[TowerTalk] Rplacement stud bolt

[Richard Thorne]

Find a Hilti dealer.  They probably have the rod and epoxy for the application.

Jepilot@aol.com wrote:

> Problem:  How to install a stud bolt in an existing concrete base.
>
> Background:  WD5FHG and I are in the process of installing/erecting a new 55
> foot crankup, self supporting tower (US Tower, HDX555).  This tower is
> replacing an earlier HDX555 which was destroyed when the cable broke on the
> fully extended tower.  What a mess.
>
> The new HDX555 tower has the same type of base as the previous tower.   Three
> stud bolts are installed in the massive concrete base, a steel T frame base is
> bolted to the three stud bolts, two legs of the tower are bolted to the base
> frame, and the tower is pulled up with an erection fixture to the vertical
> position.  I imagine a few hundred readers have been through this process.
>
> However the problem arises because one of the mounting holes in the steel
> frame does not match up with the stud bolt in the concrete base.  The holes at
> each end of the top of the T match perfectly but the hole for the bolt at the
> bottom of the T is not even close.  So we propse to install a new bolt in the
> existing concrete base.
>
> Proposed Solution:   We propose to have an all thread bolt fabricated by a
> local machine shop using high quality steel (same specs used for the factory
> furnished studs).  The stud would be 1-1/8 inch diameter and about 18 inches
> long, threaded its entire length.  A  1-1/2 inch diameter hole would be
> drilled in the concrete base about 12 inches deep which will allow the stud to
> extend about 6 inches above the top of the concrete.  The stud is to be
> threaded it's entire length to allow a better grip for the epoxy
> adhesive.Obviously there is 3/16  of an inch between the wall of the hole
> drilled in the base and the stud.
>
> Issues:  What is available to hold the stud in place?  In the old days, hot,
> liquid sulphur  was used for this purpose, which when cooled held the stud
> very well.  I suppose there is now available some type of epoxy for this
> purpose.  Any thoughts on this?
>
> Is 12 inches deep enough for this application?  The concern is, of course,
> failure of the epoxy and/or this method of installation while the bolt is in
> tension, allowing the bolt to be pulled out of the base.
>
> Is a 3/16 annulus too little, too much, just right, to allow adequate space
> for the epoxy to bind the bolt threads to the side wall of the hole?
>
> Any other thoughts?  Thanks for your comments, advice and suggestions.
>
> Jan Rehler, W5KNZ, Corpus Christi, Texas
>
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--
73,
Richard Thorne - N5ZC (Ex. KA2DSY, N2BHP, WB5M)
Amarillo, TX



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