[TowerTalk] New Tower Old Base

Thu Feb 24 09:46:57 PST 2011

My existing tower base is 7'x5'x4.5'.  I also WILL NOT raise tower about
75'.

On Wed, Feb 23, 2011 at 9:50 PM, Grant Saviers <grants2 at pacbell.net> wrote:

> All the numbers are in the 589 "Structural Analysis Report" 12/15/2010.
> Leave out whatever you like AYOR.  That's what makes lawyers rich.
>
> Do not presume there are big safety margins in this design for the given
> wind spec.  My read of the calcs would indicate otherwise.  (nothing
> like 2 to 4x of a bridge, more like an airplane 1.3 to 1.5x).
>
> Grant KZ1W
>
> On 2/23/2011 7:07 PM, Kevin Normoyle wrote:
> > the ability for a solid block foundation to resist overturning is
> > mostly dependent on the area of one side.
> > So comparing volume is misleading, if you are willing to believe you
> > have sufficient soil for the concrete you have.
> >
> > People were willing to make all sorts of compromises for the drilled
> > anchor bolts, so why not compromise (or play it with less margin,
> > basically) on the concrete? If this is a permit situation, and someone
> > asks for calcs, it's obvious the numbers won't work for hardly any of
> > it. So this has to be a no-permit situation, or one where questions
> > aren't really asked.
> >
> > The manufacturer ships what, six 27" anchor bolts for this? Seems like
> > people were perfectly willing to go with less on the anchor bolts.
> >
> > the side area comparison is just 5.5 * 9 vs 3.5*5
> > i.e. 49.5 sq ft vs 17.5..a 2.8x difference. That's within the range of
> > possible overdesign. So you can't say the existing foundation is
> > impossible to use. Just like you can't say any drilled anchor bolt
> > solution is guaranteed to fail.
> >
> > Now we don't know what kind of pullout force the anchor bolts need.
> >
> > But: if you're going to put in weaker anchor bolts (in resisting
> > pullout) than the original manufacturing spec, it makes sense that
> > your foundation only needs to be able to be good enough for your
> > anchor bolt setup.
> >
> > If people want to crank numbers, that's the set of numbers to crank:
> > what do you need for anchor bolts, to be able to overturn his existing
> > foundation. If you don't like that, then you shouldn't like it unless
> > there's a LOT of anchor bolts.
> >
> > What I don't understand, is why people jump on foundation sizes, but
> > easily look the other way when it's convenient or problematic (like
> > deep drilled anchor bolts).
> >
> > It's like we're amazing inconsistent on our engineering...yet we
> > pretend we're not.
> >
> > -kevin
> > ad6z
> >
> > On 2/23/2011 4:15 PM, Grant Saviers wrote:
> >> Actually, the current UST wet stamp calculations for my about to be
> >> installed HDX589 has a base 5'6" sq by 9' deep. (10yds of concrete)
> >>
> >> MA-550 at 3.5 x 3.5 x 5'  is 2.3 yds so that is a VERY big difference.
> >>
> >> Grant  KZ1W
> >>
> >> On 2/23/2011 4:06 PM, Mike Fatchett W0MU wrote:
> >>> Are you sure about the base?
> >>>
> >>> According to US tower the MA-550 requires a concrete base of:  3'6" x
> >>> 3'6" x 5'
> >>> The HDX-589 requires a base of:  5' x 5' x 8'
> >>>
> >>> That is difference of over 5 cubic yards of concrete.
> >>>
> >>> W0MU
> >>>
> >>> On 2/23/2011 4:35 PM, Richard Zalewski wrote:
> >>>> First, thanks to all for their comments and suggestions.  Some details
> >>>> omitted from my post:
> >>>>
> >>>> I will be replacing a Wilson MT61 (US TOWER MA550)that has the tilt
> >>>> base
> >>>> fixture with a US Tower HDX589MDPL.  Both of these towers are self
> >>>> supporting.  Both will have a SteppIR 3elment w/40m.  The existing
> >>>> concrete
> >>>> base is more than adequate for either tower.
> >>>>
> >>>> I will continue to update as more information has been acquired.*
> >>>>
> >>>> HDX-589MDPL
> >>>> **
> >>>>
> >>>> HDX-589MDPL
> >>>> **
> >>>>
> >>>> HDX-589MDPL
> >>>> *
> >>>>
> >>>>
> >>>> On Thu, Feb 10, 2011 at 7:31 AM, Paul_group<
> >>>> paul_group at greenrover.demon.co.uk>    wrote:
> >>>>
> >>>>> On 10/02/2011 13:53, pc2a at pi4cc.nl wrote:
> >>>>>> Richard Zalewski schreef:
> >>>>>>> I will be upgrading my tower and will be using my existing
> >>>>>>> base.  This
> >>>>> will
> >>>>>>> require drilling the existing concrete base and epoxing in some new
> >>>>> bolts.
> >>>>>>> I would be interested in exchanging some emails with someone who
> >>>>>>> has
> >>>>> done
> >>>>>>> this.
> >>>>> Been using them for years, holding up masts on top of buildings,
> >>>>> railway
> >>>>> overhead line gantries and all manner of structures.
> >>>>>
> >>>>> Take professional advice on the correct type to use - hilti are a
> >>>>> very
> >>>>> good supplier.
> >>>>>
> >>>>> My 80' is attached to the block with them and I sleep soundly at
> >>>>> night....
> >>>>>
> >>>>> --
> >>>>> 73 de Paul GW8IZR IO73TI
> >>>>> http://www.gw8izr.com
> >>>>>     _______________________________________________
> >>>>>
> >>>>>
> >>>>>
> >>>>> _______________________________________________
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> >>>>>
> >>> _______________________________________________
> >>>
> >>>
> >>>
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> >>
> >>
> >>
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> >
> >
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-- 
Tnx es 73
Richard W7ZR
www.w7zr.com

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