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Re: Bending Embedded Reinforcing Steel

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If it's not too long to post, I think most of us would be interested.  

This is a common situation in concrete construction in this area,
particularly at stairwell and elevator doors, where vertical reinforcing 
is  bent and rebent for ease of erecting and stripping formwork.  It also
occurs where columns terminate at the roof slab.  The turned-out bars
prevent installing the formwork in one piece -- You get the idea.

Thanx,
Fountain


----------
From: vicpeng <vicpeng(--nospam--at)sprint.ca>
To: seaint(--nospam--at)seaint.org
Subject: Re: Bending Embedded Reinforcing Steel
Date: Saturday, July 07, 2001 1:34 PM

I interpreted the report to mean a second, third, etc bend at the same
location.  I'll try to find it and sent it to you.  Shall I post it to the
list?

Thor A Tandy P.Eng
Victoria BC
Canada
e-mail: vicpeng(--nospam--at)sprint.ca
  ----- Original Message ----- 
  From: Fountain Conner 
  To: seaint(--nospam--at)seaint.org 
  Sent: Saturday, July 07, 2001 10:56 AM
  Subject: Re: Bending Embedded Reinforcing Steel


  I'm not familiar with the report, but...

  If it's correct the magic "one" bend would occur when the shop made the
"Z"
  bend.  Straightening the bar in the field would be the second bend.

  After all these years, I can count to two.

  Fountain

  ----------
  From: vicpeng <vicpeng(--nospam--at)sprint.ca>
  To: seaint(--nospam--at)seaint.org
  Subject: Re: Bending Embedded Reinforcing Steel
  Date: Saturday, July 07, 2001 12:14 PM

  There was report issued about 11 years ago in New Zealand following some
  research on the bending of rebar.  It found that one (1) cold bend of
rebar
  resulted in minimal loss of strength, however, on two (2) or bends there
  was a drastic loss of strength.  I therefore only allow one cold bend,
  however, what I don't see ....  Heating and bending is definitely out!

  Hence you need to exercise caution with on-site bending.

  Thor A Tandy P.Eng
  Victoria BC
  Canada
  e-mail: vicpeng(--nospam--at)sprint.ca
    ----- Original Message ----- 
    From: Jim Persing 
    To: SEAINT 
    Sent: Friday, July 06, 2001 11:30 PM
    Subject: Bending Embedded Reinforcing Steel


    I have a detail on my plans with #4 bars bent 90 degrees from vertical
in
  a
    concrete stem wall to horizontal into a slab on grade.  Nothing
unusual.
    The contractor wants to install embedded bars in the stem wall with the
  90
    degree bend to horizontal and then another 90 degree bend back to the
    vertical just outside of the stem wall to make kind of a vertical Zee. 
  This
    last bend is temporary and will be bent back to horizontal when the
slab
  is
    placed.    I have an older CRSI book which allows it only with the
  approval
    of the engineer and also a CRSI Engineering Data Report Number 12 which
    seems to indicate that it is probably OK for smaller bars.

    I can think of lots of reasons why this should not be done but just
  wonder
    if anyone else has had this detail presented to them and whether or not
  they
    approved it and why.

    Thanks,
    Jim Persing, SE
    Advanced Structural Concepts
    Bellevue, WA


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