Prefabricated steel channel beam and construction method for appearance consistency thereof

Abstract

The application provides a prefabricated steel channel beam and a construction method for appearance consistency thereof, and belongs to the technical field of channel beam paint corrosion prevention construction. The method solves the problems of traditional paint corrosion prevention construction methods, such as being constrained by environmental protection, on-site construction environment conditions, long construction period, many construction measures, great construction risk, high cost and the like. The technical scheme comprises a bottom plate, webs arranged on both sides of the top of the bottom plate, a top plate arranged on the top of the webs, internal components arranged between the webs, and a lifting lug assembly; and a welding hole protection tool is arranged at the welding hole. The application has the beneficial effects that the scheme can avoid the contact between the scaffold and the uncoated part by installing the overhanging scaffold, and the overall paint spraying effect of the subsequent paint is affected; the construction method of the welding hole structure sealant follows the principle of from local to whole, the local welding hole is blocked first, and then the whole component is sand-blasted and coated, which is more convenient for construction.

Description

Technical Field

[0001] This invention relates to the field of anti-corrosion construction technology for channel beams, and in particular to a construction method for precast steel channel beams and their consistent appearance. Background Technology

[0002] To ensure structural durability, steel channel beams are typically treated with paint for external corrosion protection. The consistency of the paint application directly determines the final aesthetic appearance. Since paint applied at different times is often affected by environmental factors, color variations can occur. To ensure consistent appearance, a final coat of paint is usually applied on-site. Additionally, due to structural connection requirements, steel channel beams often have through holes and weld holes at joints for stress relief. These need to be sealed to meet both internal corrosion protection and overall aesthetic requirements. This is generally done after the first coat of paint, with the final coat applied uniformly. This construction method is constrained by environmental regulations and on-site conditions, resulting in a long construction period, numerous construction measures, high risks, and high costs.

[0003] How to solve the above-mentioned technical problems is the challenge facing this invention. Summary of the Invention

[0004] The purpose of this invention is to provide a construction method for prefabricated steel channel beams and their consistent appearance, which solves the problems of traditional paint anti-corrosion construction methods being constrained by environmental protection and on-site construction conditions, resulting in long construction periods, numerous construction measures, high construction risks, and high costs.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a prefabricated steel channel beam, comprising a bottom plate, web plates disposed on both sides of the top of the bottom plate, and a top plate disposed on the top of the web plates, wherein internal components and lifting lug components are disposed between the web plates;

[0006] The steel channel beam has weld holes at the joint structure, and the weld holes are equipped with weld hole protection fixtures.

[0007] The weld hole protection fixture includes a weld hole sealing plate disposed at the joint plate and a middle limiting plate, an upper limiting plate, and a lower limiting plate disposed on one side of the weld hole sealing plate;

[0008] The upper limiting plate is equipped with a locking nut and a locking bolt.

[0009] The through-weld hole sealing plate is vertically installed on the ground, and a slot is opened on one side of the through-weld hole sealing plate;

[0010] The central limiting plate is located in the middle of the through-weld hole sealing plate and is flush with the outer edge of the slot.

[0011] The upper limiting plate is located on the upper part of the middle limiting plate and is flush with the groove of the through-weld hole sealing plate and the upper edge of the middle limiting plate;

[0012] The lower limiting plate is located below the middle limiting plate and is flush with the groove of the through-weld hole sealing plate and the lower edge of the middle limiting plate.

[0013] The locking nut is vertically positioned in the middle of the upper limiting plate; the locking bolt is fixedly connected to the upper limiting plate through the locking nut.

[0014] The lifting lug assembly includes a set of symmetrically arranged vertical lifting lugs and a set of symmetrically arranged oblique lifting lugs. Both the vertical lifting lugs and the oblique lifting lugs are located on the inner side of the web. The vertical lifting lugs are matched with double-hook lifting slings, and the oblique lifting lugs are matched with single-hook lifting slings.

[0015] Each of the vertical lugs is provided with an oblique lug on one side, and the vertical lugs and the oblique lugs are connected by a stiffening plate.

[0016] The construction method based on the appearance consistency of precast steel channel beams includes the following steps:

[0017] Step S1, Hanging Lug Design:

[0018] Components must be hoisted from the factory to the bridge site. If temporary lifting lugs are placed externally, they are easily damaged during hoisting, and after hoisting, they need to be cut off and repaired, leading to significant inconsistencies. If the lifting lugs are placed internally, the environment is better than that of temporary external lifting lugs, and it does not affect the consistency and aesthetics of the external paint finish. Therefore, the lifting lugs should be internal. To reduce temporary structures, stiffening plates are integrated with the lifting lugs in the structural design, satisfying both internal structural strength and hoisting requirements. The hoisting lug design includes one set of vertical lifting lugs and one set of angled lifting lugs to meet the applicable conditions for double-hook and single-hook hoisting. The vertical and angled lifting lugs are placed on the inside of the web. When hoisting components from the factory to the bridge site, hoisting slings are used first, and auxiliary hooks are used to install the hoisting slings to avoid damaging the surface paint with the paint slings.

[0019] Step S2, partial paint application:

[0020] S2.1 Localized sand flushing

[0021] Thoroughly sandblast the weld holes, through holes, and surrounding areas to achieve the smoothness required by the structural sealant.

[0022] S2.2 Partial Coating

[0023] Apply a primer of about 20mm to the edges of the weld holes and through holes to prevent rust from returning to the hole edges and sandblasting again, which would affect the sealant. Apply tape to the painted area to protect the primer.

[0024] S2.3 Structural Sealant Application

[0025] By selecting a sealant that has a certain degree of hardness without affecting stress release, the side of the weld hole inside the structure is sealed with tape to prevent the sealant from sticking to the weld hole protection fixture. The weld hole protection fixture is tightly attached to the outside of the tape and used as a backing for the structural sealant application. After the surface is dry, the weld hole protection fixture is removed and the tape is torn off. The sealant area is then sanded. After the treatment is qualified, the weld hole protection fixtures on both sides are installed to prevent sand from damaging the sealant structure.

[0026] S2.4 Fabrication and Installation Steps for Weld Hole Protection Fixtures

[0027] The upper and lower limit plates are placed across the joint plate and tightly fitted with the middle limit plate; the through-weld hole sealing plate is tightly attached to the load-bearing component, and the through-weld hole protection fixture is tightened to the joint plate using locking bolts.

[0028] Follow these steps to install the weld hole protection fixture on the other side;

[0029] Step S3, overall sandblasting and coating:

[0030] S3.1 Sandblasting and Painting Construction Scaffold Fabrication and Coating

[0031] Erect cantilevered scaffolding and place the horizontal supports on the top plate of the steel channel beam;

[0032] The beam segment is subjected to overall sandblasting and coating operations. The coating process requires spraying up to the intermediate coat (the coating process is divided into primer, intermediate coat, and topcoat).

[0033] The beam segment was relocated. Before the relocation, the area of ​​the corresponding support position was painted with the final topcoat, and the original jig support position was sandblasted and coated.

[0034] S3.2 Overall Sandblasted Coating Topcoat

[0035] S3.2.1 Scaffolding Erection

[0036] Extend the bottom of the cantilevered scaffold to support it on the ground, remove the horizontal supports that are in contact with the top plate, and adjust the cantilevered scaffold into a ground-supported full-span scaffold.

[0037] If a mobile construction platform is used, the overlapping treatment may not be properly handled during the platform's movement, affecting consistency. The time difference for repairing the formwork position should be as short as possible to ensure consistency, so this period should be minimized before moving the formwork position.

[0038] S3.2.2 Top plate paint spraying

[0039] Painting workers stand on ground-mounted scaffolding to spray paint. Before spraying paint on the top plate, the web plate must be protected to prevent paint mist from affecting the appearance.

[0040] S3.2.3 Web plate painting

[0041] When painting the web, the work surface is divided into upper and lower areas according to the height of the web of the beam segment. Each area is divided into several sections, which are painted by personnel A and B respectively. The length of each section is about 2.5 meters. For example, in the 1-2 construction section, personnel A paints sections 1-6 and then sections 12-17. After personnel A paints sections 1-6, personnel B paints sections 7-12. The web painting is carried out in sequence.

[0042] S3.2.4 Base plate paint spraying

[0043] Repeat the above steps to paint the base plate area.

[0044] The thickness of the sealing plate for the weld hole is equal to the weld size plus 2mm, to avoid interference with the weld.

[0045] The inner opening size L1 of the weld hole sealing plate is equal to the thickness of the joint plate plus 10mm. It has a wide range of applications and can be adjusted and fixed by locking nuts and locking bolts.

[0046] The outer opening size L2 of the weld hole sealing plate is equal to the thickness of the upper / lower limiting plate + the weld size + 2mm, to avoid interference with the weld.

[0047] In step S3, when spraying paint on the top plate during the overall sandblasting and topcoat process, the front and rear spraying areas need to overlap by 50mm to ensure that the paint film thickness at the overlap is consistent (the paint sprayed from the paint gun is in an arc shape, and the upper part is relatively thin).

[0048] In step S3, when spraying paint on the web plate during the overall sandblasting and topcoat process, the overlapping areas of the workers operating in the upper and lower areas must overlap by 50mm to ensure that the overall paint film thickness remains consistent.

[0049] Compared with the prior art, the beneficial effects of this invention are as follows: This solution, through cantilevered scaffolding installation, avoids contact between the scaffolding and unpainted parts, thus preventing impact on the overall paint spraying effect; the construction method of the sealant for weld hole structures follows the principle of from local to overall, first sealing the local weld holes, then sandblasting and coating the entire component, making construction more convenient; pre-sandblasting of the weld holes ensures sufficient smoothness of the component's sealant surface; sandblasting and sealing of weld holes can be carried out according to actual construction conditions, with oxidation time (after sandblasting of the component)... The constraints of the material (which rusts after being exposed to air for 4 hours) are relatively small; the pre-coated joint plate does not require secondary sanding or grinding; a weld hole protection fixture is used to effectively protect the adhesive application area from damage to the structural adhesive during sanding; the weld hole protection fixture can be adjusted according to the thickness of the joint plate by adjusting the locking bolts, making it widely applicable; the weld hole protection fixture is easy to install and remove, requiring only the adjustment of the locking bolts; using this construction method, all painting work can be completed, and only partial painting is needed at the bridge site, shortening the construction cycle and minimizing environmental impact. Attached Figure Description

[0050] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0051] Figure 1 This is a schematic diagram of the channel beam according to an embodiment of the present invention.

[0052] Figure 2 This is a schematic diagram of the structure of the lug assembly according to an embodiment of the present invention.

[0053] Figure 3 This is a schematic diagram of the hanging strap according to an embodiment of the present invention.

[0054] Figure 4 This is a schematic diagram of the lifting and hoisting of the double hooks with slings according to an embodiment of the present invention.

[0055] Figure 5 This is a schematic diagram of the single-hook lifting sling lifting in an embodiment of the present invention.

[0056] Figure 6 This is a schematic diagram of the installation of a single-sided weld hole protection fixture according to an embodiment of the present invention.

[0057] Figure 7 This is a side view of a single-sided weld hole protection fixture according to an embodiment of the present invention.

[0058] Figure 8 This is a front view of a single-sided weld hole protection fixture according to an embodiment of the present invention.

[0059] Figure 9 This is a left view of a single-sided through-weld hole protection fixture according to an embodiment of the present invention.

[0060] Figure 10 This is a schematic diagram of the through-weld hole sealing plate according to an embodiment of the present invention.

[0061] Figure 11 This is a schematic diagram of the erection of a cantilevered scaffolding construction platform according to an embodiment of the present invention.

[0062] Figure 12 This is a front view of the ground-mounted scaffolding construction platform erected according to an embodiment of the present invention.

[0063] Figure 13 This is a schematic diagram illustrating the erection of a ground-mounted scaffolding construction platform according to an embodiment of the present invention.

[0064] Figure 14 This is a schematic diagram of the paint spraying sequence according to an embodiment of the present invention.

[0065] The attached figures are labeled as follows: 20, base plate; 30, web plate; 21, internal component; 22, lifting lug assembly; 2201, vertical lifting lug; 2202, inclined lifting lug; 40, joint plate; 50, lifting sling; 11, through-weld hole sealing plate; 12, middle limiting plate; 13, upper limiting plate; 14, lower limiting plate; 15, locking nut; 16, locking bolt. Detailed Implementation

[0066] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0067] Example 1

[0068] See Figures 1 to 13 The present invention provides a technical solution as follows: a precast steel channel beam, which includes a bottom plate 20, web plates 30 disposed on both sides of the top of the bottom plate 20, and a top plate disposed on the top of the web plates 30. An internal component 21 and a lifting lug component 22 are disposed between the web plates 30.

[0069] The steel channel beam has weld holes at the joint structure, and the weld holes are equipped with protective fixtures.

[0070] The through-weld hole protection fixture includes a through-weld hole sealing plate 11 installed at the joint plate 40, and a middle limiting plate 12, an upper limiting plate 13, and a lower limiting plate 14 installed on one side of the through-weld hole sealing plate 11.

[0071] The upper limit plate 13 is equipped with a locking nut 15 and a locking bolt 16.

[0072] The through-weld hole sealing plate 11 is vertically installed on the ground, and a slot is opened on one side of the through-weld hole sealing plate 11;

[0073] The middle limiting plate 12 is located in the middle of the through-weld hole sealing plate 11 and is flush with the outer edge of the groove;

[0074] The upper limiting plate 13 is disposed on the upper part of the middle limiting plate 12 and is flush with the groove of the through-weld hole sealing plate 11 and the upper edge of the middle limiting plate 12;

[0075] The lower limiting plate 14 is located below the middle limiting plate 12 and is flush with the groove of the through-weld hole sealing plate 11 and the lower edge of the middle limiting plate 12.

[0076] The locking nut 15 is vertically positioned in the middle of the upper limiting plate 13; the locking bolt 16 is fixedly connected to the upper limiting plate 13 through the locking nut 15.

[0077] The lifting lug assembly 22 includes a set of symmetrically arranged vertical lifting lugs 2201 and a set of symmetrically arranged oblique lifting lugs 2202. Both the vertical lifting lugs 2201 and the oblique lifting lugs 2202 are located inside the web 30. The vertical lifting lugs 2201 are matched with the double-hook lifting sling 50, and the oblique lifting lugs 2202 are matched with the single-hook lifting sling 50.

[0078] Each vertical lug 2201 is provided with an oblique lug 2202 on one side, and the vertical lug 2201 and the oblique lug 2202 are connected by a stiffening plate.

[0079] The construction method based on the appearance consistency of precast steel channel beams includes the following steps:

[0080] Step S1, Hanging Lug Design:

[0081] Components must be hoisted from the manufacturing plant to the bridge site. If temporary lifting lugs are placed externally, they are easily damaged during hoisting, and after hoisting, they need to be cut off and repaired, which will lead to obvious inconsistencies. If the hoisting lugs are placed internally, the environment of the lugs is better than that of temporary external lugs, and it will not affect the consistency and aesthetics of the external paint coating. Therefore, the hoisting lugs should be internal. In order to reduce temporary structures, the stiffening plate is combined with the lifting lugs in the structural design to meet the hoisting requirements while satisfying the internal structural strength. The hoisting lug design includes one set of vertical lifting lugs and one set of inclined lifting lugs to meet the applicable conditions of double hook and single hook hoisting. The vertical lifting lugs 2201 and the inclined lifting lugs 2202 are placed inside the web 30. When hoisting components from the manufacturing plant to the bridge site, the hoisting slings 50 are used first, and auxiliary hooks are used to install the hoisting slings 50 to avoid the paint slings damaging the surface paint.

[0082] Step S2, partial paint application:

[0083] S2.1 Localized sand flushing

[0084] Thoroughly sandblast the weld holes, through holes, and surrounding areas to achieve the smoothness required by the structural sealant.

[0085] S2.2 Partial Coating

[0086] Apply a primer of about 20mm to the edges of the weld holes and through holes to prevent rust from returning to the hole edges and sandblasting again, which would affect the sealant. Apply tape to the painted area to protect the primer.

[0087] S2.3 Structural Sealant Application

[0088] By selecting a sealant that has a certain degree of hardness without affecting stress release, the side of the weld hole inside the structure is sealed with tape to prevent the sealant from sticking to the weld hole protection fixture. The weld hole protection fixture is tightly attached to the outside of the tape and used as a backing for the structural sealant application. After the surface is dry, the weld hole protection fixture is removed and the tape is torn off. The sealant area is then sanded. After the treatment is qualified, the weld hole protection fixtures on both sides are installed to prevent sand from damaging the sealant structure.

[0089] S2.4 Fabrication and Installation Steps for Weld Hole Protection Fixtures

[0090] The upper limiting plate 13 and the lower limiting plate 14 are placed across the joint plate 40 and tightly fitted with the middle limiting plate 12; the through-weld hole sealing plate 11 is tightly fitted to the load-bearing component, and the through-weld hole protection fixture is tightened to the joint plate 40 using the locking bolt 16.

[0091] Follow these steps to install the weld hole protection fixture on the other side;

[0092] Step S3, overall sandblasting and coating:

[0093] S3.1 Sandblasting and Painting Construction Scaffold Fabrication and Coating

[0094] Erect cantilevered scaffolding and place the horizontal supports on the top plate of the steel channel beam;

[0095] The beam segment is subjected to overall sandblasting and coating operations. The coating process requires spraying up to the intermediate coat (the coating process is divided into primer, intermediate coat, and topcoat).

[0096] The beam segment was relocated. Before the relocation, the area of ​​the corresponding support position was painted with the final topcoat, and the original jig support position was sandblasted and coated.

[0097] S3.2 Overall Sandblasted Coating Topcoat

[0098] S3.2.1 Scaffolding Erection

[0099] Extend the bottom of the cantilevered scaffold to support it on the ground, remove the horizontal supports that are in contact with the top plate, and adjust the cantilevered scaffold into a ground-supported full-span scaffold.

[0100] If a mobile construction platform is used, the overlapping treatment may not be properly handled during the platform's movement, affecting consistency. The time difference for repairing the formwork position should be as short as possible to ensure consistency, so this period should be minimized before moving the formwork position.

[0101] S3.2.2 Top plate paint spraying

[0102] The painting workers stand on the ground-mounted scaffolding to spray paint. Before spraying the paint on the top plate, the web plate 30 needs to be protected to prevent paint mist from affecting the appearance.

[0103] S3.2.3 Web plate painting

[0104] S3.2.4 Base plate paint spraying

[0105] Repeat the above steps to paint area 20 of the base plate.

[0106] The thickness of the sealing plate 11 through the weld hole is equal to the weld size plus 2mm, to avoid interference with the weld.

[0107] The inner opening size L1 of the through-weld hole sealing plate 11 is equal to the thickness of the joint plate + 10mm. It has a wide range of applications and can be adjusted and fixed by locking nut 15 and locking bolt 16.

[0108] The outer opening size L2 of the through-weld hole sealing plate 11 is equal to the thickness of the upper / lower limiting plate + the weld size + 2mm, to avoid interference with the weld.

[0109] Example 2

[0110] See Figure 14 Based on Example 1, when painting the web plate 30, the working surface is divided into upper and lower areas according to the height of the web plate of the beam segment. Each area is divided into several sections, which are constructed by personnel A and personnel B respectively. The length of each section is about 2.5 meters. For example, in construction section 1-2, personnel A constructs area 1-6. After that, they construct area 12-17. After personnel A constructs area 1-6, personnel B constructs area 7-12. The painting of the web plate 30 is carried out in sequence.

[0111] Dividing the tall web surface into upper and lower areas, and further subdividing each area into sections, allows different personnel to spray different areas and sections, which can improve work efficiency and avoid the inefficiency of one person spraying the entire tall area from bottom to top.

[0112] Dividing the work into zones and sections allows each person to focus on a specific area, improving overall painting quality. Different personnel can collaborate effectively; for example, after worker A completes zones 1-6, worker B can take over for zones 7-12. This two-person teamwork ensures continuous work, preventing omissions or repetitions. It also eliminates the need for one person to move up and down, reducing safety hazards associated with working at heights. Furthermore, zoned and segmented work allows for phased inspections, ensuring that the painting quality of each zone and segment meets requirements.

[0113] Example 3

[0114] Based on Example 1, in step S3, when spraying paint on the top plate during the overall sandblasting and coating process, the front and rear spraying areas need to overlap by 50mm to ensure that the paint film thickness at the overlap is consistent (the paint sprayed from the paint gun is in an arc shape, and the upper part is relatively thin).

[0115] Without overlap, gaps may appear between adjacent areas, leading to missed areas. Setting a certain overlap range can prevent this problem. Consistent paint film thickness at the overlap ensures uniform coating quality across the entire surface, preventing localized thin coatings and improving overall construction quality. Workers can control the spraying area based on the fixed overlap distance, making the operation simple and systematic, preventing discontinuities. A certain overlap between adjacent areas increases the smoothness of the coated surface, preventing unevenness. Consistent paint thickness at the overlap makes the entire coated surface appear smoother and more aesthetically pleasing.

[0116] Example 4

[0117] Based on Example 1, in step S3, when spraying paint on the web plate during the overall sandblasting and topcoat process, the overlapping areas of the workers operating in the upper and lower areas need to overlap by 50mm to ensure that the overall paint film thickness is consistent and to prevent uneven thickness.

[0118] Proper overlap can prevent gaps between upper and lower areas from causing missed coatings and also avoid material waste caused by repeated coating. Workers only need to overlap at fixed intervals, eliminating the need for repeated measurements and adjustments, which can improve work efficiency. Fixed overlap distances are easy for workers to control and operate. Consistent coating thickness at the overlaps makes the entire web coating surface smoother and prevents unevenness. Continuous and uniform coating layers improve the product's appearance and aesthetics. Coatings with uniform thickness provide better corrosion protection.

[0119] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A precast steel channel beam, characterized in that, It includes a base plate (20), a web plate (30) disposed on both sides of the top of the base plate (20), and a top plate disposed on the top of the web plate (30). An internal component (21) and a lifting lug component (22) are disposed between the web plates (30). The steel channel beam has weld holes at the joint structure, and the weld hole is equipped with a weld hole protection fixture. The through-weld hole protection fixture includes a through-weld hole sealing plate (11) disposed at the joint plate (40) and a middle limiting plate (12), an upper limiting plate (13), and a lower limiting plate (14) disposed on one side of the through-weld hole sealing plate (11). The upper limiting plate (13) is provided with a locking nut (15) and a locking bolt (16). The lug assembly (22) includes a set of symmetrically arranged vertical lugs (2201) and a set of symmetrically arranged oblique lugs (2202), both of which are arranged inside the web (30).

2. The precast steel channel beam according to claim 1, characterized in that, The through-weld hole sealing plate (11) is vertically installed on the ground, and a slot is opened on one side of the through-weld hole sealing plate (11); The middle limiting plate (12) is located in the middle of the through-weld hole sealing plate (11) and is flush with the outer edge of the slot; The upper limiting plate (13) is located on the upper part of the middle limiting plate (12) and is flush with the groove of the through-weld hole sealing plate (11) and the upper edge of the middle limiting plate (12); The lower limiting plate (14) is located below the middle limiting plate (12) and is flush with the groove of the through-weld hole sealing plate (11) and the lower edge of the middle limiting plate (12); The locking nut (15) is vertically positioned in the middle of the upper limiting plate (13); the locking bolt (16) is fixedly connected to the upper limiting plate (13) through the locking nut (15).

3. A precast steel channel beam according to claim 1, characterized in that, The vertical lifting lug (2201) is matched with the double-hook lifting sling (50), and the angled lifting lug (2202) is matched with the single-hook lifting sling (50); Each of the vertical lugs (2201) is provided with an inclined lug (2202) on one side, and the vertical lugs (2201) and the inclined lugs (2202) are connected by a stiffening plate.

4. A construction method for ensuring the uniformity of appearance of precast steel channel beams as described in claim 1, characterized in that, Includes the following steps: Step S1, Hanging Lug Design: The vertical lifting lug (2201) and the inclined lifting lug (2202) are set inside the web (30). The component is hoisted from the factory to the bridge site. During hoisting, the hoisting sling (50) is used first, and the auxiliary hook is used to install the hoisting sling (50). Step S2, partial paint application: S2.1 Localized sand flushing Thoroughly sandblast the weld holes, through holes, and the area around the holes; S2.2 Partial Coating Apply a primer to the edges of the weld holes and through holes, about 20mm thick. S2.3 Structural Sealant Application Use sealant to seal the side of the weld hole inside the structure with tape to prevent the sealant from sticking to the weld hole protection fixture. Apply the tape tightly to the outside of the weld hole protection fixture and use it as a backing for the structural sealant application. After it is surface dry, remove the weld hole protection fixture and tear off the tape. Grind the sealant area. After the treatment is qualified, install the weld hole protection fixtures on both sides. S2.4 Fabrication and Installation Steps for Weld Hole Protection Fixtures The upper limiting plate (13) and the lower limiting plate (14) are passed over the joint plate (40) and tightly fitted with the middle limiting plate (12); the through-weld hole sealing plate (11) is tightly attached to the load-bearing component, and the through-weld hole protection fixture is tightened to the joint plate (40) using the locking bolt (16); Follow these steps to install the weld hole protection fixture on the other side; Step S3, overall sandblasting and coating: S3.1 Fabrication and painting of sandblasting and painting scaffolding Erect cantilevered scaffolding and place the horizontal supports on the top plate of the steel channel beam; The entire beam segment is subjected to sandblasting and coating operations, and the coating needs to be sprayed up to the intermediate paint. The beam segment was relocated. Before the relocation, the area of ​​the corresponding support position was painted with the final topcoat, and the original jig support position was sandblasted and coated. S3.2 Overall sandblasted coating topcoat S3.2.1 Scaffolding Erection Extend the bottom of the cantilevered scaffold to support it on the ground, remove the horizontal supports that are in contact with the top plate, and adjust the cantilevered scaffold into a ground-supported full-span scaffold. S3.2.2 Top plate paint spraying The painting personnel stand on the ground-mounted scaffold to spray paint. Before spraying the top plate, the web plate (30) needs to be protected to avoid the paint mist affecting the appearance. S3.2.3 Web plate painting When painting the web (30), the working surface is divided into upper and lower areas according to the height of the web of the beam segment. Each area is divided into several sections, which are carried out by personnel A and personnel B respectively. The spraying length of one section is 2.5 meters. Personnel A will work on areas 1-6 and then on areas 12-17 after the work is completed. After personnel A works on areas 1-6, personnel B will work on areas 7-12. The painting of the web (30) is carried out in sequence. S3.2.4 Base plate paint spraying Repeat the above steps to paint the base plate (20) area.

5. The construction method for ensuring the uniform appearance of precast steel channel beams according to claim 4, characterized in that, The thickness of the weld hole sealing plate (11) is equal to the weld size plus 2mm.

6. The construction method for ensuring the uniform appearance of precast steel channel beams according to claim 4, characterized in that, The inner opening size L1 of the weld hole sealing plate (11) is equal to the thickness of the joint plate plus 10mm.

7. The construction method for ensuring the uniform appearance of precast steel channel beams according to claim 4, characterized in that, The outer opening size L2 of the weld hole sealing plate (11) is equal to the thickness of the upper / lower limiting plate + the weld size + 2mm.

8. The construction method for ensuring the uniform appearance of precast steel channel beams according to claim 4, characterized in that, In step S3, when spraying paint on the top plate during the overall sandblasting and topcoat process, the front and rear spraying areas need to overlap by 50mm.

9. The construction method for ensuring the uniform appearance of precast steel channel beams according to claim 4, characterized in that, In step S3, when spraying paint on the web plate during the overall sandblasting and topcoat process, the overlapping area of ​​the workers working in the upper and lower areas must overlap by 50mm.

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