Modular steel structure special-shaped column herringbone bolt connection node and assembly method

Abstract

This invention discloses a modular steel structure irregular column U-shaped bolt connection node, including node module units and square tubes; the node module unit includes an irregular hollow tube and channel steel. A channel steel is welded to the bottom of each of the two surfaces of the L-shaped outer side plate of the irregular hollow tube, and the first side plate is flush with the end of the irregular hollow tube. The bottom plate is aligned with the edge where the L-shaped outer side plate intersects with the side plate. The side plates of the irregular hollow tubes of the four node module units with channel steel below are connected to form an upper column with a U-shaped cross section. The bottom plates of the channel steel of adjacent node module units are connected. The upper crossbeam, with an I-shaped cross-section, is formed by contacting and bolting together. The side plates of the four irregularly shaped hollow tubes of the channel steel node units above are connected to form a lower column with a U-shaped cross-section. The bottom plates of the channel steel of adjacent node module units are also connected by bolts to form an I-shaped lower crossbeam. The upper part of the square tube is inserted into the U-shaped inner tube of the upper column and connected by bolts, while the lower part is inserted into the U-shaped inner tube of the lower column and connected by bolts. The first side plates of the upper and lower crossbeams are in contact and fixed together by bolts. The column, a U-shaped column composed of four irregularly shaped hollow tubes, not only increases the strength of the column but also enhances the connection's robustness by fixing the column to the square tube at two points through the third and fourth bolt holes.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, specifically to a modular steel structure irregular column U-shaped bolt connection node and assembly method. Background Technology

[0002] Modular steel structure buildings are constructed by modularly dividing the structure into building units, prefabricating them in a factory into modular units with integrated functions, and then transporting them to the construction site for assembly. They offer advantages such as rapid construction, environmental friendliness, prefabricated construction, and detachability. In modular buildings, load transfer and deformation coordination are achieved through the connection nodes between module units, which play a crucial role in the overall stability of the structure. The following are some existing technologies related to modular steel structure connection nodes. Patent publication number CN117364918 A discloses a detachable modular steel structure connection node, which includes module units and connectors. The modular unit includes columns, horizontal beams, and arc-shaped triangular plates. The ends of the horizontal beams that are close to each other are welded to the adjacent side walls of the columns. The arc-shaped triangular plates are welded between the two horizontal beams at the intersection of the beams and columns. Bolt holes are opened on the side walls of the columns with horizontal beams and on the arc-shaped triangular plates. The connecting parts include a base steel plate with a square opening. A small square steel pipe is welded to the square opening. The outer diameter of the small square steel pipe is adapted to the inner diameter of the column. Bolt holes are opened on the side walls of the base steel plate and the small square steel pipe. Long cylindrical nuts are welded to the inside of the small square steel pipe at the positions corresponding to the bolt holes. Patent CN117306694 A discloses a modular prefabricated steel structure building connection system, including two pairs of C-shaped modular columns. Each modular column is horizontally connected to a ceiling beam at its upper end and to a floor beam at its lower end. The C-shaped open ends of each pair of modular columns are arranged opposite each other and connected by a column horizontal connection kit I. The horizontal connection of adjacent modular columns is achieved through the column horizontal connection kit I. Node connectors are inserted at the column end openings in the node area between the horizontal connection kits I of adjacent steel structure modular frame units. Beam end connectors are inserted at the beam end joints of the ceiling beams and floor beams of the corresponding modular columns in adjacent steel structure modular frame units. The vertical connection of adjacent modular columns is achieved through the node connectors and beam end connectors.

[0003] While the above solutions eliminate the need for on-site welding and allow for bolt reuse, they still suffer from the following problems: 1) Complex node design, numerous connecting components, high construction difficulty and cost, unclear force transmission between components of the connecting node, and challenging design verification, hindering widespread adoption; 2) Excessively long bolts in the connecting nodes make them more susceptible to bending or buckling under lateral loads, and also reduce torsional stiffness along their length. Therefore, this application designs a modular steel structure irregular column U-shaped bolt connection node and assembly method. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a modular steel structure irregular column U-shaped bolt connection node, which solves the problems of complex design, cumbersome assembly and disassembly of existing modular steel structure connection nodes.

[0005] To achieve the above objectives, the present invention relates to a modular steel structure irregular column U-shaped bolt connection node, comprising a node module unit and a square tube; the node module unit comprises an irregular hollow tube and a channel steel, the irregular hollow tube comprising an L-shaped outer side plate, an L-shaped inner side plate and a side plate, the parallel L-shaped outer side plate and L-shaped inner side plate are connected on the left and right sides by a side plate to form an L-shaped cavity; the channel steel comprises a first side plate, a second side plate and a bottom plate, the first side plate and the second side plate are respectively connected to the two sides of the bottom plate; a channel steel is welded to the bottom of the two surfaces of the L-shaped outer side plate of the irregular hollow tube, and the first side plate is flush with the end of the irregular hollow tube; the bottom plate intersects with the edge of the L-shaped outer side plate and the side plate. The four hollow tubes of the channel steel at the bottom of the unit connect to form an upper column with a U-shaped cross section. The bottom plates of the channel steel of adjacent node module units contact each other and are connected by bolts to form an upper beam with an I-shaped cross section. The four hollow tubes of the channel steel at the top of the unit connect to form a lower column with a U-shaped cross section. The bottom plates of the channel steel of adjacent node module units contact each other and are connected by bolts to form a lower beam with an I-shaped cross section. The upper part of the square tube is inserted into the U-shaped inner tube of the upper column and connected by bolts, and the lower part is inserted into the U-shaped inner tube of the lower column and connected by bolts. The first side plates of the upper beam and the lower beam contact each other and are fixedly connected by bolts.

[0006] Specifically, the outer diameter of the square tube is exactly equal to the inner diameter of the U-shaped inner tube.

[0007] Specifically, a first bolt hole is made on the base plate, and the bolt passes through the first bolt hole on the two adjacent base plates of the upper or lower crossbeam.

[0008] Specifically, a second bolt hole is made on the first side plate, and the bolt passes through the second bolt hole on the first side plate of the upper crossbeam and the second bolt hole on the first side plate of the lower crossbeam, respectively.

[0009] Specifically, a third bolt hole is made on the L-shaped outer side plate, and a fourth bolt hole is made at the corresponding position on the L-shaped inner side plate. At least two rows of fifth bolt holes are provided on each side of the upper part of the square tube, and at least two rows of sixth bolt holes are provided on each side of the lower part of the square tube. The upper part of the square tube is inserted into the U-shaped inner tube of the upper column, and the lower part is inserted into the U-shaped inner tube of the lower column. Bolts pass through the third bolt hole, the fourth bolt hole, and the fifth bolt hole to connect the square tube and the upper column. Bolts pass through the third bolt hole, the fourth bolt hole, and the sixth bolt hole in sequence to connect the square tube and the lower column.

[0010] Specifically, matching nuts are welded to the fifth bolt holes in at least two adjacent rows at the corner of the inner surface of the square tube.

[0011] Specifically, a third bolt hole is provided on the L-shaped outer side plate, and the third bolt hole is surrounded by channel steel.

[0012] The present invention relates to an assembly method for a modular steel structure irregular column U-shaped bolt connection node, specifically including the following steps:

[0013] (1) A first bolt hole is made on the bottom plate of the channel steel, a second bolt hole is made on the first side plate, a third bolt hole is made on the L-shaped outer side plate of the irregular hollow tube, a fourth bolt hole is made at the corresponding position on the L-shaped inner side plate, and a channel steel is welded to the bottom of the two surfaces of the L-shaped outer side plate of the irregular hollow tube respectively. The first side plate of the channel steel is flush with the end of the irregular hollow tube, and the bottom plate and the L-shaped outer side plate are aligned with the side plate to form a node module unit.

[0014] At least two rows of fifth bolt holes are provided on each side of the upper part of the square tube, and matching nuts are welded at the two adjacent rows of fifth bolt holes at a corner on the inner surface of the square tube. At least two rows of sixth bolt holes are provided on each side of the lower part of the square tube.

[0015] (2) The side plates of the irregular hollow tubes of the four node module units on the channel steel are connected to form a lower column with a cross section of U-shape. The bottom plates of the channel steel of the adjacent node module units are in contact, and the bolts are passed through the first bolt holes on the left and right bottom plates in sequence to fix them, forming a lower cross beam with a cross section of I-shape.

[0016] (3) Insert the lower part of the square tube into the U-shaped inner tube of the lower column, and hold the first bolt and insert it into the square tube. Place the head of the first bolt inside the square tube. The bolt of the first bolt passes through the sixth bolt hole, the fourth bolt hole and the third bolt hole from the inside to the outside in sequence, and is finally fixed by the outer nut.

[0017] (4) Assemble the four node module units with the channel steel at the bottom in sequence on the top of the lower column. The side plates of the irregular hollow tubes of the four node module units are connected to form the upper column with a cross section of U-shape. The first three node module units are fixed, and the fourth bolt hole in the irregular hollow tube is aligned with the corresponding fifth bolt hole in the square tube. Hold the first bolt and insert it into the square tube. The head of the first bolt is placed inside the square tube. The screw of the first bolt passes through the fifth bolt hole, the fourth bolt hole and the third bolt hole from the inside to the outside in sequence. Finally, it is fixed by the nut on the outside. The fourth bolt hole in the irregular hollow tube of the last fixed node module unit is aligned with the fifth bolt hole in part A. The head of the second bolt is placed on the outside of the column. The screw of the second bolt passes through the third bolt hole, the fourth bolt hole and the fifth bolt hole from the outside to the inside in sequence. Finally, it is fixed by the nut welded near the fifth bolt hole.

[0018] Compared with the prior art, the present invention has the following advantages: (1) The column is a U-shaped column composed of four irregular hollow tubes, which can not only increase the strength of the column, but also fix the column and the square tube through two points of the third bolt hole and the fourth bolt hole, which increases the firmness of the connection; (2) The traditional square tube beam is replaced with a channel steel beam, which can facilitate the installation and disassembly of the upper column and the lower column with the square tube; (3) The connection between the upper column and the lower column can be realized by using only a simple square tube, which greatly simplifies the structure of the connecting parts. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the modular steel structure irregular column U-shaped bolt connection node involved in Example 1.

[0020] Figure 2 This is an exploded view of the modular steel structure irregular column U-shaped bolt connection node structure involved in Example 1.

[0021] Figure 3 This is a schematic diagram of the node module unit structure involved in Example 1.

[0022] Figure 4 This is a schematic diagram of the irregular hollow tube involved in Example 1.

[0023] Figure 5 This is a schematic diagram of the channel steel involved in Example 1.

[0024] Figure 6 This is a schematic diagram of the square tube involved in Example 1.

[0025] Figure 7 This is a schematic diagram of the square tube and bolt assembly involved in Example 1.

[0026] Figure 8 This is a schematic diagram of the structure obtained in step (2) of the assembly method of the modular steel structure irregular column U-shaped bolt connection node involved in Example 1.

[0027] Figure 9 This is a schematic diagram of the structure obtained in step (4) of the assembly method of the modular steel structure irregular column U-shaped bolt connection node involved in Example 1.

[0028] Among them, 1 is an irregular hollow tube, 2 is a channel steel, 3 is a square tube, 4 is an upper column, 5 is an upper crossbeam, 6 is a lower column, 7 is a lower crossbeam, 8 is the first bolt, 9 is the second bolt, 101 is an L-shaped outer side plate, 102 is an L-shaped inner side plate, 103 is a side plate, 104 is the third bolt hole, 105 is the fourth bolt hole, 201 is the first side plate, 202 is the second side plate, 203 is the bottom plate, 204 is the first bolt hole, 205 is the second bolt hole, 301 is the fifth bolt hole, and 302 is the sixth bolt hole. Detailed Implementation

[0029] The present invention will be further described below through specific embodiments.

[0030] Example 1

[0031] The terms "first," "second," etc., used in this embodiment are merely for distinguishing components and do not constitute a limitation on the scope of protection. The directional terms such as "left," "right," "front," and "rear" are for describing the relative positions between components and do not constitute a limitation on the scope of protection.

[0032] like Figure 1 As shown, this embodiment involves a modular steel structure irregular column U-shaped bolt connection node, including a node module unit and a square tube 3; the node module unit includes an irregular hollow tube 1 and a channel steel 2. The irregular hollow tube 1 includes an L-shaped outer side plate 101, an L-shaped inner side plate 102, and a side plate 103. The parallel L-shaped outer side plate 101 and L-shaped inner side plate 102 are connected on the left and right sides by a side plate 103 to form an L-shaped cavity. The channel steel 2 includes a first side plate 201, a second side plate 202, and a bottom plate 203. The first side plate 201 and the second side plate 202 are respectively connected to the two sides of the bottom plate 203. A channel steel 2 is welded to the bottom of the two surfaces of the L-shaped outer side plate 101 of the irregular hollow tube, and the first side plate 201 is flush with the end of the irregular hollow tube. The bottom plate 203 is connected to the L-shaped outer side plate 101. The edges intersecting with the side plate 103 are aligned. The side plates 103 of the irregular hollow tubes of the four node module units of the channel steel 2 below are connected to form an upper column 4 with a cross section of U-shape. The bottom plates 203 of the channel steel 2 of the adjacent node module units are in contact and connected by bolts to form an upper beam 5 with a cross section of I-shape. The side plates 103 of the irregular hollow tubes of the four node module units of the channel steel 2 above are connected to form a lower column 6 with a cross section of U-shape. The bottom plates 203 of the channel steel 2 of the adjacent node module units are in contact and connected by bolts to form a lower beam 7 with a cross section of I-shape. The upper part of the square tube is inserted into the U-shaped inner tube of the upper column 4 and connected by bolts. The lower part is inserted into the U-shaped inner tube of the lower column 6 and connected by bolts. The first side plates 201 of the upper beam 5 and the lower beam 7 are in contact and fixedly connected by bolts.

[0033] Preferably, the irregularly shaped hollow tube is made of steel.

[0034] Specifically, the outer diameter of the square tube is exactly equal to the inner diameter of the U-shaped inner tube, meaning the outer wall of the square tube is tightly attached to the inner wall of the U-shaped inner tube.

[0035] Specifically, a first bolt hole 204 is made on the base plate 203, and bolts are passed through the first bolt holes 204 on the two adjacent base plates 203 of the upper crossbeam 5 or the lower crossbeam 7 respectively to fix the two adjacent channel steels 2 on the left and right.

[0036] Specifically, a second bolt hole 205 is opened on the first side plate 201, and bolts are respectively passed through the second bolt hole 205 of the first side plate 201 of the upper crossbeam 5 and the second bolt hole 205 of the first side plate 201 of the lower crossbeam 7 to fix the two adjacent channel steels 2.

[0037] Specifically, a third bolt hole 104 is provided on the L-shaped outer side plate 101, and a fourth bolt hole 105 is provided at the corresponding position on the L-shaped inner side plate 102. At least two rows of fifth bolt holes 301 are provided on each side of the upper part of the square tube 3, and at least two rows of sixth bolt holes 302 are provided on each side of the lower part of the square tube 3. The upper part of the square tube 3 is inserted into the U-shaped inner tube of the upper column 4, and the lower part is inserted into the U-shaped inner tube of the lower column 6. Bolts pass through the third bolt hole 104, the fourth bolt hole 105 and the fifth bolt hole 301 to connect the square tube 3 and the upper column 4. Bolts pass through the third bolt hole 104, the fourth bolt hole 105 and the sixth bolt hole 302 in sequence to connect the square tube 3 and the lower column 6.

[0038] Specifically, matching nuts are welded to at least one corner of the inner surface of the square tube 3 at two adjacent rows of fifth bolt holes 301. The fifth bolt hole 301 corresponding to this nut is the bolt hole for the last connection.

[0039] Specifically, a third bolt hole 104 is provided on the L-shaped outer side plate 101, and the third bolt hole 104 is surrounded by the channel steel 2.

[0040] This embodiment relates to an assembly method for a modular steel structure irregular column U-shaped bolt connection node, which specifically includes the following steps:

[0041] (1) A first bolt hole 204 is opened on the bottom plate 203 of the channel steel 2, a second bolt hole 205 is opened on the first side plate 201, a third bolt hole 104 is opened on the L-shaped outer side plate 101 of the irregular hollow tube, and a fourth bolt hole 105 is opened at the corresponding position on the L-shaped inner side plate 102. A channel steel 2 is welded to the bottom of the two surfaces of the L-shaped outer side plate 101 of the irregular hollow tube. The first side plate 201 of the channel steel 2 is flush with the end of the irregular hollow tube, and the bottom plate 203 and the L-shaped outer side plate 101 and the side plate 103 intersect at the same edge to form a... Figure 3 The node module unit shown;

[0042] At least two rows of fifth bolt holes 301 are provided on each side of the upper part of the square tube 3, and matching nuts are welded at the two rows of fifth bolt holes 301 adjacent to a corner on the inner surface of the square tube 3. At least two rows of sixth bolt holes 302 are provided on each side of the lower part of the square tube 3. The work described in step (1) is completed in the factory, and when used, it is installed directly on the construction site according to steps (2)-(4).

[0043] (2) The side plates of the irregular hollow tubes of the four node module units on the channel steel 2 are connected to form a lower column 6 with a cross section of U-shape. The bottom plates 203 of the channel steel 2 of the adjacent node module units are in contact. The bolts pass through the first bolt holes 204 on the left and right bottom plates 203 in sequence to fix them, forming a lower cross beam 7 with a cross section of I-shape.

[0044] (3) Insert the lower part of the square tube 3 into the U-shaped inner tube of the lower column 6, and hold the first bolt 8 and insert it into the square tube 3. The head of the first bolt 8 is placed inside the square tube. The screw of the first bolt 8 passes through the sixth bolt hole 302, the fourth bolt hole 105 and the third bolt hole 104 from the inside to the outside in sequence, and is finally fixed by the outer nut to form a shape like Figure 8 The structure shown;

[0045] (4) Assemble the four node module units below the channel steel 2 sequentially on top of the lower column 6. The side plates of the irregular hollow tubes of the four node module units are connected to form the upper column 4 with a cross-section of U-shape. The four node module units that are fixed first are aligned with the fourth bolt hole 105 in the irregular hollow tube and the corresponding fifth bolt hole 301 in the square tube 3. Hold the first bolt 8 and insert it into the square tube 3. The head of the first bolt 8 is placed inside the square tube. The screw of the first bolt 8 passes through the fifth bolt hole 301, the fourth bolt hole 105 and the third bolt hole 104 sequentially from the inside to the outside. Finally, it is fixed by the outer nut to form a shape like... Figure 9 The structure shown has the fourth bolt hole 105 in the irregular hollow tube of the final fixed node module unit aligned with the fifth bolt hole 301 in part A. The head of the second bolt 9 is placed on the outside of the column. The screw of the second bolt 9 passes through the third bolt hole 104, the fourth bolt hole 105 and the fifth bolt hole 301 in sequence from the outside to the inside, and is finally fixed by a nut welded near the fifth bolt hole 301.

[0046] A square tube length of less than 60cm is sufficient to meet the load-bearing requirements of the joint; the length of an adult's arm plus hand is over 70cm. Furthermore, based on commonly used modular column dimensions, the internal clear dimensions of the square tube are approximately 20cm x 20cm. The shape of the modular column can be adjusted as needed to increase the clearance in the U-shape and further increase the internal clear dimensions of the square tube. Considering these two points, there is sufficient construction space within the square tube to complete the aforementioned operations. If the length of the square tube needs to be increased, special pliers can be used to clamp the bolts and pass them through the inside of the square tube.

Claims

1. A modular steel structure irregular column U-shaped bolt connection node, characterized in that, The system includes node module units and square tubes. Each node module unit comprises an irregularly shaped hollow tube and channel steel. The irregularly shaped hollow tube includes an L-shaped outer side plate, an L-shaped inner side plate, and side plates. The parallel L-shaped outer and inner side plates are connected on their left and right sides by side plates to form an L-shaped cavity. The channel steel includes a first side plate, a second side plate, and a bottom plate. The first and second side plates are respectively connected to the two sides of the bottom plate. A channel steel is welded to the bottom of each of the two surfaces of the L-shaped outer side plate of the irregularly shaped hollow tube. The first side plate is flush with the end of the irregularly shaped hollow tube, and the bottom plate is aligned with the intersection of the L-shaped outer side plate and the side plate. The irregularly shaped channel steel is located in the four node module units below. The side plates of the hollow tubes are joined to form an upper column with a U-shaped cross section. The bottom plates of the channel steel of the adjacent node module units are in contact and connected by bolts to form an upper beam with an I-shaped cross section. The side plates of the irregular hollow tubes of the four node module units with channel steel on top are joined to form a lower column with a U-shaped cross section. The bottom plates of the channel steel of the adjacent node module units are in contact and connected by bolts to form a lower beam with an I-shaped cross section. The upper part of the square tube is inserted into the U-shaped inner tube of the upper column and connected by bolts. The lower part is inserted into the U-shaped inner tube of the lower column and connected by bolts. The first side plates of the upper beam and the lower beam are in contact and fixedly connected by bolts.

2. The modular steel structure irregular column U-shaped bolt connection node according to claim 1, characterized in that, The outer diameter of the square tube is exactly equal to the inner diameter of the U-shaped inner tube.

3. The modular steel structure irregular column U-shaped bolt connection node according to claim 2, characterized in that, The first bolt hole is made on the base plate, and the bolt passes through the first bolt hole on the two adjacent base plates of the upper or lower crossbeam.

4. The modular steel structure irregular column U-shaped bolt connection node according to claim 3, characterized in that, A second bolt hole is made on the first side plate, and the bolt passes through the second bolt hole on the first side plate of the upper crossbeam and the second bolt hole on the first side plate of the lower crossbeam, respectively.

5. The modular steel structure irregular column U-shaped bolt connection node according to claim 4, characterized in that, A third bolt hole is made on the L-shaped outer side plate, and a fourth bolt hole is made at the corresponding position on the L-shaped inner side plate. At least two rows of fifth bolt holes are provided on each side of the upper part of the square tube, and at least two rows of sixth bolt holes are provided on each side of the lower part of the square tube. The upper part of the square tube is inserted into the U-shaped inner tube of the upper column, and the lower part is inserted into the U-shaped inner tube of the lower column. Bolts pass through the third bolt hole, the fourth bolt hole, and the fifth bolt hole to connect the square tube and the upper column. Bolts pass through the third bolt hole, the fourth bolt hole, and the sixth bolt hole in sequence to connect the square tube and the lower column.

6. The modular steel structure irregular column U-shaped bolt connection node according to claim 5, characterized in that, Matching nuts are welded to the fifth bolt holes of two adjacent rows at at least one corner of the inner surface of the square tube.

7. The modular steel structure irregular column U-shaped bolt connection node according to claim 6, characterized in that, A third bolt hole is made on the L-shaped outer side plate, and the third bolt hole is surrounded by channel steel.

8. An assembly method for the modular steel structure irregular column U-shaped bolt connection node as described in claim 1, characterized in that, Specifically, the following steps are included: (1) A first bolt hole is made on the bottom plate of the channel steel, a second bolt hole is made on the first side plate, a third bolt hole is made on the L-shaped outer side plate of the irregular hollow tube, a fourth bolt hole is made at the corresponding position on the L-shaped inner side plate, and a channel steel is welded to the bottom of the two surfaces of the L-shaped outer side plate of the irregular hollow tube respectively. The first side plate of the channel steel is flush with the end of the irregular hollow tube, and the bottom plate and the L-shaped outer side plate are aligned with the side plate to form a node module unit. At least two rows of fifth bolt holes are provided on each side of the upper part of the square tube, and matching nuts are welded at the two adjacent rows of fifth bolt holes at a corner on the inner surface of the square tube. At least two rows of sixth bolt holes are provided on each side of the lower part of the square tube. (2) The side plates of the irregular hollow tubes of the four node module units on the channel steel are connected to form a lower column with a cross section of U-shape. The bottom plates of the channel steel of the adjacent node module units are in contact, and the bolts are passed through the first bolt holes on the left and right bottom plates in sequence to fix them, forming a lower cross beam with a cross section of I-shape. (3) Insert the lower part of the square tube into the U-shaped inner tube of the lower column, and hold the first bolt and insert it into the square tube. Place the head of the first bolt inside the square tube. The bolt of the first bolt passes through the sixth bolt hole, the fourth bolt hole and the third bolt hole from the inside to the outside in sequence, and is finally fixed by the outer nut. (4) Assemble the four node module units with the channel steel at the bottom in sequence on the top of the lower column. The side plates of the irregular hollow tubes of the four node module units are connected to form the upper column with a cross section of U-shape. The first three node module units are fixed, and the fourth bolt hole in the irregular hollow tube is aligned with the corresponding fifth bolt hole in the square tube. Hold the first bolt and insert it into the square tube. The head of the first bolt is placed inside the square tube. The screw of the first bolt passes through the fifth bolt hole, the fourth bolt hole and the third bolt hole from the inside to the outside in sequence. Finally, it is fixed by the nut on the outside. The last node module unit is fixed, and the fourth bolt hole in the irregular hollow tube is aligned with the fifth bolt hole. The head of the second bolt is placed on the outside of the column. The screw of the second bolt passes through the third bolt hole, the fourth bolt hole and the fifth bolt hole from the outside to the inside in sequence. Finally, it is fixed by the nut welded near the fifth bolt hole.

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