1.1 This standard specifies terms and definitions, manufacturing process and delivery conditions, classification and designations, technical requirements, overall dimension and sectional properties, delivery weight, delivery length, test methods, acceptance rules, packing, marking, quality certificate, etc. of cold-formed steel hollow sections for building structures.
1.2 This standard is applicable to cold-formed welded steel hollow sections for building structures, also for other structures such as bridges; Grade I steel hollow sections are applicable to primary member in building and bridge structures and to the conditions bearing relatively large dynamic load; Grade II steel hollow sections are applicable to general load bearing capacity in building structures.
2 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. For undated references, the latest edition of the normative document referred to applies.
GB/T 222 "Method of Sampling Steel for Determination of Chemical Composition and Permissible Variations for Product Analysis"
GB/T 223 "Methods for Chemical Analysis of Iron, Steel and Alloy"
GB/T 228 "Metallic Materials-Tensile Testing at Ambient Temperature"
GB/T 229 "Metallic Materials-Charpy Notch Impact Test"
GB/T 699-1988 "Specification for Quality Carbon Structural Steels"
GB/T 700 "Carbon Structural Steels"
GB/T 714 "Structural Steel for Bridge"
GB/T 1591 "High Strength Low Alloy Structural Steels"
GB/T 2101 "General Requirement of Acceptance Packaging, Marking and Certification for Section Steel"
GB/T 2975 "Steel and Steel Products-Location and Preparation of Test Pieces for Mechanical Testing"
GB/T 3075 "Method of Axial Force Controlled Fatigue Testing of Metals"
GB/T 4171 "Superior Atmospheric Corrosion Resisting Structural Steel"
GB/T 7735 "Steel Tubes-The Inspection Method on Eddy Current Test"
GB/T 11345 "Method for Manual Ultrasonic Testing and Classification of Testing Results for Ferritic Steel Welds"
GB/T 17505 "Steel and Steel Products-General Technical Delivery Requirements"
3 Terms and Definitions
For the purposes of this standard, the following terms and definitions apply.
3.1
Direct forming square
A forming method to directly conduct continuous bend angle deformation for cold-rolled or hot-rolled steel strip to form steel hollow sections after high frequency welding, which is also known as square-to-square forming.
3.2
Round to square forming
A forming method to directly conduct continuous flexural deformation for cold-rolled or hot-rolled steel strip to form round tube after high frequency welding and finally form steel hollow sections through shaping, which is also known as round-to-square forming.
3.3
Concavo-convex
Height depressed or raised along the width direction of the same surface of cold-formed steel hollow sections, see Figure 3.
3.4
Curving
Maximum axial bending height of cold-formed steel hollow sections along length direction, see Figure 4.
3.5
Twisting
Place one surface of cold-formed steel hollow sections on one horizontal plane, compress one end tightly on the horizontal plane, and determine the height between corresponding angles of two opposite surfaces along the horizontal plane which is taken as the reference, see Figure 5.
4 Ordering Information
The order contract or order according to this standard shall include the following content:
a) Standard number;
b) Product specification;
c) Steel grade designation of raw material and yield strength grade of corresponding product;
d) Product property and quality requirement grade;
e) Delivery weight (actual weight or theoretical weight) and delivery length;
f) Agreement requirements.
