Construction method of multi-layer large-span less-support steel truss

Abstract

The invention relates to the technical field of building construction, and discloses a multi-layer large-span less-support steel truss construction method which comprises the following steps: step 1, carrying out stress analysis on an orthogonal steel truss by utilizing MIDAS software, and carrying out visual lofting by utilizing BIM software; secondly, a first-layer standard jig frame is manufactured, and a locking assembly used for locking a nut is installed at the joint of the first-layer standard jig frame and the second-layer standard jig frame; thirdly, the truck crane is adopted for carrying out high-altitude bulk packing on the main trusses; fourthly, an assembling platform is arranged on the ground for the secondary trusses; 5, mounting a subsequent orthogonal truss; and sixthly, the temporary supports and the first-layer standard jig frame are dismantled. In the construction preparation and implementation stage, the MIDAS software is combined with multiple parameters such as the construction rhythm and the hoisting condition to carry out accurate stress analysis on the orthogonal steel truss, the primary truss and the secondary truss are scientifically and reasonably segmented, the arching value is calculated, the number of supports and the number of welding times are effectively reduced, the construction precision is improved, and the use amount of turnover materials is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of building construction, and specifically relates to a construction method for a multi-story large-span steel truss with few supports. Background Art

[0002] In the field of building engineering, multi-story large-span steel truss structures are widely used in buildings such as large stadiums and commercial complexes due to their good mechanical properties and spatial performance. However, there are many problems in the existing construction methods for multi-story large-span steel trusses.

[0003] In terms of truss segmentation and camber value calculation, traditional construction methods often cannot accurately analyze actual construction parameters such as construction rhythm and hoisting conditions, resulting in unreasonable segmentation of primary and secondary trusses, excessive support numbers, and frequent welding times; this not only increases construction costs but also makes it difficult to ensure construction accuracy. In terms of construction mode, for the construction of multi-story large-span steel trusses, some projects fail to make full use of site conditions for scientific planning, lack effective visual guidance, use a large number of support falsework, have difficulty controlling welding accuracy, and have slow construction progress, unable to meet the requirements of modern building engineering for high-efficiency construction. In terms of structural stability and safety, the nuts of the support system in the existing steel truss construction are prone to loosen due to factors such as vibration during construction, resulting in a decrease in the stability of the support system and potential safety hazards.

[0004] In summary, the existing construction methods for multi-story large-span steel trusses have obvious defects in construction efficiency, cost control, construction accuracy, and structural stability and safety. Therefore, a new construction method is needed to solve these problems.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] To solve the above technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0007] A construction method for a multi-story large-span steel truss with few supports, comprising the following method steps:

[0008] Step 1: Use MIDAS software to perform a force analysis on the orthogonal steel truss, segment the primary and secondary trusses and calculate the camber value, and use BIM software for visual lofting;

[0009] Step 2: Fabricate the first-floor standard falsework, and connect the support rods to the first-floor standard falsework through high-strength bolts, and install a locking component for locking the nuts at the connection between the two;

[0010] Step 3: Use a truck crane to perform aerial bulk installation of the main truss, and connect the main truss to the support rods through secondary trusses;

[0011] Step 4: For the secondary trusses, first set up an assembly platform on the ground, assemble them using a truck crane, then hoist them as a whole. Butt welds are used for each part, and weld flaw detection is carried out.

[0012] Step 5: After the construction of the main cross trusses on the current layer is completed, use the already installed support rods as simple temporary supports for the installation layer, and then install the subsequent orthogonal trusses.

[0013] Step 6: Remove the temporary supports and the standard formwork of the first layer.

[0014] As a preferred embodiment of the present invention, when using MIDAS software to perform a stress analysis on the orthogonal steel trusses, considering the construction rhythm, hoisting conditions, vehicle load capacity, on-site plane layout, ground load, and hoisting equipment parameters, the main and secondary trusses are reasonably segmented.

[0015] As a preferred embodiment of the present invention, in Step 1, it also includes using MIDAS finite element software to model, checking the forces during the installation process of the temporary supports and the steel trusses, ensuring that the design and layout of the temporary support system meet the requirements, designing the camber value according to the on-site construction segmentation and support positions, pre-assembling the steel trusses in the factory after they are fabricated, and making the camber according to the design requirements.

[0016] As a preferred embodiment of the present invention, when using a truck crane to perform aerial bulk installation of the main trusses, the construction follows the principle of "first columns then beams, from bottom to top". After the components are hoisted in place, they are temporarily fixed using connecting plates and guy ropes, and CO2 gas shielded welding is used for welding.

[0017] As a preferred embodiment of the present invention, when removing the temporary supports and the standard formwork of the first layer, following the principle of removing the whole layer and from top to bottom, first remove the temporary supports, and finally remove the standard formwork of the first layer. Select flame cutting to cut the "shims" at the top of the support formwork to ensure there is a slight gap between the formwork and the main structure, thereby determining that the formwork is not under support force. Use a crane to hook the support frame and tighten the steel wire rope, cut the welds at the bottom of the support frame, and strictly control the movement of the support frame during the disassembly process to prevent the support frame from colliding with the non-unloaded support frames.

[0018] As a preferred embodiment of the present invention, the standard formwork of the first layer is composed of four vertical pipes. There are top seats installed at the tops of the four vertical pipes, strengthening frames are installed between adjacent vertical pipes, there are bases installed at the bottoms of the four vertical pipes, the bases are in the shape of a convex platform, there are four bolts installed on the tops of the top seats, and the bolts are used to connect the support rods, and matching nuts are screwed on the bolts.

[0019] As a preferred embodiment of the present invention, a base plate is installed at the bottom of the support rod. A positioning hole is provided on the base plate, and the positioning hole is adapted to a bolt. A cross is installed inside the base plate. The center position of the cross is connected to the support rod, and a reinforcing rib is installed between the side wall of the support rod and the cross, and the reinforcing rib is triangular.

[0020] As a preferred embodiment of the present invention, corresponding I-beams are installed on the outer side wall of the main truss, and mounting holes are provided on the I-beams, and the mounting holes are used to connect the main truss.

[0021] As a preferred embodiment of the present invention, the secondary truss includes two pairs of sleeves. The two pairs of sleeves are respectively placed on both sides of the main truss, and the sleeves are slidably arranged on the support rod, and the two are connected by screwing with bolts. A mounting plate is installed on the side wall of the sleeve, and the mounting plate is connected to the main truss, and a rib plate is installed between the side wall of the mounting plate and the sleeve.

[0022] As a preferred embodiment of the present invention, the locking assembly includes a pressing plate. A through groove is provided on the pressing plate, and the through groove penetrates the bolt, and the pressing plate covers the nut. A vertical plate is installed at the end of the pressing plate, and a synchronous shaft is installed at the rotation center of the vertical plate. The synchronous shaft is rotatably connected to a guide seat installed at the top of the first-layer standard tire rack, and a torsion spring is clamped between the vertical plate and the guide seat. A positioning sleeve is installed on the side wall of the first-layer standard tire rack. A baffle is slidably arranged inside the positioning sleeve. A return spring is installed between the baffle and the side wall of the positioning sleeve. A positioning plate is installed at the top of the baffle. A push plate is installed on the side wall of the positioning plate. A top plate is obliquely installed at the rotation center of the vertical plate, and the top plate is attached to the positioning plate.

[0023] The present invention has the following beneficial effects compared with the prior art:

[0024] In the construction preparation and implementation stages of the present invention, the orthogonal steel truss is precisely analyzed for its stress by using the MIDAS software in combination with various parameters such as the construction rhythm and hoisting conditions. The main and secondary trusses are scientifically and reasonably segmented and the camber values are calculated, effectively reducing the number of supports and the number of welding operations. This not only improves the construction accuracy but also reduces the usage amount of turnover materials. At the same time, in combination with the site conditions, BIM visual lofting is carried out. For the construction of multi-layer large-span steel trusses, the innovative mode of high-altitude bulk laying of the main trusses and integral hoisting of the secondary trusses is adopted, greatly reducing the input of construction machinery and the usage amount of support falsework, significantly improving the welding accuracy, and accelerating the construction progress. In addition, the unique structural design of the first-floor standard falsework, combined with the support rods connected by high-strength bolts and the anti-loosening limit of the lock nut by the locking assembly, ensures the stability of the support system during the construction process. The locking assembly, through its ingenious mechanical structure, can still effectively prevent the nut from loosening under complex working conditions such as vibration, ensuring reliable connection, greatly improving the construction safety, reducing the risk of safety accidents, and realizing the multiple optimizations of construction efficiency, quality, cost, and safety.

[0025] The following further describes in detail the specific implementation manners of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the drawings:

[0027] Figure 1 is the three-dimensional construction structure schematic diagram of the present invention;

[0028] Figure 2 is of the present invention Figure 1 plan view;

[0029] Figure 3 is the partial structure schematic diagram of the present invention;

[0030] Figure 4 is of the present invention Figure 3 partial Figure 1 ;

[0031] Figure 5 is of the present invention Figure 3 partial Figure 2 ;

[0032] Figure 6 is of the present invention Figure 5 enlarged view at A in;

[0033] Figure 7 is the sectional view at the locking assembly of the present invention;

[0034] Figure 8 is of the present invention Figure 3 partial Figure 3 ;

[0035] In the figures:

[0036] 1. First - floor standard formwork; 11. Vertical pipe; 111. Reinforcing frame; 12. Base; 13. Top seat; 131. Bolt; 132. Nut;

[0037] 2. Support rod; 21. Base plate; 211. Cross - shaped frame; 212. Reinforcing rib; 213. Positioning hole;

[0038] 3. Main truss; 31. I - beam; 311. Installation hole;

[0039] 4. Secondary truss; 41. Sleeve; 42. Installation plate; 421. Rib plate;

[0040] 5. Locking assembly; 51. Pressing plate; 511. Through - slot; 52. Vertical plate; 521. Synchronous shaft; 522. Guide seat; 523. Torsion spring; 53. Positioning sleeve; 531. Positioning plate; 532. Baffle; 533. Return spring; 534. Pushing plate; 54. Top plate. Detailed implementation mode

[0041] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments in conjunction with the accompanying drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention.

[0042] Embodiment 1:

[0043] As Figures 1 to 8 shown, a construction method for a multi - layer large - span and less - supported steel truss includes the following method steps:

[0044] Step 1: Use MIDAS software to conduct a stress analysis on the orthogonal steel truss, segment the main and secondary trusses and calculate the camber value, and use BIM software for visual lofting; through the accurate analysis of MIDAS software in this step, it can scientifically segment and calculate the camber value in combination with actual construction parameters, reduce the number of supports and welding times, and improve construction accuracy; with the help of visual lofting of BIM software, the construction process can be simulated in advance, the construction process can be optimized, construction errors can be avoided, thereby improving construction efficiency and reducing construction costs.

[0045] Step 2: Fabricate the first - floor standard formwork 1, and connect the support rod 2 to the first - floor standard formwork 1 through high - strength bolts 131, and install a locking assembly 5 for locking the nut 132 at the connection between the two; the setting of the first - floor standard formwork 1 and the locking assembly 5 ensures the stability of the support system. The locking assembly 5 effectively prevents the nut 132 from loosening, ensures reliable connection, improves construction safety, and avoids safety accidents caused by unstable support systems.

[0046] Step 3: Use a truck crane to perform aerial bulk assembly of the main truss 3. The main truss 3 is interconnected with the secondary truss 4 and the support rod 2. This method realizes the coordinated force-bearing among the main truss, the secondary truss, and the support rod, effectively disperses the load, reduces the dependence on a large number of supports, not only reduces the usage amount of the support falsework, but also ensures the stability of the truss structure during the construction process.

[0047] Step 4: First, set up an assembly platform on the ground for the secondary truss 4, use a truck crane for assembly, and then perform integral hoisting. Each part is welded with butt welds and the welds are inspected for flaws. The ground assembly ensures the assembly accuracy of the secondary truss, and the integral hoisting reduces the amount of aerial work and improves the construction safety. The weld flaw detection ensures the structural strength and quality of the secondary truss, providing guarantee for the stability of the entire steel truss structure.

[0048] Step 5: After the construction of the current-layer main cross truss is completed, use the already installed support rod 2 as a simple temporary support for the installation layer, and then install the subsequent orthogonal trusses. Using the already installed support rod 2 as a temporary support, there is no need to additionally set up a complex support structure, effectively reducing the construction material and time costs. At the same time, it ensures the stability of the upper-layer truss construction and speeds up the construction progress.

[0049] Step 6: Remove the temporary support and the first-layer standard falsework 1. The reasonable removal steps and methods ensure the safety and orderliness of the removal process, avoid damaging the already completed truss structure, reduce the material loss and labor costs during the removal process, and improve the overall economic benefits of the construction.

[0050] As Figures 1 to 8 shown, in the specific implementation, when using MIDAS software to perform a force analysis on the orthogonal steel truss, considering the construction rhythm, hoisting conditions, vehicle load-bearing, on-site plane layout, ground load, and hoisting equipment parameters, the main and secondary trusses are reasonably segmented. Segmenting by fully considering various construction parameters makes the truss segmentation more in line with the actual construction requirements, further optimizing the construction plan and improving the feasibility and efficiency of the construction.

[0051] As Figures 1 to 8 shown, further, in Step 1, it also includes using MIDAS finite element software to model, checking the forces during the installation process of the temporary support and the steel truss to ensure that the design and layout of the temporary support system meet the requirements, designing the camber value according to the on-site construction segmentation and the support position, performing pre-assembly in the factory after the steel truss is fabricated, and making the camber according to the design requirements. Through finite element software modeling and checking and factory pre-assembly, potential problems are discovered and solved in advance, ensuring the reliability of the temporary support system and the steel truss structure, ensuring the smooth progress of the construction process, and improving the construction quality.

[0052] Example 2:

[0053] The difference between this embodiment and Embodiment 1 is as follows: As Figures 1 to 8 shown, when using a truck crane to assemble the main truss 3 in the air, the construction follows the principle of "columns first, beams later, from bottom to top". After the components are hoisted in place, they are temporarily fixed with connecting plates and guy ropes, and CO2 shielded welding is used for welding. Following specific construction principles and using appropriate welding methods ensure the stability of the main truss installation and the welding quality, improve the construction safety and reliability, and ensure that the main truss can be firmly installed in the designed position.

[0054] As Figures 1 to 8 shown, in the specific implementation, when demolishing the temporary support and the first-floor standard falsework 1, following the principle of demolishing the whole floor and from top to bottom, first demolish the temporary support, and finally demolish the first-floor standard falsework 1. Select flame cutting to cut the "wedge" at the top of the support falsework to ensure there is a slight gap between the falsework and the main structure, thereby determining that the falsework is not under support force. Use a crane to hook the support frame and tighten the steel wire rope, cut the weld at the bottom of the support frame, and strictly control the movement of the support frame during the disassembly process to prevent the support frame from colliding with the unloaded support frame. This demolition method and operation method ensure the safety of the demolition process, avoid damaging the completed structure, and reduce the demolition risk and cost.

[0055] Embodiment 3:

[0056] The difference between this embodiment and Embodiment 2 is as follows: As Figures 1 to 8 shown, the first-floor standard falsework 1 is composed of four vertical pipes 11. There are top seats 13 installed at the tops of the four vertical pipes 11, strengthening frames 111 are installed between adjacent vertical pipes 11, and there are bases 12 installed at the bottoms of the four vertical pipes 11. The base 12 is in a convex shape. There are four bolts 131 installed on the top of the top seat 13, and the bolts 131 are used to connect the support rods 2, and there are matching nuts 132 screwed on the bolts 131. This structural design of the first-floor standard falsework 1 enhances the overall strength and stability of the falsework, can better bear the loads during the construction process, and provides a reliable support foundation for the steel truss construction.

[0057] As Figures 1 to 8 shown, in the specific implementation, there is a base plate 21 installed at the bottom of the support rod 2. There are positioning holes 213 opened on the base plate 21, and the positioning holes 213 are adapted to the bolts 131. There is a cross 211 installed inside the base plate 21. The center position of the cross 211 is connected to the support rod 2, and there are strengthening ribs 212 installed between the side wall of the support rod 2 and the cross 211, and the strengthening ribs 212 are triangular. The structural design of the support rod 2 improves its own structural strength and stability, makes its connection with the first-floor standard falsework 1 more firm, and ensures that it can effectively transfer and bear the loads during the construction process.

[0058] As Figures 1 to 8As shown in the figure, further, the outer side wall of the main truss 3 is provided with a corresponding I-beam 31, and the I-beam 31 is provided with a mounting hole 311, and the mounting hole 311 is used to connect the main truss 3. The secondary truss 4 includes two pairs of sleeves 41, the two pairs of sleeves 41 are respectively arranged on both sides of the main truss 3, and the sleeves 41 are slidably arranged on the support rod 2, and the two are connected by screwing with bolts. An installation plate 42 is installed on the side wall of the sleeve 41, and the installation plate 42 is connected to the main truss 3, and a rib plate 421 is installed between the installation plate 42 and the side wall of the sleeve 41. These structural designs achieve stable connection and coordinated force-bearing among the main truss, the secondary truss and the support rod, effectively disperse the load, and ensure the overall stability and reliability of the steel truss structure.

[0059] As Figures 1 to 8 shown in the figure, further, the locking assembly includes a pressing plate 51. A through groove 511 is provided on the pressing plate 51, and the through groove 511 penetrates through the bolt 131, and the pressing plate 51 covers the nut 132. A vertical plate 52 is installed at the end of the pressing plate 51, and a synchronous shaft 521 is installed at the rotation center of the vertical plate 52. The synchronous shaft 521 is rotatably connected to a guide seat 522 installed at the top of the first-layer standard tire rack 1. A torsion spring 523 is clamped between the vertical plate 52 and the guide seat 522. A positioning sleeve 53 is installed on the side wall of the first-layer standard tire rack 1. A baffle 532 is slidably arranged inside the positioning sleeve 53. A return spring 533 is installed between the baffle 532 and the side wall of the positioning sleeve 53. A positioning plate 531 is installed at the top of the baffle 532. A push plate 534 is installed on the side wall of the positioning plate 531. A top plate 54 is inclinedly installed at the rotation center of the vertical plate 52, and the top plate 54 is attached to the positioning plate 531. During the construction process, even if there is an upward vibrating force generated by vibration, both the pressing plate 51 and the positioning plate 531 will have an upward movement force due to vibration. Since the upward movement trends of the two are the same and the relative positions remain unchanged, the positioning plate 531 will not move downward, so that the top plate 54 always tightly abuts against the side wall of the positioning plate 531, continuously restricting the rotation of the vertical plate 52 and the pressing plate 51. In this way, the pressing plate 51 can continuously limit the nut 132, and rely on the friction force between the two and the component structure to prevent the nut 132 from loosening and ensure that the nut 132 cannot have an actual displacement.

[0060] The implementation principle of a construction method for a multi-layer large-span steel truss with few supports of the present invention is as follows:

[0061] In the construction preparation stage, the MIDAS software is used to conduct a stress analysis of the orthogonal steel truss. Considering various factors such as the construction rhythm, hoisting conditions, vehicle load-bearing capacity, on-site layout, ground load, and hoisting equipment parameters, the main and secondary trusses are reasonably segmented and the camber values are calculated. This is the foundation of the entire construction method. Through precise stress analysis, the segmented positions and camber values of the truss can be scientifically determined, ensuring the structural stability of the truss during construction and reducing unnecessary support settings. The BIM software is used for visual lofting to simulate the construction and installation process, enabling potential problems to be discovered in advance, optimizing the construction process, and ensuring the smooth progress of the actual construction.

[0062] Entering the installation stage of the first-floor standard falsework and supports, the first-floor standard falsework 1 is fabricated. Its unique structural design ensures good load-bearing performance. Four vertical pipes 11 are combined to form the main framework. The top seat 13 and the bottom base 12 enhance the overall stability. The stiffening frames 111 between adjacent vertical pipes 11 further improve the strength of the falsework. The support rod 2 is connected to the first-floor standard falsework 1 through high-strength bolts 131. The positioning holes 213 on the base plate 21 are adapted to the bolts 131, making the connection precise and firm. At the same time, the cross 211 and the reinforcing ribs 212 inside the base plate 21 enhance the structural strength and stability of the support rod 2, ensuring that it can bear the loads during subsequent construction.

[0063] And the locking assembly 5 set at its connection effectively prevents the nut 132 from loosening through the coordinated action of components such as the pressure plate 51, vertical plate 52, synchronous shaft 521, guide seat 522, torsion spring 523, positioning sleeve 53, baffle 532, return spring 533, positioning plate 531, push plate 534, and top plate 54, ensuring the reliability of the connection and the stability and safety of the entire support system during construction. During the installation process, the support rod 2 is first connected to the first-floor standard falsework 1 through high-strength bolts 131. At this time, the bolts 131 pass through the positioning holes 213 on the base plate 21 and are matched with the corresponding threaded holes on the first-floor standard falsework 1 and the nuts 132 are tightened. The pressure plate 51 covers the upper surface of the nut 132, and the anti-loosening is achieved by relying on the structural limitation of the locking assembly between the two.

[0064] When the nut 132 loosens due to external forces, the nut 132 will have a tendency to rotate upward and move axially along the bolt 131, exerting an upward pushing force on the pressure plate 51. So as long as the pressure plate 51 does not move upward, the nut 132 will not loosen at this time. Therefore, the locking assembly and the pressure plate 51 are used for position limitation. Because the upward force on the pressure plate 51 will drive the vertical plate 52 to rotate, and the top plate 54 at the rotation center of the vertical plate 52 is squeezed and positioned by the positioning plate 531, the pressure plate 51 cannot rotate.

[0065] During the construction process, even if a vibration acting force that causes upward movement is generated due to vibration, both the pressure plate 51 and the positioning plate 531 will have an upward movement force due to the vibration. Since the upward movement trends of the two are the same and their relative positions remain unchanged, the positioning plate 531 will not move downward, causing the top plate 54 to always closely abut against the side wall of the positioning plate 531, continuously restricting the rotation of the vertical plate 52 and the pressure plate 51. In this way, the pressure plate 51 can continuously limit the nut 132. Relying on the friction force between the two and the component structure, the loosening of the nut 132 is prevented, ensuring that the nut 132 cannot have an actual displacement. Only when the restriction of the top plate 54 by the positioning plate 531 is manually released, for example, by moving the baffle 532 through a specific operation to drive the movement of the positioning plate 531 and release the extrusion on the top plate 54, can the pressure plate 51 rotate upward under the action of the torsion spring 523, and then the restriction on the nut 132 is released. This design enables the locking component to effectively prevent the nut from loosening in complex construction environments such as vibration, making the nut locking more sufficient, and greatly improving the reliability of the connection of the support system.

[0066] During the aerial bulk construction of the main truss, a truck crane is used to conduct the aerial bulk of the main truss 3, following the principle of "columns first, beams later, from bottom to top". After the components are hoisted in place, connecting plates and guy ropes are used for temporary fixation to provide stable conditions for the welding work. CO2 gas shielded welding is used for welding to ensure the welding quality and firmly install the main truss 3 at the designed position. The main truss 3 is interconnected with the secondary truss 4 and the support rod 2. The sleeve 41 of the secondary truss 4 is slidably arranged on the support rod 2 and is connected by screwing with bolts. The mounting plate 42 on the side wall of the sleeve 41 is interconnected with the main truss 3, and the rib plate 421 enhances the connection strength. This connection method realizes the coordinated force-bearing among the main truss, secondary truss, and support rod, effectively disperses the load, and reduces the dependence on a large number of supports.

[0067] During the construction of the secondary truss, a assembly platform is first set up on the ground, and a truck crane and a manual hoist are used for assembly to ensure the assembly accuracy. Then, it is hoisted as a whole, and butt welds are used for welding at each part, and weld flaw detection is carried out to ensure the structural strength and quality of the secondary truss. The method of hoisting as a whole improves the construction efficiency, and at the same time reduces the amount of aerial work and the use of support scaffolds.

[0068] During the subsequent truss installation process, after the current layer of the main cross truss construction is completed, the installed support rod 2 serves as a simple temporary support for the installation layer, providing a stable support point for the installation of the subsequent orthogonal truss. Due to the reliable connection between the support rod 2 and the first-layer standard scaffold 1 and its own structural strength, it can effectively bear the construction load of the upper-layer truss, enabling the construction to proceed smoothly upward without the need to additionally set up a large number of complex support structures, greatly improving the construction efficiency and reducing the construction cost.

[0069] After all the orthogonal trusses are installed and fixed and form a stable structure with the surrounding secondary beams, the demolition stage begins. In accordance with the principles of demolishing the whole floor and starting from the upper part and then moving downwards, first remove the temporary simple supports on the upper floor, then remove the temporary supports on the lower floor, and finally remove the standard falsework 1 on the first floor. Select flame cutting to cut the "wedge" at the top of the support falsework to ensure a slight gap between the support falsework and the main structure, so as to determine that the support falsework is not under support force, and thus the demolition operation can be carried out safely. Use a crane to hook the support frame and tighten the wire rope, cut the weld at the bottom of the support frame, and strictly control the movement of the support frame during the disassembly process to prevent the support frame from colliding with the unloaded support frame, ensuring that the demolition process is safe and orderly and avoiding damage to the completed truss structure.

[0070] Through the close cooperation of the above steps and the coordinated work of each component, this construction method realizes the efficient and safe construction of multi-layer large-span steel trusses with few supports. While ensuring the construction quality, it significantly reduces the usage amount of support falsework and construction costs, improves the construction efficiency, and has good economic and social benefits.

Claims

1. A construction method for a multi-layer large-span steel truss with few supports, characterized in that, It includes the following method steps: Step 1: Use MIDAS software to conduct a stress analysis on the orthogonal steel truss, segment the primary and secondary trusses and calculate the camber value, and use BIM software for visual lofting; Step 2: Fabricate the first-floor standard falsework (1), and connect the support rods (2) to the first-floor standard falsework (1) through high-strength bolts (131), and install a locking component (5) for locking the nuts (132) at the connection between the two; Step 3: Use a truck crane to perform aerial bulk installation of the main truss (3), and the main truss (3) is interconnected with the support rods (2) through secondary trusses (4); Step 4: First, set up an assembly platform on the ground for the secondary truss (4), use a truck crane for assembly, and then perform overall hoisting. Butt welds are used for welding at each part, and weld flaw detection is carried out; Step 5: After the construction of the main intersection truss of the current layer is completed, use the already installed support rods (2) as a simple temporary support for the installation layer, and then install the subsequent orthogonal trusses; Step 6: Remove the temporary support and the first-floor standard falsework (1).

2. The construction method of a multi-layer large-span steel truss with few supports according to claim 1, characterized in that, When using MIDAS software to conduct a stress analysis on the orthogonal steel truss, the primary and secondary trusses are reasonably segmented in combination with the construction rhythm, hoisting conditions, vehicle load-bearing, on-site plane layout, ground load, and hoisting equipment parameters.

3. A construction method for a multi-layer large-span steel truss with few supports according to claim 1, characterized in that, In Step 1, it also includes using MIDAS finite element software for modeling, checking the stress during the installation process of the temporary support and the steel truss, ensuring that the design and layout of the temporary support system meet the requirements, designing the camber value according to the on-site construction segmentation and support position, pre-assembling the steel truss in the factory after it is fabricated, and making the camber according to the design requirements.

4. A construction method for a multi-layer large-span steel truss with few supports according to claim 1, characterized in that, When using a truck crane to perform aerial bulk installation of the main truss (3), the construction follows the principle of "first columns and then beams, from bottom to top". After the components are hoisted in place, they are temporarily fixed using connecting plates and guy ropes, and CO2 gas shielded welding is used for welding.

5. A construction method for a multi-layer large-span steel truss with few supports according to claim 1, characterized in that, When removing the temporary support and the first-floor standard falsework (1), in accordance with the principle of removing the whole layer and from top to bottom, first remove the temporary support, and finally remove the first-floor standard falsework (1). Select flame cutting to cut the "wedge iron" at the top of the support falsework to ensure there is a slight gap between the falsework and the main structure, thereby determining that the falsework is not under support force. Use a crane to hook the support frame and tighten the steel wire rope, cut the weld at the bottom of the support frame, and strictly control the movement of the support frame during the disassembly process to prevent the support frame from colliding with the non-unloaded support frame.

6. A construction method for a multi-layer large-span steel truss with few supports according to claim 1, characterized in that, The first-floor standard falsework (1) is composed of four vertical pipes (11). A top seat (13) is installed at the top of the four vertical pipes (11). A strengthening frame (111) is installed between adjacent vertical pipes (11). A base (12) is installed at the bottom of the four vertical pipes (11). The base (12) is in the shape of a convex platform. Four bolts (131) are installed at the top of the top seat (13), and the bolts (131) are used to connect the support rods (2), and matching nuts (132) are screwed on the bolts (131).

7. A construction method for a multi-layer large-span steel truss with few supports according to claim 1, characterized in that, A base plate (21) is installed at the bottom of the support rod (2). A positioning hole (213) is formed in the base plate (21). The positioning hole (213) is adapted to a bolt (131). A cross (211) is installed inside the base plate (21). The center position of the cross (211) is connected to the support rod (2). A reinforcing rib (212) is installed between the side wall of the support rod (2) and the cross (211). The reinforcing rib (212) is triangular.

8. A construction method for a multi-layer large-span steel truss with few supports according to claim 1, characterized in that, Corresponding I-beams (31) are installed on the outer side wall of the main truss (3). An installation hole (311) is formed in the I-beam (31). The installation hole (311) is used to connect the main truss (3).

9. A construction method for a multi-layer large-span steel truss with few supports according to claim 1, characterized in that The secondary truss (4) includes two pairs of sleeves (41). The two pairs of sleeves (41) are respectively arranged on both sides of the main truss (3). The sleeves (41) are slidably arranged on the support rod (2). The two are connected by screwing with bolts. An installation plate (42) is installed on the side wall of the sleeve (41). The installation plate (42) is connected to the main truss (3). A rib plate (421) is installed between the side wall of the installation plate (42) and the sleeve (41).

10. A construction method for a multi-layer large-span steel truss with few supports according to claim 1, characterized in that, The locking assembly includes a pressure plate (51). A through groove (511) is formed in the pressure plate (51). The through groove (511) penetrates through the bolt (131). The pressure plate (51) covers the nut (132). A vertical plate (52) is installed at the end of the pressure plate (51). A synchronous shaft (521) is installed at the rotation center of the vertical plate (52). The synchronous shaft (521) is rotatably connected to a guide seat (522) installed at the top of the first-layer standard tire rack (1). A torsion spring (523) is clamped between the vertical plate (52) and the guide seat (522). A positioning sleeve (53) is installed on the side wall of the first-layer standard tire rack (1). A baffle (532) is slidably arranged inside the positioning sleeve (53). A return spring (533) is installed between the baffle (532) and the side wall of the positioning sleeve (53). A positioning plate (531) is installed at the top of the baffle (532). A push plate (534) is installed on the side wall of the positioning plate (531). A top plate (54) is obliquely installed at the rotation center of the vertical plate (52). The top plate (54) is attached to the positioning plate (531).

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