1、Designation: A1061/A1061M 09A1061/A1061M 16Standard Test Methods forTesting Multi-Wire Steel Prestressing Strand1This standard is issued under the fixed designation A1061/A1061M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the
2、year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods describe procedures for testing the mechanical as well as relaxation properties of multi-wi
3、re steelprestressing strand.1.2 These test methods are intended for use in evaluating specific strand properties prescribed in specifications for multi-wiresteel prestressing strand, but they do not quantify acceptance criteria specified in the applicable specification for the strand beingtested.1.3
4、 The values stated in either SIinch-pound units or inch-poundSI units are to be regarded separately as standard. Within thetext, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shallbe used independently of the other. Combinin
5、g values from the two systems may result in non-conformance with the standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and deter
6、mine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A370 Test Methods and Definitions for Mechanical Testing of Steel ProductsE4 Practices for Force Verification of Testing MachinesE83 Practice for Verification and Classification of Extensometer Sy
7、stemsE328 Test Methods for Stress Relaxation for Materials and Structures3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 breaking strength, nmaximum force at or after which one or more wires fracture.3.1.2 free span, nthe distance between the gripping jaws occupied by the leng
8、th of strand to be tested in which the strand isnot contacted or detrimentally influenced by the gripping system.3.1.3 length of lay, lay length, nthe axial distance required to make one complete revolution of any wire of a strand.3.1.4 strand, ntwo or morea group of two, three or seven steel wires
9、wound together in a helical form.form with uniform laylength of not less than 12 and not more than 16 times the nominal diameter of the strand.3.1.5 yield strength, nmeasured force at 1.0 % extension under load (EUL).4. Significance and Use4.1 The mechanical properties breaking strength and elongati
10、on of the strand are determined by a test one or more tensile testsin which fracture of the specimen ideally occurs in the free span between the jaws of the testing machine.span.4.2 Mechanical properties of the strand will be negatively affected if proper care is not taken to prevent damage such as
11、severebending, abrasion, or nicking of the strand during sampling.1 These test methods are 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 June 1, 2009Marc
12、h 1, 2016. Published June 2009April 2016. Originally approved in 2009. Last previous edition approved in 2009 asA1061/A1061M 09. DOI: 10.1520/A1061_A1061M-09.10.1520/A1061_A1061M-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.or
13、g. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit
14、may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Ha
15、rbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.3 Premature failure of the test specimens may result if there is appreciable notching, cutting, or bending of the specimen bythe gripping devices of the testing machine.4.4 Errors in testing will result if the wires constitut
16、ing the strand are not loaded uniformly.4.5 The mechanical properties of the strand will be materially affected by excessive heating during test specimen collection orpreparation.4.6 Gripping difficulties will be minimized by following the suggested methods of gripping described in Section 7.5. Appa
17、ratus5.1 Tensile testtesting machine calibrated in accordance with Practices E4.5.2 Class B-1 extensometer as described in Practice E83.5.3 Class D extensometer as described in Practice E83.; alternately, a linear dial gauge or ruler with precision of 6116 in. 1.5mm.6. Sampling6.1 Unless otherwise s
18、pecified in the material standard, applicable specification for the strand being tested, test specimens shallbe taken from the finished productstrand prior to packaging. The number of test specimen(s)specimens shall be taken as specifiedin the applicable specification for the material strand being t
19、ested.7. Gripping Devices7.1 Due to inherent physical characteristics of individual tensile testing machines, it is not practical to recommend a universalgripping proceduremethod that is suitable for all tensile testing machines. Therefore, it is necessary to determine which of themethods of grippin
20、g described in 7.1.1 7.1.37.1.5 is most suitable for the tensile testing equipmentmachine available. Thegripping devices shall be designed such that during testing the load is distributed along the entire length of the grips. The minimumeffective gripping length as a minimum shall should be equal to
21、 the or greater than the lay length of lay of the strand.7.1.1 Standard V-Grips with Serrated Teeth (Note 1).7.1.2 Standard V-Grips with Serrated Teeth (Note 1), Using Cushioning MaterialIn this method, material is placed betweenthe grips and the test specimen to minimize the notching effect of the
22、teeth. Materials that have been used include, but are notlimited to lead foil, aluminum foil, carborundum cloth, and brass shims. The type and thickness of material required is dependenton the shape, condition, and coarseness of the teeth.7.1.3 Special Grips with Smooth, Semi-Cylindrical Grooves (No
23、te 2, Fig. 1)The grips can be used as is or in conjunction withan abrasive slurry applied to the grooves of the grips and the gripped portion of the test specimen to prevent slippage. The slurryconsists of abrasive such as Grade 3-F aluminum oxide and a carrier such as water or glycerin.7.1.4 Dead-E
24、nd Eye SplicesThese devices are available in sizes designed to fit each size of strand to be tested.7.1.4 Chucking DevicesUse of chucking devices of the type generally used for applying tension to strands in casting beds isnot recommended or post-tensioning anchorages shall not be used as primary gr
25、ipping devices for testing purposes. Tests involvingchuck devices or post-tensioning anchorages as the primary gripping device shall be considered invalid. It shall be permissible touse chucking devices or post-tensioning anchorages as a secondary gripping system, coupled with one of the methods lis
26、ted above,to prevent strand slippage.NOTE 1The number of teeth should be 1510 to 30 per inch 25 mm.NOTE 2The radius of curvature of the grooves should be approximately the same as the radius of the strand being tested. To prevent the two gripsfrom closing tightly when the test specimen is in place,
27、theeach groove should be located 132 in. 0.79 mm above the flat face of the grip.grip (see Fig.1).8. Speed of Testing8.1 The speed of testing shall not be greater than that at which load and strain readings can be made accurately. Refer to speedof testing in Test Methods A370 on Testing Apparatus an
28、d Operations.FIG. 1 Note the 132 in. 0.79 mm Spacing Between the Flat Face and the Radius of the GripA1061/A1061M 1629. Test Procedures9.1 Yield StrengthUse As listed in 5.2, a Class B-1 extensometer (Note 3) shall be used as described in Practice E83. Applyan initial load of 10 % of the required mi
29、nimum breaking strength to the specimen, attach the extensometer and adjust it to areading of 0.1 % of gage length. Increase the load until the extensometer indicates an extension of 1 %. Record the load for thisextension as the yield strength. The extensometer may be removed from the specimen after
30、 the yield strength has been determined.Data acquisition software is available that allows automatic collection of yield strength data. (See with a gauge length equal to orgreater than the lay length of the strand. Typically, an extensometer with a 24 in. 600 mm gauge length is used. Theforce-elonga
31、tion data collected while loading, when plotted, shall produce a smooth curve free of irregular step-wise movementsor other evidence of non-uniform force-elongation loading of the test specimen. One of the two following methods shall be usedto correct for gripper seating losses and other sources of
32、elongation error normally present during the initial loading of the testspecimen. Note 4.)9.1.1 Preload MethodAfter loading the specimen in the test frame, apply and hold an initial load of 10 % of the requiredminimum breaking strength to the specimen. Next, attach the extensometer described in 5.2
33、and adjust it to a reading of 0.1 % ofgauge length. Continue loading until the extensometer indicates a total extension of 1.0 % of the extensometer gauge length(including the 0.1 % extension during pre-loading.) Record the load at 1.0 % extension as the yield strength. The extensometerremains attac
34、hed to the strand until at least 1.05 % EULis reached to ensure the yield strength is accurately measured and recorded;typically, the extensometer is then removed from the specimen to avoid possible extensometer damage due to strand rupture.9.1.2 Elastic Modulus Extrapolation MethodUse a computerize
35、d data acquisition system with a software-based test procedureto calculate the elastic modulus of the specimen as load is applied. The calculation of the elastic modulus shall use either the actualcross-sectional area of the specimen or the nominal cross-sectional area as defined in the applicable s
36、pecification for the size andgrade of strand being tested. The elastic modulus shall be calculated using a sum-of-least-squares linear regression in thelinear-elastic portion of the curve. To prevent errors potentially introduced during the initial loading phase, the linear regressionshall not utili
37、ze data points measured until a minimum of 20 % of the minimum breaking strength is reached.Also, to safely avoidthe non-linear elastic portion of the force-elongation curve as the yielding process starts, the linear regression shall not use datapoints collected after 65 % of the minimum breaking st
38、rength is reached. Between 20 % and 65 % of the minimum breakingstrength, the linear regression shall collect data over at least 70 % of this range to ensure sufficient data is included to generatethe elastic modulus value. Once the elastic modulus is measured, the software shall extrapolate the for
39、ce-elongation curve usingthe measured slope of the elastic modulus to identify the intersection with the elongation axis zero force point. This is the originfrom which the 1.0 % EUL shall be determined. The extensometer remains attached to the strand until at least 1.05 % EUL isreached to ensure the
40、 yield strength is accurately measured and recorded; typically, the extensometer is then removed from thespecimen after the yield strength has been determined to avoid possible extensometer damage due to strand rupture.9.2 ElongationUse As listed in 5.3, a Class D extensometer (Note 3) as described
41、in Practice E83, having a gage length ofnot a linear dial gauge, or ruler with precision of 61/16 in. 2.0 mm shall be used. The gauge length shall not be less than 24 in.600 mm (Note 3). Apply an initial load of 10 % of the required minimum breaking strength to the specimen. Attach theextensometer a
42、nd adjust it to a zero reading. Increase the load until the extensometer indicates an elongation value equal to orgreater than the minimum specified in the applicable specification. Total elongation value is determined when one or more wiresfail during the test. It is not necessary to determine the
43、total percent elongation at maximum force.force if the specified minimumelongation has been reached. One of the two methods described below shall be used.9.2.1 Pre-Load MethodApply an initial load of 10 % of the required minimum breaking strength to the test specimen. Attachthe extensometer and adju
44、st it to a zero reading. Increase the load until the extensometer indicates an elongation value equal toor greater than the minimum specified in the applicable specification.9.2.2 Elongation After Measuring Yield Strength MethodIn practice, the total percent Total elongation at maximum forcefracture
45、 may be determined by measuring the movement between the gripping jaws using a linear dial gage gauge, a ruler, or alinear precision ruler.Class D extensometer. After the yield strength is achievedmeasured, loading is stopped and the extensometerremoved. The load is maintained; the distance between
46、the gripping jaws is measured. measured to establish the current gaugelength of the loaded specimen. The extensometer used to measure the yield strength may be removed. Loading is then continueduntil failure of one or more wires. The wires, or until an elongation value equal to or greater than the m
47、inimum specified in theapplicable specification is measured. If a wire failure occurs, loading (movement) is immediately stopped and the distance betweenthe jaws is again measured. measured or the incremental movement of the test frames moving crosshead is recorded. The totalpercent elongation is th
48、en calculated as a percentage of the change in the jaw-to-jaw distance and adding this valuewhich is thenadded to the percent elongation value obtained by the extensometer. In any case, the total elongation value is determined whenone or more wires fail during the test. (Seeextensometer during the y
49、ield strength Note 5.) portion of the test.9.3 Breaking StrengthContinue loading to determine the maximum load at which the strand until either the minimum specifiedbreaking strength is achieved or until failure of one or more wires of the strand are fractured. Record this load as the occurs. Recordthe actual breaking strength of the strand. (Seestrand (3.1.1). Note 6.)9.3.1 Fracture LocationIf a fracture occurs within a distance of 0.25 in. 6.0 mm from the grips and falls below the specifiedminimum breaking strength, yield strength, or elo
