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RE: Non-shrink grout at steel columns

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Albert,

A couple general items to remember when dealing with grout under base plates
with or without leveling plates.

1) Generally grouted base plates are used to help level the column base
plates.  Therefore, any grout depth should include the expected variance
needed to level the columns.

2) Typically the thickness of a bolt on an anchor rod is near the diameter
of the rod. (i.e. 3/4" thick nut for 3/4" anchor rod)

3) The grout thickness needs to be thick enough to allow proper field
placement (or they won't place it properly)

With the above items in mind I generally ask for twice the bolt diameter
PLUS the thickness of the leveling plate (if desired) as a rule of thumb.

One small warning is to make sure that the anchor rod projection is called
out and placed properly.  The threads must extend to be flush with the last
nut on the anchor bolt as a minimum (in a perfect world).  Since things are
rarely perfect I like to leave room for an extra nut in the rod length to
allow for mistakes in setting the rods, bowed base plates, etc.

As far as using or not using leveling plates, I would tend to agree with
Matthew and leave that up to the erector.  Once grouted I don't know of any
advantage one way or another.  I have heard that leveling plates can be
easier to use since one can level the leveling plate prior to installing the
column.  I would also tend to agree to place the grout as soon as you could
since the grout would tend to take the compressive forces instead of the
anchor rods.

HTH,
Greg Effland, P.E.
KC, MO USA



-----Original Message-----
From: Albert Meyer [mailto:Ameyer(--nospam--at)martinaia.com]
Sent: Wednesday, January 23, 2002 7:55 AM
To: seaint(--nospam--at)seaint.org
Subject: Non-shrink grout at steel columns


I've seen different thicknesses of non-shrink grout specified for the gap
between the column base plate and the top of footing.  I have also had steel
fabricators specify leveling plates typically of 1/4" thickness, leaving a
grout depth of what was specified on the drawings less 1/4".  I'd like to
know if anyone has any recommendations on what the most reasonable grout
thickness is that should be specified so that it gets installed correctly
and has the best performance.  Also, are there any negatives to consider in
allowing the use of leveling plates?  Thanks in advance for your response.

Albert J. Meyer, Jr., P.E.
Martin Engineering
(215) 665-8570 Tel
(215) 561-5064 Fax
ameyer(--nospam--at)martinaia.com


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