1. When straightening steel bar with hoist, attention should be paid to controlling cold drawing rate: Grade I steel bar should not be greater than 4%; Grade Ⅱ ~ Ⅲ steel bars and structures that are not allowed to use cold-drawn steel bars should not be greater than 1%. When straightening steel bars with straightening machine and straightening coarse steel bars with hammering method, surface scars should not reduce the cross-sectional area by more than 5%. Straightened steel bars should be straight without local distortion, and there should be no obvious scratches on the surface of cold-drawn low-carbon steel bars. It should be noted that the tensile strength of cold-drawn low-carbon steel wire is generally reduced by 10~ 15% after being straightened by a straightener, so the inspection should be strengthened before use, and the selection should be made according to the straightened tensile strength.

2. The reinforcement of the same specification should be collocated and typeset according to different lengths; Generally, the long material is broken first, and then the short material is broken to reduce the short head and loss. Avoid measuring long materials with a short ruler to prevent accumulated errors. The workbench should be marked with size and scale, and a baffle should be set to control the size of broken materials. If cracks, shrinkage or severe bending are found during cutting, they must be removed. After cutting, the fracture surface of steel bar shall not be horseshoe-shaped or bent, and the length deviation of steel bar shall not be less than 10 mm.

3. When the steel bar is bent, the position of each bending point should be marked, and the marking size should be deducted from the adjustment value of steel bar bending according to different bending angles and steel bar diameters. Scribing should be done on the workbench. If there is no marking table, mark directly with a scale, and use a wooden ruler with appropriate length, instead of measuring with a short ruler (wooden folding ruler) to prevent mistakes. After the first steel bar is bent and formed, it should be aligned with the ingredients, and then processed in batches after it meets the requirements. After forming, the steel bar should be in the correct shape, with no concave curvature on the plane and no cracks at the bend. The allowable dimension deviation is: total length 10mm, bending point displacement of bent steel bar 20mm, bending height of bent steel bar 5 mm and stirrup side length 5 mm.

4.( 1) Before welding, the rust, slag, burr residue and other impurities on the surface of the weldment shall be removed.

(2) Four welds shall be used for double-sided welding, and single-sided welding shall be used in case of difficulty. The total cross-section of the slats shall not be less than 1.2 times of the cross-section area of welded steel bars (grade I steel bars) and 1.5 times (grade II and III steel bars). The reinforcing bars shall be steel bars with the same diameter as the welded steel bars, and the axes of the two reinforcing bars shall be in the same plane with the center of the welded steel bars. If reinforcement is different from welded reinforcement, it should be converted according to the design strength of reinforcement.

(3) Double-sided welding should also be adopted for lap welding, and single-sided welding should be adopted when the operation is difficult.

(4) The groove of steel bar shall be cut or sawed by oxyacetylene flame, and arc cutting shall not be adopted.

(5) Measures such as symmetrical, constant-speed welding and layered alternating welding should be taken to reduce deformation.

(6) covered electrode should be kept dry. If it is wet, it should be baked at 100 ~ 350℃ for 0.5 ~1h.

(7) When welding secondary and tertiary steel bars at negative temperature, the welding current should be increased (10 ~ 15% higher than that in summer) to slow down the welding speed, reduce the temperature gradient of weldments and delay the cooling. At the same time, start the arc from the middle of the weldment and gradually deliver the arc to the end, or weld a short seam in the middle to preheat the weldment and reduce the temperature gradient.

(8) When conducting arc welding in winter, measures should be taken to prevent snow, wind and heat preservation, and covered electrode with good toughness should be selected. Contact with ice and snow immediately after welding is strictly prohibited.