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RE: More On Ungrouted Baseplates for Traffic Signal/Signage Struc ture s

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Bill,

I would be very surprised if the Texas DOT assumes the embedded template is
serving as a mechanical anchor.  The Texas DOT was the sponsor of several
studies by Lee, Breen, Cook, Doerr, Klinger, Collins and Polyzois on anchor
bolts at the Center for Highway Research and the Center for Transportation
Research at the University of Texas in Austin that concluded that the
embedded nut was more than adequate for anchor bolt anchorage.

In the TIA and EIA world of tower construction, the embedded template is
just to keep the bolts plumb and in the right position.  I would suspect the
Texas DOT is using the templates for the same reason.

I can only speculate that the omission of the grout is for corrosion
considerations or for frangible connections or both.

Regards,
Harold Sprague


> -----Original Message-----
> From:	Polhemus, Bill [SMTP:wlpolhemus(--nospam--at)sbinfra.com]
> Sent:	Tuesday, May 16, 2000 11:08 AM
> To:	'seaint(--nospam--at)seaint.org'; 'structx(--nospam--at)topica.com'
> Subject:	More On Ungrouted Baseplates for Traffic Signal/Signage
> Structure s
> 
> Some time back I mentioned that I was being "taken to task" by a reviewer
> for putting grout beneath my column baseplates for an overhead sign
> structure. Well, mea culpa (I guess) because the guy was right in pointing
> out that the Texas Department of Transportation standard drawings AND
> specifications explicitly state "no grout under baseplates".
> 
> First, I'm not sure why they have a problem with it, but I'll let that
> slide.
> 
> Studying their standard details (duh!) I note that they seem to expect all
> the tension AND compression loading on the baseplate to be taken directly
> by
> the anchor bolts themselves. These anchor bolts project either directly
> into
> a drilled shaft foundation, or into a "camelback" piece of traffic railing
> that is itself supported by drilled shaft foundations.
> 
> The anchor bolts are four in number, arranged in a rectangular pattern as
> close (it appears as possible to the supported column). They consist of
> threaded bar stock typically 1 1/2" in diameter and 3 ft to 4 ft in
> length.
> They are "connnected" to one another at the bottom of the bolts with at
> rectangular steel "template" of unspecified thickness, which itself has a
> rectangular opening to allow passage of conduit for cables, etc.
> 
> It APPEARS that this template is acting as a mechanical anchor for the
> anchor bolts, but I'm not sure how they modeled it. Your pardon if this
> seems like it should be obvious, but I just don't see this. If this is
> such
> a wondrous system, why arre we wasting all our time with grouted base
> plates?
> 
> I'd like someone to give such insights as they have into how all this
> works.
> 
> Thanks for the discussion.
>