Foreword
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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces JG/T 161-2004 Unbonded prestressing steel strand, and the following main technical changes have been made with respect to JG/T 161-2004:
——Terms and definitions and symbols have been modified (see Clause 3 hereof; Clause 3 of Edition 2004);
——The clause "General requirements" has been added (see Clause 5 hereof);
——"Materials" has been deleted (see 5.1 of Edition 2004);
——Requirements for anticorrosion lubricating coating have been modified, (see 6.4 hereof; 5.1.2 of Edition 2004);
——Sheathing properties and test method have been modified (see 6.5 and 7.4 hereof; 5.1.3 and 6.3 of Edition 2004);
——Value and test method of the friction coefficient have been modified (see 6.6 and Annex B hereof; 5.2 and 6.4 of Edition 2004);
——The inspection classification has been modified (see 8.1 hereof; 7.1 of Edition 2004);
——Inspection items have been modified (see 8.2 hereof; 7.2 of Edition 2004);
——The rules of raw material batching, sampling and judgment have been deleted (see 7.3 of Edition 2004);
——The rules of batching, sampling and judgment have been modified (see 8.3 hereof; 7.4 of Edition 2004);
——The storage has been modified (see 10.2 hereof; 8.4 of Edition 2004);
——The original annex "Acceptance and application instructions" has been deleted (see Annex A of Edition 2004);
——The annex "Test method for tensile properties of sheathing" has been added (see Annex A hereof).
This standard was proposed by the Research Institute of Standards and Norms of Ministry of Housing and Urban-Rural Development.
This standard is under the jurisdiction of the Technical Committee of Standardization Administration of the Ministry of Housing and Urban-Rural Development.
The previous editions of this standard are as follows:
——JG 3006-1993;
——JG 161-2004.
Unbonded prestressing steel strand
1 Scope
This standard specifies the terms and definitions, symbols and designation, general requirements, requirements, test methods, inspection rules, marking, packaging, quality certificate, transportation and storage of unbonded prestressing steel strand.
This standard is applicable to unbonded prestressing steel strands used in post-tensioned prestressing concrete structures.
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 5224 Steel strand for prestressed concrete
GB/T 11115 Polyethylene(PE) resin
GB/T 17200 Technical specification for tensile compression and flexural testing machines for rubber and plastics (constant rate of traverse)
JG/T 430 Anticorrosion lubricating grease for unbonded tendons
3 Terms, definitions and symbols
For the purposes of this document, the following terms and definitions apply.
3.1 Terms and definitions
3.1.1
unbonded prestressing steel strand
prestressing steel strand coated with anticorrosion lubricating coating, enveloped by sheathing, which can slide permanently against sheathing
3.1.2
prestressing steel strand
steel strand twisted from cold drawn round wire
3.1.3
anticorrosion lubricating coating
coating applied to the surface of prestressing steel strand to prevent corrosion and reduce friction between steel strand and sheathing.
3.1.4
sheathing
sleeve wrapped around a prestressing steel strand and an anticorrosion lubricating coating to protect the prestressing steel strand from corrosion and to prevent bonding with surrounding concrete
3.1.5
tensile stress at yield
initial stress, from which the specimen stress does not increase but the strain increases in the tensile process
3.1.6
nominal tensile strain at break
increment of the original length of the distance between the two fixtures when the specimen breaks after yielding during stretching, expressed as a percentage (%)
3.2 Symbols
κ——considering the influence coefficient of local deviation of sheath wall (per meter) of unbonded prestressing steel strand on friction;
μ——friction coefficient between steel strand and sheathing wall in unbonded prestressing steel strand.
4 Designation
The designation of unbonded prestressing steel strand consists of product name code, nominal diameter of steel strand, nominal tensile strength of steel strand and standard number:
Examples:
Unbonded prestressing steel strands with nominal diameter of 15.20 mm and nominal tensile strength of 1860 MPa shall be designated as:
UPS 15.20 1860 JG/T 161 2016
Foreword i
1 Scope
2 Normative references
3 Terms, definitions and symbols
4 Designation
5 General requirements
6 Requirements
7 Test methods
8 Inspection rules
9 Marking, packaging and quality certification documents
10 Transportation and storage
Annex A (Normative) Test method for tensile properties of sheathing
Annex B (Normative) Test method for determination of friction coefficient
