ASTM WK67738

    Revision of A706 / A706M - 16 Standard Specification for Deformed and Plain Low-Alloy Steel Bars for Concrete Reinforcement

    (What is a Work Item?)

    Active Standard: A706 / A706M - 16

    Developed by Subcommittee: A01.05 | Committee A01 | Contact Staff Manager



    WK67738


    Keywords

    alloy steel; concrete reinforcement; deformations (protrusions); steel bars;;

    Rationale

    There has been an industry-wide effort over the past five years to accomplish several goals. First and foremost to modernize reinforced concrete design and construction. Secondly to incorporate higher strength reinforcing steel into seismic design. Thirdly, to determine the properties of the steel that are necessary to support the first two objectives. Review of international seismic design reinforcing standards was conducted, including standards from Japan, New Zealand, Australia, and Europe. Review of standards and additional Research was coordinated by the Charles Pankow Foundation, was funded by Pankow, the American Concrete Institute, the Concrete Reinforcing Steel Institute, and directly by cash contribution and material donations representing over 95% of the reinforcing steel steel manufacturers, was conducted by over eight different major universities and by researchers widely recognized as authorities on seismic design, several private practitioners, and was peer reviewed by other researchers, practitioners, manufacturers, and other industry partners. Research spanned a five year period, and represents a combined total of $26M in actual dollars spent, donated materials, and donated time. The universities involved in the research were UC Berkeley, UC San Diego, UT San Antonio, UT Austin, NC State, Perdue University, University of Kansas, and Kansas State, among others. Anyone interested in reviewing the research may find it at www.pankow.org. The Pankow Foundation has made all research related to building code modernization public domain. In order to support the afore-mentioned, industry-wide effort, this ballot is being written to update A706 on behalf of all afore-mentioned stakeholders with the improved properties necessary to support improved public safety, building design and construction, and to prevent explosion of inventory unnecessarily. It was discussed at length among the above participants, and the clear desire of industry was to update A706 to include all the requirements as balloted herein to maintain all seismic design reinforcing steel bar requirements in the A706 specification. The summary of changes is as follows: 1.A706 Grade 60 is not being modified in any way, including ongoing maintenance of chemical requirements to preserve common weldability (the ability to weld with few heating controls and the use of common electrodes). 2.Grade 100 is being added with the balloted mechanical properties and no expectation of common weldability (meaning lack of heating practices and use of common electrodes). Mechanical coupling will be required when using proposed A706 grade 100 in seismic design application. It is the design community intention in this regard as well 3.Grade 80 is being considered generally not weldable due to microalloy additions that typically exceed ASTM definitions of low alloy. (again, referring to the lack of heating practices and the use of common electrodes is ill-advised even on current weldable A706 grade 80 as determined by the American Welding Society). As such mechanical couplers are required for use to A706 grade 80 in seismic design unless welding is performed in a manner consistent with AWS requirements for the actual chemistry of the bar. Grade 80 may still be provided with a maximum CE at the request of the purchaser. 4.Bar Marking D for ductile is being introduced to separate bars with the expectation of weldability from bars that have the required mechanical ductility for Seismic Design provisions. 5.Uniform elongation is being added using values that agree with CalTrans design provision AND were determined by the above mentioned research to be the minimum necessary for consistently good seismic performance in both monotonic and in-concrete testing of special columns, special walls, and moment frames. 6.Inclusion of a minimum radius at the junction where the transverse deformation meets the body of the bar. It was determined in research that this feature was one of the highest contributing factor to low cycle fatigue performance and was determined to be necessary for seismic design. 7.Methods for determining uniform elongation, also called Uniform strain at peak stress. Uniform elongation can be measured directly via break away or optical strain gauge as per ASTM E8 or manually per the added Annex A2 as part of this ballot. a.The manual method in the balloted mandatory Annex A2 was based on the Canadian method for indirectly determining uniform elongation (Agt) including the elastic strain. b.The method was modified to preserve the standard 8 gauge length. c.The method was researched independently by two manufacturers who arrived at the same conclusion. Data is available comparing the described manual method to the direct method using an extensometer to determine Agt. Over 30,000 data points are in the analysis, and are available on request. 8.The balloted provisions and requirements have been written into the ACI 318 building code as substantive in the 2019 revision year. They will be published in June or July of 2019, and ultimately will be adopted by the International Building Code (IBC), which is managed by the International Code Counsel (ICC). Failure to adopt these changes will result in ASTM A706 being out of phase with the concrete building codes, which will mean that every bar produced to this standard would be required to be produced according to Supplemental Purchasing requirements and not according to the standard, which will be injurious to the industry and will render the standard obsolete. This increases the urgency to ballot and pass the provisions on behalf of the industry in order to avoid harm to the reinforced concrete construction industry. Ballot History: This ballot was originally balloted at A01.05 subcommittee in 2017, and received two negative votes with a third vote after conclusion of balloting being informally changed to negative at the request of the voter. At the Spring 2018 ASTM meeting, one of the three negative voters was present, and was given the floor to discuss his concerns at length. At the conclusion of this time, the negative voter agreed to help refine the ballot item to try to resolve the negatives. What is now being balloted is a result of an addition full year of time from the meeting to attempt to reach consensus. The negative voters concerns can be generally categorized as follows: 1.The removal of weldability from the A706 standard was not desired. a.Response: Weldability was not removed in the ballot item. It was proposed by the present negative voter in the spring 2018 A01.05 meeting that improved formatting of the standard would better indicate the applications for weldable vs seismic design only and resolve the negative voters concerns. This reformatting was performed cooperatively by the balloter and the negative voter who proposed the solution at the Spring 2018 meeting. 2.The desire for addition of Charpy performance requirements. a.Response: The balloter is submitting a separate ballot via a separate work item to this ballot for the addition of the charpy requirements as a non-mandatory supplemental annex S1 on behalf of the negative voters. The second work item was also written in cooperation between one negative voter and the balloter. 3.The desire for the provisions to be written into a third standard instead of inclusion into A706 a.Response: This option was considered by manufacturers, practitioners, academia, designers, and construction representatives in multiple settings and meetings. It was determined that a third standard would create undesired explosion of inventory and other undesireable consequences. As a result, based on the very clear will of the entire reinforced concrete design and construction industry, the provisions are being reballoted for inclusion into A706 having addressed all other concerns of all negative voters. 4.The desire for inclusion of uniform strain requirements. a.Response: The research mentioned earlier determined certain minimum values necessary for seismic design provisions for uniform strain, also discussed above in the rationale. In some cases, CalTrans requirements were higher, and in other cases, the research concluded a higher value than what CalTrans prescribed was required. In all cases, the more conservative value was chosen for inclusion into this ballot item. 5.Editorial changes a.Response: Numerous editorial suggestions were made. Any omissions are unintentional and can hopefully be addressed via voter comments.

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    Work Item Status

    Date Initiated:
    04-03-2019

    Technical Contact:
    Jacob Selzer

    Status:
    Draft Under Development