A construction method for a basket-type steel structure between buildings

Abstract

The present invention discloses a construction method for a basket-type steel structure between buildings, which includes the following steps: Step 1: Position and install the steel frame structure on the building structure; Step 2: Divide the basket-type steel structure into four truss units according to its four faces, and each truss unit is divided into upper and lower module trusses; Step 3: Perform ground hardening treatment and position and install embedded parts; Step 4: Assemble the truss units on the ground and weld and fix the single-pipe supports to the lower module trusses; Step 5: First install the truss units on the side connected to the building structure, and then install the truss units on the other two sides. When hoisting each truss unit, first hoist the lower module truss as a whole; then perform the positioning and installation of the support falsework and the segmented hoisting of the upper module truss; Step 6: Gradually unload the support falsework and then remove the single-pipe supports. This application provides a new structural form for the passage structure between buildings, with beautiful appearance, more spacious site, and more conducive to personnel flow.

Description

Technical Field

[0001] The present invention relates to the technical field of steel structure construction, and particularly relates to a construction method for a basket-type steel structure between buildings. Background Art

[0002] A certain theater project consists of a professional large-scale acrobatic main theater, a local drama theater, a comprehensive theater and its supporting rooms. It is a comprehensive performing arts building integrating multiple functions such as cultural performances, exchange exhibitions, and entertainment. According to the building's usage functions, it is divided into Area A small theater building area, Area B pedestrian passage area, and Area C acrobatic main theater area. Through the pedestrian passage area B, one can enter Area A and Area C, and it also plays the role of rain protection and sun shading.

[0003] The existing connection ceiling for a commercial square with the application number CN202023186413.3 includes a polygonal passage, a central vertical beam, an elevator, a plurality of ceiling vertical beams, a plurality of connection mechanisms, and a ceiling; wherein, the polygonal passage is fixedly arranged above a plurality of support plates, and an elevator hole is opened at the central position of the polygonal passage; the central vertical beam is arranged in the elevator hole, and a sliding groove is arranged on the side wall of the central vertical beam; the elevator is arranged in the sliding groove; a plurality of ceiling vertical beams are spaced and fixedly arranged on the upper surface of the polygonal passage, and a fixing groove is opened at the top of each ceiling vertical beam; a plurality of connection mechanisms are correspondingly arranged at the tops of the plurality of ceiling vertical beams; the ceiling is arranged above the polygonal passage, and its bottom is respectively connected to the plurality of connection mechanisms and the central vertical beam. The connection ceiling for the commercial square of the present utility model has a simple and reasonable structure, high safety, and strong stability.

[0004] The above scheme has the following problems: 1. With the development of urban construction, in addition to functional needs, people are more pursuing the visual impact and coordination with the surrounding building shapes in design to meet the needs of special scenarios. However, the existing connection channels have a single shape and poor landscape effect, unable to meet people's needs; 2. Most of the existing channel structures are slab-column structures, and the columns are arranged dispersedly and disorderly. For large-span area channels, support columns need to be set both inside and outside. For large-scale performing arts buildings, this undoubtedly increases the difficulty of pedestrian flow and is prone to congestion. Summary of the Invention

[0005] The present invention provides a construction method for a basket-type steel structure between buildings, providing a new structural form for the channel structure between buildings, with beautiful appearance, more open space, and more conducive to personnel flow; and the assembly and positioning accuracy control of the arc-shaped steel structure is better, which is applicable to the construction of the basket-type steel structure.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A construction method for a basket-type steel structure between buildings. The basket-type steel structure is used to connect between two buildings and includes longitudinal members, transverse members, and web members. Four longitudinal members are provided, respectively arranged at the four corner positions, and the longitudinal members are gradually curved outward from bottom to top. The transverse members are connected between adjacent longitudinal members and are arranged in multiple rows along the length direction of the longitudinal members. Multiple web members are provided, connected between adjacent transverse members, and the web members and the transverse members form multiple triangular frame structures. A support member is connected to the lower part of the lowermost transverse member. The construction method includes the following steps:

[0008] Step 1: Position and install the steel frame structure on the building structure;

[0009] Step 2: Divide the basket-type steel structure into four truss units according to its four faces. Each truss unit is divided into an upper and a lower modular truss. The lower modular truss is hoisted as a whole, and the upper modular truss is hoisted in sections and welded at high altitude;

[0010] Step 3: Conduct ground hardening treatment and position and install embedded parts;

[0011] Step 4: Assemble the truss units on the ground and weld and fix the single-pipe supports to the lower modular truss;

[0012] Step 5: First install the truss units on the side connected to the building structure, and then install the truss units on the other two sides. When hoisting each truss unit, first hoist the lower modular truss as a whole. After the lower modular truss is in place, gradually relax the tension connection of the modular truss and position it on the ground. The single-pipe support remains vertical and supports on the ground, and weld and fix the lower modular truss to the embedded parts. Then conduct the positioning and installation of the support falsework and the sectional hoisting of the upper modular truss, and then conduct the welding between the members and the welding of the bracket and the steel frame structure;

[0013] Step 6: Gradually unload the support falsework and then remove the single-pipe supports.

[0014] For a construction method for a basket-type steel structure between buildings according to the present invention, further, in Step 4: Establish a ground assembly coordinate system. Use Tekla software to convert the three-dimensional model diagram of the truss unit into a planar line model diagram, and then use CAD software to set the coordinate of one end of the center line of the transverse member at the end of the truss unit as the origin coordinate (0, 0, 0), and at the same time correspond the X-axis or Y-axis in the space coordinate system to the center line of this transverse member. Subsequently, extract the coordinates of the butt joints and intersecting joints of each member. When conducting on-site lofting, use the above coordinates as the positioning basis for each member during truss assembly.

[0015] The invention discloses a construction method for a flower basket type steel structure between buildings. Further, the method comprises the following steps: laying out, setting up a total station at an assembly site, determining the point (0,0,0), using the total station to lay out the coordinates (x1,y1,z1) and (x2,y2,z2) of the joints and intersection nodes of each rod, mapping the coordinates to the ground as positioning coordinates, locating the installation position of a tire frame, placing the tire frame at the positioning position, assembling the rods on the ground by combining the elevation value calibrated on the tire frame with an assembly line model, and adjusting the rods to predetermined positions by combining a plumb bob with the positioning coordinates on the ground after the rods are installed. During the assembly process, each rod needs to be measured and positioned. After the assembly is completed, the truss unit is re-measured to ensure that the assembly error is within a controllable range.

[0016] The present invention provides a construction method for a basket-type steel structure between buildings. Further, in step 5: after the truss units are assembled and before they are hoisted, a measurement control point is set at the end of each module truss, and the three-dimensional design value of the point is calculated, and a reflective sheet is pasted on the interface of the control point as an installation space position control point. When measuring, aim at the identification point at the end of the rod and read the value. After comparing with the design control value, the correction direction is determined and the hoisting personnel are instructed to make corrections.

[0017] The invention provides a construction method for a flower basket type steel structure between buildings. Further, in step 5: a segmented closing measure is firstly performed, wherein a clamping plate is welded and fixed at the closing mouth, and then the closing mouth is welded to the main weld, and the clamping plate is cut off after welding.

[0018] The invention provides a construction method for a basket-like steel structure between buildings. Further, the closing welding sequence is symmetrically performed from the middle to both ends, and except for one end of the closing interface which is reserved for non-welding, other interface parts are welded in sequence.

[0019] The present invention provides a construction method for a flower basket type steel structure between buildings. Further, in step 5: when each module truss is hoisted, two steel wire ropes are used for hoisting, and are connected to the left and right sides of the module truss; two hand winches are used as angle adjustment measures, and are connected to the upper and lower sides of the module truss; two sliding ropes are used to control the aerial posture of the module truss, one is connected to the upper left part of the module truss, and the other is connected to the lower right part of the module truss.

[0020] The invention provides a construction method for a flower basket type steel structure between buildings. Further, the welding points between the column tooling and the truss unit at the top of the tire cap are cut off by flame, and the contact surface between the component and the column tooling is leveled. When the flame cuts the length of the column tooling, each 10mm height is taken as a line, and the width of each cutting seam is 2mm. The steel structure is slowly lowered onto the column tooling, and the first step of unloading is completed; the above steps are repeated until the steel structure is completely separated from the supporting tire frame, and the unloading is finally completed.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Due to the diverse shapes and numerous types of the members of the basket-type steel structure, it is difficult to position and assemble them on-site, with high requirements for positioning accuracy. The installation accuracy cannot be guaranteed. In this application, the basket-type steel structure is divided into four truss units, and a relative coordinate system and ground positioning coordinates are established on the ground for the truss units, which is convenient for controlling the coordinates of the butt joints and intersecting joints of each member and ensuring the installation accuracy. At the same time, each truss unit is divided into upper and lower parts. The lower module truss is hoisted integrally with the single-pipe support. On the one hand, the cooperation between the single-pipe support and the lower module truss facilitates the positioning of the lower module truss. On the other hand, the verticality of the module truss can be controlled through the single-pipe support, ensuring the installation accuracy of the module truss and solving the problem that the installation accuracy of the arc truss cannot be guaranteed.

[0023] 2. The upper module truss is hoisted in sections. On the one hand, due to the large span and heavy weight of the upper module truss, hoisting in sections can reduce the requirement for the lifting weight. On the other hand, it reduces the requirement for the size of the site.

[0024] 3. The truss hoisting is coordinated with steel wire ropes, chain hoists and guy ropes, which is convenient for adjusting the aerial attitude and installation position of the truss and can ensure the installation accuracy of the truss.

[0025] 4. The closing welding sequence is carried out symmetrically from the middle to both ends, so that the symmetry of the structure is maintained during the closing process. Except for one end of the closing butt joint that is reserved without welding, other joint parts are welded in time to enhance the overall stability of the structure, control welding deformation, eliminate residual stress, prevent lamellar tearing and welding defects.

[0026] 5. This application changes the existing form of the passage structure and creatively uses the basket-type steel structure as the support structure of the passage, giving a shape to the passage between two buildings, making the passage structure coordinated with the surrounding building shapes, increasing the design effect of the structure and meeting the needs of special scenarios.

[0027] 6. By gradually extending the meridional members outward from bottom to top, a basket structure with a smaller bottom and a larger top is formed, thereby reducing the occupation of the bottom space and increasing the coverage area of the top space to meet the needs of the ceiling. And the support structure of the basket steel structure is concentrated in the central area of a small range in the middle, with the surrounding area used as a pedestrian passage, making the site more spacious and more conducive to personnel flow.

[0028] The present invention will be further described below with reference to the accompanying drawings. Description of the Drawings

[0029] Figure 1 is the installation structure schematic diagram of the present invention;

[0030] Figure 2 is the ground assembly schematic diagram of the truss unit of the present invention;

[0031] Figure 3 Schematic diagram of hoisting the modular truss of the present invention;

[0032] Figure 4 Schematic diagram of the installation structure of the lower modular truss of the present invention;

[0033] Figure 5 Schematic diagram of the completion of the installation of a single truss unit of the present invention;

[0034] Figure 6 Schematic diagram of the completion of the installation of two truss units of the present invention;

[0035] Figure 7 Schematic diagram of the completion of the installation of three truss units of the present invention;

[0036] Figure 8 Schematic diagram of the completion of the installation of the basket-type steel structure of the present invention;

[0037] Figure 9 Schematic diagram of the unloading node of the present invention;

[0038] Figure 10 Schematic diagram of the completed structure after unloading of the present invention.

[0039] Reference numerals:

[0040] 1, building structure; 2, meridional member; 3, zonal member; 4, web member; 5, support member; 6, corbel; 7, steel frame structure; 8, truss unit; 9, modular truss; 10, single-pipe support; 11, support falsework; 12, steel wire rope; 13, chain block; 14, guy rope; 15, column tooling. Detailed implementation manners

[0041] As Figure 1-10 shown, the present invention discloses a construction method for a basket-type steel structure between buildings. The basket-type steel structure is connected between two building structures to form a passage. It includes meridional members, zonal members and web members. Four meridional members are provided, which are respectively arranged at the four corner positions, and the meridional members are gradually curved outward from bottom to top. The zonal members are connected between adjacent meridional members and are arranged in multiple rows at intervals along the length direction of the meridional members. Multiple web members are provided and are connected between adjacent zonal members, and the web members and the zonal members form multiple triangular frame structures to form a truss structure to ensure the stability of the steel structure. By gradually extending the meridional members outward from bottom to top, a basket structure with a smaller bottom and a larger top is formed, thereby reducing the occupation of the bottom space and increasing the coverage area of the top space to meet the needs of the ceiling; and the support structure of the basket steel structure is concentrated in the central area of a small range in the middle, and the surrounding area is used as a pedestrian passage, making the site more spacious and more conducive to personnel flow.

[0042] Among them, through holes are provided at the joints of the weft rods and the web members, and the weft rods and the web members are intersecting welded at the through holes.

[0043] The weft rod located at the bottommost layer is connected with a support rod member. The lower end of the support rod member is fixedly connected to the foundation, and the lower end of the warp rod is fixedly connected to the foundation, thereby playing a role in supporting the entire flower basket steel structure.

[0044] The support rod members close to the warp rod are inclined towards the warp rod and are connected to the foundation together with the warp rod. Specifically, an anchor plate is fixedly provided on the foundation, and a three-pronged plate is vertically welded on the anchor plate. The warp rod and the support rod members are respectively located in the three regions of the three-pronged plate and are welded and fixed to the three-pronged plate and the anchor plate.

[0045] The support rod members located in the middle are connected in pairs. An anchor plate is fixedly provided on the foundation, and a vertical plate is welded on the anchor plate. The two support rod members are respectively located on both sides of the vertical plate and are welded and fixed to the vertical plate and the anchor plate.

[0046] Brackets are fixedly provided at intervals on the weft rod located at the uppermost part, and a steel frame structure is installed on the building structure, and the steel frame structure is connected and fixed to the brackets.

[0047] The construction method includes the following steps:

[0048] Step 1: Position and install the steel frame structure on the building structure.

[0049] Step 2: Divide the flower basket type steel structure into four truss units according to its four faces. Each truss unit is divided into upper and lower module trusses. The lower module truss is hoisted as a whole, and the upper module truss is hoisted in sections and welded at high altitude.

[0050] Step 3: Conduct ground concrete hardening treatment and position and install embedded parts to ensure the assembly accuracy of components, prevent assembly errors caused by uneven settlement of the jig during the assembly process of components. The assembly site is required to be flat, and at the same time, to ensure the stability of the assembly jig.

[0051] Step 4: Conduct overall ground assembly. Since the segmented trusses have different shapes, it is difficult to position during on-site assembly and the positioning accuracy requirements are high. Establishing an assembly coordinate system is particularly important for the assembly accuracy. Re-establish a relative coordinate system within the assembly site to control the relative positions of each rod during the assembly of the flower basket type steel structure.

[0052] Use Tekla software to convert the 3D model of the truss unit into a plane line model. Then use CAD software to set the coordinates of one end of the center line of the latitudinal member at the end of the truss unit to the origin coordinates (0,0,0). At the same time, correspond the X-axis or Y-axis in the spatial coordinate system to the center line of this latitudinal member. At this point, the spatial coordinate system of the truss unit is established. Subsequently, the coordinates of the docking and intersecting nodes of each member are extracted. During on-site layout, the above coordinates are used as the basis for positioning each member when assembling the truss.

[0053] Layout, set up the total station at the assembly site, determine the (0,0,0) point, use the total station to lay out the coordinates (x1,y1,z1) and (x2,y2,z2) of the docking and intersection nodes of each member, and map the above coordinates to the ground as positioning coordinates, locate the installation position of the tire frame, and place the tire frame at the positioning position. The members are assembled on the ground according to the elevation value calibrated on the tire frame and the assembly line model. After the members are installed on the tire, the members are adjusted to the predetermined position by the plumb bob and the positioning coordinates on the ground. During the assembly process, each member needs to be measured and positioned. After the assembly is completed, the truss unit is re-measured to ensure that the assembly error is within a controllable range.

[0054] Step 5: The truss units are hoisted in blocks. The truss units on the side connected to the building structure are installed first, and then the truss units on the other two sides are installed. When hoisting each truss unit, the lower module truss is hoisted as a whole first, and then the supporting rods and embedded parts are welded and fixed. Finally, the upper module truss is hoisted in sections, followed by welding between rods and welding of the corbels to the steel frame structure.

[0055] Specifically, after the truss unit is assembled and before hoisting, a measurement control point is set at the end of each module truss, and the three-dimensional design value of this point is calculated. A reflective sheet is pasted on the interface of the control point as the installation space position control point. When measuring, aim at the identification point at the end of the rod and read the value. After comparing with the design control value, determine the correction direction and direct the hoisting personnel to make corrections.

[0056] The segmented closing measures, in order to avoid tensile damage due to temperature changes during the welding process of the closing joint butt weld, first weld and fix the clamping plate of the closing joint, then weld the closing joint butt main weld, and cut off the clamping plate after welding. The closing welding sequence is carried out symmetrically from the middle to both ends to keep the structural symmetry during the closing process. Except for one end of the closing joint that is reserved for welding, other joint parts are welded in time to enhance the overall stability of the structure.

[0057] When hoisting each module truss, two steel wire ropes are used for hoisting and are connected to the left and right sides of the module truss; two manual hoists are used as measures to adjust the angle and are connected to the upper and lower sides of the module truss; two guy ropes are used to control the attitude of the module truss in the air, one is connected to the upper left part of the module truss and the other is connected to the lower right part of the module truss. The theoretical height difference between the upper and lower openings of the module truss is measured through the original model. After the module truss is hoisted, the attitude of the module truss in the air and the height of the upper and lower openings are adjusted through the manual hoist to match the theoretical data.

[0058] For the elevation control of the truss unit, since the truss unit is arc-shaped, the elevations of various points on the truss unit also change relatively. Therefore, it is crucial to correctly control its elevation. According to the truss segmentation, the closest intersection node to the segmentation point is selected as the elevation control point. The backsight elevation is successively measured to a certain point on the support falsework through a level, and marks are made to serve as the backsight basis. According to the measured backsight points of each elevation, the actual elevations of the corresponding control node marking points on the truss are respectively measured, and then compared with the designed elevations of the corresponding control nodes to obtain the height difference, which is used as the basis for the elevation of segmented assembly.

[0059] In addition, the temporary supports include single-pipe supports and support falseworks. The single-pipe supports and the lower module truss are taken as a whole and hoisted together. After the structure is in place, the tension connections are gradually relaxed and positioned on the ground, and the verticality is measured.

[0060] The support falsework is fabricated on-site, hoisted and installed as a whole, and installed on the non-building structure side to support the upper module truss. The total station coordinate method is used for measurement and spatial positioning installation.

[0061] Step 6: Unloading of the support falsework. During the unloading process, the internal forces of the members of the basket-type steel structure itself and the forces on the temporary supports will both change. Different unloading steps will have a greater impact on the structure itself and the support falsework. Therefore, during unloading, a method of graded and synchronous unloading is adopted. During construction, column toolings are set on the support falsework at the unloading points, and graded unloading is achieved by gradually shortening the column toolings step by step. Before unloading, according to the theoretical unloading amount of each support point, scale marks are made on the column toolings to control the cutting amount of unloading.

[0062] Specifically, the welding points between the column tooling at the top of the tire cap and the truss unit are removed by flame cutting, and the contact surface between the component and the column tooling is leveled to reduce the horizontal resistance of the column tooling to the component of the truss unit during unloading, and at the same time avoid applying horizontal thrust on the support falsework during the unloading process.

[0063] When flame cutting the length of the column tooling, one cut is made every 10 mm in height, and the width of each cutting seam is 2 mm, so that the steel structure slowly descends onto the column tooling, and the first step of unloading is completed.

[0064] After the first step of synchronous unloading construction of the steel structure is completed, the second flame cutting is carried out, and the above steps are repeated in a cycle until the steel structure is completely separated from the supporting falsework, and the unloading is finally completed. Then, the single-pipe support is removed.

[0065] The embodiments described above are only used to describe the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A construction method for a flower basket type steel structure between buildings, characterized in that: The basket-like steel structure is used to connect two buildings, and includes warp rods, weft rods and web rods; four warp rods are provided, which are respectively provided at four corners, and the warp rods are gradually arranged in an arc shape from bottom to top toward the outside; the weft rods are connected between adjacent warp rods, and are spaced in multiple rows along the length direction of the warp rods; multiple web rods are provided, connected between adjacent weft rods, and the web rods and weft rods form multiple triangular frame structures; the lower part of the weft rods located at the lowest layer is connected to support rods; the construction method includes the following steps: Step 1: Positioning and installing the steel frame structure on the building structure; Step 2: Divide the basket-like steel structure into four truss units according to its four faces. Each truss unit is divided into two upper and lower module trusses. The lower module truss is hoisted as a whole, and the upper module truss is hoisted in sections and welded at high altitude. Step 3: Harden the ground and locate and install embedded parts; Step 4: Assemble the truss units on the ground and weld and fix the single tube support to the lower module truss; Step 5: First install the truss unit on the side connected to the building structure, and then install the truss units on the other two sides. When hoisting each truss unit, first hoist the lower module truss as a whole. After the lower module truss is in place, gradually relax the pulling connection of the module truss and the ground position. The single tube support remains in a vertical state and supported on the ground, and the lower module truss is welded and fixed to the embedded parts; then the support frame is positioned and installed, and the upper module truss is hoisted in sections, followed by welding between rods and welding of the brackets and the steel frame structure; Step 6: Unload the supporting tire frame in stages and then remove the single tube support.

2. The construction method of a building basket-type steel structure according to claim 1, characterized in that: In step 4: the ground assembly coordinate system is established, and the three-dimensional model diagram of the truss unit is converted into a plane line model diagram using Tekla software. Then, the coordinates of one end of the center line of the latitudinal member at the end of the truss unit are set as the origin coordinates (0,0,0) through CAD software. At the same time, the X-axis or Y-axis in the space coordinate system is corresponded to the center line of this latitudinal member. Subsequently, the coordinates of the docking and intersecting nodes of each member are extracted. During on-site layout, the above coordinates are used as the basis for positioning each member during truss assembly.

3. The construction method of a building basket-type steel structure according to claim 2 is characterized in that: Layout, set up the total station at the assembly site, determine the (0,0,0) point, use the total station to lay out the coordinates (x1,y1,z1) and (x2,y2,z2) of the docking and intersection nodes of each member, and map the above coordinates to the ground as positioning coordinates, locate the installation position of the tire frame, and place the tire frame at the positioning position. The members are assembled on the ground according to the elevation value calibrated on the tire frame and the assembly line model. After the members are installed on the tire, the members are adjusted to the predetermined position by the plumb bob and the positioning coordinates on the ground. During the assembly process, each member needs to be measured and positioned. After the assembly is completed, the truss unit is re-measured to ensure that the assembly error is within a controllable range.

4. The construction method of a building basket-type steel structure according to claim 1, characterized in that: In step 5: After the truss units are assembled and before they are hoisted, set a measurement control point at the end of each module truss and calculate the three-dimensional design value of this point. Paste a reflective sheet at the interface of the control point as the installation space position control point. When measuring, aim at the identification point at the end of the rod and read the value. After comparing it with the design control value, determine the correction direction and instruct the hoisting personnel to make corrections.

5. The construction method of a building basket-type steel structure according to claim 1 is characterized in that: In step 5: the segmented closing measures are firstly to fix the closing mouth with a clamping plate, and then to weld the closing mouth to the main weld, and after welding is completed, the clamping plate is cut off.

6. The construction method of a building basket-type steel structure according to claim 5, characterized in that: The closing welding sequence is carried out symmetrically from the middle to both ends. Except for one end of the closing interface which is reserved for welding, the other interface parts are welded in sequence.

7. The construction method of a building basket-type steel structure according to claim 1, characterized in that: In step 5: when hoisting each module truss, two steel wire ropes are used for hoisting, connected to the left and right sides of the module truss; two hand winches are used as angle adjustment measures, connected to the upper and lower sides of the module truss; two sliding ropes are used to control the aerial posture of the module truss, one is connected to the upper left part of the module truss, and the other is connected to the lower right part of the module truss.

8. The construction method of a building basket-type steel structure according to claim 1, characterized in that: Use flame to cut off the welding points between the column fixture and the truss unit at the top of the tire cap, and level the contact surface between the component and the column fixture. When flame cutting the length of the column fixture, take every 10mm height as a line, and the width of each cutting seam is 2mm. Slowly lower the steel structure onto the column fixture, and the first step of unloading is completed; repeat the above steps until the steel structure is completely separated from the supporting tire frame, and the unloading is finally completed.

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