GB 50755-2012Code for Construction of Steel Structures (English PDF)

1.0.1 This Code is formulated with a view to implementing the national technical

and economic policies in the construction of steel structures and achieving safety and usability, guaranteed quality, advanced technology, and economy and rationality.

1.0.2 This Code is applicable to construction of steel structures in industrial and civil buildings and structures.

1.0.3 The construction of steel structures shall be carried out according to those specified in this Code and quality acceptance shall be carried out for it according to the current national standards of "Unified Standard for Constructional Quality Acceptance of Building Engineering" (GB 50300) and "Code for Acceptance of Construction Quality of Steel Structures" (GB 50205).

1.0.4 The construction of steel structures shall not only meet the requirements of this Code, but also comply with those in the current relevant standards of the nation.

2.1 Terms

2.1.1 Design document

A general term for such technical documents as design drawing, design instruction and design change completed by the design organization.

2.1.2 Design drawing

The technical drawing prepared by the design organization as the engineering construction basis.

2.1.5 Temporary measure

Some necessary structures or temporary parts and member bars, such as lifting hole, connecting plate and auxiliary member that are arranged with a view to meeting the construction demands and guaranteeing engineering safety during the construction period.

2.1.12 Test assembling

The test assembling carried out in advance to inspect whether the shape and dimension of the member meet the quality requirements.

2.1.13 Ambient temperature

The temperature at the site during the fabrication or installation

2.2 Symbols

2.2.1 Geometric parameters

2.2.3 Other

3.0.2 Before the construction of the steel structures, technical documents such

as construction organization design and its supporting specific construction plan approved by the technical principal of the construction organization shall be provided and submitted to the supervision engineer or the Owner's representative according to the relevant requirements; experts shall be organized to review the technical plan and safety emergency plan for the construction of important steel structures.

3.0.7 For the construction of steel structures, quality process control shall be carried out according to the following requirements.

4.1 General Requirements

4.1.1 This Chapter is applicable to the design of steel structure construction

stage, including structure analysis and checking, design for the preset structure deformation and detail drawing design.

4.2 Structure Analysis of Construction Stage

4.2.1 When the construction method or sequence of steel structures has larger

influence on their internal force and deformation or special requirements are made in the design documents, the structure analysis of construction stage shall be carried out;

4.3 Preset Deformation of Structure

4.3.1 During the normal use or in the construction stage, when any deformation

due to the deadweight and other load action exceeds the limit specified in the design documents or current relevant standards of the nation or preset deformation requirements are made for the major structure in the design documents, preset deformation shall be adopted for the structure during the construction period.

4.4 Detail Design

4.4.1 The detail drawing for construction of steel structures shall be prepared according to structure design documents and relevant technical documents and shall be confirmed by the original design organization; where the connection design is necessary, the connection design document also shall be confirmed by the original design organization.

4.4.2 The detail design of steel structures shall meet relevant technical requirements such as construction structures, construction process and member transportation.

4.4.3 The detail drawing for construction of steel structures shall include drawing list, general design description, member layout, detail drawing for the member and connection installation etc.

4.4.4 The member weight shall be calculated and listed in the detail drawing for construction of steel structures;

5.1 General Requirements

5.1.1 This Chapter is applicable to ordering, site acceptance, re-inspection and storage management of steel structure materials.

5.1.2 Materials used in the steel structures shall meet the requirements of design documents and current relevant standards of the nation;

5.2 Steel Materials

5.2.1 When the steel materials are ordered, the variety, specification and performance shall meet the requirements of the design documents and current standards of the nation with regard to steel materials; the standards of common steel products should be adopted according to those specified in Table 5.2.1.

5.2.3 The site acceptance for the steel materials shall not only meet those

5.2.4 The re-inspection for the steel materials shall cover the mechanical performance test and chemical composition analysis;

5.3 Welding Materials

5.3.1 The variety, specification and performance of welding materials shall meet the requirements of the current relevant product standards of the nation and the design requirements.

5.5 Steel Castings, Anchorages and Pins

5.5.1 Casting materials selected for the steel castings shall meet the requirements of the standards listed in Table 5.5.1 and the design document.

5.5.2 The prestress steel structure anchorages shall be selected according to the variety, anchorage requirements and pretension process etc.;

5.5.3 The specification and performance of the pins shall meet the relevant requirements of the design document and the current national standard "Clevis Pin with Head" (GB/T 882).

5.6 Coating Materials

5.7 Material Storage

5.7.1 Specified person, who should take the enterprise training, shall be assigned to be in charge of the management of material storage and finished products.

6.1 General Requirements

6.1.1 This Chapter is applicable to constructions such as shielded metal arc

welding, gas shielded arc welding, submerged arc welding, electroslag welding and stud welding during the construction of steel structures.

6.1.2 The construction organization of steel structures shall meet basic conditions and personnel qualification of the current national standard "Code for Welding of Steel Structures" (GB 50661).

6.2 Welding Personnel

6.2.1 Welding technician (welding engineer) shall be provided with corresponding qualification certificate; for large and important steel structures, the welding technical principal shall obtain intermediate technical title or above and have over five-year welding production or construction experience.

6.2.2 The welding quality inspectors shall have received the welding technology

6.3 Welding Procedure

I Welding Procedure Qualification and Scheme

6.3.1 For parameters such as the steel materials, welding materials, welding method, joint type, welding position and post-weld heat treatment as well as combination of parameters that are firstly adopted by the construction organization, the welding procedure qualification test shall be carried out before the fabrication and installation of steel structures.

6.3.5 Before welding, tools such as wire brush and grinding wheel shall be adopted to remove the foreign bodies such as scale, rust and oil stain on the surface to be welded; the weld groove should be inspected according to the relevant requirements of the current national standard "Code for Welding of Steel Structures" (GB 50661).

6.3.15 The adopted welding procedure and sequence shall minimize the member deformation and shrinkage and the following welding sequences to control the deformation may be adopted.

7.1 General Requirements

7.1.1 This Chapter is applicable to connection of fasteners such as ordinary bolt

in the manufacturing and installation of steel structures, tor-shear type high strength bolt, high strength large hexagon head bolt, high strength bolts for bolted spherical node of steel space frame, rivet and tapping screw and fastener.

7.2 Preparation of Connecting Pieces and Friction Surface Treatment

7.2.1 The bolt holes of connecting pieces shall be prepared according to the relevant requirements of Chapter 8 in this Code;

7.3 Connection of Ordinary Fasteners

7.3.1 Ordinary bolt may be fastened with an ordinary spanner so that the contact surface of the connected piece, bolt head and nut are closely contacted with the member surface. The ordinary bolt shall be fastened firstly from the middle and then to both sides in symmetry. In addition, secondary screwing should be adopted for large joint.

7.3.2 When the ordinary bolt is regarded as a permanent connecting bolt, the fastening shall meet the following requirements.

8.1 General Requirements

8.1.1 This Chapter is applicable to the processing of parts and components in the fabrication of the steel structures.

8.2 Setting out and Marking-off

8.2.1 The setting out and marking-off shall be carried out according to the detail drawing for construction and process document; and an allowance shall be reserved as required.

8.3 Cutting

8.3.1 Gas cutting, mechanical cutting and plasma cutting methods may be adopted for the cutting of the steel materials; the selected cutting method shall meet the requirements of the process document and the flash and burr after cutting shall be cleaned up.

8.3.5 The thickness of the parts under mechanical shearing should be less than or equal to 12.0 mm; the cut surface shall be flat and smooth. 8.7 Processing of Bolted Spheres and Welded Hollow Spheres

8.7.1 Hot forging should be adopted for the formation of bolted spheres; heating

temperature should be 1150 °C ~ 1250 °C. The final forging temperature shall be greater than or equal to 800 °C. The bolted spheres after formation shall be free from crack, wrinkle and over-burning.

8.8 Processing of Cast Steel Node

8.8.1 Casting process and processing quality of the cast steel node shall meet

the requirements of the design document and current relevant standards of the nation.

8.9 Processing of Rope Nodes

8.9.1 Rope nodes may be processed into a blank by methods such as casting, forging and welding, subject to the machining such as turning, milling, planing, drilling and boring.

9.1 General Requirements

9.1.1 This Chapter is applicable to assembling and processing of members in the fabrication and installation process of the steel structures.

9.1.5 Reasonable member assembling sequence shall be determined

according to the design requirements, member type, connecting mode, welding method and welding sequence.

9.1.6 Concealed position of the member shall be closed after the welding and coating are qualified in the inspection; and coating may be omitted for the internal surface of the fully-closed member.

9.2 Assembling of Components

9.2.1 The spacing between the assembling joints of the welded H steel flange plate and the web plate should be greater than or equal to 200 mm.

9.3 Assembling of Members

9.3.1 The member should be assembled on the assembly platform, support or special equipment. The assembly platform and support shall not only have adequate strength and stiffness, but also be convenient for assembling/disassembling and positioning. On the assembly platform or support, reference lines such as the center line of the member, position line of end face, contour line and elevation line should be drawn.

9.5 Rectification of Members

9.5.1 The member shape should be rectified according to sequences from the overall to the local, from the primary to the secondary and from the lower to the upper.