A/AM – 07 Standard Specification for Headed Steel Bars for Concrete Reinforcement, carbon-steel reinforcing bars, concrete reinforcement. ASTM A Headed Steel Bars锚固头钢筋标准_自然科学_专业资料。Designation : A /A M – 07 Standard Speci?cation for Headed Steel. Terminator headed bar systems comply with the requirements of , and editions of ASTM A Class A. • The D6, D14, and D16 families of.
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ASTM A970/A970M – 18
A number in parentheses indicates the year of last reapproval. A superscript epsilon e indicates an editorial change since the last revision or reapproval. Attachment can be accomplished through welding, by integrally hot forging of a head from the reinforcing bar end, by internal threads in the head mating to threads on the bar end, or by a separate threaded nut to secure the head to the bar. Heads are forge formed, machined from bar stock, or cut from plate. The requirements of this speci?
The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Such requirements shall include but are not limited to the following: Current edition approved Oct.
Originally awtm in Material and Manufacture 5. For a97 headed bars or threaded headed bars, the reinforcing bars shall conform to Speci?
Head dimensions shall de? Alternate head dimensions supplied by the manufacturer shall be permitted if agreed to in advance by the purchaser. The manufacturer shall furnish documentation to the purchaser, in the form of calculations or test reports, or both, that con? The head shall either thread onto the bar directly, or it shall be held on the bar end by a nut and counternut.
Mechanical Test and Performance Requirements 6. Mechanical testing also shall be performed at intervals during production. Failure mode shall be reported as partial or total fracture of a70 bar, the head, or the head-to-bar connection. The minimum awtm of the test specimen shall be the greater of mm [10 in. The test specimen shall be placed in the testing machine with the head supported to prevent movement and a9700 of the head.
ASTM A / AM – 07 Standard Specification for Headed Steel Bars for Concrete Reinforcement
Provisions shall be made for clearance between the support and any weld or forming material on the reinforcing bar-to-head connection. The opposite bar end of the bar, without a head attached, shall be gripped by the testing machine and loaded to failure. Class A has been introduced for applications that only require the development of the minimum tensile strength of the reinforcing bar. The Class B criteria requires the head and the head-to-bar connection to meet or exceed the minimum speci?
In the previous criteria, the failure of the head or the head-to-bar connection within the attachment region was cause for rejection. The required mandrel dimensions for bend testing are prescribed in Table 1. The centerline of the bend test mandrel shall be placed at the intersection of the reinforcing bar and the weld, as shown in Fig. Where the welded head interferes with placement of the bend test mandrel, sufficient head material and any excess material associated with the welding process shall be removed along one edge of the reinforcing bar to provide a?
This preparation shall ensure that the contact point of the bend mandrel is directly at the base of the reinforcing bar diameter as shown in Fig. Frequency of Testing 7. Bend testing of welded headed bars in sizes No. The tests shall be repeated for each combination of head and bar material speci? A minimum of two tests shall be conducted during the production shift or period. One test at the start and one test at the end of each 8-h shift or less than 8-h production period or at random intervals during the production period shall be conducted.
During production tests of welded, forged, or threaded bars, if any tensile test specimen fails to not meet the requirements for tensile properties in 6. Two specimens taken at random from the production lot shall be tested during a retest.
Both specimens shall pass the tension test requirements of Section 6, or the production lot shall be rejected. If the results of both test specimens meet the speci? The manufacturer shall afford the inspector reasonable access to the facilities to satisfy the inspector that the materials and procedures are in accordance with this speci? In case of dissatisfaction with the results of the test, the manufacturer shall make claim for a rehearing within that time.
A copy of the test report shall be provided to the purchaser upon request. Notwithstanding the absence of a signature, the organization submitting the EDI transmission is responsible for the content of the report. NOTE 4—The industry de? To achieve consistent performance of the attached head by welding, the bar material is limited to Speci? The chemical composition requirements of the bar for a forging operation are such that low-alloy steel or carbon steels can be used.
Thus, integrally forged headed bars are allowed to use either Speci? The head may be internally threaded so that it directly screws on the threaded bar end. The other option is for the head to have a non-threaded hole so that the w970 is held on asfm bar end by a nut and a counternut.
In either case the threads should be carefully cut or rolled so that the engagement of the threads results in a uniform load in the head-to-bar connection.
For machine straight threads, additional quality inspection of the reinforcing steel will be required to eliminate bars that may be excessively out of round. Individual manufacturers will have to establish their own standards for the out-of-roundness that can be tolerated with their particular threading system.
Designers are cautioned to consult the speci? These testing requirements are designed to test both the preproduction headed bars as well as actual production products to verify that Class B head-to-bar connection is as strong as the parent head and bar materials and that the connection has sufficient ductility. Nominal head dimensions were previously provided to inform manufacturers of these systems as to typical head dimensions.
The head dimensions found in editions prior to of this speci? The anchorage of the bar via the head provides the shortest tensile development length possible and essentially means that the headed bar is immediately anchored. No nominal head dimensions are now provided in the speci? Designers should be cognizant that the head sizes must be evaluated to ensure that adequate anchorage is provided, that the steel and concrete stresses are not excessive for the loadings, and that the detailing of the connection is consistent with the intended usage.
Nominal head dimensions historically have called for gross head area to be ten times the bar area with the net bearing area of the head to be nine times the bar area. The head dimensions provided in previous editions of this speci? Designers, purchasers, and manufacturers who have no other information regarding head proportioning may refer to these dimensions as a starting point.
Class A headed steel bars ensure that the speci?
Whereas, Class B headed steel bars ensure that the tensile strength of the actual bar is achieved along with the speci? One metallographic examination and hardness survey should be carried out on a section of the head and welded or forged zone.
This examination and survey should q970 used for diagnostic purposes in the event that later production testing reveals unacceptable tension or bend test performance. This type of diagnostic examination should be conducted prior to continuous production for each combination of bar and head materials that will be produced. The information obtained can be essential in eliminating problems with strength or ductility of the welded or forged head-to-bar connection, or both.
The data on this in-process axtm should be recorded and aztm by the manufacturer for a minimum of one year after manufacture of the welded headed bars. The records to be maintained include, but are not limited to, certi? The information should be traceable to speci? In addition, the Structural Concrete Building Code Committee of the American Concrete Institute is currently working on developing design and detailing provisions for the use of s970 bars in concrete structures.
These rules will provide designers with appropriate guidance for the design of structures using headed reinforcing bars so that the anchorages remain ductile, even under earthquake loading. Bend testing of the large bar sizes is subject to agreement between purchaser and manufacturer.
Class A and Class B. ASTM International takes no position respecting the validity of any patent rights asserted in connection with a9770 item mentioned in this standard.
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