Hi Les,
Get yourself over to trylon.com and check out their methods of anchoring
freestanding towers to rock.
I forget the exact dimension, but I think their rock anchors are 48 inches
and they spec out the right kind of epoxy. They're designed to be used
when the tower is installed on ONLY rock, so a rock-concrete combination
SHOULD be even stronger.
Not sure what UST specs for the base attachment, but if I were putting up
a Trylon in your situtation, here's what I'd have my engineer look over: sink
the Trylon rock bolts into the rock and use them to anchor Trylon base
stubs, shortened as necessary, with a levelling scheme in place. Once
the base section and stubs are mounted and the assembly is plumbed,
pour in concrete to come up above grade.
Perhaps that idea could translate to whatever the UST base arrangement
is.
Kelly
> From: "Les Kalmus" <w2lk@earthlink.net>
> Date: 2006/02/16 Thu PM 01:34:02 CST
> To: <towertalk@contesting.com>
> Subject: Re: [TowerTalk] UST HDX589 crank-up tower base on rock?
>
> That's exactly the point. I don't want to blast a hole in the rock and then
> fill it up with concrete. I want to anchor the tower base to the rock with
> only enough concrete to come a few inches above grade. My concerns
are the
> following:
>
> -How much up force will the anchors handle? There will be a lot of
leverage
> produced by the wind on the tower.
>
> -How deep into the rock should I go? A few inches doesn't seem to be
enough
> given the winds and exposed location on top of the hill.
>
> -The "T" base of the tower is drilled for three pairs of one inch bolts. Can
> the holes in the rock be aligned accurately enough for the bolts to slide
> through the base holes easily? If a pair of holes are drilled a few inches
> apart will the rock between them still retain its strength?
>
> -Normally, in concrete, J bolts are used and tied to the rebar in the
> footing. I guess I would need longer threaded rods with whatever is
used to
> anchor them to the rock on the bottom end.
>
> Les
>
> -----Original Message-----
> From: K7LXC@aol.com [mailto:K7LXC@aol.com]
> Sent: Thursday, February 16, 2006 10:16 AM
> To: towertalk@contesting.com; w2lk@earthlink.net
> Subject: Re: [TowerTalk] UST HDX589 crank-up tower base on rock?
>
>
> In a message dated 2/13/2006 3:17:48 A.M. Pacific Standard Time,
> towertalk-request@contesting.com writes:
> > Hi TTians,
>
> > In a few months I will be starting construction on a new house
which
> will be
> located on top of a hill on a adjacent piece of property. My HDX589 is
> currently installed on the manufacturer's recommended base of
5x5x8.5
> feet
> of concrete with rebar.
>
> > Test holes in the vicinity of the new house have revealed between
16
> and 40
> inches of soil on top of the rock the hill is made of. A blasting
> contractor
> has told me that the stone is very strong and stable and he will not
> have
> any problems blasting for the house basement and foundation.
>
> > I won't be able to dig another hole and use the same method as the
> current
> location. Instead, I have been told there are bolts or rods that can be
> set
> into holes drilled into the stone and epoxied in place which can
support
> the
> tower.
>
> > I will probably need an engineer but don't know where to begin to
> find one
> familiar with this type of work or what alternatives exist. Anyone
> familiar
> with this technique or alternative method who can steer me in the right
> direction? Any particulars I need to provide to him/her that I need to
> research in advance?
>
> Well, getting an engineer's blessing is always a good idea. Maybe
> you can talk to a couple and get some off-the-record feedback on what
you've
> got and what's possible.
>
> I would be in favor of using the rock as the base and then you only
> have to use a little concrete to get the top of the base a little above
> grade. Why would you dynamite out a bunch of rock and then fill in the
hole
> with concrete when the rock by itself would accomplish the same thing?
>
> You can rent a rock corer to drill the appropriate holes for the
> factory anchor bolts - or have someone come out and do it - and then
you can
> epoxy them in or use rock expansion bolts - or both. It'll be real strong.
> Cheers,
> Steve K7LXC
> TOWER TECH -
> Professional tower services for amateurs
> Cell: 206-890-4188
> _______________________________________________
>
>
>
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