1、Designation: A779/A779M 16Standard Specification forSteel Strand, Seven-Wire, Uncoated, Compacted forPrestressed Concrete1This standard is issued under the fixed designation A779/A779M; the number immediately following the designation indicates the yearof original adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This specification covers two types and three grades ofcompacted, seven-wire, uncoated strand for use
3、in prestressedconcrete construction. The two types of strand are low-relaxation and stress-relieved (normal-relaxation). The threegrades are 245 1700, 260 1800 and 270 1860.1.2 This specification is applicable for orders in eitherinch-pound units (as Specification A779) or in SI units (asSpecificati
4、on A779M).1.3 The values stated in either inch-pound or SI units are tobe regarded as standard. Within the text, the SI units are shownin brackets. The values stated in each system may not be exactequivalents; therefore, each system shall be used independentlyof the other. Combining values from the
5、two systems mayresult in non-conformance with the specification.2. Referenced Documents2.1 ASTM Standards:2A751 Test Methods, Practices, and Terminology for Chemi-cal Analysis of Steel ProductsA994 Guide for Editorial Procedures and Form of ProductSpecifications for Steel, Stainless Steel, and Relat
6、edAlloysA1061/A1061M Test Methods for Testing Multi-Wire SteelPrestressing Strand2.2 U.S. Military Standard3MIL-STD-129 Marking for Shipment and Storage2.3 U.S. Federal Standard3Fed. Std. No. 123 Marking for Shipments (Civil Agencies)3. Terminology3.1 Definitions of Terms Specific to This Standard:3
7、.1.1 compacted strandstrand that has been compacted bydrawing through a die or a similar compacting process andsubsequently stress-relieved prior to winding into reels orreelless packs.3.1.2 lotall of the compacted strand of the same grade inthe reels or reelless packs produced on the same productio
8、nequipment and submitted for inspection at the same time.3.1.3 stranda group of wires having a center wire en-closed tightly by six helically placed outer wires with auniform pitch of not less than 14 and not more than 18 timesthe nominal diameter of the strand.4. Classification4.1 Grade 245 1700Nom
9、inal diameter of 0.7 in. 18.0mm with tensile strength of 247 ksi 1705 MPa based onnominal area of the strand.4.2 Grade 260 1800Nominal diameter of 0.6 in. 15.2mm with tensile strength of 263 ksi 1815 MPa based onnominal area of the strand.4.3 Grade 270 1860Nominal diameter of 0.5 in. 12.7mm with ten
10、sile strength of 270 ksi 1860 MPa based onnominal area of the strand.5. Ordering Information5.1 It shall be the responsibility of the purchaser to specifyall requirements that are necessary for material ordered to thisspecification. Such requirements to be considered include, butare not limited to,
11、the following:5.1.1 Quantity (feet metres),5.1.2 Type of strand (low-relaxation or stress-relieved(normal-relaxation),5.1.3 Grade and nominal diameter of strand (Section 4),5.1.4 Load-elongation curve, if desired (12.2.1),5.1.5 Outside inspection, if required (Section 13),5.1.6 Packaging (16.1), and
12、5.1.7 ASTM designation and date of issue.1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.05 on Steel Reinforcement.Current edition approved Sept. 1, 2016. Published September 2016. Ori
13、ginallyapproved in 1980. Last previous edition approved in 2012 as A779/A779M 12.DOI: 10.1520/A0779_A0779M-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the st
14、andards Document Summary page onthe ASTM website.3Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/dodssp.daps.dla.mil.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 10
15、0 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16. Materials and Manufacture6.1 The steel shall be of such quality that, when processed,the finished wire shall be free of detrimental flaws and unduesegregation.6.2 Wire from which the strand is to be fabricated shall
16、 bein the cold-drawn condition and have a common dry-drawnfinish.6.3 After stranding and compacting, all low-relaxationstrand shall be subjected to a continuous thermal-mechanicaltreatment to produce the prescribed mechanical properties. Forstress-relieved (normal-relaxation) strand, only thermal tr
17、eat-ment is necessary. Temper colors which result from thestress-relieving operation are considered normal for the fin-ished appearance of this strand.7. Chemical Requirements7.1 The chemical analysis of each heat shall be determinedin accordance with Test Methods, Practices, and TerminologyA751.7.2
18、 Variations in production processes and equipment ne-cessitate the individual selection of an appropriate chemicalcomposition at the discretion of the manufacturer.7.3 Phosphorus and sulfur values shall not exceed thefollowing:Phosphorus 0.040 % maxSulfur 0.050 % max8. Mechanical Property Requiremen
19、ts8.1 Tests for mechanical properties shall be conducted inaccordance with Test Methods A1061/A1061M.8.2 Breaking StrengthThe breaking strength of the fin-ished strand shall conform to the values specified in Table 1.8.3 Yield StrengthYield strength in pounds kN shall bemeasured at 1 % extension und
20、er load. The minimum load at1 % extension shall conform to the specified values shown inTable 2. Initial loads are listed in Table 2.8.3.1 The extension under load shall be measured by anextensometer calibrated with the smallest division not largerthan 0.0001 in. /in. 0.0001 mm/mm of gage length.8.4
21、 ElongationThe total elongation of the strand undermaximum load shall not be less than 3.5 % using a gage lengthof not less than 24 in. 600 mm. It shall be permissible todetermine the total elongation value by adding, to the 1.0 %yield extension, the percent extension or movement betweenthe jaws gri
22、pping the strand after yield determination. Thepercent is calculated on the new base length of jaw-to-jawdistance.8.5 Relaxation PropertiesLow-relaxation strand shallhave relaxation losses of not more than 2.5 % when initiallyloaded to 70 % of specified minimum breaking strength after1000 hours of t
23、esting.8.5.1 If required, relaxation evidence shall be provided fromthe maufacturers records of tests on similarly dimensionedstrand of the same grade.9. Dimensions and Permissible Variations9.1 The size of the finished strand shall be expressed as thenominal diameter of the strand in inches millime
24、tres.9.2 Prior to compacting, the diameter of the center wire ofany strand shall be larger than the diameter of any outer wireby a minimum of 2 %.9.3 After compacting, the strand shall conform to a sizetolerance of plus 0.016 in. 0.4 mm or minus 0.008 in. 0.2mm from the nominal diameter when measure
25、d across thecrowns of the wire.10. Workmanship10.1 Joints:10.1.1 There shall be no strand joints or strand splices in anylength of the completed strand.10.1.2 During the process of manufacture of individualwires for stranding, welding shall be permitted only prior to thestart of wire drawing.10.2 Th
26、e finished compacted strand shall be uniform indiameter and shall be free of imperfections.10.3 When the strand is cut without seizings, the wires shallnot fly out of position. If a wire or wires flies out of positionand can be replaced by hand, the strand will be consideredsatisfactory.10.4 The str
27、and shall not be oiled or greased. Slight rusting,provided it is not sufficient to cause pits visible to a person withnormal or corrected vision, shall not be cause for rejection.10.5 Curvature of the finished compact strand shall be notmore than 3 in. 75 mm in a length of 3 ft 1 m when lyingon a fl
28、at surface.11. Sampling11.1 Test specimens cut from either end of reels or reellesspacks are permitted.TABLE 1 Breaking Strength RequirementsNominal Diameter of Strand Specified MinimumBreaking Strengthof Strand, lbf kNNominal Steel Area of Strand Nominal Mass (Weight) ofStrands lb/1000 ft kg/1000 m
29、in. mm in.2mm2Grade 270 18600.5 12.7 47 000 209 0.174 112 600 890Grade 260 1800(0.6 15.2 67 440 300 0.256 165 873 1295Grade 245 17000.7 18.0 85 430 380 0.346 223 1176 1750A779/A779M 16212. Number of Tests12.1 One test specimen shall be taken from each 30-ton27-tonne production lot of finished strand
30、, and tested forbreaking strength, yield strength, and elongation.12.2 Typical load-elongation curves, based on accumulateddata, shall be delivered to the purchaser on each lot shipped.12.2.1 When specified in the purchase order or contract, aload-elongation curve shall be made from one test specime
31、nrepresenting the lot.13. Inspection13.1 If outside inspection is required, the manufacturer shallafford the inspector representing the purchaser reasonableaccess to the facilities, which concern the manufacture of thematerial ordered, to satisfy the inspector that the material beingfurnished is in
32、accordance with this specification. All tests andinspections shall be made at the place of manufacture prior toshipment, and shall be so conducted as not to interfereunnecessarily with the manufacturers operations.14. Rejection14.1 Failure of any test specimen to comply with therequirements of the s
33、pecification shall constitute grounds forrejection of the lot represented by the specimen.14.2 The lot shall be resubmitted for inspection by testing aspecimen from each reel or reelless pack and sorting outnon-conforming material.14.3 If there is a reasonable doubt in the initial testing as tothe a
34、bility of the strand to meet any requirement of thisspecification, two additional tests shall be made on specimensof strand from the same reel or reelless pack, and if failureoccurs in either of these tests, the strand shall be rejected.15. Certification15.1 If outside inspection is not required, a
35、manufacturerscertification that the material has been tested in accordancewith, and meets the requirements of this specification, shall bethe basis of acceptance of the material. The certification shallinclude the specification number, year-date of issue, andrevision letter, if any.15.2 A material t
36、est report, certificate of inspection, orsimilar document printed from or used in electronic form froman electronic data interchange (EDI) transmission shall beregarded as having the same validity as a counterpart printed inthe certifiers facility. The content of the EDI transmitteddocument shall me
37、et the requirements of the invoked ASTMstandard(s) and conform to any existing EDI agreement be-tween the purchaser and the manufacturer. Notwithstanding theabsence of a signature, the organization submitting the EDItransmission is responsible for the content of the report.NOTE 1The industry definit
38、ion as invoked here is: EDI is thecomputer-to-computer exchange of business information in a standardformat such as ANSI ASC X12.16. Packaging and Package Marking16.1 The strand shall be furnished on reels or in reellesspacks having a minimum inside diameter of 36 in. 910 mm.The length of strand on
39、reels or reelless packs shall be asagreed upon at time of purchase. The strand shall be wellprotected from mechanical damage during shipment. Each reelor reelless pack shall have two durable tags securely fastenedto it showing the grade, length, type (low-relaxation orstress-relieved (normal-relaxat
40、ion), lot number, ASTM A779/A779M, and the name of the manufacturer. One tag shall bepositioned where it will not be inadvertently lost during transit,such as the core of a reelless pack. The other tag shall be placedon the outside for easy identification. Special packaging,protection, or tagging sh
41、all be agreed upon between thepurchaser and manufacturer at the time of purchase.16.2 When specified in the contract or purchase order, andfor direct procurement by or direct shipment to the U.S.government, marking for shipment, in addition to requirementsspecified in the contract or purchase order,
42、 shall be in accor-dance with Fed. Std. No. 123 for civil agencies and MIL-STD-129 for military agencies.17. Keywords17.1 compacted strand (tendon); prestressed concrete; steelwireTABLE 2 Yield Strength RequirementsNominal Strand Diameter Initial Load,lbf kNSpecified MinimumLoad at 1 %Extension, lbf
43、 kNin. mm Normal-Relaxation Low-RelaxationGrade 270 18600.5 12.7 4700 20.9 40 900 182 42 300 188Grade 260 18000.6 15.2 6740 30.0 58 700 261 60 700 270Grade 245 17000.7 18.0 8540 38.0 74 300 330 76 900 342A779/A779M 163SUMMARY OF CHANGESCommittee A01 has identified the location of selected changes to
44、 this standard since the last issue(A779/A779M 12) that may impact the use of this standard. (Approved Sept. 1, 2016.)(1) Revised 12.1.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this stand
45、ard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andi
46、f not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, wh
47、ich you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
48、United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 164
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