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RE: Welding rebar

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Bob,

You have already seen in a previous post the information from CRSI, and have received all of the obligatory warnings. Another aspect of rebar of that age is that it was not very consistent. The carbon contents and metal chemistry will be all over the map. Expect carbon lenses.

Look at Erico for possible mechanical connectors from their family of connectors.
http://www.erico.com/

The first question should be, "Is there any alternative to welding rebar?" If not, keep reading.

If after all of that, you still elect to weld existing rebar consider the following: 1. If at all possible avoid butt welds in tension. If possible design for compression only. If not, try to add a coupler. If that does not work, consider a backer like an angle where the welds would be in shear as opposed to tension.
2.  Test as much of the existing rebar that you can to determine chemistry
3.  Assume the worst (CE > 0.75)
4. Develop a welding procedure and preheat based on the AWS D 1.4, with a CE greater than 0.75
5.  Get a welding inspector with a track record on testing old welded rebar
6.  Require UT

Regards,
Harold Sprague





From: "Garner, Robert /SD" <rgarner(--nospam--at)moffattnichol.com>
Reply-To: <seaint(--nospam--at)seaint.org>
To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
Subject: Welding rebar
Date: Fri, 3 Sep 2004 08:10:15 -0700


I'm writing some specs for butt-welding some 1928 era reinforcing bars.
Does anyone have any idea what the yield strength of that steel may be?
Under Section 6.2.7.1 of AWS D1.4, the welds have to be tested and must
develop 125% of the specified yield strength of the bars. What do you think
that yield strength may be?  Could it vary by bar size?  I seem to recall
that back then, certain bar sizes were made from square bars.  I think the
smaller bars were round.  Thank you all in advance.

Bob Garner, S.E.

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