8. The unequal-length and differential-stiffness floating body fulcrum type truss offshore photovoltaic floating support structure according to claim 1, characterized in that The corner support beam (1.4) includes eight corner support beam horizontal rods (1.41) and four corner support beam vertical rods (1.42); the eight corner support beam horizontal rods (1.41) form upper and lower square frames, and the four corner support beam vertical rods (1.42) connect the upper and lower square frames.

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