1. Check whether the steel grade, diameter, shape, size and quantity of finished steel bars conform to the bill of materials. If there are any mistakes and omissions, they should be corrected and supplemented.
2. Prepare wire for binding, binding tools (such as steel hooks and small crowbars with wrenches) and binding racks.
Steel wire for steel bar binding can be 20~22 # steel wire, of which 22 # steel wire is only used for binding steel bars with diameter less than12 mm. For the length of steel wire, please refer to the values in Table 9-80. Because the wire is supplied in rolls, it is customary to cut it with a part of the circumference of each roll of wire.
3. Prepare cement mortar pad or plastic card to control the concrete protective layer.
The thickness of cement mortar pad should be equal to the thickness of protective layer. Plane size of the pad: 30mm×30mm when the thickness of the protective layer is equal to or less than 20 mm, and 50mm×50mm when it is greater than 20 mm. When the pad iron is used in the vertical direction, 20 # iron wire can be embedded in the pad iron.
The plastic card has two shapes: plastic pad and plastic ring, as shown in Figure 9- 1 15. Plastic cushion blocks are used for horizontal members (such as beams and slabs), and there are grooves in both directions to adapt to the thickness of two protective layers. Plastic rings are used for vertical members (such as columns and walls), and when in use, steel bars enter the clamping cavity from the clamping opening; Because the plastic ring is elastic, the size of the clamping cavity can adapt to the change of the diameter of the steel bar.
4. Draw the rebar position line. Plate or wallboard reinforcement, marking on the template; Column stirrup, draw points on two diagonal main bars; Beam stirrups, draw points on the frame uprights; For the reinforcement of foundation, take a reinforcement in each direction and mark it or mark it on the cushion.
The position of steel bar joints shall be staggered according to the specifications of incoming materials and in combination with the provisions of Article 9-2- 1-3 on the position and quantity of joints, and marked on the template.
5. When binding complex structural members, first of all, we should study the sequence of inserting steel bars in place one by one, and contact the formwork worker to discuss the sequence of formwork support and steel bar binding, so as to reduce the binding difficulty.