GB/T 5224-2023 Steel strand for prestressed concrete
1 Scope
This document specifies the classification, code and designation, order contents, dimensions, sectional shape, weight and permissible deviation, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of steel strand for prestressed concrete.
This document is applicable to the steel strand for prestressed concrete structures made by twisting cold drawn smooth round wire, indented wire and helical rib wire (hereinafter referred to as "steel strand").
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 5223 Steel wires for prestressed concrete
GB/T 21839 Test methods of steel for prestressing concrete
YB/T 081 Rule for rounding off of numberical values and judgment of testing values for technical standards of metallurgy
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
standard strand
steel strand made by twisting cold drawn smooth round wire
3.2
indented strand
steel strand made by twisting indented wire
3.3
helical rib strand
steel strand made by twisting helical rib wire
3.4
compact strand
steel strand made by twisting and then cold drawing
3.5
nominal diameter
nominal dimension of circumscribed circle diameter of steel strand
3.6
stabilizing treatment
short-time heat treatment of the steel strand under a certain tension for a purpose of reducing stress relaxation in application
4 Classification, code and designation
4.1 Classification and code
The general structure of steel strand is classified into the following 9 categories, and the structure codes are:
a) Standard strand made by twisting two cold drawn smooth round wires 1×2
b) Standard strand made by twisting three cold drawn smooth round wires 1×3
c) Indented strand made by twisting three indented wires 1×3I
d) Standard strand made by twisting seven cold drawn smooth round wires 1×7
e) Indented strand made by twisting six indented wires and one cold drawn smooth round central wire 1×7I
f) Helical rib strand made by twisting six helical rib wires and one cold drawn smooth round central wire 1×7H
g) Compact strand made by twisting and then cold drawing seven cold drawn smooth round wires (1×7)C
h) 1+9+9 Seale strand made by twisting nineteen cold drawn smooth round wires 1×19S
i) 1+6+6/6 Warrington strand made by twisting nineteen cold drawn smooth round wires 1×19W
4.2 Designation
Contents
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Classification, code and designation
4.1 Classification and code
4.2 Designation
5 Order contents
6 Dimensions, sectional shape, weight and permissible deviation
7 Technical requirements
7.1 Manufacture
7.2 Mechanical properties
7.3 Surface quality
7.4 Straightness of steel strand
7.5 Fatigue, deflected tensile and stress corrosion properties
8 Test methods
8.1 Surface inspection
8.2 Boundary dimension inspection
8.3 Measurement and calculation of amplification ratio of central wire diameter of 1×7 steel strand
8.4 Tensile test
8.5 Straightness
8.6 Measurement and calculation of nominal weight deviation per meter
8.7 Stress relaxation property test
8.8 Fatigue test
8.9 Deflected tensile test
8.10 Stress corrosion test
8.11 Rounding off for numerical values
9 Inspection rules
9.1 Inspection classification
9.2 Delivery inspection
9.3 Characteristic value inspection
10 Packaging, marking and quality certificate
10.1 Packaging
10.2 Marking
10.3 Quality certificate
Annex A (Normative) Inspection rules for characteristic values
A.1 Test batching
A.2 Sampling and inspection quantity per batch
A.3 Evaluation of test results
Bibliography
