A method for testing welding of cluster type cylindrical head welding studs of a steel-concrete composite beam bridge

Abstract

The application discloses a kind of steel mixed combination beam bridge cluster type cylindrical head weld stud test welding methods, comprising: making reinforcement cage tool, and it is spot-welded and fixed on welding test plate;Welding stud magnetic ring is placed in the center of the area to be welded, adjust the welding process parameters of arc stud welder;Review cylindrical head weld stud arc starting knot and surface quality, arc starting knot should be complete and convex end surface 2mm or more;According to the selected welding process parameters, three cylindrical head weld studs are tested;Knock off weld stud magnetic ring, check the appearance and size of cylindrical head weld stud weld, weld size should meet: along the axis direction, the minimum height of weld leg is not less than times weld stud diameter, the minimum diameter of steel plate side weld toe is not less than times weld stud diameter;Remove reinforcement cage tool, 30° angle bending test is carried out to three cylindrical head weld studs for test welding, after test qualified, formal welding is carried out.The application can guarantee that weld stud in reinforcement cage has high first-time welding qualified rate, improve construction efficiency, shorten construction period.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, specifically to a method for test welding of clustered cylindrical head weld studs in steel-concrete composite beam bridges. Background Technology

[0002] In steel-concrete composite beams employing clustered welded studs, precast concrete slabs have recessed slots at the locations of the welded stud clusters on the cylindrical heads, within which orthogonal longitudinal and transverse reinforcing bars are arranged. Currently, the industry standard is to weld the studs onto the steel beams before the precast slabs are stacked (factory prefabrication). However, during the stacking process of each precast concrete slab, there are as many as 200-300 alignment points between the reinforcing mesh and the welded studs. This easily leads to positional conflicts between the reinforcing bars and welded studs in the precast concrete slabs, making the installation of the precast slabs difficult. Consequently, on-site cutting of the welded studs is required, which not only prolongs the construction period but also significantly reduces the strength of the connection system, leaving potential quality hazards. Summary of the Invention

[0003] Purpose of the Invention: The applicant sought a novel approach, attempting to transform the factory welding of clustered studs for steel-concrete composite beam bridges into on-site welding. However, poor on-site welding conditions, the difficulty of welding within the reinforcing cage, and the challenges of bending and repairing studs have created new problems, hindering the efficiency of steel-concrete composite beam bridge erection. Therefore, the purpose of this invention is to address the problems of poor first-pass yield of studs within the reinforcing cage and uncontrollable stud cluster connection quality during on-site welding. It provides a method for trial welding clustered cylindrical head studs for steel-concrete composite beam bridges, ensuring a high first-pass yield of studs within the reinforcing cage and guaranteeing the quality of stud cluster connections.

[0004] Technical solution: The method for test welding of clustered cylindrical head weld studs in steel-concrete composite beam bridges according to the present invention includes:

[0005] (1) Fabricate steel cage fixtures according to the actual welding environment;

[0006] (2) Place the steel cage fixture on the welding test plate and fix it by spot welding. The steel plate material of the welding test plate is consistent with the steel plate material of the top plate of the steel beam.

[0007] (3) Place a welding stud magnetic ring in the center of the area to be welded on the welding test plate and adjust the welding process parameters of the arc stud welding machine;

[0008] The welding process parameters are selected in Table 1 below according to the different diameters of the cylindrical head welding studs;

[0009] Table 1

[0010]

[0011] (4) Check the arc-starting joint and surface quality of the cylindrical head weld stud. The arc-starting joint should be complete and protrude more than 2mm from the end face.

[0012] (5) According to the selected welding process parameters, test weld three cylindrical head studs using the electric arc stud welding method;

[0013] (6) Remove the magnetic ring from the weld stud and inspect the appearance and dimensions of the cylindrical head weld stud. There must be no defects, including cracks or lack of fusion. The weld dimensions should meet the following requirements: the minimum height of the weld leg along the axial direction should not be less than... The diameter of the weld stud should be twice the diameter of the weld toe on the steel plate, and the minimum diameter of the weld toe on the steel plate should not be less than the diameter of the weld stud. Double the diameter of the welding stud;

[0014] (7) After the appearance and dimensions of the weld are inspected and approved, the steel cage fixture is removed. A sleeve is used to perform a 30° angle bending test on the three cylindrical head weld studs of the trial weld. Only after the test is approved can the formal welding of the day be carried out.

[0015] The criteria and requirements for the 30° bend test of cylindrical head weld studs are shown in Table 3 below:

[0016] Table 3

[0017]

[0018] Furthermore, in step (6), the weld size determination requirements are further determined based on the diameter of the cylindrical head weld stud as shown in Table 2:

[0019] Table 2

[0020]

[0021]

[0022] Furthermore, in step (1), the steel cage tooling is equipped with a steel cage, with baffles on the left and right sides, and ribs on the front and rear sides respectively; the steel cage is made according to the longitudinal and transverse center spacing of the steel bars in the precast concrete slab and the maximum diameter of the steel bars, and the steel mesh size with the smallest construction space is selected; the overall height of the steel cage and the longitudinal and transverse steel bar arrangement are consistent with the structure of the precast concrete slab's precast groove.

[0023] Furthermore, in step (2), a handheld straight grinder is used to grind the dirt and coating in the area to be welded directly below the steel mesh so that its surface reveals a metallic luster; the cleaning range of the area to be welded shall not be less than twice the diameter of the cylindrical head weld nail rod.

[0024] Furthermore, in step (3), the arc stud welding gun that is matched with the arc stud welding machine has an extended gun rod.

[0025] Furthermore, the arc stud welding torch was lengthened to be 150mm longer than the height of the rebar cage fixture.

[0026] Furthermore, the extended section of the arc stud welding torch is made of brass.

[0027] Furthermore, in step (3), the arc stud welding machine is equipped with a voltage regulator to ensure stable welding voltage, thereby ensuring the connection quality of the cylindrical head stud.

[0028] Furthermore, in step (5), the arc stud welding machine adopts the DC positive connection method, the positive power line of the welding machine is connected to the welding test plate, and the negative power line of the welding machine is connected to the matching welding gun.

[0029] Furthermore, in step (5), the trial welding process should be carried out when the ambient temperature is not lower than 5°C. When the ambient temperature is too low, the welding test plate should be preheated to above 20°C before the trial welding can be performed.

[0030] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0031] This invention addresses key industry pain points by employing a novel approach. Extensive human and material resources were allocated to conduct numerous experiments to determine the process parameters for arc stud welding, weld size criteria, and the criteria and requirements for the 30° angle bending test of cylindrical head studs (Tables 1 to 3). The overall solution effectively resolves the current problems of poor first-pass weld qualification rates for studs within reinforcing cages and uncontrollable stud cluster connection quality. Currently, this invention has been successfully applied to a river-crossing tunnel in Jiangsu Province, achieving a first-pass weld qualification rate of over 95% for cylindrical head studs. This significantly improves on-site welding efficiency and drastically shortens the construction period for steel-concrete composite beam bridges.

[0032] This invention fills a gap in the industry, and its successful application provides a precedent that the industry can learn from. Attached Figure Description

[0033] Figure 1 This is a structural schematic diagram of the steel cage tooling in the embodiments of this application;

[0034] Figure 2 This is a schematic diagram of the steel cage tooling assembled on the welding test plate in an embodiment of this application;

[0035] Figure 3 This is a schematic diagram of the welding of the cylindrical head studs inside the reinforcing cage in the embodiments of this application;

[0036] Figure 4 This is a schematic diagram showing the completion of welding in an embodiment of this application;

[0037] Figure 5 yes Figure 4 A schematic diagram showing the steel cage fixture after removal;

[0038] Figure 6 This is a schematic diagram of the weld seam of the cylindrical head stud in an embodiment of this application;

[0039] Figure 7This is a welding test plate after a 30° angle bending test was performed on the cylindrical head welding stud in the embodiments of this application. Detailed Implementation

[0040] The invention will now be further described with reference to the accompanying drawings.

[0041] Appendix Figures 1 to 7 The accompanying figure labels are as follows:

[0042] 1. Rebar cage fixture; 2. Baffle; 3. Rib plate; 4. Rebar cage; 5. Welding test plate; 6. Cylindrical head welding stud; 7. Arc stud welding torch; 8. Extended torch rod; 9. Positive power cord; 10. Negative power cord; 11. Weld seam.

[0043] A method for test welding of clustered cylindrical head weld studs in a steel-concrete composite beam bridge, specifically including the following steps:

[0044] (1) Based on the actual welding environment, fabricate steel cage fixture 1, such as... Figure 1 As shown;

[0045] The steel cage fixture 1 is equipped with a steel cage 4, with baffles 2 on the left and right sides, and ribs 3 on the front and rear sides respectively. The steel cage 4 is made according to the longitudinal and transverse center spacing of the steel bars in the precast concrete slab and the maximum diameter of the steel bars, and the steel mesh size with the smallest construction space is selected. The overall height of the steel cage 4 and the longitudinal and transverse steel bar arrangement are consistent with the structure of the precast concrete slab's precast groove.

[0046] (2) Place the reinforcing cage fixture 1 on the welding test plate 5 and fix it by spot welding. The steel plate material of the welding test plate 5 should be consistent with the steel plate material of the top plate of the steel beam. Figure 2 As shown;

[0047] Use a handheld straight grinder to grind away dirt and coatings in the area to be welded directly below the steel mesh, so that the surface reveals a metallic luster; the cleaning range of the area to be welded should not be less than twice the diameter of the 6-bar section of the cylindrical head weld stud.

[0048] (3) Place a welding stud magnetic ring in the center of the area to be welded on the welding test plate 5, and adjust the welding process parameters of the electric arc stud welding machine;

[0049] The welding process parameters are selected in Table 1 below according to the different diameters of the cylindrical head welding studs 6;

[0050] Table 1

[0051]

[0052] See Figure 3, the arc stud welding gun 7 supporting the arc stud welding machine has an extended gun barrel 8. The arc stud welding gun 7 is extended to be 150 mm more than the height of the steel cage tooling 1. The extended section of the arc stud welding gun 7 is made of brass. The arc stud welding machine is equipped with a voltage stabilizer to ensure the stability of the welding voltage.

[0053] (4) Recheck the arc initiation knot and surface quality of the cylinder head stud 6. The arc initiation knot should be complete and protrude more than 2 mm from the end face;

[0054] (5) According to the selected welding process parameters, weld three cylinder head studs 6 by the arc stud welding method; the welding test should be carried out when the ambient temperature is not lower than 5 °C. When the ambient temperature is too low, the welding test plate 5 should be preheated to more than 20 °C before welding. The arc stud welding machine uses the DC straight polarity connection method. The positive power supply wire 9 of the welding machine is connected to the welding test plate 5, and the negative power supply wire 10 of the welding machine is connected to the supporting welding gun.

[0055] (6) Knock out the stud magnetic ring, and check the appearance and dimensions of the weld 11 of the cylinder head stud 6. There shall be no defects including cracks and lack of fusion; the dimensions of the weld 11 shall meet the requirements: the minimum height of the weld leg along the axis direction shall not be less than times the stud diameter, and the minimum diameter of the weld toe on the steel plate side shall not be less than times the stud diameter;

[0056] The requirements for judging the dimensions of the weld 11 are further determined according to the diameter of the cylinder head stud 6 as shown in Table 2:

[0057] Table 2

[0058]

[0059] The welded cylinder head stud 6 is as Figures 4 to 6 shown, where Figure 6 shows the weld leg height and the weld toe diameter on the steel plate side in Table 2.

[0060] (7) After the appearance and dimensions of the weld 11 are inspected and qualified, remove the steel cage tooling 1, and use a sleeve to conduct a 30° angle bending test on the three welded cylinder head studs 6. As Figure 7 shown, after the test is qualified, the formal welding of the day can be carried out;

[0061] The judgment and requirements for the 30° angle bending test of the cylinder head stud are shown in Table 3 below:

[0062] Table 3

[0063]

[0064]

[0065] A specific example is given below.

[0066] Taking the clustered cylindrical head weld stud test welding of a steel-concrete composite beam of a Yangtze River Bridge as an example, the precast concrete slab and the steel beam are connected by cylindrical head weld studs arranged on the top plate of the steel beam. Except for the weld studs near the central support point which use Φ25 weld studs, all other positions use Φ22 weld studs. The weld stud material is ML15Al. The number of weld studs welded in the steel reinforcement mesh on site is about 1.2 million. Using the clustered cylindrical head weld stud test welding method of the present invention for steel-concrete composite beam bridge, the first-time forming qualification rate of the cylindrical head weld studs reaches more than 95%, which significantly improves the welding construction efficiency on site and greatly shortens the construction period of steel-concrete composite beam bridge.

[0067] Specifically, steps (1) to (7) refer to the above content.

[0068] In step (4), the welding process parameters are determined according to Table 1 as follows:

[0069]

[0070] In step (5), the weld size determination requirements are determined according to Table 2 as follows:

[0071]

Claims

1. A method for test welding clustered cylindrical head weld studs in a steel-concrete composite beam bridge, characterized in that, include: (1) Based on the formal welding environment, fabricate the steel cage fixture (1); (2) Place the steel cage fixture (1) on the welding test plate (5) and spot weld it in place. The steel plate material of the welding test plate (5) is consistent with the steel plate material of the top plate of the steel beam. (3) Place a welding stud magnetic ring in the center of the area to be welded on the welding test plate (5) and adjust the welding process parameters of the electric arc stud welding machine. The welding process parameters are selected in Table 1 below according to the different diameters of the cylindrical head welding studs (6); Table 1 (4) Check the arc-starting joint and surface quality of the cylindrical head weld stud (6). The arc-starting joint should be complete and protrude more than 2mm from the end face. (5) According to the selected welding process parameters, test weld three cylindrical head studs using the electric arc stud welding method (6); (6) Remove the magnetic ring from the weld stud and inspect the appearance and dimensions of the weld (11) of the cylindrical head weld stud (6). There should be no defects including cracks or lack of fusion. The dimensions of the weld (11) should meet the following requirements: the minimum height of the weld leg along the axial direction should not be less than The diameter of the weld stud should be twice the diameter of the weld toe on the steel plate, and the minimum diameter of the weld toe on the steel plate should not be less than the diameter of the weld stud. Double the diameter of the welding stud; (7) After the appearance and dimensions of the weld (11) are inspected and approved, the steel cage fixture (1) is removed. The three cylindrical head weld studs (6) of the trial weld are subjected to a 30° angle bending test using a sleeve. Only after the test is qualified can the formal welding of the day be carried out. The criteria and requirements for the 30° bend test of cylindrical head weld studs are shown in Table 3 below: Table 3 2. The method for test welding clustered cylindrical head weld studs in steel-concrete composite beam bridges according to claim 1, characterized in that, In step (6), the weld (11) size determination requirements are further determined based on the diameter of the cylindrical head weld stud (6) as shown in Table 2: Table 2 3. The method for test welding clustered cylindrical head weld studs in steel-concrete composite beam bridges according to claim 1, characterized in that, In step (1), the steel cage tooling (1) is equipped with a steel cage (4), with baffles (2) on the left and right sides, and ribs (3) on the front and rear sides respectively; the steel cage (4) is made according to the longitudinal and transverse center spacing of the steel bars in the precast concrete slab and the maximum diameter of the steel bars, and the steel mesh size with the smallest construction space is selected; the overall height of the steel cage (4) and the longitudinal and transverse steel bar arrangement are consistent with the structure of the precast concrete slab.

4. The method for test welding clustered cylindrical head weld studs in steel-concrete composite beam bridges according to claim 1, characterized in that, In step (2), a handheld straight grinder is used to grind the dirt and coating in the area to be welded directly below the steel mesh so that its surface shows a metallic luster; the cleaning range of the area to be welded should not be less than twice the diameter of the rod of the cylindrical head welding stud (6).

5. The method for test welding clustered cylindrical head weld studs in steel-concrete composite beam bridges according to claim 1, characterized in that, In step (3), the arc stud welding gun (7) of the arc stud welding machine has an extended gun rod (8).

6. The method for test welding clustered cylindrical head weld studs in steel-concrete composite beam bridges according to claim 5, characterized in that, The arc stud welding gun (7) is extended to be 150mm longer than the height of the steel cage tooling (1).

7. The method for test welding clustered cylindrical head weld studs in steel-concrete composite beam bridges according to claim 5, characterized in that, The extended section of the arc stud welding gun (7) is made of brass.

8. The method for test welding clustered cylindrical head weld studs in steel-concrete composite beam bridges according to claim 1, characterized in that, In step (3), the arc stud welding machine is equipped with a voltage regulator to ensure stable welding voltage.

9. The method for test welding clustered cylindrical head weld studs in steel-concrete composite beam bridges according to claim 1, characterized in that, In step (5), the arc stud welding machine adopts the DC positive connection method. The positive power line (9) of the welding machine is connected to the welding test plate (5), and the negative power line (10) of the welding machine is connected to the matching welding gun.

10. The method for test welding clustered cylindrical head weld studs in steel-concrete composite beam bridges according to claim 1, characterized in that, In step (5), the trial welding process should be carried out when the ambient temperature is not lower than 5°C. When the ambient temperature is too low, the welding test plate (5) should be preheated to above 20°C before the trial welding can be performed.

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