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Re: Bending Embedded Reinforcing Steel

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In reply to Bill, Roger, & Nicholas, the report may well be rigorously applicable to only lab conditions, however, bar bending done either in the lab for research, or on site is usually done with "standard" bar bending equipment, and therefore, provided "std" equipment is used, I would suggest that any particular bend should not vary significantly from lab to site. 
 
As I recall, the report I read was in response to the issues of arbitrary bending on site, such as bending wall bars already cast into position for a future slab etc., but bent out of the way during slab construction.  I have seen instances of those bars bent 3 or more times during such procedures.  The report identified that bars bent more than twice had a high probability if losing up to 65% of strength.  Ergo, do not bend more than twice at any given location.  The report also pointed out that the condition is no different where previous bent bars are re-bent for a different purpose.  It's "paper clip fiddling" again, a no-brainer.  Bend it back & forth too much and it'll break!  Small bars appear to be more prone to this since they are easier to "push" aside by hand.

Thor A Tandy P.Eng
Victoria BC
Canada
e-mail: vicpeng(--nospam--at)sprint.ca