A double-tube multi-limb square column with restorable function and its assembly method

Abstract

The present invention provides a double-tube multi-limb square column with restorable functions and a manufacturing method thereof, wherein an outer tube frame is sleeved on the outside of an inner tube frame to form a double-tube multi-limb support structure, and the stability and adaptability of the structure are improved in view of the complex situations in earthquakes; wherein the steel brackets on the inner tube frame disperse the vertical forces received to the load-bearing main beams of the outer tube frame, and the forces borne by each component individually are reduced; the replaceable components can consume the forces received in non-vertical directions, and further ensure the stability of the structure; at the same time, the replaceable components can be replaced after being damaged, and the service life of the structure is extended; the present application has a compact structure, occupies a small space, can solve the complex damage of relatively high-intensity earthquakes, and solves the problems of weak stability, complex structure and low strength of building structure column supports in the prior art.

Description

Technical Field

[0001] The invention relates to the field of structural technology, in particular to a double-tube multi-limb square column with restorable functions and an assembly method thereof. Background Art

[0002] A column is a vertical load-bearing component. Traditional columns are subject to bending, shearing and torsion in earthquakes, which can easily lead to structural damage and loss of structural function. Once a column is damaged to the point of endangering structural safety, the entire building must be evacuated. In the worst case, the building needs to be demolished and rebuilt. This process poses a great threat to people's lives and property.

[0003] Restorable function is a new type of structural function. Structures with restorable function can be simply repaired after a small earthquake and replaced in time after a large earthquake to quickly restore their structural functions. However, it is difficult for columns to achieve restorable function. The reasons are that the overall force on the columns is complex, the columns are difficult to replace, and the engineering construction process is complex. Summary of the invention

[0004] The components in the prefabricated frame structure can withstand vertical and horizontal forces. The overall force and load transfer path of the prefabricated frame structure is clear, and the cross-sections of each component are regular, which makes the construction of the prefabricated frame structure simple. If the prefabricated frame structure is regarded as consisting of an inner frame and an outer frame, and the connection between the inner frame and the outer frame is interrupted, the inner and outer frames can become two independent structures. However, there are few technologies in China that produce vertical relative displacement and energy consumption of inner and outer frames. In view of the problems existing in the prior art, the present invention provides a double-tube multi-limb square column with restorable function and an assembly method thereof. Using the above-mentioned ideas and methods, a structural column that can support the upper structure and have a restorable function is provided.

[0005] The present invention is achieved through the following technical solutions:

[0006] A double-tube multi-limb square column with restorable functions, characterized in that it comprises an inner tube frame and an outer tube frame sleeved outside the inner tube frame;

[0007] The inner tube frame comprises four inner tube side columns, and the four inner tube side columns are vertically arranged to form a square column structure;

[0008] The square column structure includes an upper support surface, a multi-level middle support surface and a lower support surface;

[0009] The upper support surface includes corbels arranged opposite to adjacent side walls of the inner tube side columns, and corbel connecting beams are connected between the corbels on adjacent inner tube side columns; the multi-level middle support surface and the lower support surface are arranged at intervals, and include inner tube connecting beams connected to adjacent side walls of adjacent inner tube side columns;

[0010] The upper support surface has a steel corbel extending in the reverse direction to the area of ​​the side column side wall of the inner tube, and the inner tube connecting beam of the multi-level middle support surface has a steel corbel extending in the reverse direction to the area of ​​the side column side wall of the inner tube;

[0011] The outer tube frame comprises four outer tube side columns and a main load-bearing beam arranged horizontally and vertically between adjacent outer tube side columns;

[0012] The lower top surfaces of the ends of the steel brackets are all arranged on the upper top surface of the force-bearing main beam, and a vertical outer tube connecting column is arranged in the gap between the lower top surfaces of the force-bearing main beam;

[0013] The inner tube connecting beam extends in the opposite direction to the inner tube side column and the side wall of the outer tube connecting column

[0014] Furthermore, the main bearing beam comprises an I-beam, and shear members are arranged on both sides of the web of the I-beam;

[0015] Coordinated deformation rubber is arranged on the upper part of the I-beam and the outer side of the shear-resistant member.

[0016] Furthermore, an upper connector is embedded at the upper end of the inner tube side column;

[0017] The upper surface of the upper connecting head is provided with an X-direction connecting groove and a Y-direction connecting groove which intersect in a cross shape.

[0018] Furthermore, a plurality of short-limb connecting beams are horizontally and vertically arranged between the outer tube connecting limb columns and between the outer tube connecting limb columns and the outer tube side columns.

[0019] Furthermore, diagonal braces are provided between the replaceable components adjacent to each other in the height direction.

[0020] Furthermore, the lower supporting surface is no less than one level.

[0021] Furthermore, the centroid distance between adjacent outer tube connecting limb columns is equal to the centroid distance between adjacent inner tube side columns.

[0022] Furthermore, the replaceable component is a damper or an I-beam.

[0023] A method for preparing a double-tube multi-limb square column with restorable functions comprises the following steps:

[0024] S1: Connect the inner tube connecting beam to the inner tube side column according to the preset position, connect the corbel connecting beam between the corbels, and connect the steel corbels at the preset position on the outer wall of the inner tube side column to complete the setting of the inner tube frame;

[0025] S2: The outer tube side columns are arranged at the preset positions outside the inner tube frame, and the four outer tube side columns are connected by the main bearing beam, and the upper top surface of the main bearing beam is arranged to fit the lower top surface of the end of the steel corbel;

[0026] S3: Set the outer tube connecting limb columns between the outer tube side columns, then install the diagonal web members and replaceable components, and finally connect the short limb connecting beams to complete the installation of the outer tube frame.

[0027] Further, in S3, outer tube connecting limb columns are arranged between the outer tube side columns. The specific steps are: firstly, a detachable weak connection is fixed, and then the diagonal web members and replaceable components are installed, and then the weak connection on the short limb connecting beam is gradually removed while being fixed with bolts until the installation of the outer tube frame is completed.

[0028] Compared with the prior art, the present invention has the following beneficial technical effects:

[0029] The present invention provides a double-cylinder multi-limb square column with recoverable functions, which is sleeved on an outer cylinder frame outside an inner cylinder frame to form a double-cylinder multi-limb support structure, and improves the stability and adaptability of the structure in view of complex situations in earthquakes; wherein the steel brackets on the inner cylinder frame disperse the vertical force to the load-bearing main beam of the outer cylinder frame, so that the multi-limb square column can evenly transfer the load; the replaceable components can shear and dissipate energy when the inner cylinder frame and the outer cylinder frame undergo relative displacement, and at the same time, the replaceable components can be replaced after being damaged, thereby extending the service life of the structure, and solving the problem in the prior art that the structural columns cannot be replaced to recover the structural functions after an earthquake.

[0030] Furthermore, the load-bearing main beam includes coordinated deformation rubber, which is deformed when squeezed by the steel bracket, so that the inner tube frame and the outer tube frame can produce relative displacement in the height direction when transferring the load.

[0031] Furthermore, the centroid distance between adjacent outer tube connecting limb columns is equal to the centroid distance between adjacent inner tube side columns, so that the forces between the components of the structure are uniform, the stability of the structure is improved, and at the same time, it is convenient to install replaceable components and diagonal braces.

[0032] The present invention provides a method for preparing a double-tube multi-limb square column with restorable functions. Most of the components used in the method adopt existing structures and can be widely used in industrial production. At the same time, the method has simple steps and is highly feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of a double-tube multi-limb square column inner tube frame with restorable functions in a specific embodiment of the present invention;

[0034] Figure 2 It is a side view of a double-tube multi-limb square column inner tube frame with restorable functions in a specific embodiment of the present invention;

[0035] Figure 3 It is a top view of a double-tube multi-limb square column inner tube frame with restorable functions in a specific embodiment of the present invention;

[0036] Figure 4 It is a structural schematic diagram of a double-tube multi-limb square column outer tube frame with restorable functions in a specific embodiment of the present invention;

[0037] Figure 5 It is a side view of a double-tube multi-limb square column outer tube frame with restorable functions in a specific embodiment of the present invention;

[0038] Figure 6 It is a structural schematic diagram of a double-tube multi-limb square column with restorable functions in a specific embodiment of the present invention;

[0039] Figure 7 It is a side view of a double-tube multi-limb square column with restorable functions in a specific embodiment of the present invention;

[0040] Figure 8 It is a top view of a double-tube multi-limb square column with restorable functions in a specific embodiment of the present invention;

[0041] Fig. 9 It is a schematic diagram of the connection structure of the inner tube side column and the outer tube connecting limb column in a double-tube multi-limb square column with recoverable functions in a specific embodiment of the present invention;

[0042] Fig.10 It is a side view of the connection between the inner tube side column and the outer tube connecting limb column in a double-tube multi-limb square column with recoverable functions in a specific embodiment of the present invention;

[0043] Fig.11 It is a structural schematic diagram of an upper connecting head of a double-tube multi-limb square column with restorable functions in a specific embodiment of the present invention;

[0044] Fig.12 It is a top view of the middle and upper connecting head of a double-tube multi-limb square column with restorable functions in a specific embodiment of the present invention;

[0045] Fig.13 It is a schematic cross-sectional view of a load-bearing main beam in a double-tube multi-limb square column with recoverable functions in a specific embodiment of the present invention.

[0046] In the figure: inner tube frame 20, outer tube frame 30, inner tube side column 1, steel corbel 2, corbel 3, corbel connecting beam 31, inner tube connecting beam 4, outer tube side column 5, outer tube connecting limb column 51, bearing main beam 6, coordinated deformation rubber 61, I-beam 62, shear member 63, short limb connecting beam 7, upper connecting head 8, X-direction connecting groove 81, Y-direction connecting groove 82, diagonal web member 9, replaceable component 10. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0048] The present invention provides a double-tube multi-limb square column with restorable functions, such as Figure 1 and Figure 2 As shown, it includes an inner cylinder frame 20 and an outer cylinder frame 30 sleeved outside the inner cylinder frame 20;

[0049] The inner tube frame 20 includes four inner tube side columns 1, and the four inner tube side columns 1 are vertically arranged to form a square column structure;

[0050] The square column structure includes an upper support surface, a multi-level middle support surface and a lower support surface in sequence along the height direction;

[0051] The upper support surface includes a corbel 3 arranged opposite to the adjacent side walls on a section of the inner tube side column 1, the inner tube side column 1 and the corbel 3 are integrally cast, and a corbel connecting beam 31 is connected between adjacent corbels 3, and the corbel connecting beam 31 and the corbel 3 are detachably connected by embedded parts. Specifically, the upper support surface can play a supporting role for the upper connector 8; the multi-level middle support surface and the lower support surface are arranged at intervals, and include an inner tube connecting beam 4 connected to the adjacent side walls of the adjacent inner tube side columns 1;

[0052] Specifically, the inner tube side column 1 is a square columnar structure;

[0053] Further, the middle support surface and the lower support surface both include a portion of the inner tube side column 1 and an inner tube connecting beam 4 connected to adjacent side walls of the inner tube side column 1, wherein four inner tube connecting beams 4 are arranged at the same height to form a first-level middle support surface or a lower support surface;

[0054] The corbel 3 of the upper supporting surface is extended in the reverse direction to the area of ​​the side wall of the inner tube side column 1, and a steel corbel 2 is extended therefrom. The inner tube connecting beam 4 of the multi-level middle supporting surface is extended in the reverse direction to the area of ​​the side wall of the inner tube side column 1, and a steel corbel 2 is extended therefrom. Specifically, the inner tube connecting beam 4 is detachably connected to the inner tube side column 1 by using embedded parts, and the inner tube connecting beam 4 is made of I-shaped steel.

[0055] The outer tube frame 30 includes four outer tube side columns 5 and a main force-bearing beam 6 arranged horizontally and vertically between adjacent outer tube side columns 5. The main force-bearing beam 6 and the outer tube side columns 5 are detachably connected by embedded parts, such as Figure 4 , Figure 5 and Figure 6 As shown;

[0056] The lower top surface of the end of the steel bracket 2 is arranged on the upper top surface of the main beam 6, and a gap is arranged between the lower top surface of the main beam 6 and the upper top surface of the outer tube connecting column 51, such as Figure 6 As shown;

[0057] The inner tube connecting beam 4 of the lower support surface extends in the reverse direction to the inner tube side column 1 and the outer tube connecting limb column 51. A replaceable component 10 is arranged between the side walls. The replaceable component 10 can be sheared to dissipate energy. Specifically, the replaceable component 10 is detachably connected to the inner tube side column 1 and the outer tube connecting limb column 51 through embedded parts. Figure 7 As shown, the function of the replaceable component 10 is to dissipate shear energy when the inner cylinder frame 20 and the outer cylinder frame 30 are relatively displaced in the height direction;

[0058] Specifically, the working principle of the present application is as follows: the inner tube frame 20 and the outer tube frame 30 are two relatively independent frame systems. The steel corbel 2 in the inner tube frame 20 is set on the upper part of the load-bearing main beam 6 that can undergo elastic deformation. The amount of relative displacement that can occur in the height direction of the inner tube frame 20 and the outer tube frame 30 during an earthquake is determined by the number of stages and component design of the steel corbel 2 and the load-bearing main beam 6. The more stages there are, the greater the amount of relative displacement that occurs in the height direction. When the inner tube frame 20 and the outer tube frame 30 in the multi-limb square column of the present application undergo relative displacement in the height direction, the energy is consumed by the replaceable component 10 that can be shear-deformed. The diagonal web 9 ensures that the distance between the inner tube frame 20 and the outer tube frame 30 is constant, ensuring that the multi-limb square column of the present application has sufficient overall stability. At the same time, the present application can replace the replaceable component 10 or adjust its position in a targeted manner after the earthquake, so as to quickly restore the structural function of the multi-limb square column of the present application.

[0059] A preferred embodiment provided by the present invention is as follows: Fig.13 As shown, the main bearing beam 6 comprises an I-beam 62, and shear members 63 are arranged on both sides of the web of the I-beam 62;

[0060] The upper part of the I-beam 62 and the outer side of the shear member 63 are provided with a coordinated deformation rubber 61. Specifically, the load-bearing main beam 6 includes the coordinated deformation rubber 61, which generates elastic deformation when squeezed by the steel corbel 2, thereby improving the overall stability of the structure.

[0061] Another preferred embodiment provided by the present invention is that an upper connector 8 is embedded at the upper end of the inner tube side column 1;

[0062] The upper surface of the upper connector 8 is provided with an X-direction connection groove 81 and a Y-direction connection groove 82 arranged in a cross shape. Fig.11 and Fig.12 As shown, the X-direction connecting groove 81 and the Y-direction connecting groove 82 are used for connecting beams, and the lower end of the upper connecting head 8 is fixedly connected to the corbels 3 on the four inner tube side columns 1. Furthermore, concave notches are provided at the four corners of the upper connecting head 8, so that the upper connecting head 8 and the inner tube side columns 1 are all engaged, ensuring that the upper connecting head 8 will not be twisted relative to the four inner tube side columns 1.

[0063] Another preferred embodiment provided by the present invention is as follows: Figure 5 Figure 6 As shown, a plurality of short-limb connecting beams 7 are horizontally and vertically arranged between the outer tube connecting limb columns 51 and between the outer tube connecting limb columns 51 and the outer tube side columns 5. The short-limb connecting beams 7 are detachably connected to the outer tube connecting limb columns 51 or the outer tube side columns 5 by using embedded parts. Specifically, when replacing or adjusting the replaceable component 10, the short-limb connecting beams 7 can be removed to facilitate replacement or adjustment of the replaceable component 10; wherein, the short-limb connecting beams 7 can further improve the stability of the present structure, and the short-limb connecting beams 7 are made of I-shaped steel.

[0064] Another preferred embodiment provided by the present invention is that a diagonal brace 9 is provided between the replaceable components 10 adjacent in the height direction. Specifically, the two ends of the diagonal brace 9 are connected to the inner tube side column 1 and the outer tube connecting column 51. The diagonal brace 9 has a shear resistance function, which is used to ensure that the distance between the inner tube frame 20 and the outer tube frame 30 remains unchanged, and prevent the inner tube frame 20 and the outer tube frame 30 from having a relative displacement trend other than in the height direction; further, if the number of lower support surfaces of the replaceable component 10 is one level, the diagonal brace The rod 9 is arranged in the area between the inner tube side column 1 and the outer tube connecting column 51 above the replaceable component 10 and the lower flange of the nearest adjacent steel corbel 2; if the number of lower supporting surfaces with replaceable components 10 is not less than two levels, then diagonal web rods 9 need to be arranged in the area between the replaceable components 10 of the two adjacent lower supporting surfaces, and the designer can choose whether to arrange diagonal web rods 9 in the area between the inner tube side column 1 and the outer tube connecting column 51 above the uppermost replaceable component 10 and the lower flange of the nearest steel corbel 2 according to the working conditions.

[0065] Another preferred embodiment provided by the present invention is that the lower supporting surface is not less than one level, specifically, it is used to enable the inner tube frame 20 and the outer tube frame 30 to bear the load transmitted from the upper beam as a whole by bearing the steel corbel 2.

[0066] Another preferred embodiment provided by the present invention is that the centroid distance between adjacent outer cylinder connecting limb columns 51 is equal to the centroid distance between adjacent inner cylinder side columns 1. Specifically, this is to ensure that the replaceable component 10 and the diagonal web rod 9 can be connected between the inner cylinder side column 1 and the outer cylinder connecting limb column 51, and a short limb connecting beam 7 is connected between every two adjacent outer cylinder connecting limb columns 51, and a short limb connecting beam 7 is connected between the outer cylinder side column 5 and the adjacent outer cylinder connecting limb column 51, which can improve the overall stability of the structure.

[0067] Since the main bearing beam 6 in the present application is elastic, and the inner cylinder frame 20, the upper connecting head 8, and the beam all have a large deadweight, the weight of these components themselves will cause the inner cylinder frame 20 and the outer cylinder frame 30 to be relatively displaced in the height direction, so the multi-limbed square column of the present application connecting the replaceable component 10 and the diagonal brace 9 should be installed and connected after the upper connecting head 8 is set. In addition, when installing the multi-limbed square column of the present application, the top surface elevation of the inner cylinder frame 20 should be higher than the top surface elevation of the outer cylinder frame 30. After the upper connecting head 8 is installed, the top and bottom surface elevations of the inner cylinder frame 20 and the outer cylinder frame 30 should be controlled within a small error.

[0068] Another preferred embodiment provided by the present invention is that the replaceable component 10 adopts a damper or an I-beam.

[0069] The present invention provides an assembly method of a double-tube multi-limb square column with restorable functions, comprising the following steps:

[0070] S1: Connect the inner tube connecting beam 4 to the inner tube side column 1 according to the preset position, connect the corbel connecting beam 31 between the corbels 3, and connect the steel corbel 2 to the preset position of the outer wall of the inner tube side column 1 to complete the setting of the inner tube frame 20;

[0071] S2: an outer tube side column 5 is arranged at a preset position outside the inner tube frame 20, and a bearing main beam 6 is used to connect the four outer tube side columns 5, and the upper top surface of the bearing main beam 6 is arranged to fit the lower top surface of the end of the steel corbel 2;

[0072] S3: The outer tube connecting limb columns 51 are arranged between the outer tube side columns 5, and then the diagonal web members 9 and the replaceable components 10 are installed, and finally the short limb connecting beams 7 are connected to complete the installation of the outer tube frame 30.

[0073] Specifically, in S2, the upper top surface of the main beam 6 is arranged to fit the lower top surface of the end of the steel corbel 2, and then the upper connector 8 is arranged on the upper part of the corbel 3, and then the beam is connected;

[0074] Furthermore, in S3, an outer tube connecting limb column 51 is arranged between the outer tube side columns 5. The specific steps are: firstly, a detachable weak connection is fixed, and then the diagonal web member 9 and the replaceable component 10 are installed, and then the weak connection on the short limb connecting beam 7 is gradually removed while being fixed with bolts until the installation of the outer tube frame 30 is completed.

[0075] When using the square column of the present application, it is possible to choose whether to seal the exposed area of ​​the outer tube frame, but when sealing, a technology or process that is easy to disassemble should be selected.

Claims

1. A double-tube multi-limb square column with restorable function, characterized in that: It comprises an inner cylinder frame (20) and an outer cylinder frame (30) sleeved outside the inner cylinder frame (20); The inner cylinder frame (20) comprises four inner cylinder side columns (1), and the four inner cylinder side columns (1) are vertically arranged to form a square column structure; The square column structure includes an upper support surface, a multi-level middle support surface and a lower support surface; The upper support surface comprises corbels (3) arranged opposite to adjacent side walls of the inner tube side columns (1), and corbel connecting beams (31) are connected between the corbels (3) on adjacent inner tube side columns (1); the multi-level middle support surface and the lower support surface are arranged at intervals, and comprise inner tube connecting beams (4) connected to adjacent side walls of adjacent inner tube side columns (1); The corbel (3) of the upper support surface extends in the reverse direction to the area of ​​the side wall of the inner tube side column (1) and is provided with a steel corbel (2); the inner tube connecting beam (4) of the multi-level middle support surface extends in the reverse direction to the area of ​​the side wall of the inner tube side column (1) and is provided with a steel corbel (2); The outer tube frame (30) comprises four outer tube side columns (5) and a load-bearing main beam (6) arranged horizontally and vertically between adjacent outer tube side columns (5); The lower top surfaces of the ends of the steel brackets (2) are arranged on the upper top surface of the force-bearing main beam (6), and a vertical outer tube connecting column (51) is arranged in the gap between the lower top surface of the force-bearing main beam (6); The inner tube connecting beam (4) extends in the opposite direction to the side walls of the inner tube side column (1) and the outer tube connecting limb column (51); A plurality of short-limb connecting beams (7) are arranged horizontally and vertically between the outer cylinder connecting limb columns (51) and between the outer cylinder connecting limb columns (51) and the outer cylinder side columns (5); The inner tube connecting beam (4) of the lower supporting surface extends in the reverse direction to a side wall between the inner tube side column (1) and the outer tube connecting limb column (51), and a replaceable component (10) is provided therebetween. The replaceable component (10) can dissipate energy by shearing.

2. According to claim 1, a double-tube multi-limb square column with restorable function, characterized in that: The load-bearing main beam (6) comprises an I-beam (62), and shear-resistant parts (63) are arranged on both sides of the web of the I-beam (62); Coordinated deformation rubber (61) is provided on the upper part of the I-beam (62) and on the outer side of the anti-shear member (63).

3. The double-tube multi-limb square column with restorable function according to claim 1, characterized in that: An upper connecting head (8) is embedded at the upper end of the inner tube side column (1); The upper surface of the upper connecting head (8) is provided with an X-direction connecting groove (81) and a Y-direction connecting groove (82) that intersect in a cross shape.

4. The double-tube multi-limb square column with restorable function according to claim 1, characterized in that: Diagonal braces (9) are provided between adjacent replaceable components (10) along the height direction.

5. The double-tube multi-limb square column with restorable function according to claim 1, characterized in that: The lower supporting surface is not less than one level.

6. The double-tube multi-limb square column with restorable function according to claim 1, characterized in that: The centroid distance between adjacent outer cylinder connecting limb columns (51) is equal to the centroid distance between adjacent inner cylinder side columns (1).

7. The double-tube multi-limb square column with restorable function according to claim 1, characterized in that: The replaceable component (10) is a damper or an I-beam.

8. A method for preparing a double-tube multi-limb square column with restorable function, characterized in that: A double-tube multi-limb square column with restorable functions according to any one of claims 1 to 7 comprises the following steps: S1: Connecting the inner tube connecting beam (4) to the inner tube side column (1) at a preset position, connecting the corbel connecting beam (31) between the corbels (3), and connecting the steel corbel (2) at a preset position on the outer wall of the inner tube side column (1), thereby completing the setting of the inner tube frame (20); S2: an outer tube side column (5) is arranged at a preset position outside the inner tube frame (20), and a load-bearing main beam (6) is used to connect the four outer tube side columns (5), and the upper top surface of the load-bearing main beam (6) is arranged to fit the lower top surface of the end of the steel corbel (2); S3: an outer tube connecting limb column (51) is arranged between the outer tube side columns (5), and then the diagonal web member (9) and the replaceable component (10) are installed, and finally the short limb connecting beam 7 is connected to complete the installation of the outer tube frame (30).

9. A method for preparing a double-tube multi-limb square column with restorable functions according to claim 8, characterized in that: In S3, an outer tube connecting limb column (51) is arranged between the outer tube side columns (5), and the specific steps are: firstly, a detachable weak connection is fixed, and then the diagonal web member (9) and the replaceable component (10) are installed, and then the weak connection on the short limb connecting beam (7) is gradually removed and bolted, until the installation of the outer tube frame (30) is completed.

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