1、Designation: A779/A779M 10Standard Specification forSteel Strand, Seven-Wire, Uncoated, Compacted, Stress-Relieved for Prestressed Concrete1This standard is issued under the fixed designation A779/A779M; the number immediately following the designation indicates the yearof original adoption or, in t
2、he case of revision, 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 describes three grades of compacted,seven-wire, uncoated, stress-
3、relieved strand for use in pre-tensioned and post-tensioned prestressed concrete construc-tion.1.2 Supplement I describes low-relaxation strand and low-relaxation testing.1.3 The values stated in either inch-pound or SI units are tobe regarded as standard. Within the text, the inch-pound unitsare sh
4、own in parentheses. The values stated in each system arenot exact equivalents; therefore, each system shall be usedindependently of the other, without combining values in anyway.2. Referenced Documents2.1 ASTM Standards:2A751 Test Methods, Practices, and Terminology for Chemi-cal Analysis of Steel P
5、roductsA1061/A1061M Test Methods for Testing Multi-Wire SteelStrand3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 compacted strandstrand that has been compacted bydrawing through a die or a similar compacting process andsubsequently stress-relieved prior to winding into coils
6、 orreelless packs.3.1.2 lotall of the compacted strand of the same grade andpackage size produced on the same production equipment andsubmitted 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
7、of not less than 14 and not more than 18 timesthe nominal diameter of the strand.4. Classification4.1 Grade 1700 (245)Nominal diameter of 18.0 mm (0.7in.) with tensile failure stress of 1705 MPa (247 ksi) based onnominal area of the strand.4.2 Grade 1800 (260)Nominal diameter of 15.2 mm (0.6in.) wit
8、h tensile failure stress of 1815 MPa (263 ksi) based onnominal area of the strand.4.3 Grade 1860 (270)Nominal diameter of 12.7 mm (0.5in.) with tensile failure stress of 1860 MPa (270 ksi) based onnominal area of the strand.5. Ordering Information5.1 It shall be the responsibility of the purchaser t
9、o specifyall requirements that are necessary for material ordered to thisspecification. Such requirements shall include, but are notlimited to, the following:5.1.1 Quantity (meters (feet),5.1.2 Grade of strand (Section 4),5.1.3 Special inspection requirements, if desired (see Sec-tion 13),5.1.4 Pack
10、aging,5.1.5 ASTM designation and date of issue, and5.1.6 Special requirements, if any.NOTE 1A typical ordering description is as follows: 100 000 m Grade260 compacted low-relaxation strand in approximately 3700 m reellesspacks to ASTM A779/A779M (328 000 ft Grade 1800 compactedlow-relaxation strand
11、in approximately 12 000 ft-reelless packs to ASTMA779/A779M.)6. 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 bein the cold-drawn
12、condition and have a common dry-drawnfinish.6.3 After stranding and compacting, all strand shall besubjected to a stress-relieving continuous thermal treatment toproduce the desired mechanical properties. Temper colors1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stain
13、less Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.05 on Steel Reinforcement.Current edition approved April 1, 2010. Published July 2010. Originallyapproved in 1980. Last previous edition approved in 2005 as A779/A779M 05.DOI: 10.1520/A0779_A0779M-10.2For referenced AS
14、TM 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 standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright AS
15、TM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.which result from the stress-relieving operation are considerednormal for the finished appearance of this strand.7. Chemical Requirements7.1 The chemical analysis of each heat shall be determinedin
16、accordance with Test Methods, Practices, and DefinitionsA751.7.2 Variations in production processes and equipment ne-cessitates the individual selection of an appropriate chemicalcomposition at the discretion of the producer.7.3 Phosphorus and sulfur values shall not exceed thefollowing:Phosphorus 0
17、.040 % maxSulfur 0.050 % max8. Mechanical Properties8.1 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 Load at 1 % ExtensionThe mini
18、mum load at 1 %extension shall conform to the specified values shown in Table28.4 ElongationThe total elongation of the strand undermaximum load shall not be less than 3.5 % measured in a gagelength of not less than 600 mm (24 in.).8.4.1 Strand specimens that break outside of the extensom-eter or in
19、 the testing machine grips and meet the minimumspecified value, shall be considered as meeting the elongationrequirements of this specification.8.5 If any strand specimen breaking within the grips of thetesting machine results in test values below those specified,those results shall be considered in
20、valid and retesting shall berequired.9. Dimensions and Permissible Variations9.1 The size of the finished strand shall be expressed as thenominal diameter of the strand in fractions or decimal fractionsof an inch.9.2 Prior to compacting, the diameter of the center wire ofany strand shall be larger t
21、han the diameter of any outer wireby a minimum of 2 %.9.3 After compacting, the strand shall conform to a sizetolerance of plus 0.4 mm (0.016 in.) or minus 0.2 mm (0.008in.) from the nominal diameter when measured across thecrowns of the wire.10. Workmanship10.1 Joints:10.1.1 There shall be no stran
22、d 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 The finished compacted strand shall be uniform indiameter and shall be free of imperfectio
23、ns not consistent withgood commercial drawing and stranding practice.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 strand shall not be oiled
24、 or greased. Slight rusting,provided it is not sufficient to cause pits visible to the unaidedeye, shall not be cause for rejection.10.5 Curvature of the finished compact strand shall be notmore than 75 mm (3 in.) in a length of1m(3ft)when lyingon a flat surface.11. Sampling11.1 One specimen for tes
25、t shall be taken from each 18 Mg(20 ton) or fraction thereof from the lot of compacted strand.The test specimen shall be cut from the outside ends of reels oreither end of coils or reelless packs.12. Test Methods12.1 Test specimens obtained in 11.1 shall be tested fordimensions (Section 9), breaking
26、 strength (8.2), load at 1 %extension (8.3), elongation (8.4), and workmanship (Section10).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 m
27、ade from one test specimenrepresenting the lot.TABLE 1 Breaking Strength RequirementsNominal Diameter of Strand Specified MinimumBreaking Strengthof Strand, kN (lbf)Nominal Steel Area of Strand Nominal Mass (Weight) ofStrands kg/1000 m (lb/1000 ft)mm (in.) mm2(in.)2Grade 1860 (270)12.7 (0.5) 209 (47
28、 000) 112 (0.174) 890 (600)Grade 1800 (260)15.2 (0.6) 300 (67 440) 165 (0.256) 1295 (873)Grade 1700 (245)18.0 (0.7) 380 (85 430) 223 (0.346) 1750 (1176)TABLE 2 Yield Strength RequirementsNominal Strand Diameter Initial Load,kN (lbf)Specified MinimumLoad at 1 %Extension, kN (lbf)mm (in.)Grade 1860 (2
29、70)12.7 (0.5) 20.9 (4700) 182 (40 900)Grade 1800 (260)15.2 (0.6) 30.0 (6740) 261 (58 700)Grade 1700 (245)18.0 (0.7) 38.0 (8540) 330 (74 300)A779/A779M 10213. Inspection13.1 Inspection of the material shall be agreed upon by thepurchaser and the supplier as part of the purchase contract.13.2 If purch
30、aser inspection is required, the supplier shallafford the inspector representing the purchaser all reasonablefacilities so that the inspector is satisfied that the material beingfurnished is in accordance with this specification. All tests andinspections shall be made at the place of manufacture pri
31、or toshipment and shall be conducted as not to interfere unneces-sarily with the operation of the works.14. Rejection and Rehearing14.1 Material that fails to conform to the requirements ofthis specification shall be subject to rejection. Rejection shallbe reported to the producer or supplier prompt
32、ly and in writing.In case of dissatisfaction with the test results, the producer orsupplier shall have the right to make claim for a rehearing.15. Certification15.1 If inspection by the purchaser is waived, a manufac-turers certification that the material has been tested in accor-dance with, and mee
33、ts the requirements of this specification,shall be the basis of acceptance of the material. The certifica-tion shall include the specification number, year-date of issue,and revision letter, if any.15.2 A material test report, certificate of inspection, orsimilar document printed from or used in ele
34、ctronic 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 must meet the requirements of the invoked ASTMstandard(s) and conform to any existing EDI agr
35、eement be-tween the purchaser and the supplier. Notwithstanding theabsence of a signature, the organization submitting the EDItransmission is responsible for the content of the report.NOTE 2The industry definition as invoked here is: EDI is thecomputer-to-computer exchange of business information in
36、 a standardformat such as ANSI ASC X12.16. Packaging and Marking16.1 The strand shall be furnished on reels, reelless packs,or in coils having a minimum inside diameter of 910 mm (36in.). Each package shall be protected from mechanical damageduring shipment. A strong tag securely attached to eachpac
37、kage shall show the grade, length, reel or lot number,ASTM A779/A779M, special requirements, if any, and nameor mark of the manufacturer. Special packaging, protection, ortagging shall be agreed upon between the purchaser andsupplier at the time of purchase.16.2 Low-relaxation compacted strand meeti
38、ng the require-ment of Supplement I shall be specifically identified.17. Keywords17.1 compacted strand (tendon); prestressed concreteSUPPLEMENTARY REQUIREMENTSI. LOW-RELAXATION COMPACTED STRANDS1. ScopeS1.1 This supplement details those special properties thatare applicable to low-relaxation compact
39、ed strand which are inaddition to the properties prescribed in this specification.S1.2 Relaxation testing methods as applicable to compactedstrand are also prescribed.S2. Applicable DocumentsS2.1 ASTM Standards:A1061/A1061M Test Methods for Testing Multi-Wire SteelStrandS3. SamplingS3.1 Test specime
40、ns shall be selected from those obtained inSection 11, representative of the process. The number ofsamples to be tested shall be agreed upon between thepurchaser and producer.S4. Test MethodsS4.1 Compacted strand shall be tested for relaxation prop-erties in accordance with Test Methods A1061/A1061M
41、.S5. Load at 1 % ExtensionS5.1 The load at 1 % extension of compacted strand withlow relaxation properties shall be not less than 90 % of thespecified minimum breaking strength as described in 8.2.S6. Conditions of Relaxation TestS6.1 The temperature of the test specimen and testingequipment shall b
42、e maintained at 20 6 2C (68 6 3.5F).S6.2 The test specimen shall not be subjected to loadingprior to the relaxation test.S6.3 The initial load shall be applied uniformly over aperiod of not less than 3 min and not more than 5 min, and thegage length shall be maintained constant; load relaxationreadi
43、ngs shall begin 1 min after application of total load.S6.3.1 The initial load shall be 70 % of the actual breakingload of a test specimen obtained adjacent to the specimen beingtested.S6.4 Over-stressing of the test specimen during the loadingoperation shall not be permitted.S6.5 Duration of the tes
44、t shall be 1000 h or a shortercomputed period extrapolated to 1000 h which can be shownby test data to provide similar relaxation values.A779/A779M 103S6.6 The test gage length shall be at least 60 times thenominal diameter of the strand. If this gage length exceeds thecapacity of the extensometer o
45、r testing machine, then it ispermitted to substitute a gage length of 40 times the nominaldiameter of the strand.S7. Relaxation PropertiesS7.1 Low-relaxation, compacted strand shall meet the di-mensional, breaking load, and elongation requirements of thisspecification with the added requirement that
46、 the relaxationloss after 1000 h under conditions of Section S 6 shall be notmore than 2.5 %.SUMMARY OF CHANGESCommittee A01 has identified the location of selected changes to this standard since the last issue(A779/A779M 05) that may impact the use of this standard. (Approved April 1, 2010.)(1) Rev
47、ised Sections 2 and 8 and Sections S2 and S4 inSupplementary Requirements to replace Test Methods A370with Test Methods A1061/A1061M as the testing standard formechanical properties and deleted Test Methods E328 becauseTest Methods A1061/A1061M includes testing for relaxationproperties.ASTM Internat
48、ional takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely the
49、ir own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif 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, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known t
