Something I have always wanted to ask. Have you ever seen a tower come down due
to a failed base?
73,
Joe kk0sd
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Dick Blumenstein
Sent: Saturday, April 7, 2018 12:24 PM
To: towerTalk@Contesting.com
Cc: Don Rasmussen <wb8yqj@yahoo.com>
Subject: Re: [TowerTalk] Unitary tower strength
Hi Don-
I can't provide specific info on adding a 30 foot crank up to your existing
base and a section of the old tower.
All I can say is that my 72' steel US Tower required 6@ 1" diameter steel bolts
at least 27" long into a concrete base that was 5' x 5' x 8.5' deep with
intricate steel rebar cage. I looked at the US Tower spreadsheet by their
structural engineer and, to say the least, it was unbelievably complicated to
calculate the strength required for the max anticipated wind loads (105 mph)!!
I had to get a County permit to put up my tower. Since I'm an engineer and a
"by-the-book" kind of guy, I just pointed at the detailed installation
specifications provided by the manufacturer (US Tower) and showed the County
that I was following their directions.
I don't know exactly where your tower is/will be in relation to other
structures, but a hodge-podge set up (i.e. not following the manufacturer's
instructions) can be a legal nightmare in case it ever fails and falls on some
one or some thing.
You also didn't state whether it is a steel crank-up (I assume it is).
Dick, K0CAT
=============================
Don Rasmussen via TowerTalk wrote on 4/6/2018 10:38 PM:
> Hello All,
> Have a 30 foot aluminum tower mounted to a steel base in concrete.
> Would like to install a crankup mast in it's place. Maybe a concrete bolt at
> the base of the crankup and use a house mount a few feet up against the old
> tower.
> If I cut the base tower section in half, wondering if what is left might be
> sturdy enough to bolt the crankup mast up against, or if the remaining base
> section would be so compromised by cutting it that it wouldbe worthless to
> use as a support. Section could be cut just abovea set of horizontal cross
> members.
> Would be interested in any comments on this, or ways of convertinga Universal
> Tower 4-30 base output lugs into something strong enough to support the sway
> from a 30 foot crankup mast.
> de Wb8yqj Don
> _______________________________________________
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