Pre assembly of steel structure truss

1., the pre assembled site should be flat and solid, pre assembled male frame should be carried out strength and stiffness calculation, and the accuracy of each supporting point can be adjusted by measuring instruments side by side. The supporting frame of heavy and large frame should be checked, and the small component pre assembled tire frame can be determined according to construction experience. According to the component type of the pre assembled unit, the pre assembled pads can be made of steel platform, supporting stool and shaped steel.

2. the pre assembly shall be provided with the side datum, the reference point and the elevation line.

3. if necessary, the temporary connecting plate can be provided before the pre assembled steel member.

4., pre assembled in accordance with the structure of the form, the use of monomer pre assembled, flat pre assembled and standing off pre assembled. The steel member shall be pre assembled in the free state, and shall not be forcibly fixed. In addition to shell structure for stereo pre assembled and card, fixture, other structures are usually flat pre assembled, pre assembled components should be in a free state, can not be forcibly fixed, pre assembled quantity can be performed according to the design requirements of the contract or.

5. steel members shall be pre assembled, mounted and positioned according to site lofting dimensions. Site lofting shall meet the following requirements.

5.1. lofting dimensions shall include construction drawings, control dimensions, required camber values, weld joints, weld allowances and other required control dimensions

5.2. site lofting shall be in accordance with the pre assembled vertical projection, which shall include the centerline of the member and the end face datum line.

Before the 5.3. pre assembly, the site lofting shall be checked in size.

5.4. lofting of points and line marking should be clear.

The pre assembly sequence of the 6. steel structural truss elements and the assembly unit shall be determined according to the design requirements and the structure form. The portal steel frame is erected and assembled first, and then assembled with the steel column on the half face after correction

Multilayer board 7. high strength bolts and ordinary bolts connecting the 1 pre assembly should use nail positioning and temporary bolts, fitting bolts in a set of holes shall not be less than the number of bolt holes 20%, and not less than 2, fitting should make lamellar stickers, nail bolt holes shall not be less than the total number of 10%. should be used for inspection pass rate test hole plate hole

7.1. when the hole diameter of the bore is smaller than I. 0 mm, the passing rate of each hole shall be no less than 85%.

7.2. when using a larger than the bolt nominal diameter 0.3 mm test hole test, the pass rate should be 100%.

When the pass rate of the 8. panels is not up to the above requirements, the hole shall be repaired. When the wrong hole is less than 3 mm in general, reamer cutter, milling or reaming, reaming diameter shall not exceed 1.2 times the diameter of the bolt when the wrong hole is more than 3 mm, the general electrode welding hole plugging, and grinding formation, no bump phenomenon, low hydrogen electrode electrodes should be used to match with the parent material. No packing steel block in the hole. The steel block packing is actually false hole blocking, will cause serious consequences, it is absolutely not allowed.

9. when performing dimensional checks, the component should be in a free state. The so-called "free state" that can be used in the pre assembly process, fixture, welding fixture, tension device in the temporary fixing member, adjust the size of each part, the connection part of each hole with no more than 1/3 and not less than two of ordinary bolt group, and then remove the fixture, fixture, welding point, tension device etc. temporary fixed parts size check

10. when the pre unit component, component and component to connect surface friction, friction surface connection between each board close inspections, inspection methods for beating people board edge 2O depth gauge mm, measuring clearance among plates should meet the following requirements.

10.1. clearance should be less than 0.2mm.

The gap in 10.2. depth is 0.2-0.3mm, and the length should not exceed 10%. of the side length of the plate

The gap in 10.3. depth is 0.3-1 mm, and the length should not exceed 5%. of the side length of the plate

11., after the completion of the pre assembly, after the self-test qualified, the supervision unit should be checked and accepted, and good quality records.

12. pre assembly inspection should be marked after the central line, control the mark and other markings, if necessary, should be set locator. The assembled components shall be marked with the paint immediately at the visible part, and the drawing number, the component number and the number of packages shall be indicated for the purpose of finding.