1、Designation: A886/A886M 17Standard Specification forSteel Strand, Indented, Seven-Wire Stress-Relieved forPrestressed Concrete1This standard is issued under the fixed designation A886/A886M; the number immediately following the designation indicates the yearof original adoption or, in the case of re
2、vision, 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 two grades ofindented seven-wire uncoated, steel strand f
3、or use in pre-stressed concrete construction. The two types of strand arelow-relaxation and stress-relieved (normal-relaxation). Grade250I 1725I and Grade 270I 1860I have minimum tensilestrengths of 250 ksi 1725 MPa and 270 ksi 1860 MPa,respectively, based on the nominal area of the strand.1.2 This
4、specification is applicable for orders in eitherinch-pound units (as Specification A886) or in SI units (asSpecification A886M).1.3 The values stated in either inch-pound units or SI unitsare to be regarded separately as standard. Within the text, theSI units are shown in brackets. The values stated
5、 in eachsystem are not exact equivalents; therefore, each system shallbe used independently of the other. Combining values from thetwo systems may result in non-conformance with the specifi-cation.1.4 This international standard was developed in accor-dance with internationally recognized principles
6、 on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standard:2A1061/A1061M Test Methods for Testing
7、Multi-Wire SteelPrestressing Strand2.2 U.S. Military Standard:MIL-STD-129 Marking for Shipment and Storage32.3 U.S. Federal Standard:Fed. Std. No. 123 Marking for Shipments (Civil Agencies)33. Terminology3.1 Definition of Term Specific to this Specification:3.1.1 strand, na group of wires having a c
8、enter wireenclosed tightly by six helically placed outer wires withuniform pitch of not less than 12 and not more than 16 timesthe nominal diameter of the strand.3.1.1.1 DiscussionThe direction of lay is either right-handed or left-handed.4. Ordering Information4.1 Orders for indented seven-wire ste
9、el strand under thisspecification shall contain the following information:4.1.1 Quantity (feet metres),4.1.2 Nominal diameter of strand (inches millimetres),4.1.3 Grade of strand,4.1.4 Type of strand (low-relaxation or stress-relieved(normal-relaxation), and4.1.5 ASTM designation A886 A886M and year
10、 of issue.4.2 The purchaser shall have the option to specify additionalrequirements, including but not limited to, the following:4.2.1 Relaxation evidence from similarly dimensionedstrand of the same grade (6.5.1),4.2.2 Other types of indented wire (7.4.2),4.2.3 If joints or splices are permitted (8
11、.1.1),4.2.4 Weldless, if desired (8.1.4),4.2.5 Requirements for inspection (11.1),4.2.6 Load-elongation curve, if desired (13.2),4.2.7 Packaging and package marking (Section 14), and4.2.8 Other special requirements, if any.5. Materials and Manufacture5.1 Base MetalThe base metal shall be carbon stee
12、l ofsuch quality that when it is drawn to wire, subjected to the1This 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 Nov. 1, 2017. Publish
13、ed November 2017. Originallyapproved in 1988. Last previous edition approved in 2016 as A886/A886M 16.DOI: 10.1520/A0886_A0886M-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informa
14、tion, refer to the standards Document Summary page onthe ASTM website.3Available from U.S. Government Printing Office, Superintendent ofDocuments, 732 N. Capitol St., NW, Washington, DC 20401-0001, http:/www.access.gpo.gov.*A Summary of Changes section appears at the end of this standardCopyright AS
15、TM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Sta
16、ndards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1indentation process, fabricated into strand, and then thermallytreated, it shall have the properties and characteristics pre-scribed in this specification.5.2 WireThe wire from whic
17、h the strand is to be fabricatedshall have a common dry-drawn finish.NOTE 1This product is a composite of seven wires and is produced toonly the prescribed mechanical properties. The chemical composition ofall wires or any individual wire is not pertinent to this application, andheat identity is not
18、 necessarily maintained. It is possible that wire frommore than one heat may be used in the manufacture of a reel or reellesspack. Traceability is based on the identity of reels or reelless packs asmaintained and reported by the manufacturer.5.3 IndentationsThe outer wires shall have indentationstha
19、t inhibit longitudinal movement of the strand relative to theconcrete surrounding the strand in prestressed concrete con-struction. Indentations shall conform to the provisions inSection 7.4. The surface of the outer wires shall be suitablydeformed mechanically by rolling to produce a series ofinden
20、tations. Indentations shall be in two or more lines spaceduniformly around the wire. Indentations in adjacent lines shallbe staggered throughout the length of the wire.At least 90 % ofthe indentations in any 2 ft 0.6 m length of strand shall meetthe pitch and shape requirements of Table 1. The cente
21、r wireneed not be indented.5.4 TreatmentAfter stranding, low-relaxation strand shallbe subjected to a continuous thermal-mechanical treatment toproduce the prescribed mechanical properties. For stress-relieved (normal-relaxation) strand, only thermal treatment isnecessary. Temper colors which result
22、 from the stress-relievingoperation are considered normal for the finished appearance ofthis strand.6. Mechanical Property Requirements6.1 Tests for mechanical properties shall be conducted inaccordance with Test Methods A1061/A1061M.6.2 Breaking StrengthThe breaking strength of the fin-ished strand
23、 shall conform to the requirements prescribed inTable 2.6.3 Yield StrengthYield strength in lbs kN shall bemeasured at 1 % extension under load. The minimum yieldstrength shall be 90 % for low-relaxation strand and 85 % forstress-relieved (normal-relaxation) strand of the breakingstrength listed in
24、Table 2. Initial loads for the test and minimumyield strengths are listed in Table 3.6.3.1 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.6.4 ElongationThe total elongation under load shall
25、notbe less than 3.5 % using a gage length of not less than 24 in.600 mm. It shall be permissible to determine the totalelongation value by adding to the 1 % yield extension thepercent extension or movement between the jaws gripping thestrand after yield determination. The percent is calculated onthe
26、 new base length of jaw-to-jaw distance.6.5 Relaxation PropertiesLow-relaxation strand shallhave relaxation losses of not more than 2.5 % when initiallyloaded to 70 % of specified minimum breaking strength or notmore than 3.5 % when loaded to 80 % of specified minimumbreaking strength of the strand
27、after 1000 hours of testing.TABLE 1 Nominal Dimensions of IndentationsFig.Wire Diameter, d Nominal Diameterof StrandDepth, a Length, L Pitch, Pin. mm in. mm in. mm in. mm in. mm1(a) # 0.104 # 2.6 0.312 7.9 0.002 to 0.004 0.05 to 0.10 0.079 2.0 0.220 5.61(a) 0.125 3.2 0.375 9.5 0.002 to 0.005 0.05 to
28、 0.13 0.108 2.7 0.220 5.60.438 11.10.500 12.71(b) # 0.125 # 3.2 0.375 9.5 0.002 to 0.006 0.05 to 0.15 0.115 2.9 0.220 5.6TABLE 2 Breaking Strength RequirementsNomminalDiameter of Strand Breaking Strengthof Strand, lbf kNSteelArea of Strand,in.2mm2Mass Weight ofStrand,lb/1000 ftkg/1000 min. mmGrade 2
29、50I 1725I0.250 6.4 9 000 40.0 0.036 23.2 122 1820.313 7.9 14 500 64.5 0.058 37.4 197 2940.375 9.5 20 000 89.0 0.080 51.6 272 4050.438 11.1 27 000 120.1 0.108 69.7 367 5480.500 12.7 36 000 160.3 0.144 92.9 490 7300.600 15.2 54 000 240.5 0.216 139.4 737 1094Grade 270I 1860I0.313 7.9 16 500 74.3 0.061
30、39.4 210 3130.375 9.5 23 000 101.9 0.085 54.8 290 4320.438 11.1 31 000 138.0 0.115 74.2 390 5820.500 12.7 41 300 183.6 0.153 98.7 520 7750.600 15.2 58 600 260.4 0.217 140.0 740 1102TABLE 3 Yield Strength RequirementsANominalDiameter ofStrandInitial Load,lbf kNMinimum Load at 1 % Extension,kN lbfin.
31、mm Stress-Relieved(NormalRelaxation)ALowRelaxationBGrade 1725I 250I0.250 6.4 900 4.0 7 650 34.0 8 100 36.00.313 7.9 1 450 6.5 12 300 54.8 13 050 58.10.375 9.5 2 000 8.9 17 000 75.6 18 000 80.10.438 11.1 2 700 12.0 23 000 102.3 24 300 108.20.500 12.7 3 600 16.0 30 600 136.2 32 400 144.30.600 15.2 5 4
32、00 24.0 45 900 204.4 48 600 216.5Grade 1860I 270I0.313 7.9 1 650 7.3 14 030 63.2 14 850 66.90.375 9.5 2 300 10.2 19 550 86.6 20 700 91.70.438 11.1 3 100 13.8 26 350 117.3 27 900 124.20.500 12.7 4 130 18.4 35 000 156.1 37 170 165.20.600 15.2 5 860 26.1 49 800 221.3 52 740 234.4AMinimum yield strength
33、 is 85 % of specified minimum breaking strength.BMinimum yield strength is 90 % of specified minimum breaking strength.A886/A886M 1726.5.1 If required, relaxation evidence shall be provided fromthe manufacturers records of tests on similarly dimensionedstrand of the same grade.7. Dimensions and Perm
34、issible Variations7.1 The size of the finished strand shall be expressed as thenominal diameter of the strand in inches mm. All nominaldimensional requirements for wires and strands shall refer tothe wire and strand before indenting.7.2 The diameter of the center wire of any strand shall belarger th
35、an the diameter of any outer wire in accordance withTable 4.7.3 Permissible Variations in Diameter:7.3.1 All Grade 250I 1725I strand shall conform to a sizetolerance of 60.016 in. 60.40 mm from the nominal diam-eter measured across the crowns of the wire.7.3.2 All Grade 270I 1860I strand shall confo
36、rm to a sizetolerance of +0.026 in., 0.006 in. +0.65 mm, 0.15 mmfrom the nominal diameter measured across the crowns of thewire.7.3.3 Variation in cross-sectional area and in stress resultingtherefrom shall not be cause for rejection provided the diameterdifferences of the individual wires and the d
37、iameters of thestrand are within the tolerances specified.7.4 Indentations:7.4.1 Two acceptable types of indented wire are shown inFig. 1 (a) and (b) with dimensions given in Table 1.7.4.2 Other types of indented wire are permitted, by agree-ment between the purchaser and manufacturer.8. Workmanship
38、, Finish, and Appearance8.1 Joints:8.1.1 There shall be no strand joints or strand splices in anylength of the completed strand unless specifically permitted bythe purchaser.8.1.2 During the process of manufacture of the individualwires for stranding, welding is permitted only prior to or at thesize
39、 of the last thermal treatment, for example, patenting orcontrol cooling. There shall be no welds in the wire after it hasbeen drawn through the first die in the wire drawing except asprovided in 8.1.3.8.1.3 During fabrication of the strand, butt-welded joints arepermitted in the individual wires, p
40、rovided there is not morethan one such joint in any 150-ft 45-m section of the finishedstrand.8.1.4 When specifically ordered as “Weldless,” a productfree of welds shall be furnished. When “Weldless” is specified,the strand is produced as one continuous length with no weldsas allowed in 8.1.3.8.2 Th
41、e finished strand shall be uniform in diameter andshall be free of imperfections.8.3 When strand is cut without seizing, if no wire flies outof position, or if any wire that flies out of position can berepositioned by hand, the strand shall be considered satisfac-tory.8.4 The strand shall not be oil
42、ed 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.9. Sampling9.1 Test specimens cut from either end of the reels orreelless packs are permitted. Any specimen found to contain awire joint shal
43、l be discarded and a new specimen obtained.10. Number of Tests10.1 One test specimen shall be taken from each 30-ton27-tonne production lot of finished strand and tested forbreaking strength, yield strength, and elongation.11. Inspection11.1 Inspection of the indented steel strand shall be agreedupo
44、n between the purchaser and the manufacturer as part of thepurchase order or contract.12. Rejection12.1 Failure of any test specimen to comply with therequirements of this specification shall constitute grounds forrejection of the lot represented by the specimen.12.2 The lot may be resubmitted for i
45、nspection by testing aspecimen from each reel or reelless pack and sorting outnon-conforming material.TABLE 4 Diameter Relation Between Center and Outer WiresNominal Diameter of StrandMinimum Difference Between CenterWire Diameter and Diameter ofAny Outer Wirein. mm in. mmGrade 1250I 1725I0.250 6.4
46、0.001 0.0250.313 7.9 0.0015 0.0380.375 9.5 0.002 0.0510.438 11.1 0.0025 0.0640.500 12.7 0.003 0.0760.600 15.2 0.004 0.102Grade 270I 1860I0.313 7.9 0.0015 0.03810.375 9.5 0.002 0.05080.438 11.1 0.0025 0.06350.500 12.7 0.003 0.07620.600 15.2 0.004 0.1016FIG. 1 Acceptable Types of Indented WireA886/A88
47、6M 17312.3 If there is a reasonable doubt in the initial testing as tothe ability of the strand to meet any requirement of thisspecification, two additional tests shall be made on specimensfrom the same reel or reelless pack, and if failure occurs ineither of these tests, the represented reel or ree
48、lless pack shallbe rejected.13. Certification13.1 At the time of shipment, the purchaser shall befurnished with a written certification that specimens represent-ing each lot of strand have been either tested or inspected asrequired in this specification and the requirements have beensatisfied. The certification shall include ASTM designationA886 A886M, year-date of issue, and revision letter, if any.13.2 When requested in the purchase order or contract, themanufacturer shall furnish a representative load-elongationcurve for each
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