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GB/T 6728-2017 English PDF (GBT6728-2017)

GB/T 6728-2017 English PDF (GBT6728-2017)

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GB/T 6728-2017: Cold forming hollow sectional steel for general structure

This Standard specifies the ordering content, classification, code, cross-section, dimension and permissible deviation, length and permissible deviation, shape, weight and permissible deviation, technical requirements and marking example of cold forming hollow sectional steel for general structure. This Standard is applicable to round, rectangular and square cold forming hollow sectional steel (hereinafter referred to as sectional steel) made of cold-rolled or hot-rolled steel plates, sheets and strips on continuous roll cold forming units. It is also applicable to continuous hot-dip plated sectional steel. However, it is not applicable to sectional steel made by drawing, stamping, bending, etc., and sectional steel made of galvanized steel plates, sheets and strips which are cold-formed and welded.
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.140.70 H 44
GB/T 6728-2017
Replacing GB/T 6728-2002
Cold forming hollow sectional steel for general structure
Issued on. July 12, 2017 Implemented on. April 01, 2018
Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China; Standardization Administration of the People's Republic of China. Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Ordering content ... 4
4 Classification, code ... 5
5 Cross-section, dimension and permissible deviation ... 5
6 Length and permissible deviation ... 23
7 Shape ... 24
8 Weight and permissible deviation ... 25
9 Technical requirements ... 25
10 Marking example ... 26
Annex A (informative) Formulae for calculating cross-sectional characteristics ... 27
Bibliography ... 29
Foreword
This Standard is drafted in accordance with the rules given in GB/T 1.1-2009. This Standard replaces GB/T 6728-2002 ?€?Cold formed steel hollow sections for general structure -Dimensions, shapes, weight and permissible deviations?€?, compared with GB/T 6728-2002, main changes are as follows. MODIFY the standard name;
DELETE the relevant specifications for shaped tubes;
ADD the specification of thin-walled sectional steel;
ADD the relevant specifications for the side verticality;
- MODIFY the relevant specifications for the bending degree;
-ADD the relevant specifications for the technical requirements.
This Standard was proposed by China Iron and Steel Association.
This Standard shall be under the jurisdiction of National Technical Committee on Steel of Standardization Administration of China (SAC/TC 183). Drafting organizations of this Standard. China Metallurgical Information and Standardization Institute, Tianjin Youfa Steel Pipe Group Co., Ltd., Handan Zhengda Pipe Manufacturing Co., Ltd., Wuhan Iron and Steel Jiangbei Group Cold-formed Sections Co., Ltd., Taian Tongtaixing Metal Structure Manufacturing Co., Ltd., Shanxi Dingrong Cold-formed Sections Co., Ltd., Tangshan Jinghua Pipe Manufacturing Co., Ltd. Main drafters of this Standard. Wang Yujie, Zhang Songming, Jiang Haidong, Zhu Shaowen, Zhao Yong, Niu Yun, Wen Chaojiang, Liu Baoshi, Ding Xiuchen, Li Yi, Sheng Zhenjian, Li Juncai, Song Yuguang, Liu Chunlei, Wang Yalin, Zhang Sheng. The previous released versions replaced by this Standard are as follows. - GB/T 6728-1986, GB/T 6728-2002.
Cold forming hollow sectional steel for general structure
1 Scope
This Standard specifies the ordering content, classification, code, cross-section, dimension and permissible deviation, length and permissible deviation, shape, weight and permissible deviation, technical requirements and marking example of cold forming hollow sectional steel for general structure. This Standard is applicable to round, rectangular and square cold forming hollow sectional steel (hereinafter referred to as sectional steel) made of cold-rolled or hot-rolled steel plates, sheets and strips on continuous roll cold forming units. It is also applicable to continuous hot-dip plated sectional steel. However, it is not applicable to sectional steel made by drawing, stamping, bending, etc., and sectional steel made of galvanized steel plates, sheets and strips which are cold-formed and welded. The sectional steel specified in this Standard mainly adopts high-frequency resistance welding method. It may also adopt argon arc welding or other welding methods. 2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 6725 General requirements of cold forming steel sections
3 Ordering content
Contracts or orders ordered in accordance with this Standard shall include the following. a) Standard number;
b) Product name;
c) Grade; d) Delivery weight;
e) Dimension and shape;
f) Special requirements.
4 Classification, code
The sectional steel is divided into square, rectangular and round sectional steel according to the shape. The code name is. 1) Square sectional steel, also referred to as square tube, code. F;
2) Rectangular sectional steel, also referred to as rectangular tube, code. J; 3) Round sectional steel, also referred to as round tube, code. Y (or ??). 5 Cross-section, dimension and permissible deviation
5.1 The cross-sectional view of square sectional steel is shown in Figure 1. The cross-sectional dimension, permissible deviation, cross-sectional area, theoretical weight and cross-sectional characteristics shall comply with the specifications of Table 1. 5.2 The cross-sectional view of rectangular sectional steel is shown in Figure 2. The cross-sectional dimension, permissible deviation, cross-sectional area, theoretical weight and cross-sectional characteristics shall comply with the specifications of Table 2. 5.3 The cross-sectional view of circular sectional steel is shown in Figure 3. The cross-sectional dimension, permissible deviation, cross-sectional area, theoretical weight and cross-sectional characteristics shall comply with the specifications of Table 3. 5.4 The cross-sectional dimension, cross-sectional area, permissible deviation, theoretical weight and cross-sectional characteristics of thin-walled sectional steel may be in accordance with the relevant specifications of GB 50018. 5.5 According to the requirements of the demand party, sectional steel other than those listed in Table 1, Table 2 and Table 3 may be provided. The dimension permissible deviation shall be in accordance with the deviation of the adjacent small dimensions in the table. The cross-sectional characteristics may be calculated in accordance with Annex A. 5.6 The permissible deviation of the wall thickness of sectional steel shall not Annex A
(informative)
Formulae for calculating cross-sectional characteristics
Table 1, Table 2 and Table 3 in Clause 5 give the nominal cross-sectional characteristics within the standard dimension range of cold forming square, rectangular and round hollow sectional steel. The nominal cross-sectional characteristics of cold forming round, square and rectangular hollow sectional steel of other dimensions and thicknesses for general structure may be calculated according to the formulae in Table A.1 and Table A.2. Table A.1 -- Round hollow sectional steel
Item Symbol Unit Calculation formula
Nominal outer circle diameter D mm ?€?
Nominal thickness t mm ?€?
Nominal inner circle diameter d mm d = D - 2t
Surface area per meter length As m2/m As = ?€D/103
Cross-sectional area A cm2 A = ?€(D2 -d2)/(4 ?? 102)
Weight per unit length M kg/m M = 0.785 ?? A
Moment of inertia I cm4 I = ?€(D4 -d4)/(64 ?? 104)
Radius of gyration R cm R = (I/A)1/2
Elastic modulus Z cm3 Z = (2I ?? 10)/D
Plastic modulus S cm3 S = (D3 -d3)/(6 ?? 103)
Torsional inertia J cm4 J = 2I
Torsional modulus C cm3 C = 2Z
Table A.2 -- Square and rectangular hollow sectional steel
Item Symbol Unit Calculation formula
Nominal length of short side B mm ?€?
Nominal length of long side H mm ?€?
Nominal thickness t mm ?€?
Nominal outer corner radius R mm When t ??? 6 mm, R = 2.0t When 6 < t ??? 10 mm, R = 2.5t When t > 10 mm, R = 3.0t Nominal inner corner radius r mm r = R -t
Weight per unit length M kg/m M = 0.785A
Cross-sectional area A cm2

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