1、Designation: A970/A970M 09Standard Specification forHeaded Steel Bars for Concrete Reinforcement1This standard is issued under the fixed designation A970/A970M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revis
2、ion. 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 deformed and plain steelreinforcing bars in cut lengths, with a head attached to one orboth ends, for
3、 concrete reinforcement. Attachment can beaccomplished through welding, by integrally hot forging of ahead from the reinforcing bar end, by internal threads in thehead mating to threads on the bar end, or by a separate threadednut to secure the head to the bar. Heads are forge formed,machined from b
4、ar stock, or cut from plate.NOTE 1This specification is applicable for headed bars produced withwelded, threaded, or forged heads and used for reinforcement of concretestructures. The requirements of this specification are not applicable toheaded bars where the attachment of the head is accomplished
5、 by alternatemeans.1.2 Limitations on head dimensions and on obstructions andinterruptions of bar deformations on the non-planar features onthe bearing face of the head are presented in Annex A1. Therequirements in Annex A1 only apply when specified by thepurchaser (see 4.1.13).1.3 This specificatio
6、n is applicable for orders in either SIunits as Specification A970M or inch-pound units shown in thetext in brackets Specification A970.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents;
7、 therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this s
8、tandard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A370 Test Methods and Definitions for Mechanical Testingof Steel ProductsA615/A615M Specification for Deformed and PlainCar
9、bon-Steel Bars for Concrete ReinforcementA700 Practices for Packaging, Marking, and Loading Meth-ods for Steel Products for ShipmentA706/A706M Specification for Low-Alloy Steel Deformedand Plain Bars for Concrete Reinforcement2.2 AWS Standards:3AWS C6.1 Recommended Practices for Friction WeldingAWS
10、D1.4/D1.4M Structural Welding Code - ReinforcingSteel2.3 U.S. Military Standard:4MIL-STD-129 Marking for Shipment and Storage2.4 U.S. Federal Standard:4Fed. Std. No. 123 Marking for Shipment (Civil Agencies)2.5 ACI Standard:5ACI 318 Building Code Requirements for Structural Con-crete3. Terminology3.
11、1 Definitions:3.1.1 forged headed barsteel bar used in the reinforce-ment of concrete that has the head(s) integrally forged to one orboth ends.3.1.2 headround, elliptical, or rectangular shape used toanchor a steel bar in concrete.3.1.3 net bearing areagross cross-sectional area of thehead minus th
12、e nominal cross-sectional area of the deformedreinforcing bar.1This specification is under the jurisdiction of ASTM A01 on Steel, StainlessSteel and Related Alloys and is the direct responsibility of A01.05 on SteelReinforcement.Current edition approved Nov. 15, 2009. Published December 2009. Origin
13、allyapproved in 1997. Last previous edition approved in 2007 as A970/A970M 07.DOI: 10.1520/A0970_A0970M-09.2For 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 stand
14、ards Document Summary page onthe ASTM website.3Available from American Welding Society (AWS), 550 NW LeJeune Rd.,Miami, FL 33126, http:/www.aws.org.4Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS. Or visit: http:/assi
15、st.daps.dla.mil/online.5Available from American Concrete Institute (ACI), P.O. Box 9094, FarmingtonHills, MI 48333-9094, http:/www.concrete.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1
16、9428-2959, United States.3.1.4 threaded headed barsteel bar used in the reinforce-ment of concrete that has the head(s) attached to one or bothends using tapered or straight threads internal to the head or bya separate internally threaded nut securing the head to thethreaded bar end.3.1.5 welded hea
17、ded barsteel bar used in the reinforce-ment of concrete that has the head(s) welded to one or bothends.4. Ordering Information4.1 It shall be the responsibility of the purchaser to specifyall requirements that are necessary for material ordered to thisspecification. Such requirements shall include b
18、ut are notlimited to the following:4.1.1 Quantity;4.1.2 Name of product: welded, forged, or threaded headedbars for the reinforcement of concrete;4.1.3 Reinforcing bar specification and year of issue;4.1.4 Bar size;4.1.5 Deformed or plain bars;4.1.6 Head geometry, including thickness, diameter orhei
19、ght and width of the head;4.1.7 Head material specification and year of issue forwelded head bars (5.2.1);4.1.8 Bend testing of welded headed bars in sizes No. 36,43, and 57 11, 14, and 18 (6.4.1);4.1.9 Number of heads per bar length;4.1.10 Length of bar assembly;4.1.11 Packaging;4.1.12 ASTM designa
20、tion and year of issue; and4.1.13 Optional requirements of Annex A1, if applicable.5. Material and Manufacture5.1 Reinforcing BarsFor welded headed bars, the rein-forcing bars shall conform to Specification A706/A706M. Forforged headed bars or threaded headed bars, the reinforcingbars shall conform
21、to Specification A615/A615M or A706/A706M, as specified by the purchaser.5.2 Heads:5.2.1 For welded and threaded headed bars, the head mate-rial shall be selected by the manufacturer.5.3 The head dimensions shall be provided by the purchaserin the order. Head dimensions shall define the head geometr
22、yincluding thickness, height and width of the head (Fig. 1).Alternate head dimensions supplied by the manufacturer shallbe permitted if agreed to in advance by the purchaser. Themanufacturer shall furnish documentation to the purchaser, inthe form of calculations or test reports, or both, that confi
23、rmsthe suitability of alternate head dimensions for the intendedapplication.NOTE 2Alternate head dimensions resulting in a net bearing area lessthan four times the area of the deformed reinforcing bar are not suitablefor use in construction projects governed by certain consensus buildingcodes and de
24、sign standards (see 5.4 and Note 3).5.3.1 Head dimensions shall define the head geometryincluding thickness, diameter or height and width of the head(Fig. 1).5.4 When specified by the purchaser in the purchase orderor contract as a class HA headed bar, head dimensions shallmeet the requirements of A
25、nnex A1.NOTE 3The requirements for head dimensions in Annex A1 aremandated by certain consensus building codes and design standards, forexample, 9Building Code Requirements for Structural Concrete(ACI 318).95.5 WeldingA welding procedure conforming toAWS D1.4/D1.4M shall be used for all required pro
26、ductionwelding of the head to the bar, except for friction welding thatshall conform to AWS C6.1 in conjunction with the manufac-turers QA/QC procedures.5.6 ForgingFor integrally forged headed bars, the headsshall be produced by deforming the bar ends in a hot-forgingprocess.5.7 Threading:5.7.1 Thre
27、ads on bars shall be either tapered or straight. Thehead shall either thread onto the bar directly, or it shall be heldon the bar end by a nut and counternut. Thread specificationsand standards shall be selected by the manufacturer unlessotherwise agreed with the purchaser.5.7.2 The out-of-roundness
28、 in the rolled reinforcing barshall be evaluated so that the manufacturers minimum threaddimensions are maintained.FIG. 1 Headed Reinforcing BarA970/A970M 0925.7.3 It shall be permissible to hot- or cold-roll, or machinecut, threads into the surface of the bar and heads at the optionof the manufactu
29、rer.6. Mechanical Test and Performance Requirements6.1 Headed bars shall be subjected to mechanical tests toverify production method and product quality prior to manu-facture. Mechanical testing also shall be performed at intervalsduring production.6.2 Tensile Tests:6.2.1 Tensile testing of the head
30、ed bar assembly shall beperformed in accordance with the requirements described inTest Methods and Definitions A370. Failure mode shall bereported as partial or total fracture of the bar, the head, or thehead-to-bar connection.6.2.2 Specimen PreparationTensile test specimens shallbe the full cross-s
31、ection of the bar with a head attached to oneend of the reinforcing bar. The minimum length of the testspecimen shall be the greater of 250 mm 10 in. or ten timesthe nominal diameter of the bar. The test specimen shall beplaced in the testing machine with the head supported toprevent movement and be
32、nding of the head. Provisions shall bemade for clearance between the support and any weld orforming material on the reinforcing bar-to-head connection.The opposite bar end of the bar, without a head attached, shallbe gripped by the testing machine and loaded to failure.6.3 Tensile Requirements:6.3.1
33、 Tensile PropertiesThe tensile properties of the testspecimen shall conform to one of the following classes:6.3.1.1 Class ADevelop the minimum specified tensilestrength of the reinforcing bar.6.3.1.2 Class BDevelop the minimum specified tensilestrength and the minimum specified elongation of the rei
34、nforc-ing bar.NOTE 4Reference Specifications A615/A615M and A706/A706Mrequirements for minimum reinforcing bar tensile properties. Class A hasbeen introduced for applications that only require the development of theminimum tensile strength of the reinforcing bar. The Class B criteriarequires the hea
35、d and the head-to-bar connection to meet or exceed theminimum specified tensile strength and the minimum specified elongationrequirements of the reinforcing bar. In the previous criteria, the failure ofthe head or the head-to-bar connection within the attachment region wascause for rejection.6.4 Ben
36、d Test Requirements:6.4.1 Only welded headed bars in sizes No. 10 to 32 3 to10 shall be subject to bend testing. Bend testing of weldedheaded bars in sizes No. 36, 43, and 57 11, 14, and 18 shallbe subject to agreement between the purchaser and manufac-turer.NOTE 5Serious safety issues may be involv
37、ed in performing bendtests on welded headed bars in sizes No. 36, 43, and 57 11, 14, and 18.Thus, 6.4 requires such bend testing to be subject to agreement betweenthe purchaser and manufacturer.6.4.2 ProcedureThe test specimen shall be bent around amandrel of suitable diameter to an angle of at leas
38、t 90 with noobserved partial or total fracture of the head, the bar, or thehead-to-bar connection.6.4.3 Bend Test MandrelThe mandrel shall be placed soas to directly bend the welded region. The required mandreldimensions for bend testing are prescribed in Table 1. Thecenterline of the bend test mand
39、rel shall be placed at theintersection of the reinforcing bar and the weld, as shown inFig. 2.6.4.4 Specimen PreparationBend test specimens shall bethe full cross-section of the bar with a head attached to one endof the reinforcing bar. Where the welded head interferes withplacement of the bend test
40、 mandrel, sufficient head materialand any excess material associated with the welding processshall be removed along one edge of the reinforcing bar toprovide a flat surface on the specimen for the bend mandrel.This preparation shall ensure that the contact point of the bendmandrel is directly at the
41、 base of the reinforcing bar diameteras shown in Fig. 2.7. Frequency of Testing7.1 Number of Tests:7.1.1 Pre-ProductionPrior to production, a testing pro-gram shall be undertaken that includes two bend tests and twotensile tests for welded headed bars, and two tensile tests forforged or threaded hea
42、ded bars. The tests shall be repeated foreach combination of head and bar material specification, gradeor type, and welding, threading, or forging process.7.1.2 ProductionIt shall be permissible to use either thetensile test prescribed in 6.3, or the bend test prescribed in 6.4to verify the producti
43、on method and product quality. A mini-mum of two tests shall be conducted during the productionshift or period. One test at the start and one test at the end ofeach 8-h shift or less than 8-h production period or at randomintervals during the production period shall be conducted.7.1.2.1 In the event
44、 different heats of head or bar material,or both, within the same material specification are used toproduce welded, threaded, or forged headed bars during aproduction run, a minimum of two tensile tests in accordancewith 6.3 or two bend tests in accordance with 6.4 shall beconducted to verify the pr
45、oduction method, product quality,and welding, forging, or threading quality or weldability of theheats of materials prior to continuing production.7.2 Retests:7.2.1 Pre-ProductionAny identified procedural or perfor-mance deficiencies shall be corrected and pre-productiontesting repeated until the te
46、nsile and bend test results meet theperformance requirements of this specification.7.2.2 ProductionFor welded headed bars, when partial ortotal fracture(s) of the bend or tensile test specimens occur(s)in the weld, the production lot shall be rejected and a retestshall be conducted as shown in 7.2.2
47、.1 or 7.2.2.3. Duringproduction tests of welded, forged, or threaded bars, if anytensile test specimen fails to not meet the requirements fortensile properties in 6.3.1, the production lot shall be retestedas shown in 7.2.2.1. For threaded components used to assembleTABLE 1 Bend Test RequirementsBar
48、 Designation Mandrel Diameter10, 13 and 16 3, 4, and 5 3dA19, 22 and 25 6, 7, and 8 4d29, 32 and 36 9, 10, and 11 6d43 and 57 14 and 18 8dAd = nominal diameter of barA970/A970M 093the threaded headed bars, if thread dimensions are found not tomeet the manufacturers specifications for the thread, the
49、production lot shall be rejected.7.2.2.1 If the result of a tension test fails to meet therequirements for tensile properties in 6.3.1, then a retest shallbe allowed. Two specimens taken at random from the produc-tion lot shall be tested during a retest. Both specimens shallpass the tension test requirements of Section 6, or the produc-tion lot shall be rejected.7.2.2.2 If any test specimen fails because of mechanicalreasons, such as failure of the testing equipment or from flawscaused by specimen preparation, shipment, or other d
