A method for installing a large flat plate of a roof suspended ceiling

Abstract

The present application relates to the technical field of building construction, and particularly relates to a roof suspended ceiling large flat plate installation method, comprising the following steps: S1, according to the plane size of a to-be-installed suspended ceiling and the layout position of a steel beam, the size and installation position of a suspended ceiling steel plate back stiffener and the block size and number of the suspended ceiling steel plate are determined; S2, the installation of a steel column, a main steel beam and a secondary steel beam is sequentially performed according to a construction sequence, and the stiffener is welded and fixed on the main and secondary steel beams, wherein the stiffener comprises a transverse stiffener and a longitudinal stiffener, and a layered welding process is adopted; after welding is completed, overall levelness re-measurement and correction are performed; S3, the pre-numbered suspended ceiling steel plate is hoisted to a corresponding installation position, and is temporarily fixed by adopting intermittent welding, with the welding seam depth controlled to be 1 / 3 of the thickness of the steel plate; S4, the suspended ceiling steel plate is welded and fixed from one side to the other side in a predetermined sequence, and the deformation in the welding process is controlled.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, specifically to a method for installing a large flat panel for roof ceiling. Background Technology

[0002] In contemporary large-span spatial structures such as public buildings, stadiums, transportation hubs, and industrial plants, roof ceiling systems not only serve important decorative and spatial enclosure functions but also often integrate various equipment pipelines for lighting, fire protection, heating, ventilation, air conditioning (HVAC), and audio systems. Therefore, the design and construction of ceiling systems must simultaneously meet multiple stringent requirements, including structural safety, installation precision, functional integration, and aesthetics. Especially for large-area flat steel plate ceilings exceeding 350 square meters, their immense weight, the extreme pursuit of installation flatness, and the complex internal pipeline distribution present unprecedented technical challenges to construction.

[0003] Currently, the construction of such large-span roof ceiling transfer layers typically relies on traditional steel structure welding methods or prefabricated connection technologies. Traditional welding methods involve welding numerous vertical poles, diagonal braces, and transfer grids onto the main steel beams of the roof to form a rigid transfer layer. While this method provides strong structural support, its drawbacks are significant: First, the on-site welding work is extensive, generating large amounts of smoke, arc light, and noise, placing high demands on the construction environment and safety; second, the dense welding inevitably generates enormous welding stress and thermal deformation within the steel structure, making it difficult to control the flatness of the transfer layer grid and even the final ceiling panel surface, often requiring substantial manpower and resources for correction later; third, this method lacks flexibility. When large air ducts, water pipes, or cable trays need to pass through the ceiling, it is often necessary to cut the original transfer layer members, severely damaging the structural integrity and force transmission path, leaving safety hazards.

[0004] To reduce on-site welding, another prefabricated connection structure has gradually been adopted. This involves prefabricating connectors (such as lugs) onto steel beams in the factory, and then installing the transition layer steel on-site using bolts. While this method improves construction efficiency and reduces damage to fire-retardant coatings to some extent, its inherent limitations become apparent in large-span, high-load projects: First, the load-bearing capacity and stiffness of the connection nodes (such as lugs and bolts) are limited, making it difficult to cope with the enormous self-weight and deformation requirements of large-span steel plate ceilings, which can easily lead to loosening or deformation; second, the overall integrity of this structural system is poor, lacking effective spatial stiffness, and it is prone to swaying under dynamic loads (such as wind vibration and equipment vibration), affecting the stability and durability of the ceiling; third, it lacks an effective system-level solution for the overall leveling of large-area ceiling panels, making it difficult to guarantee the final installation accuracy.

[0005] In summary, existing technologies for large-span roof ceiling transition layers, whether using traditional welding methods or prefabricated connections, struggle to achieve an ideal balance between structural safety, installation accuracy, construction efficiency, and economy. For ultra-large planar steel plate ceilings, developing a novel installation method that can effectively control structural deformation, ensure extremely high flatness, and coordinate with various professional piping systems has become a critical technical challenge that urgently needs to be addressed in this field. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this application provides a method for installing a large flat panel for roof ceiling, which aims to ensure the flatness of the ceiling steel panel while improving the overall appearance.

[0007] The technical means adopted by this invention to solve its technical problem is: a method for installing a large flat panel on a roof ceiling, the improvement of which includes: Step S1: Based on the planar dimensions of the ceiling to be installed and the layout of the main and secondary steel beams, design and determine the dimensions and installation position of the stiffening plate on the back of the ceiling steel plate, as well as the segment dimensions and numbering of the ceiling steel plate. Step S2: Install the steel columns, main steel beams and secondary steel beams in sequence according to the construction order, and weld and fix the stiffening plates to the main and secondary steel beams. The stiffening plates include transverse stiffening plates and longitudinal stiffening plates, and adopt a layered welding process. After the welding is completed, the overall levelness is re-measured and corrected to ensure that the lower surface of the stiffening plates is flush with the lower flange surface of the main and secondary steel beams. Step S3: Hoist the pre-numbered ceiling steel plate to the corresponding installation position, attach it to the stiffening plate and temporarily fix it with intermittent welding, and control the weld depth to 1 / 3 of the steel plate thickness; Step S4: Weld and fix the ceiling steel plates one by one from one side of the ceiling to the other in a predetermined order, and control the deformation during the welding process.

[0008] The installation of the stiffening plate in step S2 of the above technical solution includes: step S201, first welding the transverse stiffening plate and re-measuring the levelness; step S202, then spot welding the longitudinal stiffening plate, performing layered welding, and after forming an integral whole, re-measuring and correcting the levelness.

[0009] Step S2 in the above technical solution includes: The installation sequence is as follows: steel column installation, second-floor main steel beam installation, second-level steel beam installation, third-floor main steel beam and tie rod installation, third-level steel beam installation, and large flat plate base plate stiffening plate installation.

[0010] During the installation of the steel columns described in the above technical solution, a truck crane is used for hoisting. After the columns are hoisted into place, a theodolite is used for correction, and the elevation of the column top is adjusted to meet the design requirements. The rated lifting capacity of the truck crane, after being corrected by a reduction factor, is greater than the maximum installation weight.

[0011] When installing the two-layer main and secondary steel beams as described in the above technical solution, the centerline and longitudinal distance are controlled by the corresponding control points and lines on the steel columns and the main and secondary steel beams. The centerline, longitudinal distance and the elevation of the main and secondary steel beams are monitored with measuring instruments. After adjusting the centerline, longitudinal distance and the elevation of the main and secondary steel beams, the main and secondary steel beams and steel columns are fixed. The second-layer steel beams are connected to the second-layer main steel beams through connecting plates. After adjusting the axis position and horizontal height, the screws are tightened and welded.

[0012] During the installation of the three-layer main steel beams, tie rods, and secondary steel beams described in the above technical solution, the axial position and horizontal height of the three-layer main steel beams are located on the steel columns, and positioning steel plates are welded on them. After the three-layer main steel beams are hoisted into place with tie rods, the horizontality is adjusted by the tie rods, and the axial position is monitored by measuring instruments to ensure that it coincides with the positioning line. After adjusting the elevation, the three-layer main steel beams are fixed on the steel columns and the tie rods are tightened. Finally, the three-layer steel beams are installed and their horizontal height is controlled.

[0013] When installing the stiffening plates of the large flat plate base plate described in the above technical solution, the transverse stiffening plates are first leveled and spot-welded to the main and secondary steel beams, and then welded symmetrically in layers. After the horizontality is re-measured and meets the requirements, the longitudinal stiffening plates are spot-welded and then welded in layers. After all the stiffening plates and the main and secondary steel beams are connected into a whole, the horizontality is re-measured and corrected again so that the lower surface of the lower stiffening plate is in a plane with the lower flange surface of the main and secondary steel beams.

[0014] Step S3 in the above technical solution includes: The lower-level segmented base plates are hoisted and positioned sequentially from one side to the other. After leveling, they are spot-welded to the main and secondary steel beams and stiffening plates. First, the welds between the transverse stiffening plates and the base plate are welded in sections, then the welds between the longitudinal stiffening plates and the base plate are welded in sections, and finally the welds between the base plates are welded. The depth of the welds between the plates is controlled to be 1 / 3 of the thickness of the steel plate.

[0015] Step S4 in the above technical solution includes: On the ground, the upper-layer panel and its stiffening plate are assembled and welded into a whole. After ensuring that the flatness of each small unit meets the installation requirements, they are hoisted into place in sequence and spot-welded to the main and secondary steel beams. First, the stiffening plate is welded to the main and secondary steel beams, and finally the panel is welded to the upper flange of the main and secondary steel beams. The weld depth is controlled to 1 / 3 of the steel plate thickness.

[0016] The beneficial effects of this invention are: Through systematic process design, meticulous procedure control, and multi-stage retesting and calibration, the overall flatness and structural stability of large-scale suspended ceiling installations are effectively guaranteed. Employing layered welding, sequential installation, and modular pre-assembly processes significantly reduces welding deformation, improves installation accuracy and construction efficiency, and enhances structural integrity, making it suitable for complex roofing projects with large spans and high precision requirements. Attached Figure Description

[0017] Figure 1This is a flowchart illustrating a method for installing a large flat panel on a roof ceiling, as shown in an embodiment of the present invention. Figure 2 This is a flowchart illustrating the installation process of the stiffening plate according to an embodiment of the present invention; Figure 3 This is a flowchart illustrating the installation process of the main and secondary steel beams and stiffening plates according to an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the installation of the main and secondary steel beams and stiffening plates according to an embodiment of the present invention; Figure 5 This is a diagram illustrating the panel structure according to an embodiment of the present invention. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] The following will clearly and completely describe the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Furthermore, all connections / linkages involved in the patent do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this invention can be combined interactively without contradicting each other.

[0020] like Figure 1 As shown, this application provides a method for installing a large flat panel on a roof ceiling, the method comprising: Step S1: Based on the planar dimensions of the ceiling to be installed and the layout of the main and secondary steel beams, design and determine the dimensions and installation position of the stiffening plate on the back of the ceiling steel plate, as well as the segment dimensions and numbering of the ceiling steel plate.

[0021] Step S2: Install the steel columns, main steel beams and secondary steel beams in sequence according to the construction order, and weld and fix the stiffening plates to the main and secondary steel beams. The stiffening plates include transverse stiffening plates and longitudinal stiffening plates, and adopt a layered welding process. After the welding is completed, the overall levelness is re-measured and corrected to ensure that the lower surface of the stiffening plate is flush with the lower flange surface of the main and secondary steel beams.

[0022] Specifically, such as Figure 2 As shown, the installation of the stiffening plate includes: Step S201: First, weld the transverse stiffening plate and then re-measure the levelness; Step S202: Spot weld the longitudinal stiffening plates, perform layered welding, and after forming the whole, re-measure and correct the levelness.

[0023] In one possible implementation, such as Figure 3 As shown, the installation sequence is as follows: steel column installation, second-floor main steel beam installation, second-level steel beam installation, third-floor main steel beam and tie rod installation, third-level steel beam installation, and large flat plate stiffening plate installation. A detailed schematic diagram is shown below. Figure 4 As shown.

[0024] During the installation of the steel column, a truck crane is used for hoisting. After hoisting and positioning, a theodolite is used for correction, and the column top elevation is adjusted to the design requirements. The rated lifting capacity of the truck crane, after being corrected by a reduction factor, is greater than the maximum installation weight.

[0025] Specifically, the heaviest single steel column weighs 514.5 kg and is 4.4 m long. A 25-ton truck crane will be used for lifting. The installation radius is approximately 12 m, the boom height is 14 m, and the boom angle is 60°. Therefore, the boom length is: The maximum boom length is set at 20.85m. When the steel column is outside the working radius of the truck crane, the position of the truck crane should be adjusted in a timely manner to ensure safety.

[0026] (1) Install lifting capacity The maximum weight of the steel column is Q1=0.51T, and the maximum weight of the lock and other components is Q2=0.25T. Therefore, the maximum weight during installation is Q=Q1+Q2=0.51+0.25=0.76T.

[0027] (2) Selection of truck crane A 25T truck crane with its outriggers fully extended was selected. According to the crane's operating condition table, under the condition of a working radius of 12m and a boom extension of 20.855m, the rated lifting capacity is 4.1T. That is, 4.1T × 0.85 (crane reduction coefficient) = 3.49 > 0.76T, which proves that the lifting conditions of the truck crane meet the requirements (25-ton truck crane performance table).

[0028] (3) Selection of wire rope: The standard “General Purpose Wire Rope” (GB / T 20118-2006) and “Important Purpose Wire Rope” (GB / T8918-2006) shall be implemented.

[0029] The steel wire rope used in the hoisting process is selected according to the maximum weight of the component, and two hoisting points are set up for hoisting.

[0030] The tension in each wire rope is F = 0.76 ÷ 2 = 0.38 T = 3.8 KN.

[0031] Using 6×37+1 wire 1850Mpa grade, Ф17.5mm diameter steel wire rope for binding and lifting, the total breaking tensile force is... 156kN.

[0032] The allowable tensile force of the wire rope is: It meets safety requirements.

[0033] (4) Shackle selection: Follow the standard "Forged Shackles for General Lifting" (JB-8112).

[0034] Given that the maximum force at a single lifting point is 3.8 kN, two "D" type rigging shackles with a safe load of 10 kN are selected. That is, 10 kN > 3.8 kN, which meets the requirements.

[0035] During the installation of the two-layer main and secondary steel beams, the centerline and longitudinal distance are controlled by the corresponding control points and lines on the steel columns and the main and secondary steel beams. The centerline, longitudinal distance and the elevation of the main and secondary steel beams are monitored by measuring instruments. After the centerline, longitudinal distance and the elevation of the main and secondary steel beams are adjusted, the main and secondary steel beams and steel columns are fixed. The second-layer steel beams are connected to the second-layer main steel beams through connecting plates. After adjusting the axis position and horizontal height, the screws are tightened and welded.

[0036] During the installation of the three-layer main steel beams, tie rods, and secondary steel beams, the axial position and horizontal height of the three-layer main steel beams are located on the steel columns, and positioning steel plates are welded on them. After the three-layer main steel beams are hoisted into place with tie rods, the horizontality is adjusted by the tie rods, and the axial position is monitored by measuring instruments to ensure that it coincides with the positioning line. After adjusting the elevation, the three-layer main steel beams are fixed on the steel columns and the tie rods are tightened. Finally, the three-layer steel beams are installed and their horizontal height is controlled.

[0037] When installing the stiffening plates of the large flat plate base, the transverse stiffening plates are first leveled and spot-welded to the main and secondary steel beams, and then welded symmetrically in layers. After the horizontality is re-measured and meets the requirements, the longitudinal stiffening plates are spot-welded and then welded in layers. After all the stiffening plates and the main and secondary steel beams are connected into a whole, the horizontality is re-measured and corrected again so that the lower surface of the lower stiffening plate is in a plane with the lower flange surface of the main and secondary steel beams.

[0038] Specifically, first determine the thickness of the steel plate. Assuming the steel plate is a platform plate, the common thickness tp = 6-12mm, take tp = 12mm.

[0039] Next, the stiffening rib dimensions are initially selected. The rib height hs is generally 1 / 10 to 1 / 15 of the span. Given hs = 1800 / 15 = 120mm, we take 120mm. The rib thickness ts is not less than the steel plate thickness tp, and it satisfies local stability (avoiding buckling): ts≥max(tp,hs / 15)=max(12,120 / 15=8)→Take 16mm; Next, the stiffening rib spacing aa is calculated. To prevent local instability of the steel plate and limit the deformation of the welding heat-affected zone, a≤30tp-60tp.

[0040] For tp=12mm: a≤30×12=360mm or 60×12=720mm; to balance economy and effect, take a=500mm.

[0041] Finally, the stiffness ratio is checked. The ratio of the moment of inertia of the stiffener to that of the steel plate should satisfy: Is / Ip≥3 (empirical threshold). Moment of inertia per unit width of steel plate: Ip = (1 × tp) 3 ) / 12=12 3 / 12=144mm 3 ; Moment of inertia of a single stiffening rib: Is = (ts x hs) 3 / 12 = (16 × 120) 3 / 12=2.3×10 6 mm 4 ; Equivalent unit wide moment of inertia (amortized over a spacing a=500): I s,eq =Is / a=2.310 6 / 500=4676mm 3 Stiffness ratio: I s,eq / Ip=2880 / 144=32>3 (Meets requirements) Step S3: Hoist the pre-numbered ceiling steel plate to the corresponding installation position, attach it to the stiffening plate and temporarily fix it with intermittent welding, and control the weld depth to 1 / 3 of the steel plate thickness.

[0042] Specifically, the lower-level segmented base plates are hoisted and positioned sequentially from one side to the other. After leveling, they are spot-welded to the main and secondary steel beams and stiffening plates. First, the welds between the transverse stiffening plates and the base plates are welded in sections, then the welds between the longitudinal stiffening plates and the base plates are welded in sections, and finally the welds between the base plates are welded. The depth of the welds between the plates is controlled to be 1 / 3 of the thickness of the steel plate.

[0043] In order to achieve a better flatness effect, since the weld between the plates only serves as an aesthetic function of sealing the surface layer and does not serve as a load-bearing support for the steel plate, in order to reduce the impact of the weld on the deformation of the base plate, the weld between the plates is only welded to about 3mm at 1 / 3 of the weld.

[0044] Step S4: Weld and fix the ceiling steel plates one by one from one side of the ceiling to the other in a predetermined order, and control the deformation during the welding process.

[0045] Specifically, during the installation of the large flat panel, the upper-layer segmented panels and their stiffening plates are assembled and welded together on the ground to ensure that the flatness of each small unit meets the installation requirements. Then, they are hoisted into place in sequence and spot-welded to the main and secondary steel beams. First, the stiffening plates are welded to the main and secondary steel beams, and finally, the panels are welded to the upper flanges of the main and secondary steel beams. The weld depth is controlled to be 1 / 3 of the steel plate thickness.

[0046] Among them, such as Figure 5 As shown, the large flat plate consists of two identical layers, with a base plate specification of 30700. 12150mm, the base plate is divided into 42 pieces, with the largest piece area being 6350mm. 2000mm in diameter, weighing 797.56kg; the panel is divided into 56 sections, with the largest section area being 4450mm. 1850mm, weight 517kg. The top and bottom stiffening plates are mesh-like, with a mesh size of 500. 500mm, stiffening plate specification PL90 16mm, full length, connecting to the main and secondary steel beams.

[0047] In addition, by analyzing the possible causes of steel plate deformation in steel structure welding processes, the welding process was optimized. ① CO2 gas shielded welding uses thin welding wire, has a high current density, concentrates heating, and results in minimal deformation. 0.8mm welding wire was selected for CO2 gas shielded welding. ② Higher heat input leads to greater welding deformation. Welding deformation increases with increasing welding current and arc voltage, and decreases with increasing welding speed. Welding parameters were adjusted, using lower voltage and current as much as possible, and increasing welding speed. ③ Continuous welding and intermittent welding produce different temperature fields, resulting in different thermal deformations. Smaller weld leg sizes and shorter welds were chosen whenever possible. Symmetrical welding was used to effectively reduce welding deformation. A segmented back-welding method was employed, welding from the middle outwards, generally in 100mm segments. After the transverse weld was completed, a hammering method was used, where a small round-headed hammer was used to tap the weld to extend it appropriately, compensating for shrinkage during welding and reducing overall weld shrinkage. Then, the longitudinal spot welds are ground off to restore the steel plate to its original structural form as much as possible, and then the longitudinal welds are applied.

[0048] Through the above embodiments, this application employs a systematic process design, meticulous process control, and multi-stage retesting and correction to effectively ensure the overall flatness and structural stability of large-scale ceiling installations. It utilizes layered welding, intermittent welding, sequential installation, and modular pre-assembly processes, significantly reducing welding deformation, improving installation accuracy and construction efficiency, while enhancing structural integrity. This makes it suitable for complex roofing projects with large spans and high precision requirements.

[0049] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A method for installing a large flat panel for roof ceiling, characterized in that, The method includes: Step S1: Based on the planar dimensions of the ceiling to be installed and the layout of the main and secondary steel beams, design and determine the dimensions and installation position of the stiffening plate on the back of the ceiling steel plate, as well as the segment dimensions and numbering of the ceiling steel plate. Step S2: Install the steel columns, main steel beams and secondary steel beams in sequence according to the construction order, and weld and fix the stiffening plates to the main and secondary steel beams. The stiffening plates include transverse stiffening plates and longitudinal stiffening plates, and adopt a layered welding process. After the welding is completed, the overall levelness is re-measured and corrected to ensure that the lower surface of the stiffening plates is flush with the lower flange surface of the main and secondary steel beams. Step S3: Hoist the pre-numbered ceiling steel plate to the corresponding installation position, attach it to the stiffening plate and temporarily fix it with intermittent welding, and control the weld depth to 1 / 3 of the steel plate thickness; Step S4: Weld and fix the ceiling steel plates one by one from one side of the ceiling to the other in a predetermined order, and control the deformation during the welding process.

2. The method for installing a large flat panel for roof ceiling according to claim 1, characterized in that, The installation of the stiffening plate in step S2 includes: Step S201: First, weld the transverse stiffening plate and then re-measure the levelness; Step S202: Spot weld the longitudinal stiffening plates, perform layered welding, and after forming the whole, re-measure and correct the levelness.

3. The method for installing a large flat panel for roof ceiling according to claim 1, characterized in that, Step S2 includes: The installation sequence is as follows: steel column installation, second-floor main steel beam installation, second-level steel beam installation, third-floor main steel beam and tie rod installation, third-level steel beam installation, and large flat plate base plate stiffening plate installation.

4. The method for installing a large flat panel for roof ceiling according to claim 3, characterized in that, During the installation of the steel columns, a truck crane is used for hoisting. After the columns are hoisted into place, a theodolite is used for correction, and the elevation of the column top is adjusted to meet the design requirements. The rated lifting capacity of the truck crane, after being corrected by a reduction factor, is greater than the maximum installation weight.

5. The method for installing a large flat panel for roof ceiling according to claim 3, characterized in that, During the installation of the second-layer main and secondary steel beams, the centerline and longitudinal distance are controlled by the corresponding control points and lines on the steel columns and the main and secondary steel beams. The centerline, longitudinal distance and the elevation of the main and secondary steel beams are monitored with measuring instruments. After the centerline, longitudinal distance and the elevation of the main and secondary steel beams are adjusted, the main and secondary steel beams and steel columns are fixed. The second-layer steel beams are connected to the second-layer main steel beams through connecting plates. After adjusting the axis position and horizontal height, the screws are tightened and welded.

6. The method for installing a large flat panel for roof ceiling according to claim 3, characterized in that, During the installation of the three-layer main steel beams, tie rods, and secondary steel beams, the axial position and horizontal height of the three-layer main steel beams are located on the steel columns, and positioning steel plates are welded on them. After the tie rods are hoisted into place, the horizontality of the three-layer main steel beams is adjusted using the tie rods. The axial position is monitored with measuring instruments to ensure it coincides with the positioning line. After adjusting the elevation, the three-layer main steel beams are fixed on the steel columns, and the tie rods are tightened. Finally, the three-layer steel beams are installed, and their horizontal height is controlled.

7. The method for installing a large flat panel for roof ceiling according to claim 3, characterized in that, When installing the stiffening plates of the large flat plate base, first level and spot weld the transverse stiffening plates onto the main and secondary steel beams, then weld them symmetrically in layers. After re-measuring the levelness and ensuring it meets the requirements, spot weld the longitudinal stiffening plates and weld them in layers. After connecting all the stiffening plates and the main and secondary steel beams into a whole, re-measuring the levelness and correcting it so that the lower surface of the lower stiffening plate is on the same plane as the lower flange of the main and secondary steel beams.

8. The method for installing a large flat panel for roof ceiling according to claim 1, characterized in that, Step S3 includes: The lower-level segmented base plates are hoisted and positioned sequentially from one side to the other. After leveling, they are spot-welded to the main and secondary steel beams and stiffening plates. First, the welds between the transverse stiffening plates and the base plate are welded in sections, then the welds between the longitudinal stiffening plates and the base plate are welded in sections, and finally the welds between the base plates are welded. The depth of the welds between the plates is controlled to be 1 / 3 of the thickness of the steel plate.

9. The method for installing a large flat panel for roof ceiling according to claim 1, characterized in that, Step S4 includes: On the ground, the upper-layer panel and its stiffening plate are assembled and welded into a whole. After ensuring that the flatness of each small unit meets the installation requirements, they are hoisted into place in sequence and spot-welded to the main and secondary steel beams. First, the stiffening plate is welded to the main and secondary steel beams, and finally the panel is welded to the upper flange of the main and secondary steel beams. The weld depth is controlled to 1 / 3 of the steel plate thickness.

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