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Re: Baseplate Anchorage

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David,

I will second Roger's (and your) concern about "stabbing" the anchors into
the concrete.  Not particularly a good idea and something that I typically
don't permit.

Having said that, if you are "forced" into that situation, then you could
look at headed studs or rebar with a hook on it to act as anchors, as
someone else pointed out.  The headed stud are actually meant to be welded
on in that fashion.  Rebars could attached in a number of
fashions...welded directly to the plate at the bar end (weld around the
perimeter of hte bar diameter), welded directly to the plate by first
bending a horizontal leg and then welding that leg (although would have to
worry about a possible "zipper" effect on the welded portion), could weld
a threaded coupler (from someone like Erico) then thread the bar to the
coupler (again these types of couplers are designed to be welded in this
fashion), etc.

HTH,

Scott
Ypsilanti, MI


On Tue, 29 Oct 2002, M. David Finley, P.E. wrote:

> Roger,
>
> Acutally they will be constructing a frame to hold the "new" plates in
> position.  I agree with your concerns about stabbing anchors into plastic
> concrete.  I also anticipate requiring c couple of holes in the baseplate to
> allow trapped air to escape and help ensure proper concrete consolidation.
>
> I had envisioned endplates on the angles or channels - a similar concept to
> headed anchors.  If  I use anchor rods, I would probably use ASTM F1554
> grade 55.  How is the weldability supplement speicified?  ASTM F1554, Grade
> 55 with weldability supplement?  or is there a slightly more formal
> phrasing?  Of course, my initial concern was just how good a welded tension
> connection could be made between the anchor rod and the bottom of the new
> baseplate.
>
> M. David Finley, P.E.
> 2086 SW Main Boulevard - Suite 111
> Lake City, FL  32025
> 386-752-6400
>
> ----- Original Message -----
> From: "Roger Turk" <73527.1356(--nospam--at)compuserve.com>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Tuesday, October 29, 2002 9:50 AM
> Subject: Baseplate Anchorage
>
>
> > Dave,
> >
> > It sounds like they want to "punch" the anchors into plastic concrete. My
> > GSN specifically prohibits this as it always leaves a void above whatever
> > projection the anchor uses to engage the concrete.
> >
> > With 75 kips uplift, you have to engage 750 cu. ft. of concrete to provide
> > uplift resistance and I wouldn't want to take the chance of a void being
> > above or alongside any anchor.  Nor would I want to rely on bond on
> > vertically oriented angles for this amount of uplift.
> >
> > HTH
> >
> > A. Roger Turk, P.E.(Structural)
> > Tucson, Arizona
> >
> > David Finley wrote:
> >
> > . > I've got a project where some industrial equipment is being relocated.
> > . > Rather than cut the baseplates loose, the owner wants to cut off the
> > . > existing anchor bolts and then move the equipment to the new location.
> The
> > . > supporting legs, with baseplates still welded on, will then be set
> onto
> > . > new (larger) baseplates and the 2 plates welded together.
> >
> > . > For the new baseplate, they want to weld "j-hooks" to the bottom of
> the
> > . > plate to eliminate any projection through the baseplate. I'm somewhat
> > . > concerned about whether they will actually use weldable material (no
> > . > matter what I spec) and how good a weld can really be achieved this
> way.
> > . > Obivously there is no way to inspect the assembly after the concrete
> has
> > . > been cast.
> >
> > . > In lieu of anchor bolts, I'm considering using vertically oriented
> angles
> > . > or channels so that the weld length is substantially longer.  Any
> > . > thoughts or other suggestions?  Each leg is subject to about 75 kips
> of
> > . > uplift (service load).
> >
> > . > M. David Finley, P.E.
> >
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