GB 50205-2020Standard for acceptance of construction quality of steel structures (English PDF)

1.0.2 This standard is applicable to the acceptance of construction quality of

steel structure engineering of industrial and civil buildings and structures.

1.0.3 This standard should be used in conjunction with the current national

standard "Unified acceptance standard for building construction quality" GB 50300.

1.0.4 In addition to this standard, the acceptance of construction quality of steel

structure projects shall also comply with the current relevant national standards.

2.1 Terms

2.1.1 Part

The smallest unit that constitutes a part or component, such as a gusset sheet, a flange sheet, etc.

2.1.2 Component

A unit composed of several parts, such as welded H-beams, steel brackets, etc.

2.1.3 Element

The basic unit of steel structure composed of parts or parts and components, such as beams, columns, supports, etc.

2.1.4 The smallest assembled rigid unit

In the installation project of steel grid and reticulated shell structure, the smallest installation unit except for the loose parts, which is generally divided into two types. plane truss and cone.

2.1.5 Assemble of high strength bolt

A general term for high-strength bolts and matching nuts and washers.

2.1.6 Slip coefficient of faying surface

In the high-strength bolt connection, the ratio of the external force when the friction surface of the connecting piece is slipped to the sum of the pretension force of the high-strength bolt perpendicular to the friction surface.

2.1.7 Test preassembling

Assembling to check whether the elements meet the installation quality requirements.

2.1.8 Space rigid unit

A space-stable structure composed of elements.

2.1.9 Stud welding

A method of energizing the arc by contacting one end of the welding nail (stud)

with the surface of the sheet (or pipe) and, after the contact surface is melted, applying a certain pressure to the welding nail (stud) to complete the welding.

3.0.1 The construction organization of steel structure engineering shall have

corresponding construction technical standards, quality management system, quality control and inspection system; the construction site shall have approved construction program, construction plan and other technical documents.

3.0.2 The acceptance of construction quality of steel structure engineering must

use measuring instruments that have passed metrological verification and calibration. The witness sampling and sample delivery of steel structure engineering shall be completed by the testing agency.

3.0.3 The engineering technical documents and contract documents used in the

construction of steel structure projects shall have the requirements for the acceptance of the construction quality of not lower than the provisions of this standard.

3.0.4 The construction quality control of steel structure engineering shall be

carried out in accordance with the following provisions.

3.0.5 Acceptance of construction quality of steel structure engineering shall be

carried out in accordance with inspection batches, item work, divisional (sub-divisional) work on the basis of qualified self-inspection by the construction organization. The division of item work in the divisional (sub-divisional) work of the steel structure engineering shall be implemented in accordance with the current national standard "Unified acceptance standard for building construction quality" GB 50300.The steel structure item work shall be composed of one or several inspection batches, the inspection batches of each item work shall be divided according to the provisions of this standard;

meanwhile it shall be confirmed by the supervisor (or construction organization).

4.1 General requirements

4.1.1 The main materials, parts (components), finished parts, standard parts

and other products for steel structure shall be subject to mobilization acceptance.

4.1.2 In principle, the division of inspection batches for mobilization acceptance

should be consistent with the inspection batches of each item work. Inspection batches can also be divided according to the scale of the project and the actual conditions of incoming materials.

4.2 Steel sheet

I Main control item

4.2.1 The variety, specification and performance of steel sheets shall meet

the requirements of current national standards and meet design requirements. When the steel sheet enters the site, the test pieces shall be taken according to the current national standards, to be subject to the testing of the yield strength, tensile strength, elongation and thickness deviation. The testing results shall comply with the current national standards.

Inspection quantity. All quality certification documents are inspected; the sampling quantity is determined according to the mobilization batch and the sampling inspection plan of the product.

Inspection method. Check quality certification documents and sampling inspection report.

4.2.2 The steel sheet shall be subject to the witnessed sampling and

reinspection in accordance with Appendix A of this standard. The results of the re-inspection shall meet the requirements of the current national standards and meet the design requirements.

Inspection quantity. Inspection for all.

Inspection method. Witness the sampling and sample delivery; check the re-inspection report.

II General items

4.2.3 The thickness of the steel sheet and its allowable deviation shall meet the

requirements of its product standards and design documents.

Inspection quantity. Spot inspection for 10% of each batch of steel sheets of the same variety and specification; meanwhile it is no less than 3 pieces, 3 locations per piece shall be inspected.

Inspection method. Use vernier caliper or ultrasonic thickness gauge to make measurement.

4.2.4 The flatness of the steel sheet shall meet the requirements of its product

standards.

Inspection quantity. Spot inspection for 10% of each batch of steel sheets of the same variety and specification; meanwhile it is no less than 3 pieces, 3 locations per piece shall be inspected.

Inspection method. Use stayguy, steel ruler and vernier caliper for measurement.

4.2.5 The surface appearance quality of the steel sheet shall not only meet the

requirements of the current national standards, but also the following requirements.

5.1 General requirements

5.1.1 This chapter is applicable to the quality acceptance of welding

engineering for steel element welding and stud (welding nail) in the fabrication and installation of steel structures.

5.1.2 The inspection batch of steel structure welding engineering can be divided

into one or several inspection batch according to the division principle of inspection batch of corresponding steel structure production or installation engineering.

5.1.3 Welds shall be cooled to ambient temperature before visual inspection.

Non-destructive testing shall be performed after the visual inspection is qualified. The specific inspection time shall comply with the current national standard "Code for welding of steel structures" GB 50661.

5.1.4 After the welds are welded, they shall be marked on the corresponding

welds and positions according to the welding procedure provisions.

5.2 Welding engineering of steel member

I Main control item

5.2.1 The matching of welding consumables and base metal shall comply with

the requirements of the design documents and the provisions of the current national standards. Before use, welding materials shall be baked and stored in accordance with the product manual and welding process documents.

Inspection quantity. Inspection for all.

Inspection method. Check the quality certificate and baking records.

5.2.2 Licensed welders must perform welding within the approved scope

specified in their welder qualification certificate. Unlicensed welders are strictly prohibited from performing welding.

Inspection quantity. Inspection for all.

Inspection method. Check the welder's qualification certificate and its scope of approval and validity period.

5.2.3 The construction organization shall perform welding procedure

qualification in accordance with the current national standard "Code for welding of steel structures" GB 50661; determine the welding procedure according to the qualification report; compile welding procedure specifications and carry out the whole process quality control.

Inspection quantity. Inspection for all.

Inspection method. Check welding procedure qualification report, welding procedure specification, measurement and record of welding process parameters.

5.2.4 The grade 1 and 2 welds required by the design shall be subjected

to non-destructive testing for internal defects; the quality level and testing requirements of the grade 1 and 2 welds shall meet the requirements of

Table 5.2.4.

Inspection quantity. Inspection for all.

Inspection method. Check the ultrasonic or radiographic inspection records.

6.1 General requirements

6.1.1 This chapter can be used for the quality acceptance of the connection

engineering for ordinary bolts, torsion-shear type high-strength bolts, high-strength large hexagon head bolts, steel grid bolts, high-strength bolts for spherical joints and shooting nails, self-tapping nails, pulling rivets in the production and installation of steel structures.

6.1.2 The fastener connection engineering can be divided into one or several

inspection batches according to the division principle of the inspection batch of the production or installation engineering of corresponding steel structure.

6.2 Connection of ordinary fasteners

I Main control item

6.2.1 When ordinary bolts are used as permanent connecting bolts, when the

design has requirements or their quality is doubtful, the minimum tensile load of the bolts shall be re-inspected. The test method can be implemented in accordance with Appendix B of this standard; the results shall meet the requirements of the current country standard "Mechanical properties of fasteners - Bolts, screws and studs" GB/T 3098.1.

Inspection quantity. 8 bolts of each specification shall be randomly inspected.

Inspection method. Check the physical bolt reinspection report.

6.2.2 The specification size of self-tapping nails, pulling rivets, shooting nails

used to connect the thin steel sheets shall match the connected steel sheets;

meet the design requirements; their spacing and edge distance shall meet the design requirements.

Inspection quantity. 1% of the number of connection joints shall be randomly inspected and shall not be less than 3.

Inspection method. Observation and ruler inspection.

II General items

6.2.3 The fastening of permanent ordinary bolts shall be firm and reliable; the

number of exposed threads shall not be less than 2.

Inspection quantity. 10% of the number of connected nodes shall be randomly inspected and shall not be less than 3.

Inspection method. Observe and check by knocking with a small hammer.

6.2.4 Self-tapping screws, pulling rivets, shooting nails, etc. shall be tightly

attached to the connected steel sheet; it shall be neatly arranged.

Inspection quantity. Randomly inspect 10% of the number of connection joints and shall not be less than 3.

Inspection method. Observe or check by knocking with a small hammer.

7.2 Cutting

I Main control item

7.2.1 The cut surface or shear surface of steel shall be free of cracks, slag

inclusions, burrs and delamination.

Inspection quantity. Inspection for all.

Inspection method. Observe or use a magnifying glass. When in doubt, perform penetrant, magnetic particle or ultrasonic inspection.

II General items

7.2.2 The allowable deviation of gas cutting shall meet the requirements of

Table 7.2.2.

Inspection quantity. Randomly inspect 10% according to the number of cut surfaces and it shall not be less than 3.

Inspection method. Observation inspection or check with steel ruler or feeler gauge.

7.2.3 The allowable deviation of mechanical shearing shall meet the

requirements of Table 7.2.3.The thickness of mechanically sheared parts should not be greater than 12.0 mm; the shearing surface shall be flat. When the ambient temperature of carbon structural steel is lower than -16 °C, and the ambient temperature of low-alloy structural steel is lower than -12 °C, shearing and punching are not allowed.

Inspection quantity. Randomly check 10% of the number of cutting surfaces and shall not be less than 3.

Inspection method. Observation inspection or check with steel ruler or feeler gauge.

7.2.4 The steel pipe rods used for intersecting connection should be cut by a

pipe lathe or a CNC intersecting wire cutting machine. The allowable deviation of the steel pipe rod processing shall meet the requirements of Table 7.2.4.

Inspection quantity. Randomly check 10% of the number of rods and shall not be less than 3.

Inspection method. Observation inspection or check with steel ruler or feeler gauge.

8.1 General requirements

8.1.1 This chapter can be used for the quality acceptance of element assembly

in steel structure production and installation.

8.1.2 The steel structure assembly engineering can be divided into one or

several inspection batches according to the division principle of the inspection batch of steel structure production engineering.

8.1.3 For the assembly of elements, it shall determine a reasonable assembly

sequence according to design requirements, element form, connection mode, welding method and welding sequence.

8.1.4 The splicing of sheets and profiles shall be carried out before the

assembly of elements. The assembly of elements shall be carried out after the components are assembled, welded, rectified and passed inspection. The concealed parts of the elements shall be closed after welding, bolting and painting are qualified.

8.2 Assembling and butting of components

I Main control item

8.2.1 The quality level of welds used when splicing or butting steels and

steel components shall meet the design requirements. When there is no design requirement, penetration welds with a quality level of not less than grade 2 shall be used; for welds that directly bear tensile forces, the grade

1 penetration welds shall be used.

Inspection quantity. Inspection for all.

Inspection method. Check the ultrasonic inspection report.

II General items

8.2.2 The staggered distance between the flange splicing seams and the web

splicing seams of welded H-section steel should not be less than 200 mm. The splicing length of the flange sheet shall not be less than twice the width of the flange sheet and not less than 600 mm. The splicing width of the web shall not be less than 300 mm. The length shall not be less than 600 mm.

Inspection quantity. Inspection for all.

Inspection method. Observe and check with steel ruler.

9.1 General requirements

9.1.1 This chapter can be used for the quality acceptance of test assembling

engineering of steel elements.

9.1.2 The test assembling engineering of steel elements can be divided into

one or several inspection batches according to the division principle of the inspection batch of steel structure fabrication engineering.

9.1.3 The supporting stool or platform used for test assembling shall be

measured and leveled; all temporary fixing and tensioning devices shall be removed during inspection.

9.1.4 The quality of pre-assembled steel elements shall not only meet the

requirements of this standard, but also meet the design requirements.

9.1.5 When using computer simulation to simulate test assembling, the external

dimensions of the simulated elements or units shall be the same as the actual geometric dimensions. When the deviation of test assembling using computer simulation exceeds the relevant requirements of this standard, entity test assembling shall be carried out according to the requirements of this chapter.

9.2 Entity test assembling

I Main control item

9.2.1 For multilayer laminates connected by high-strength bolts and ordinary

bolts, a hole tester shall be used to check the passing rate of bolt holes; it shall meet the following requirements.