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Re: [TowerTalk] Concrete base - tower

To: Jim Thomson <jim.thom@telus.net>
Subject: Re: [TowerTalk] Concrete base - tower
From: RMorris <robrk@nidhog.net>
Date: Fri, 13 Oct 2017 13:38:29 -0400
List-post: <mailto:towertalk@contesting.com>

Sent from my iPad

On Oct 12, 2017, at 17:17, "Jim Thomson" <jim.thom@telus.net> wrote:

> Date: Thu, 12 Oct 2017 14:29:59 -0230
> From: Larry Horlick <llhorlick@gmail.com>
> To: towertalk@contesting.com
> Subject: [TowerTalk] Concrete base - tower
> 
> <I am preparing to install a 70' Trylon SuperTitan S500. Nothing is done at
> <this stage...I'm thinking about pouring the base first. Hi.
> 
> <The manufacturer has supplied a drawing of the required concrete base. It
> <is a pad and pier design. Doing a pad and pier is significantly more work
> <(i.e. creating the form) than, say, just a rectangular block that I could
> <simply pour in the hole with very little form work.
> 
> <My question is...Can do that? Can I change the pad/pier to a block, by
> <altering the dimensions, amount of rebar, etc. to arrive at an "equivalent"
> <to the pad/pier??
> 
> <I welcome any relevant comments/questions/suggestions.
> 
> 
> <Larry
> <VO1FOG
> 
> ##  pad + pier is a pita.   The dirt you put back in there..around the pier, 
> that
> sits on the concrete base is...free weight.  You can easily dispense with the
> form..but then  you will use a helluva lot more concrete..which is OK per 
> Trylon.
> But the re-bar setup is different. 
> 
> ##  If ground is clay, or solid enough, so the sides of the hole   dont cave 
> in, 
> you dont require the megabuck, pita  wooden form.   Flip side is.... the 
> wooden form
> is very expensive to build.  It comes out a wash,  or close to it.    Cost of 
> wooden form
> vs cost of extra concrete. 
> 
> ##  If a wooden form is used, it has to be carefully constructed.  Concrete 
> weighs aprx
> 4000 lbs  per cubic yard....=  150 lbs per cubic foot.   There is a huge 
> stress on the wooden form as is.
> There is also a huge stress on the portion of the wooden form that 
> encompasses the pad.  Thats from the
> sheer vertical compression weight of the  concrete in the pier.   Get it 
> wrong...and  form starts to come apart
> when you have poured 80% of the concrete into the form.... u are in for a 
> rude awakening. 
> 
> ##  Even if it all goes ok, the  wooden form has to be removed.   Which means 
> the hole has to be big enough
> to work in.  IE  u gotta be able to get down into the hole and squeeze 
> between the dirt side walls and the 
> wooden form, to dismantle the wooden form.   Here in BC, if the hole is 6 ft 
> deep, or deeper, the dirt sides have to be shored up,
> which involves yet a ton more wood.    WCB here in BC  will severely fine any 
> contractor violating shoring regs. 
> Ok, now you toss the wood into the scrap heap, never to be used again. 
> It would be a different story  IF you are a contractor, and are installing 
> 4-10  identical towers,  and the expensive 
> wooden form can be re-used. 
> 
> ##  BTW,   AN wireless, who makes a similar product,  depicts BOTH methods on 
> their website.   The owner tells me
> nobody uses the wooden form and  pad and pier method.   Sure, you save some 
> $$ on concrete, then you lose it all 
> on the wooden form, and elaborate re-bar bending....  PLUS a ton more effort 
> and time involved with  the form + pier + pad. 
> Contact Trylons eng dept....  and they will provide you the... normal base 
> diagram..which is not on their website.  Local tower
> contractor has installed the newer  Trylon Super titans  for commercial 
> use...and none of em used a pad + pier.  Besides the cost
> of the form...+ shoring, there is a ton of expensive labour involved, both 
> building the form + shoring, and removing it.  
> A lot quicker to just dump more concrete  in.     BTW, dont use anything less 
> than 30 MPA  concrete.    30 mpa is 50% stronger than
> 20 mpa, and you wont end  up with any hair line cracks....esp in winter, with 
> sub freezing temps.   If I remember  correctly, the pad
> + pier method also involved installing styrofoam  sheeting on top of the 
> exposed pad, after the form removed. 
> That depended on how deep the frost line is.   It was typ 1-2 inches thick. 
> More pita.  You dont require any of this with a giant
> block of concrete.    I was going to install a 90 or 100 ft of super titan, 
> with the 6 ft wide base...at my daughters place, since 
> she was on 5 acres.   She ended up selling it...and moving to denman 
> island...now on 11 acres.  I gave up on that project.  The logistics
> of driving 150 miles each way, was too much. On the island, its then a 10 min 
> ferry trip each way, on top of the drive.   And concrete
> on that island shes now on is  stupid expensive.  
> 
> Later.... Jim   VE7RF        
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