CN108436320A - A kind of U ribs and orthotropic plate unit and its welding manufacture method - Google Patents

Abstract

A kind of U ribs of present invention offer and orthotropic plate unit and its welding manufacture method.The U ribs include side web and top wing plate, and it is 3 6mm that the side web end of the U ribs, which has groove and root face, root face height,.The welding manufacture method includes the following steps：U ribs side web end groove and root face are set；Assemble U ribs and bottom plate；The side web end inner side and outer side of U ribs is welded using submerged welding process respectively.It can realize full penetration while guarantee will not puncture molten bath, and stress concentration at interior angle is greatly reduced, and, to improve fatigue performance, welding quality is excellent, efficient.

Description

A kind of U rib and orthotropic plate unit and welding manufacturing method thereof

technical field

The invention relates to the field of welding, in particular to a U-rib and orthotropic plate unit and a welding manufacturing method thereof.

Background technique

The traditional orthotropic bridge deck consists of many cold-formed U-ribs 2 arranged in order and welded on the bridge floor 1 (as shown in Figure 9). This type of steel bridge structure has been developed for 70 years. Orthotropic steel decks are widely used in large-diameter bridges due to their light structure and short construction period. Moreover, the design and construction of high-load bridges is a trend. However, judging from the performance of the existing bridges in operation, the bridges built in the early stage have suffered from structural fatigue cracking one after another, and the fatigue resistance performance is worrying. Along with this, the maintenance cost of the bridge has increased significantly, and the orthotropic steel bridge deck Durability problems have seriously restricted its further development and application, and even some bridge designers are willing to replace orthotropic steel decks with reinforced concrete decks with heavier structural weight and higher construction costs.

The traditional U-rib unit, the U-shaped rib is formed by cold-bending steel plates with equal thickness of 6-10mm, and the welding between it and the bottom plate of the bridge deck is usually performed from one side from the outside, and the single-side welding can achieve 60% to 80% fusion. Deep (as shown in Figure 6), the U rib generally has an unfused part, and the unfused part itself forms a natural initial crack, which becomes the source of fatigue cracks. Under the repeated load of the wheel, the weld between the top plate and the U rib is prone to fatigue cracking . Even if double-sided welding is used, the inner side has no penetration and the front has a larger penetration, and it is difficult to completely fuse (as shown in Figure 7), and the above problems will also occur. Severe fatigue cracks of the bridge are caused by the stress concentration at the welding root position, which is not only the most harmful, difficult or even impossible to repair, but also has the largest number of cracks, accounting for more than 70% according to statistics, causing great losses to the society, and there are serious safety hazards .

Even if special welding equipment is used to weld the fillet welds on the inner side of the U ribs, full penetration welding is achieved by using the form of double-sided fillet welds (as shown in Figure 8). Groove, retain 1-2mm blunt edge, adopt conventional gas shielded welding process on the inside, and use two-pass welding process on the outside with solid wire as the bottom and metal powder core or flux cored wire to cover the surface, meeting the penetration depth of 6.4mm Weld quality requirements. However, the double-sided welding groove is too large and the blunt side is small, which leads to the weld seam being easy to burn through and leak, and the penetration depth is unstable. And the welding efficiency of gas shielded welding is low in the prior art.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a U-rib and orthotropic plate unit and a welding manufacturing method thereof. It can achieve full penetration while ensuring no breakdown of the molten pool, greatly reducing the stress concentration at the inner corner to improve fatigue resistance, excellent welding quality and high efficiency.

In order to achieve the purpose of the above invention, the present invention provides the following technical solutions: a U-rib of an orthotropic plate unit, the U-rib includes a side web and a top flange, and it is characterized in that the side of the U-rib The web end has a bevel and a blunt edge, the thickness of the blunt edge is 3-6mm.

Specifically, the thickness of the side web of the U rib is 6-8mm, the groove is arranged on the outside of the side web, and the height of the groove is 3-5mm; or, the thickness of the side web of the U rib is greater than 8mm , the groove is arranged on the outside and inside of the side web, the height of the outside groove is 3-8mm, the height of the inside groove is 3-7mm, and the depth of the inside groove is 3-5mm.

Specifically, a vertical surface perpendicular to the bottom plate is provided between the inner groove of the end of the side web of the U rib and the inner surface of the side web.

Specifically, the maximum thickness B1 of the end of the side web of the U rib is greater than 8mm, the grooves are arranged on the outside and inside of the side web, the height of the outside groove is 3-8mm, and the height of the inside groove is 3-8mm. 7mm, the inner groove depth is 3-5mm, and the blunt edge thickness is 3-6mm.

The present invention also provides an orthotropic plate unit, comprising the U rib as described above, and a bottom plate, and the orthotropic plate unit is welded to the bottom plate on the inside and outside of the side web ends of the U rib.

Specifically, the shape of the weld seam between the end of the side web of the U rib and the bottom plate is a bell-mouth shape.

The present invention also provides a welding manufacturing method of an orthotropic plate unit, the orthotropic plate unit is the above-mentioned orthotropic plate unit, and the welding manufacturing method includes the following steps: setting the U rib side The bevel and blunt edge of the web end; the U rib and the bottom plate are assembled; the inner side and the outer side of the web end of the U rib are respectively welded by submerged arc welding process.

Specifically, the process parameters of the inner submerged arc welding of the side web end of the U rib are as follows: welding wire with a diameter of 1.6mm is used, the welding current is 385-450A, the welding voltage is 29-33V, and the welding speed is 420-520mm/min; The technical parameters of the outer submerged arc welding of the side web end of the rib are as follows: welding wire with a diameter of 3.2mm is used, the welding current is 550-620A, the welding voltage is 29-35V, and the welding speed is 550-650mm/min.

Specifically, the maximum thickness B1 of the end of the side web of the U rib is greater than 8 mm, and the outer submerged arc welding of the end of the side web of the U rib adopts double wire welding, the diameter of the front wire is 1.6-3.2 mm, and the diameter of the rear wire is 2.0-4.0 mm.

Compared with prior art, the beneficial effect of the present invention is:

(1) Increase the thickness of the blunt edge of the U rib to avoid the breakdown welding leakage defect caused by the manufacturing error of the blunt edge of the U rib. At the same time, the amount of weld filling is reduced, the welding material is saved, and the heat input is reduced.

(2) Double-sided submerged arc welding is used to ensure the depth of penetration to achieve full penetration of the weld seam, greatly improving the fatigue resistance of the joint between the U rib and the steel bridge deck, and significantly improving the welding efficiency.

(3) For thicker U ribs, the inner groove of U ribs is provided, which is conducive to the symmetry and penetration welding of double-sided welds and ensures the welding quality.

(4) By setting a vertical surface perpendicular to the bottom plate at the inner groove of the side web end of the U rib, a bell-shaped weld is formed during welding, and the inner web weld toe can realize a gentle and smooth transition, avoiding stress concentration, Effectively improve the fatigue resistance of the weld toe.

(5) The thickness of the hot-rolled U-rib can be adjusted arbitrarily, and the thickness of the web end of the U-rib is designed to 12-16mm, which is suitable for future high-load structure design. However, the connection between the U-rib and the steel bridge deck is thicker due to the weld seam, and the gas shielded welding process is not suitable. The gas shielded welding requires multiple layers and multiple passes to fill the weld seam. The deformation and work efficiency of the workpiece cannot tolerate the gas shielded welding process. The double-sided submerged arc welding process can be completed on one side and one side.

(6) theoretical calculations and current test results show that compared with traditional welding methods, the performance of the groove form of the present invention and the submerged arc welding double-sided welding connection is far superior to that of the small blunt edge and large slope in the prior art The traditional welding of mouth, the orthotropic steel bridge deck structure and its welding manufacturing method of the present invention can meet the requirement of superhigh load bridge design and construction.

Description of drawings

Fig. 1 is a schematic cross-sectional view of an orthotropic plate unit of the present invention;

Fig. 2 is a schematic cross-sectional view of a U rib of the present invention;

Fig. 3 is a schematic cross-sectional view of another U-rib of the present invention;

FIG. 4 is a partially enlarged schematic diagram of part A of FIG. 1;

Fig. 5 is the structural representation of preferred U rib of the present invention;

6 is a schematic diagram of a single-sided gas shielded welding orthotropic plate unit in the prior art;

7 is a schematic diagram of a double-sided gas shielded welding orthotropic plate unit in the prior art;

Fig. 8 is a schematic diagram of a double-sided submerged arc welding orthotropic plate unit in the prior art;

Fig. 9 is a schematic diagram of an orthotropic bridge deck;

Figure 10 is a schematic diagram of the actual deformation of the panel;

Figure 11 is a schematic diagram of the test piece tooling.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

As shown in FIG. 1 , the orthotropic plate unit has a bottom plate 1 and at least one U rib 2 , whose cross section is semicircular or U-like, and whose opening faces the surface of the bottom plate, and is welded on the bottom plate. The U rib has a wing plate 210 and a web 220, the web 220 is on both sides of the U rib, and the wing plate 210 is between the two webs 220 of the U rib, that is, the top of the inverted U rib.

Fig. 2 is a schematic diagram of an embodiment of a U-rib. The end of the side web of the U rib 2 has a bevel 201 and a blunt edge 202, and adopts a large blunt edge. The thickness B of the U rib is 6-8mm, and the thickness D of the blunt edge is more than 50% of the thickness B. Specifically, the thickness B of the U rib is 6-8 mm, and the thickness D of the blunt edge is 3-6 mm. The groove 201 is arranged on the outer side of the side web 220, the height H of the groove is 3-5mm, and the depth of the groove is W.

Fig. 3 is a schematic diagram of another U-rib embodiment of an orthotropic plate unit, the U-rib thickness B is greater than 8mm, preferably 10-16mm. The grooves are set on the outer and inner sides of the side webs, using large blunt edges. Specifically, there are outer grooves 211 and inner grooves 221, the outer groove height H1 is 3-8mm, and the groove depth is W1. The inner groove height H2 is 3-7mm, and the groove depth W2 is 3-5mm. The blunt edge thickness D is 3-6mm.

FIG. 4 is an orthotropic plate unit, which includes the U rib 2 as above, and also includes a bottom plate 1 . The orthotropic plate unit is welded to the bottom plate on the inside and outside of the end of the side web 220 of the U rib 2 . The shape of the weld seam between the end of the side web of the U rib and the bottom plate is bell-shaped. Specifically, the U-rib side web 220 is from the welding seam at the end to the inner welding toe 4 and the outer welding toe 3 on the bottom plate 1. The overall cross-sectional size gradually increases, showing a concave arc shape, with an inner welding seam The end of the weld and the outer seam are bell-shaped as a whole.

The groove opening is small, and the welding penetration is shallow and cannot achieve the effect of full penetration or close to the effect of full penetration. If the groove opening is too large, the weld toe on the side web 220 of the U-rib is prone to undercut, which seriously reduces the fatigue resistance. The present invention adopts a large blunt edge, and the thickness D of the blunt edge is 3-6mm, which can not only ensure that the welding depth is as large as possible, but also meet the requirement of flat position welding without undercut at the welding toe of the side web of the U rib. When the thickness of the lower thick side of the U rib is greater than 12mm, the groove of the outer corner can be increased accordingly, so that the middle blunt side can be controlled at about 6mm. For thicker plates with U-rib thickness B greater than 8mm, after the inner corner is beveled, the inner fillet weld not only has a larger penetration depth but also has a more reasonable and beautiful surface shape, which greatly reduces the stress concentration at the inner corner and improves fatigue resistance.

The present invention also provides a preferred solution. As shown in FIG. 5, the end of the side web 220 of the U rib 2 has grooves 211, 221 and blunt edges 202, and the maximum thickness of the end of the side web 220 is B1. The U-rib 2 itself has a certain inclination angle when assembled with the bottom plate 1 , that is, there is a certain inclination angle between the inner surface 2201 of the side web 220 and the bottom plate 1 . There is a vertical surface 222 perpendicular to the bottom plate 1 at the inner groove 221 at the end of the side web 220 . The vertical surface 222 and the inner surface 2201 of the side web 220 adopt a circular arc transition. The arc radius R of the arc is not particularly limited. Since the U-rib itself has a certain inclination angle when assembled, the angle between the inclination angle and the vertical plane is generally 12°. The outer fillet seam welding of the U rib is easy to form a smooth and transitional outer weld. The inner side is the opposite. It is difficult to form a concave smooth transition weld with the existing method, and generally a convex weld is formed. By setting the bevel on the inner side of the web end of the side of the U rib and setting the vertical surface at the bevel, the bell-shaped weld can be reliably formed during welding, and the weld toe can realize a gentle and smooth transition, avoid stress concentration, and effectively improve Fatigue resistance of weld toe. It should be noted that the vertical plane 222 and the bottom plate 1 do not need to be perpendicular to 90° in the strict sense, but only need to be substantially vertical or close to vertical. The inner side and the outer side of the end of the side web 220 of the U rib 2 are welded to the bottom plate. After the welding is completed, the weld between the end of the side web of the U rib and the bottom plate is a complete bell-mouth shape (as shown in Figure 4).

For the size of the bevel and the blunt edge, the maximum thickness B1 of the end of the U-rib shall prevail, referring to the above-mentioned bevel form. When the maximum thickness of the U-rib end is B1 greater than 8mm, the grooves are set on the outer and inner sides of the side web, the outer groove height H1 is 3-8mm, the inner groove height H2 is 3-7mm, and the inner groove depth W2 3-5mm. The blunt edge thickness D is 3-6mm.

The present invention also provides a welding manufacturing method for the above-mentioned orthotropic plate unit. The welding manufacturing method includes the following steps: setting the bevel and blunt edge at the end of the U-rib side web; assembling the U-rib and the bottom plate; The inner and outer ends of the side webs are welded by submerged arc welding.

The parameters of the submerged arc welding process for the inner side of the U-rib side web end of the orthotropic plate unit are as follows: welding wire with a diameter of 1.6mm is used, the welding current is 385-450A, the welding voltage is 29-33V, and the welding speed is 420-520mm/ min. The process parameters of the outer submerged arc welding of the side web end of the U rib are as follows: welding wire with a diameter of 3.2mm is used, the welding current is 550-620A, the welding voltage is 29-35V, and the welding speed is 550-650mm/min. When the maximum thickness B1 of the side web end of the U rib is greater than 8mm, the outer submerged arc welding of the side web end of the U rib adopts double wire welding, the diameter of the front wire is 1.6-3.2mm, and the diameter of the rear wire is 2.0-4.0mm.

In order to achieve full penetration welding and avoid fatigue cracks, the U-rib is preferably hot-rolled, and the material of the hot-rolled U-rib is uniform. Before the U-rib is assembled with the steel plate, the lower end of the side web of the U-rib is grooved. The groove of U rib is machined. The two circular arc bending areas of the traditional cold-pressed U-rib have cold-bending plastic deformation, the material becomes hard and brittle, and fatigue cracks are prone to appear if there is a slight surface scratch or overheating.

In order to prove the effect of the present invention, other groove sizes and welding methods (comparative example 1-single-sided gas shielded welding, comparative example 2-double-sided gas shielded welding) are adopted on the orthotropic steel bridge deck unit of the present invention and existing engineering welding, comparative example 3-double-sided submerged arc welding) for fatigue test comparison of orthotropic steel bridge deck units, in which, in order to ensure that the U rib plate unit is consistent with the real bridge, all test specimens simulate the orthotropic steel The bridge deck is welded and cut from its large plate. The material of the test piece is Q345qD steel. The main parameters of the design of the test piece are:

The first group: U rib side web thickness is 8mm, width 300mm, height 280mm, bottom plate thickness 16mm, U rib and bottom plate length 300mm, bottom plate width 700mm.

The second group: the maximum thickness of the side web end of the U rib is 11mm (large thickness), the width is 300mm, the height is 280mm, the thickness of the bottom plate is 16mm, the length of the U rib and the bottom plate is 300mm, and the width of the bottom plate is 700mm.

The experimental principle of the fatigue test is to imitate the number of anti-fatigue failures of a real bridge under the state of alternating loads on the wheels. As in the state of the real bridge, the bridge deck is on the top, the U rib is on the bottom, and the top flange of the U rib is fixed on the base of the fatigue testing machine , P is loaded from top to bottom by the fatigue testing machine. Simplify the wheel load into a concentrated load and act on the bridge deck, the actual deformation of the panel is shown in Figure 10.

In order to simulate the actual deformation of the bridge deck, the vertical and tangential force fatigue tests are carried out on the longitudinal welds between the U-rib and the deck. The following scheme.

As shown in Figure 11, the rolling tooling provided at the inner end P2 of the U-rib joint (bottom plate 2) limits the lateral displacement and rotation angle of the end. The outer end P1 is provided with a loading chuck to apply a load P. The bottom end P3 of the U rib 1 is fixed to the base by bolts. The resistance strain gauge is used to measure the stress level at a certain position from the weld toe as a stress reference. The fatigue test is carried out with a sine wave with a frequency of 5HZ and a maximum load of 3kN downward. Before measuring the strain, load it back and forth dozens of times to eliminate the tooling force.

Experimental example 1

Experimental example 1, as shown in Figure 2, the U rib is formed by cold bending of a flat plate, and the thickness of the web is 6mm. Set the groove on the outside, the thickness of the blunt edge is 4mm, and the height of the groove is 5mm. The submerged arc welding process is used to perform flat position fillet welding at the inner and outer corners of the closed U-rib. The intersection of the outer fillet and the inner fillet reaches 100% full penetration, forming the weld connection shape between the lower end of the U-rib web and the bottom plate as a "horn". "mouth" shape, shaped like a tree root, the test piece does not crack 10 million times, and does not crack when it reaches the fatigue infinite cycle zone.

Experimental example 2

In Example 2, as shown in Figure 2, the U-rib is formed by hot rolling, and the web thickness is 8mm. Set the groove on the outside, the thickness of the blunt edge is 5mm, and the height of the groove is 5mm. The submerged arc welding process is used to perform flat position fillet welding at the inner and outer corners of the closed U-rib. The intersection of the outer fillet and the inner fillet reaches 100% full penetration, forming the weld connection shape between the lower end of the U-rib web and the bottom plate as a "horn". "mouth" shape, shaped like a tree root, the test piece does not crack after 11 million cycles, and does not crack when it reaches the fatigue infinite cycle zone.

Experimental example 3

In Example 3, as shown in Fig. 5, the U rib is formed by hot rolling, and the maximum thickness B1 of the web end is 11 mm. Set grooves on the inner and outer sides, the thickness of the blunt edge is 5mm, the height of the outer groove is 5mm, the height of the inner groove is 5mm, and the depth of the inner groove is 3mm. The submerged arc welding process is used to perform flat position fillet welding at the inner and outer corners of the closed U-rib. The intersection of the outer fillet and the inner fillet reaches 100% full penetration, forming the weld connection shape between the lower end of the U-rib web and the bottom plate as a "horn". "mouth" shape, shaped like a tree root, the test piece did not crack 12 million times, and reached the fatigue infinite cycle zone without cracking.

Experimental example 4

In Example 4, as shown in Fig. 3, the U rib is formed by hot rolling, and the maximum thickness B1 of the web end is 13 mm. Set grooves on the inner and outer sides, the thickness of the blunt edge is 6mm, the height of the outer groove is 6mm, the height of the inner groove is 5mm, and the depth of the inner groove is 4mm. The submerged arc welding process is used to perform flat position fillet welding at the inner and outer corners of the closed U-rib. The intersection of the outer fillet and the inner fillet reaches 100% full penetration, forming the weld connection shape between the lower end of the U-rib web and the bottom plate as a "horn". "mouth" shape, shaped like a tree root, the test piece did not crack 12 million times, and reached the fatigue infinite cycle zone without cracking.

Comparative example 1

In comparative example 1, as shown in Figure 6, the U-rib is a U-rib of equal thickness formed by cold bending and pressing of a flat plate. Single-side gas shielded welding is used for ship position welding at the outer corner of the closed U rib, reaching 80% penetration. The test piece is prone to crack initiation and fracture at the weld root between the bottom plate and the U rib, and cracks occur an average of 150,000 times.

Comparative example 2

In Comparative Example 2, as shown in Figure 7, the U-rib is a U-rib of equal thickness formed by cold bending of a flat plate, the thickness is 8mm, the welding groove is an outer 52° groove, and the blunt edge is 2mm; the double-sided welding process is adopted , using gas shielded welding at the flat position of the inner corner of the closed U rib, and then performing gas shielded welding in the ship position at the outer corner of the closed U rib to realize double-sided welding. The inner corner of the weld center is not penetrated. Cracks were initiated at welding defect positions, with an average of 460,000 cracks.

Comparative example 3

In comparative example 3, as shown in Figure 8, the U-rib is a press-formed equal-thickness U-rib with a thickness of 8mm, the welding groove is an outer 52° groove, and the blunt edge is 2mm; a double-sided submerged arc welding process is adopted. Firstly, submerged arc welding is used at the inner corner of the closed U-rib in the flat position, and then submerged arc welding is performed at the outer corner of the closed U-rib in the flat position to achieve 100% full penetration. Among them, U-rib 2 with common equal thickness and base plate 1 . The test piece averaged 6 million times to initiate cracks in the weak area of the U-rib web neck.

The experimental data comparison of the above four groups of welded parts is as follows:

Comparative example 1: Cracking occurs on average 150,000 times;

Comparative example 2: Cracking occurs on average 460,000 times;

Comparative example 3: 6 million times of crack initiation in the weak area of the U-rib web neck;

Experimental Example 1: No cracking after 10 million cycles, no cracking in the fatigue infinite cycle zone.

Experimental example 2: No cracking after 11 million cycles, and no cracking in the fatigue infinite cycle zone.

Experimental example 3: No cracking after 12 million cycles, no cracking in the fatigue infinite cycle zone.

Experimental example 4: No cracking after 12 million cycles, no cracking in the fatigue infinite cycle zone.

Although the fatigue test results have great uncertainty, the results with great disparity still serve as technical support and guidance.

By comparing Experimental Examples 1-4 with Comparative Examples 1-3, it can be found that the performance of the U-rib groove form of the present invention is far superior after submerged arc welding full penetration welding or internal and external fillet welds are symmetrically close to full penetration welding Compared with the welding of small blunt sides and large grooves in the prior art, the orthotropic steel bridge deck structure and its welding manufacturing method of the present invention can meet the requirements of super-high load bridge design and construction.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (9)

1. a kind of U ribs of orthotropic plate unit, the U ribs include side web and top wing plate, which is characterized in that the U The side web end of rib has groove and root face, and the thickness of the root face is 3-6mm.

2. U ribs as described in claim 1, which is characterized in that U ribs side web thickness is 6-8mm, and the groove is located at Side web outside, groove depth 3-5mm；Alternatively, U ribs side web thickness is more than 8mm, the groove is located at side Web outside and inside, outside groove depth are 3-8mm, and inside groove depth is 3-7mm, and inside groove depth is 3-5mm.

3. such as claim 1-2 any one of them U ribs, which is characterized in that the inside groove of the side web end of the U ribs Vertical plane of the setting perpendicular to bottom plate between the medial surface of side web.

4. U ribs as claimed in claim 3, which is characterized in that the side web end maximum gauge B1 of the U ribs is more than 8mm, The groove is located at side web outside and inside, and outside groove depth is 3-8mm, and inside groove depth is 3-7mm, interior side slope Mouth depth is 3-5mm, root face height 3-6mm.

5. a kind of orthotropic plate unit, which is characterized in that further include bottom including claim 1-4 any one of them U ribs Plate, the orthotropic plate unit are welded in the side web end inner side and outer side of U ribs and bottom plate.

6. orthotropic plate unit as claimed in claim 5, which is characterized in that U ribs side web end and the bottom The weld shape of plate is broadening formation.

7. a kind of welding manufacture method of orthotropic plate unit, which is characterized in that the orthotropic plate unit is wanted for right The orthotropic plate unit described in 5, the welding manufacture method is asked to include the following steps：U ribs side web end groove is set And root face；Assemble U ribs and bottom plate；The side web end inner side and outer side of U ribs is welded using submerged welding process respectively.

8. the welding manufacture method of orthotropic plate unit according to claim 7, which is characterized in that the side abdomen of U ribs Submerged welding process parameter is on the inside of plate end：Using diameter 1.6mm welding wires, welding current is 385~450A, weldingvoltage 29 ~33V, speed of welding are 420~520mm/min；Submerged welding process parameter is on the outside of the side web end of U ribs：Using diameter 3.2mm welding wires, welding current are 550~620A, and weldingvoltage is 29~35V, and speed of welding is 550~650mm/min.

9. the welding manufacture method of orthotropic plate unit according to claim 8, which is characterized in that the side abdomen of U ribs Plate end maximum gauge B1 is more than 8mm, and submerged-arc welding is using Double Wire Welding, preceding silk diameter 1.6- on the outside of the side web end of U ribs 3.2mm, rear silk diameter 2.0-4.0mm.