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[SEAOC] RE: [SEAOC] Welded Rebar advise needed

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I am not sure I totally understand the connection, however the welding of 
rebar is addressed in the PCI Design Handbook.  The specific type of weld 
you refer to is a flare V groove weld.  Be sure to specify weldable rebar. 
 ASTM A 706 rebar is what is generally specified for weldable rebar, but it 
can be difficult to obtain.  If you choose to use ASTM A615 rebar, you need 
to obtain the mill test reports to calculate the carbon equivalents, which 
are then used to calculate the preheat.

Welding high carbon rebar should be avoided if at all possible.  If it can't 
be avoided, get it inspected by an AWS certified inspector.

One easy solution is to use deformed bar anchors, which are weldable, but 
you are somewhat limited on length availability.

You may also wish to consider couplers.

Another potential solution is to use a headed anchor bolt lapped onto a 
rebar hooked at the top.  The embedment should be sufficient to develop the 
hooked rebar.  Proper confining steel is required to avoid bursting.

The only other potential problem that I see is that the lap lengths, 
embedments, etc. are all developed for concrete not the grout contained in a 
CMU wall.  you could hold the CMU back and provide an integral conc. column 
in the wall similar to the details prevalent in wind resistant construction 
in Florida.

Since you are already placing a concrete cap, I would hold the cmu back from 
the column center line and install a reinforced concrete column integral 
with the cmu wall.  I would use vertical rebar with hooks at the top.  Run 
the horizontal rebar from the cmu wall through the reinforced concrete 
column.  Provide headed anchor bolts in the top of the concrete column, and 
connect the steel column with the anchor bolts.  To limit the lateral slip 
due to the oversized holes in the base plates, provide plate washers and 
weld the plate washer to the base plate.

Harold Sprague
From: seaoc
To: SEAOC Listservice
Subject: [SEAOC] Welded Rebar advise needed
Date: Monday, September 30, 1996 5:13PM

I am using a tube steel column to transfer shear through a header - 1.9
kips. The moment at the bottom will yield an uplift of about 10 kips per
bolt (2 per side). The bottom connection is a 12" CMU wall (basement wall)
with a 4" concrete (reinforced) cap. The base plate rests on the CMU and
the column is embedded in the concrete.
I want to resist uplift (assuming the concrete will not be used to resist
the column moment) with 7/8" diameter threaded rods welded to #6 rebar
(jamb bars) embedded into the footing.
I need a design example for the welded connection (i.e., lap and weld
design). This is the first time I've done this and am not comfortable with
Could someone please advise how to design this connection? Would it be
better to keep the base plate above the concrete for better distribution of
the crushing end of the plate?
Please advise.

Thanks in advance,
Dennis Wish PE

Respond to: wish(--nospam--at)
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