Title:
Proposed Specification for Deformed Steel Bars with Controlled Ductile Properties for Concrete Reinforcement
Author(s):
Conrad Paulson; Scott K. Graham
Publication:
CRC
Volume:
Issue:
Appears on pages(s):
Keywords:
steel, bars, specification, ductile, reinforcement, deformed, seismic, reinforced
DOI:
Date:
7/10/2015
Abstract:
As the primary activity funded by a research grant from the Charles Pankow Foundation (CPF), Wiss, Janney, Elstner Associates, Inc. (WJE) developed a complete draft of a proposed manufacturing specification for deformed steel reinforcing bars with controlled ductile properties having specified
minimum yield strengths of up to 100,000 psi (690 MPa). This effort is in support of CPF's research project in the area of High Strength Steel Bar Reinforcement (High Strength Rebar). Considerable in-kind assistance was provided by the Concrete Reinforcing Steel Institute (CRSI), its Material Properties and Bar Producers Committee, CRSI producer members, and various CRSI task groups.
The proposed specification pertains to deformed steel bars with controlled ductile properties that are intended primarily for reinforcement in members of special seismic systems made of reinforced concrete. The proposed specification is different from current specifications for ductile deformed reinforcing bars in that it provides for ductile bars with specific minimum yield strengths as large as 100,000 psi (690 MPa). Additionally, in the proposed specification, the primary measure of ductility is the uniform elongation (uniform strain) developed in the bar, coincident with the attainment of actual tensile strength. This is in contrast to current industry practice, which measures elongation across the fracture point (the constricted or necked-down region) of the expended test piece.
The proposed specification provides tentative (“placeholder”) values for certain tensile property requirements for bars with minimum yield strengths of 80,000 psi and 100,000 psi, including specified minimum uniform elongation, specified minimum tensile strength-to-yield strength ratio, and pin diameter for bend testing. The tentative values were established on the basis of currently-available engineering
information, from original research and from structural engineering publications. Laboratory tests on trial
production of Grade 100 ductile reinforcing bars indicates that the industry is capable of manufacturing reinforcing bars that conform to the proposed specification. Final values for these tensile property requirements are anticipated to be established in the future on the basis of engineering research that is
presently (mid-year 2015) underway and whose research results are anticipated to be available during 2016. It is also presently anticipated that this specification will enter into the consensus standardization process at ASTM International (ASTM) n the near future and be published as a new ASTM standard as early as 2017.