Research Note, RN-1982-1
16 pp - 1982 (original report)
Note: This Research Note was originally printed by CRSI in 1982 under the title Bending and Straightening Grade 60 Reinforcing Bars. The report described a series of bending and straightening tests on Grade 60 reinforcing bars performed by Wiss, Janney, Elstner & Associates, Inc. (WJE No. 78282, April 6, 1982). Among the test variables were mill sources (3), bar sizes (#5, #8 and #11), bend diameters (ACI 318 and half ACI 318), orientation of bending axis (weak and strong), temperature (30° F, room temperature, and 1500° F), and bend angles (15, 30, 45, 60, 75 and 90 degrees). The CRSI report has been out of stock for several years, but the research represented therein is still valid and of worth in the reinforced concrete community, so it has been reprinted here in this Research Note, verbatim.
A frequently encountered construction problem is that a partially embedded reinforcing bar requires bending or straightening. A bar may need to be bent because of incorrect fabrication, inaccurate placement, or to provide access. A bent bar may need to be straightened for any of the same reasons or because it was bent accidentally during construction. Field bending or straightening can be done by placing a steel pipe over the bar and pulling on the bar. Smaller bars can be pulled with manual effort.
A series of bending and straightening tests on Grade 60 reinforcing bars was conducted for the CRSI Technical Committee of the Associated Reinforcing Bar Producers. Field bending and straightening for various bend diameters and bend angles was simulated in the laboratory. The effect on the bars was evaluated by observation and by subsequent tensile testing.