Among the welding methods of steel bars, arc welding can be divided into binding welding and lap welding, and both can be divided into double-sided welding and single-sided welding. As the name implies, single-sided welding is single-sided welding; Double-sided welding is double-sided welding.

When binding steel bars for welding or lap welding, the assembly and welding of steel bars shall meet the following requirements:

When binding steel bars for welding, the gap between the end faces of two main bars should be 2 mm to 5 mm;

When lap welding, the welding end should be pre-bent, and the axes of two steel bars should be on the same straight line;

When binding steel bars are welded, the binding steel bars and the main reinforcement are fixed by four-point positioning welding; When lap welding, two points should be fixed; The distance between the locating weld and the end or lap end of the strap shall be greater than or equal to 20mm; ;

When welding, the arc should be struck at the weld formed by binding welding or lap welding; Before the end arc is closed, the arc pit should be filled, and the main weld should be fused with the beginning and end of the positioning weld;

The effective thickness of weld joint of tie-bar welded joint or lap welded joint should not be less than 30% of the diameter of main reinforcement; Weld width b should not be less than 80% of the diameter of the main reinforcement;

Single-side binding welding or single-side lap welding, the lap length requirements of reinforcement: HPB grade reinforcement ≥8d, HRB grade reinforcement ≥10d; Double-sided welding requires that the HPB grade steel bar is ≥8d, and the HRB grade is ≥ 10d.

Code for welding and acceptance of steel bars JGJ 18-20 12

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Answer: The three pictures from top to bottom are arc welding. The fourth picture shows the single-sided lap welding of steel bar arc welding. The contours of the two right sides are different. In Figure 3, the middle of two steel bars is black (the weld is double-sided welding, so it is called double-sided lap welding), and in Figure 4, only the right side of the middle of two steel bars is black (the weld is welded on one side and not welded on the other side, so it is called single-sided lap welding). There are also overlapping lengths of double-sided welded steel bars: HPB grade is 4d and HRB grade is 5d. One-sided welding of reinforcement length: HPB grade is 8d, and HRB grade is 10d.

Looking at the picture again, the double-sided welding on the right is more intuitive. steel