Field bending of rebar
Field bending of rebar
(OP)
ACI 318 states that field bending of rebar is not permitted unless approved by the engineer. Research has shown that (cold) field bending a bar less than a #7 usually doesn't have any negative effects to the integrity of the bar. If there is no significant yielding, cracking, or, or kinking of the bar, I would expect that it's not a problem. Does anyone else have any thoughts or experience on this matter?






RE: Field bending of rebar
Stephen Argles
Land & Marine
www.landandmarine.com
RE: Field bending of rebar
RE: Field bending of rebar
RE: Field bending of rebar
Vertical dowels at footings and horizontal dowels at wall construction joints are often bent over at 90 to facilitate foot and/or machine traffic. "L" dowels at the tops of walls to catch intersecting slabs are often bent over at 90 to facilitate backfill placement. Never a good idea.
RE: Field bending of rebar
General field bending on all bars not embedded in concrete should be done with a proper mandrel and template which most rod-bende companies have even if they don't know it!
Regards,

Qshake
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.
RE: Field bending of rebar
RE: Field bending of rebar
RE: Field bending of rebar
RE: Field bending of rebar
RE: Field bending of rebar
Of course the bars always yield when bent; they are undergoing significant plastic deformation. I don't see any problem as long as you get the minimum radius. There are bar bending tools that bend the bar over a cylinder that meets the minimum radius upto a given size bar. The ones that pull the bar across a wheel as it is bent cause less strain in the bar.
RE: Field bending of rebar
RE: Field bending of rebar
RE: Field bending of rebar
RE: Field bending of rebar
Bar size Minimum diameter
No. 3 through No. 8 = 6db
No. 9, No. 10, and No. 11 = 8db
No. 14 and No. 18 = 10db
RE: Field bending of rebar
I have been thinking about this problem before. Remember two things. First, for a bar to hold its shape, it has to be bent well past the yield point, otherwise it will just snap back into shape. Second, as it turns out, the bars are bent well past 10x the yield strain. Therefore, it is difficult to say "don't bend them too much," because I can't find someone who will define clearly what too much is. Just as an exercise, I recommend you get out a piece of paper and compute the strain in a typical bar bent into a standard hook. Compare that to the yield strain. It will open your eyes. It should also give you comfort that plastic bending can really occur for a long time before fracture. Good Luck & Merry Christmas.