[TowerTalk] Pad and Pier for ROHN SSV. Pad and Pier Foundations

[isp@bnjcomp.com]

Bob,

Please rember that I don;'t know or have access to a belling machine.  Makes me kind of paranoid to think about getting 10-12' in a hole and hand belling out hole.  Are you suggesting a big square hole (have easy access to 70' trackhole but would have to hire someone out (like a well boring person in our area) if I wanted a "round" hole) that is size of recomended rohn pad at bottom of pier?

IN my rohn bible book on page SSV-3 is where I am getting my specs.  For a 14N section:

1.  pier pad combo is 12' down with a 2' X 2' X 2' pad at bottom.  18 yards of concrete
2.  drill and bell is 14' down with a 6' bell   16.7 yards of concrete
3.  drill is  25' down  27 yards of concrete.

I am also thinking that all of these specs "assume" that you will have sections 6n - 1w which I don't so that should give me some relief.
my concrete/tower  guy wants to go 10' and put a massive pad at bottom of piers to give it weight.
I am going to ask my trackhole person how much of a "bell" he can put at bottom of 14' with his trackhole.  I mean the main hole is 3' right so that gives him room to go down and then scrap out 2' all way around right?  Guys am I way off here?

I only get to do this once so am looking for good input from this list.

thanks terry

  ----- Original Message ----- 
  From: Bob Gates 
  To: isp at bnjcomp.com 
  Sent: Friday, July 08, 2005 1:39 AM
  Subject: Re: [TowerTalk] Pad and Pier for ROHN SSV. Pad and Pier Foundations


  Terry,

  Pardon the expression, but that is a hell of a lot of digging and concrete.  Spent 30 years with a major oil company, most in Marketing Engineering.  I was a region manager when the company was going through a cost cutting exercise, and the next thing I knew the drawings for our large canopies were revised to show these spread footings.  I'm talking structures that were 48'x105'++.  There were two columns every 25' lengthwise.  Upon asking why the change, I was advised that the bell footings used less concrete, ergo less cost.  When I pointed out that digging the bell, and forming out the rest of the hole so someone couldn't get buried if a wall fell in, actually increased the cost.  The design was quickly changed back to a rectangular footing.  BTW, the canopies had a wind rating of 110mph.  Would suggest the same in your case.  Either dig a rectangular hole the size of the bottom of the bell, or auger a hole the same diameter as the bottom.  Spend a few dollars more on concrete and save significant man hours.  Net is a lower cost, and just as safe.  If you feel uneasy about this, ask a registered engineer in your area.  GL.

  73, Bob W7BJ