Method for installing a variable cross-section large cantilever steel structure with rocking columns

Abstract

The application discloses a mounting method of a variable cross-section large cantilever steel structure containing rocking columns, wherein the variable cross-section large cantilever steel structure is arranged on one side of the main body steel structure in the length direction and is fixedly connected with the top steel beam of the first layer structure of the main body steel structure; the variable cross-section large cantilever steel structure comprises a row of rocking column units and a steel beam unit arranged on the top of the rocking column units; the steel beam unit is in the shape of a variable cross-section right-angle trapezoid, and the inclined side of the steel beam unit is arranged opposite to the main body steel structure; the setting of the rocking column units is beneficial to guaranteeing the support stress of the large cantilever steel structure; the setting of the temporary supporting arm units guarantees the fixed installation of the lower rocking columns; the stability of the installation is guaranteed by the partition connection from the short side to the long side and through the small trapezoidal frames; the secondary installation of the cantilever side under the balanced stress condition of the main body of the large cantilever steel structure is guaranteed by the later installation of the long-direction outer cantilever and the short-direction outer cantilever, and the safety of the whole structure is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of large cantilever steel structure installation, in particular to a method for installing a large cantilever steel structure with variable cross-section and swing columns. BACKGROUND

[0002] In the existing steel structure construction, it is common to set a cantilever side outside the main steel structure, which enriches the style of the steel structure and improves the aesthetic appearance. Generally, the cantilever is only fixed by the main steel structure, and the length of the cantilever is small. However, there is little research on the large-span cantilever set outside the main steel structure and supported by swing columns, and there is no specific technical solution for the installation of the cantilever steel structure with variable cross-section. SUMMARY

[0003] The present application provides a method for installing a large cantilever steel structure with variable cross-section and swing columns, which solves the technical problems of designing and installing swing columns and steel frame units in the large cantilever steel structure with variable cross-section.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0005] A method for installing a large cantilever steel structure with variable cross-section and swing columns, the large cantilever steel structure with variable cross-section is arranged on one side of the main steel structure in the long direction, and is fixedly connected with the top steel beam of the first layer structure of the main steel structure below;

[0006] The large cantilever steel structure with variable cross-section comprises a row of swing column units and a steel beam unit arranged on the top of the swing column units;

[0007] The steel beam unit is in the shape of a variable cross-section right-angled trapezoid, and the inclined side is arranged opposite to the main steel structure;

[0008] The method for installing the large cantilever steel structure with variable cross-section and swing columns, the specific steps are as follows:

[0009] Step one, first construct the first layer structure and other main building parts of the main steel structure, and then pre-construct three swing column units on one side of the short side of the large cantilever steel structure with variable cross-section along the long direction of the main steel structure after the construction is completed;

[0010] Step two, install the steel cross beam in the steel beam unit on the top of the middle swing column unit, and then install the steel cross beam of the first swing column unit on one side of the short side; then install the steel longitudinal beam between the two swing column units connecting the previously installed steel cross beams; thus, the two installed steel cross beams, steel longitudinal beams and the steel beam of the installed main steel structure form a small trapezoidal frame, and then install the steel cross beam in the middle of the small trapezoidal frame;

[0011] Step three, then install the corresponding steel beam on the top of the third rocking column unit, the steel longitudinal beam connecting the middle rocking column unit and the top of the third rocking column unit forms a small trapezoidal frame, and then install the steel secondary longitudinal beam of the steel beam and the vertical steel beam in the small trapezoidal frame;

[0012] Step four, thus sequentially install the subsequent rocking column unit and the corresponding steel beam, install the steel longitudinal beam between the top of the rocking column unit and the top of the previous rocking column unit to form a small trapezoidal frame, and then install the steel secondary longitudinal beam of the steel beam in the small trapezoidal frame, until all the rocking column units are installed;

[0013] Step five, install the long and short outward side overhangs of the steel beam unit, and the short outward side overhang is one side of the long bottom side of the trapezoid; then install the steel reinforcing beam at the corresponding steel beam of the long outward side overhang, the short outward side overhang and the rocking column unit, thereby completing the overall installation of the variable cross-section large cantilever steel structure containing rocking columns.

[0014] Further, the main steel structure is a multi-layer frame steel structure composed of steel beams and steel columns, a variable cross-section large cantilever steel structure is installed on one side of the top of the first floor structure, and other floor steel structures are installed on the other side; a steel structure garage is also provided on the short side of the main steel structure.

[0015] Further, the rocking column unit comprises a rocking main column, a bottom ear plate connected to the bottom of the rocking main column, a bottom butt ear plate connected to the bottom ear plate and arranged on the top of the first floor structure, a top ear plate connected to the top of the rocking main column, a top butt ear plate connected to the top ear plate and arranged on the bottom of the steel beam unit, and a top connecting rod connected between the top of the rocking main column and the bottom of the steel beam unit.

[0016] Further, the rocking main column comprises a lower rocking column and an upper rocking column, the upper rocking column and the lower rocking column are connected by a connecting H-shaped connecting ear plate and the connecting position is welded;

[0017] In steps two and three, the three rocking column units installed first are all the lower rocking columns, and then the upper rocking columns corresponding to the pre-installed rocking main columns are installed when the steel beams are installed;

[0018] In step four, the subsequent rocking main columns are all the lower rocking columns installed in time corresponding to the upper rocking columns, and then the steel beams are installed.

[0019] Further, the bottom ear plate is provided with two and arranged in parallel, and a bottom butt ear plate is arranged between the two bottom ear plates and connected by a pin shaft.

[0020] The top ear plate is provided with two and arranged in parallel, and a top butt ear plate is arranged between the two top ear plates and connected by a pin shaft.

[0021] A top connecting rod is arranged between the top of the upper rocking column and the top ear plate.

[0022] Further, the steel beam unit comprises steel cross beams arranged along the main steel structure, steel longitudinal beams arranged at the overhanging ends of the steel cross beams, and steel secondary longitudinal beams arranged along the length of the steel cross beams; the steel cross beams, the steel secondary longitudinal beams, and the steel longitudinal beams are arranged in a grid shape and are trapezoidal.

[0023] Further, the long overhanging portion on the outer side of the steel beam unit comprises a long overhanging cross beam connected perpendicularly to the outer side of the steel longitudinal beam and a long overhanging longitudinal beam connected to the overhanging end of the long overhanging cross beam; the long overhanging cross beam is arranged corresponding to the steel cross beam, and the long overhanging longitudinal beam is arranged in the same direction as the steel longitudinal beam.

[0024] The short overhanging portion on the outer side of the steel beam unit comprises a short overhanging longitudinal beam and a short overhanging cross beam, wherein the short overhanging longitudinal beam is arranged along the extension line of the steel longitudinal beam, and the short overhanging cross beam is arranged at the overhanging end of the short overhanging longitudinal beam.

[0025] Further, the steel reinforcing beam is an X-shaped inclined bracing beam, which is arranged between the short overhanging longitudinal beams of the short overhanging portion on the outer side and between the long overhanging cross beams.

[0026] The steel reinforcing beam is arranged between the steel cross beams corresponding to the rocking column unit and the left and right steel cross beams, and is arranged sequentially on the grid formed by the steel cross beams and the steel secondary longitudinal beams on the side close to the main steel structure.

[0027] Further, in steps three and four, for the installation of the lower rocking column, a temporary supporting arm unit is used for temporary fixing of the lower rocking column.

[0028] The temporary supporting arm unit comprises two parallel supporting arm vertical rods, a supporting arm horizontal rod connected to the two supporting arm vertical rods and forming a triangle with the supporting arm hoop, and a supporting arm inclined bracing connected between the supporting arm hoop and the supporting arm vertical rods.

[0029] The bottom of the supporting arm vertical rod is fixedly connected to the top steel beam of the first floor structure through a supporting arm bottom connecting plate.

[0030] The supporting arm hoop is arranged in at least three rows, and the supporting arm hoop is detachably connected to the lower rocking column.

[0031] Further, the lower rocking column is hoisted by a tower crane during installation, and the bottom of the lower rocking column is fixedly connected to the intersection point of the top steel beam of the first floor structure through a supporting arm bottom connecting rod.

[0032] The supporting arm bottom connecting rod is arranged at intervals in the circumferential direction and is removed after the installation of the rocking main column is completed.

[0033] The beneficial effects of the present application are as follows:

[0034] This invention, through the design of the sway column unit, facilitates the support and stress distribution of the large cantilever steel structure; the hinged design of the sway column further enhances energy dissipation; and the temporary support arm unit ensures the fixed installation of the lower sway column. The invention also ensures installation stability by using small trapezoidal frames for partitioned connections from the short side to the long side. Furthermore, the subsequent installation of the long and short outward cantilevers ensures the secondary installation of the cantilever sides under balanced stress on the main body of the large cantilever steel structure, thus guaranteeing the overall structural safety. Finally, the steel reinforcing beams supplement and strengthen the cantilever sides, the sway column connections, and the connections to the main steel structure, further ensuring overall stress stability.

[0035] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention; the main objects and other advantages of the invention may be realized and obtained by means of the embodiments particularly pointed out in the description. Attached Figure Description

[0036] Figure 1 It is a three-dimensional schematic diagram of a large cantilever steel structure with variable cross-section and swaying columns and its connection structure;

[0037] Figure 2 It is a side view of a large cantilevered steel structure with a variable cross-section containing swaying columns and its connecting structure;

[0038] Figure 3 This is a schematic diagram of the lower sway column installation;

[0039] Figure 4 This is a partial schematic diagram of the lower sway column installation;

[0040] Figure 5 This is a schematic diagram of the upper swing column installation;

[0041] Figure 6 This is a schematic diagram of the pre-installation of the three lower swaying columns during construction;

[0042] Figure 7 This is a schematic diagram of the installation of the middle upper sway column;

[0043] Figure 8 This is a schematic diagram of the installation of the intermediate steel crossbeam;

[0044] Figure 9 This is a schematic diagram of the installation of the first-order upper swing column;

[0045] Figure 10 This is a schematic diagram of the installation of the first-order steel crossbeam;

[0046] Figure 11 This is a schematic diagram of the steel longitudinal beam installation;

[0047] Figure 12This is a schematic diagram of the steel beam connection within a small trapezoidal frame;

[0048] Figure 13 This is a schematic diagram of the sequential construction and installation of the sway column unit and the steel beam unit. Figure 1 ;

[0049] Figure 14 This is a schematic diagram of the sequential construction and installation of the sway column unit and the steel beam unit. Figure 2 ;

[0050] Figure 15 This is a schematic diagram of the sequential construction and installation of the sway column unit and the steel beam unit. Figure 3 ;

[0051] Figure 16 This is a schematic diagram of the sequential construction and installation of the sway column unit and the steel beam unit. Figure 4 ;

[0052] Figure 17 This is a schematic diagram of the cantilever construction and installation along the outer side;

[0053] Figure 18 This is a schematic diagram of the short-to-outward cantilever construction and installation;

[0054] Figure 19 This is a completed installation diagram of a large cantilever steel structure with a variable cross-section.

[0055] Attached reference numerals: 1-Main steel structure, 2-Steel structure garage, 3-Variable cross-section large cantilever steel structure, 31-Swing column unit, 311-Swing main column, 3111-Lower swing column, 3112-Upper swing column, 312-Bottom ear plate, 313-Bottom connecting ear plate, 314-Top ear plate, 315-Top connecting ear plate, 316-Top connecting rod, 32-Steel beam unit, 321-Steel crossbeam, 322-Steel longitudinal beam, 323-Steel secondary longitudinal beam, 324-Long cantilever crossbeam, 325-Long cantilever longitudinal beam, 326-Short cantilever longitudinal beam, 327-Short cantilever crossbeam, 328-Steel reinforcing beam, 4-Temporary handrail unit, 41-Handrail upright, 42-Handrail horizontal bar, 43-Handrail diagonal brace, 44-Handrail clamp, 45-Handrail bottom connecting rod, 46-Handrail bottom connecting plate, 5-Tower crane. Detailed Implementation

[0056] Taking the construction of a science and technology innovation center as an example, the first-floor steel structure of the main building consists of 17 steel columns and the main and secondary frame beams between them. The second floor to the roof section of the main building is located on one side of the first-floor steel structure, and a large cantilevered steel structure with variable cross-section and swaying columns is set up relative to the second floor to the roof section. Six full-height swaying columns are distributed in the east-west direction, with their upper parts connected to the roof of the main building and their bottoms resting on the first-floor steel structure. The large cantilevered steel structure with variable cross-section gradually increases in span from east to west, with a maximum span of 26.5m and a cantilever length of 4m.

[0057] likeFigures 1 to 19 As shown, the variable cross-section large cantilever steel structure 3 is set on one side of the main steel structure 1 along its length, and is fixedly connected to the top steel beam of the first floor structure in the main steel structure 1 below; the variable cross-section large cantilever steel structure 3 includes a row of sway column units 31 and steel beam units 32 set on the top of the sway column units 31; the steel beam unit 32 is a right trapezoid with a variable cross-section, and its hypotenuse is set relative to the main steel structure 1.

[0058] In this embodiment, the main steel structure 1 is a multi-layer frame steel structure composed of steel beams and steel columns. A variable cross-section large cantilever steel structure 3 is installed on the top of one side of the first floor structure, and other floor steel structures are installed on the other side. A steel structure garage 2 is also provided on the shorter side of the main steel structure 1.

[0059] In this embodiment, the rocking column unit 31 includes a rocking main column 311, a bottom lug plate 312 connected to the bottom of the rocking main column 311, a bottom connecting lug plate 313 connected to the bottom lug plate 312 and disposed at the top of the first-floor structure, a top lug plate 314 connected to the top of the rocking main column 311, a top connecting lug plate 315 connected to the top lug plate 314 and disposed at the bottom of the steel beam unit 32, and a top connecting rod 316 connecting the top of the rocking main column 311 and the bottom of the steel beam unit 32.

[0060] In this embodiment, there are two bottom ear plates 312 arranged in parallel, and a bottom mating ear plate 313 is provided between the two bottom ear plates 312 and can be hinged together by a pin; there are two top ear plates 314 arranged in parallel, and a top mating ear plate 315 is provided between the two top ear plates 314 and can be hinged together by a pin; a top connecting rod 316 is provided at intervals between the top of the upper rocker column 3112 and the top ear plate 314.

[0061] In this embodiment, the steel beam unit 32 includes steel crossbeams 321 spaced apart along the length of the main steel structure, steel longitudinal beams 322 disposed at the cantilever ends of the steel crossbeams 321, and steel secondary longitudinal beams 323 spaced apart along the length of the steel crossbeams 321; the steel crossbeams 321, steel secondary longitudinal beams 323 and steel longitudinal beams 322 are arranged in a grid pattern and are trapezoidal.

[0062] In this embodiment, the long outward cantilever in the steel beam unit 32 includes a long cantilevered crossbeam 324 vertically connected to the outside of the steel longitudinal beam 322 and a long cantilevered longitudinal beam 325 connected to the cantilever end of the long cantilevered crossbeam 324; the long cantilevered crossbeam 324 is provided one-to-one with the steel crossbeam 321, and the long cantilevered longitudinal beam 325 and the steel longitudinal beam 322 are provided in the same direction; the short outward cantilever in the steel beam unit 32 includes a short cantilevered longitudinal beam 326 and a short cantilevered crossbeam 327, wherein the short cantilevered longitudinal beam 326 is provided sequentially along the extension line of the steel longitudinal beam 322, and the short cantilevered crossbeam 327 is provided at the cantilever end of the short cantilevered longitudinal beam 326.

[0063] Combination Figures 1 to 19The installation method for a large cantilever steel structure with variable cross-section and swaying columns is further explained below, with specific steps as follows:

[0064] Step 1: First, construct the first floor structure of the main steel structure 1 and other main building parts. After the construction is completed, pre-construct one side of the variable cross-section large cantilever steel structure 3. On the short side, pre-construct three sway column units 31 along the length of the main steel structure 1.

[0065] Step 2: Install the steel crossbeam 321 of the steel beam unit 32 on the top of the middle sway column unit 31, and then install the steel crossbeam 321 of the first sway column unit 31 on the short side; then install the steel longitudinal beam 322 between the two sway column units 31 that previously connected the steel crossbeams 321; thus, the two installed steel crossbeams 321, the steel longitudinal beam 322 and the steel beam of the main steel structure 1 are enclosed to form a small trapezoidal frame, and then install the steel crossbeams 321 at intervals in the small trapezoidal frame.

[0066] Step 3: Then, install the corresponding steel crossbeam 321 on the top of the third sway column unit 31, and the steel longitudinal beam 322 connecting the top of the middle sway column unit 31 and the third sway column unit 31 to form a small trapezoidal frame. Then, install the steel crossbeam 321 and the steel secondary longitudinal beam 323 perpendicular to the steel crossbeam 321 at intervals in the small trapezoidal frame.

[0067] Step 4: Install the subsequent rocker column units 31 and corresponding steel crossbeams 321 one by one in sequence. Install the steel longitudinal beams 322 between the top of the rocker column unit 31 and the top of the previous rocker column unit 31 to form a small trapezoidal frame. Then, install the steel secondary longitudinal beams 323 of the steel crossbeams 321 at intervals in the small trapezoidal frame until all rocker column units 31 are installed.

[0068] In this embodiment, the swaying main column 311 includes a lower swaying column 3111 and an upper swaying column 3112. The upper swaying column 3112 and the lower swaying column 3111 are connected by a connecting U-shaped connecting lug and welded at the joint. In steps two and three, the three swaying column units 31 installed first are all installed by uniformly installing the lower swaying column 3111, and then the upper swaying column 3112 of the swaying main column 311 is installed in the same way when the steel beam 321 is installed. In step four, the subsequent swaying main columns 311 are all installed by promptly installing the upper swaying column 3112 after the lower swaying column 3111 is installed, and then the steel beam 321 is installed.

[0069] In steps three and four, during the installation of the lower sway column 3111, the lower sway column 3111 is temporarily fixed by the temporary arm unit 4. The temporary arm unit 4 includes two parallel arm uprights 41, a horizontal arm bar 42 connecting the two arm uprights 41 and forming a triangle with the arm clamp 44, and an arm diagonal brace 43 connecting the arm clamp 44 and the arm uprights 41. The bottom of the arm uprights 41 is fixedly connected to the top steel beam of the first floor structure through the arm bottom connecting plate 46.

[0070] At least three arm clamps 44 are provided, and the arm clamps 44 are detachably connected to the lower sway column 3111. The lower sway column 3111 is hoisted by tower crane 5 during installation. The bottom of the lower sway column 3111 is also fixedly connected to the junction of the top steel beam of the first floor structure through the arm bottom connecting rod 45. The arm bottom connecting rod 45 is set at intervals in the circumferential direction and will be removed after the sway column 311 is installed.

[0071] Step 5: Install the long outward cantilever and the short outward cantilever in the steel beam unit 32. The short outward cantilever is the long base side of the trapezoid. Then, reinforce the steel beams 328 at the long outward cantilever, the short outward cantilever and the steel beams 321 corresponding to the rocking column unit 31, thereby completing the overall installation of the variable cross-section large cantilever steel structure 3 with rocking columns.

[0072] In actual construction, the steel reinforcing beam 328 is an X-shaped diagonal bracing beam. The steel reinforcing beam 328 is arranged sequentially between the short cantilevered longitudinal beams 326 and between the long cantilevered transverse beams 324. The steel reinforcing beam 328 is arranged between the steel transverse beams 321 and the left and right steel transverse beams 321 corresponding to the rocking column unit 31. It is also arranged sequentially on the grid formed by the steel transverse beams 321 and the secondary longitudinal beams 323 on the side adjacent to the main steel structure 1.

[0073] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for installing a large cantilever steel structure with a variable cross-section and a rocking column, characterized in that, The variable cross-section large cantilever steel structure is set on one side of the main steel structure along its length, and is fixedly connected to the top steel beam of the first floor structure in the main steel structure below. The variable cross-section large cantilever steel structure includes a row of sway column units and steel beam units set on top of the sway column units; The steel beam unit is a right trapezoid with a variable cross-section, and its hypotenuse is set relative to the main steel structure. The installation method for a large cantilever steel structure with variable cross-section and swaying columns is as follows: Step 1: First, construct the first floor structure of the main steel structure and other main building parts. After the construction is completed, pre-construct one side of the short side of the variable cross-section large cantilever steel structure. On the short side, pre-construct three sway column units along the length of the main steel structure. Step 2: Install the steel crossbeam from the steel beam unit at the top of the middle sway column unit, and then install the steel crossbeam of the first sway column unit on the short side; then install the steel longitudinal beam between the two sway column units that previously connected the steel crossbeams; thus, the two installed steel crossbeams, the steel longitudinal beam, and the steel beam of the main steel structure are enclosed to form a small trapezoidal frame, and then install steel crossbeams at intervals in the small trapezoidal frame; Step 3: Then, install the corresponding steel crossbeam on the top of the third sway column unit, and connect the steel longitudinal beam between the top of the middle sway column unit and the top of the third sway column unit to form a small trapezoidal frame. Then, install steel crossbeams and steel secondary longitudinal beams perpendicular to the steel crossbeams at intervals in the small trapezoidal frame. Step 4: Install the subsequent rocking column units and corresponding steel beams one by one in this manner. Install the steel longitudinal beam between the top of the rocking column unit and the top of the previous rocking column unit to form a small trapezoidal frame. Then, install the secondary steel longitudinal beams of the steel beams at intervals in the small trapezoidal frame until all rocking column units are installed. Step 5: Install the long and short outward cantilever sections of the steel beam unit, with the short outward cantilever section being one side of the long base of the trapezoid. Then, reinforce the steel beams at the corresponding steel crossbeams of the long and short outward cantilever sections and the rocker column unit, thereby completing the overall installation of the variable cross-section large cantilever steel structure containing the rocker column.

2. The installation method of a variable cross-section large cantilever steel structure with a rocking column as described in claim 1, characterized in that, The main steel structure is a multi-layer frame steel structure composed of steel beams and steel columns. A variable cross-section large cantilever steel structure is installed on the top of one side of the first floor structure, and the steel structures of other floors are installed on the other side. A steel structure garage is also set on the short side of the main steel structure.

3. The installation method of a large cantilever steel structure with a variable cross-section and a rocking column as described in claim 2, characterized in that, The swaying column unit includes a swaying main column, a bottom lug plate connected to the bottom of the swaying main column, a bottom connecting lug plate connected to the bottom lug plate and located at the top of the first-floor structure, a top lug plate connected to the top of the swaying main column, a top connecting lug plate connected to the top lug plate and located at the bottom of the steel beam unit, and a top connecting rod connecting the top of the swaying main column and the bottom of the steel beam unit.

4. The installation method of a large cantilever steel structure with a variable cross-section and a rocking column as described in claim 3, characterized in that, The main rocking column includes a lower rocking column and an upper rocking column. The upper rocking column and the lower rocking column are connected by a connecting lug plate and welded at the joint. In steps two and three, the three swing column units installed first are all installed by uniformly installing the lower swing columns, and then the upper swing columns corresponding to the pre-installed swing main columns are installed when installing the steel crossbeams. In step four, the subsequent swaying main columns are installed in a timely manner after the lower swaying columns are installed, followed by the corresponding installation of the steel crossbeams.

5. The installation method of a variable cross-section large cantilever steel structure with a rocking column as described in claim 4, characterized in that, There are two bottom lugs arranged in parallel, with a bottom mating lug between them and a hinged connection via a pin; there are two top lugs arranged in parallel, with a top mating lug between them and a hinged connection via a pin; a top connecting rod is provided between the top of the upper rocker column and the top lugs at intervals.

6. The installation method of a large cantilever steel structure with a variable cross-section and a rocking column as described in claim 5, characterized in that, The steel beam unit includes steel crossbeams spaced apart along the length of the main steel structure, steel longitudinal beams located at the cantilever ends of the steel crossbeams, and steel secondary longitudinal beams spaced apart along the length of the steel crossbeams; the steel crossbeams, steel secondary longitudinal beams, and steel longitudinal beams are arranged in a grid pattern and are trapezoidal.

7. The installation method of a large cantilever steel structure with a variable cross-section and a rocking column as described in claim 6, characterized in that, The long outward cantilever in the steel beam unit includes a long cantilevered crossbeam perpendicularly connected to the outside of the steel longitudinal beam and a long cantilevered longitudinal beam connected to the cantilever end of the long cantilevered crossbeam; the long cantilevered crossbeam is set one by one with the steel crossbeam, and the long cantilevered longitudinal beam and the steel longitudinal beam are set in the same direction. The short outward cantilever in the steel beam unit includes a short cantilever longitudinal beam and a short cantilever transverse beam, wherein the short cantilever longitudinal beam is arranged sequentially along the extension line of the steel longitudinal beam, and the short cantilever transverse beam is arranged at the cantilever end of the short cantilever longitudinal beam.

8. The installation method of a large cantilever steel structure with a variable cross-section and a rocking column as described in claim 7, characterized in that, The steel reinforcing beam is an X-shaped diagonal bracing beam, and the steel reinforcing beam is arranged sequentially between the short cantilevered longitudinal beams and between the long cantilevered transverse beams. Steel reinforcing beams are installed between the steel crossbeams and the left and right steel crossbeams corresponding to the rocking column unit; and are sequentially installed on the grid formed by the steel crossbeams and steel secondary longitudinal beams on the side adjacent to the main steel structure.

9. The installation method of a large cantilever steel structure with a variable cross-section and a rocking column as described in claim 8, characterized in that, In steps three and four, when installing the lower sway column, the lower sway column is temporarily fixed by a temporary support arm unit; the temporary support arm unit includes two parallel support arm uprights, a support arm horizontal bar connected to the two support arm uprights and connected to the support arm clamp in a triangular shape, and a support arm diagonal brace connected between the support arm clamp and the support arm uprights. The bottom of the arm support is fixedly connected to the top steel beam of the first-floor structure via the arm support bottom connecting plate; At least three arm clamps are installed, and the arm clamps can be detached and connected to the lower swing column.

10. The installation method of a large cantilever steel structure with a variable cross-section and a rocking column as described in claim 9, characterized in that, The lower sway column is hoisted by a tower crane during installation. The bottom of the lower sway column is also fixedly connected to the junction point of the top steel beam of the first floor structure through the bottom connecting rod of the arm. The bottom connecting rods of the handrail are spaced out in the ring direction and will be removed after the main swing column is installed.

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