Construction Method Of Steel Structure-Part 1

Production of members

The order of member production is as follows: steel columns, steel beams, purlins, supports, small steel fittings, floor plates (including accessories), wall plates (accessories), etc., depending on the state of the equipment in the plant and the primary process of producing steel structures. The following items are primarily produced in accordance with the production order mentioned above:

1. Setting out

When creating a sample plate, lofting with a metal stylus is used. Starting with a 1:1 ratio, eject a bulk sample onto the sample table; if the bulk sample size is too large, it can be segmented and ejected. Some project members only have a requirement for the node, which can reduce the proportion of sample-making, but must pay attention to accuracy. Begin with a horizontal line and the member's vertical line as a benchmark, then eject the cross line; the two lines must be vertical. Then, on the basis of the cross line, draw every other point and line, and mark the size beside the node for review. Inspections are performed after lofting to ensure that the geometry size, angle, and mounting contact surface of each member machining are accurate.

2. Laying-off cutting

Before laying off, compare whether the varieties, specifications, and marks are strictly according to the technical detail; if necessary, request the relevant personnel to identify; before cutting, ensure that the material and the requirements of the drawings match. Steel plate shear and gas-cutting lines must be ejected straight, with special attention paid to wavy plates with ups and downs. Gas cutting, shearing, punching laying-off, grooving, and sawing are some laying-off cutting methods. Before cutting, the steel plate or section bar should be corrected. For butt joints, welding steel plates,s or section bars, inspection and detection of defects must be performed, cuts must be made only after qualification, and the width of a shearing machine must not be greater than that of the plate shearing machine. Corresponding measures must be taken if the shear material length exceeds the width of the plate shearing machine. Following laying-off, an inspection of the cutting plane, dimensional tolerances, cut section and spatter matters should be performed, followed by a reasonable pile-up and qualified identification and numbering.

3. Holes making

Drilling holes are commonly used for hole creation; however, punching holes can be used in project members' holes such as unimportant node plates, base plates, reinforcing plates, and angle steel bracing. Draw the center line and diameter of the hole on the member before making the holes.

4. Correction

Mechanical correction, flame correction, and other methods are commonly used for correction. Because flame rectification uses shrinkage deformation after local flame heating to offset welding deformation, if the first correction does not meet the quality requirements range, the flame correction can be repeated in the first heating position, or in the reverse direction if the correction is too large until they meet the technical requirements, but there should be a control range for the heating temperature.

5. Assemblage and assembly

Professionals will draw the center line lofting, position the line on the flat plate after laying off, take spot welding fixing on the assembly machine, and form the shape specified in the drawings. Before assembly, assembly personnel must be familiar with the construction drawings, assembly process, and requirements of the relevant documents, and check the appearance, material, specifications, and quantity of parts to be assembled; construction can begin only after the checking is completed. After the test, formal welding can be performed if the clearance dislocation, perpendicularity, angle, and parallelism of the assembly are strictly controlled and meet the requirements.

6. Welding and re-correction

Welding technicians must have certification. When welding, the corresponding welding wire, current, voltage, and welding speed must be chosen based on the steel plate specification and size as specified by the process. Before use, the welding rod, welding wire, flux, and other welding materials with drug skin shedding, fouling, metamorphism, hygroscopicity, caking, and rust should be thoroughly examined. Due to local nonuniform heating of welding to steel, welding stress and welding deformation occur in H-type steel after welding. As a result, it should be corrected using the correction machine.

7. Shot peening

The friction surface of the member must be shot peened and protected after processing. The friction surface must be produced in accordance with the requirements, and the anti-slip coefficient test must be performed to ensure that the friction coefficient meets the requirements. The treated friction surface must be free of fins, burrs, welding scars, and dirt, among other things.

8. Coating and number

After passing the rust removal test, members must be coated with the first priming paint before the rust returns. To achieve uniform spraying, with no obvious wrinkles or sagging, and good adhesion, the bottom spray coating to the member must strictly adhere to the engineering requirements in the workshop. The paint type, number of times, and thickness of the coating must meet the design requirements. When the painting is completed, the original number on the steel members should be marked; the mark can be written directly by label or paint, and the member number should be placed prominently at both ends of the member.

9. Approval of steel members

The steel member must be checked and accepted before leaving the factory; the product member that has left the factory must have a certificate and relevant technical documents, and it must be preassembled in the factory, checked to see if it meets the design size and overall quality, and it must leave the factory only after passing the inspection.