[Repeater-Builder] Tower Foundations
One of my family members is putting up a tower to support his business radio (farm) , the family GMRS repeater, and a fairly large microwave dish to obtain internet.The choice so far is a Rohn SSV compromised of the following sections: 10NH, 9NH, 8N, 7N, and 6N. Here the question: The local PE who approved the prints suggested using drilled belled foundations. This nearly doubles the cost of each foundation in terms of drilling and concrete. Typically how much additional resistance to overturning motion do they add above straight sided holes?
RE: [Repeater-Builder] Tower Foundations
Did you look at the Rohn technical prints to determine the depth of the concrete? I am putting up a Trylon SSV tower and they have the specs on their website if you need another one to compare with. trylon dot com, Self supporting. They had a tapered bottom about 18 tall then the square top part. My experience with drilled cassons (large building construction) is that the bell portion adds extra strength to the base which acts as a footing. You could dig the ground out square at the bottom, pour a footing usually 24 thick, depending upon the soil, then build your form, then pour the column portion of the concrete. Strip the forms a few days later, then slowly back fill while tamping the ground down to meet compaction specs, then fill a little more to meet compaction specs, then you have a tower base that should not go anywhere. I just poured a tower base on a mountain top and I used more concrete than was speced, plus I poured it rather stiff, and the extra was poured around the base to make the tower top stronger. Tower bases bigger is better. Good luck with your project. Butch, KE7FEL/r To: Repeater-Builder@yahoogroups.com From: mafl...@att.net Date: Sun, 13 Sep 2009 15:42:46 + Subject: [Repeater-Builder] Tower Foundations One of my family members is putting up a tower to support his business radio (farm) , the family GMRS repeater, and a fairly large microwave dish to obtain internet. The choice so far is a Rohn SSV compromised of the following sections: 10NH, 9NH, 8N, 7N, and 6N. Here the question: The local PE who approved the prints suggested using drilled belled foundations. This nearly doubles the cost of each foundation in terms of drilling and concrete. Typically how much additional resistance to overturning motion do they add above straight sided holes?
Re: [Repeater-Builder] Tower Foundations
Ask the consulting engineer if re-bar could be added near the inside perimeter to the cement base to reinforce the foundation. I did this years ago when I installed a Rohn tower in a sand ground circa 1977 in northern Wisconsin. I never had any problems with the base moving around going forward ever since. That tower is extremely solid; not one of the antenna installers ever had an issue climbing it. One of the other things that we did was to pound 3 - 10 foot metal pipes in a triangular shape below the base ground level and leaving about 3 feet above it to bond with he concrete. Hope this helps. Good luck with your project. 73's, Don, KD9PT - Original Message - From: Barry To: repeater-builder@yahoogroups.com Sent: Sunday, September 13, 2009 4:44 PM Subject: RE: [Repeater-Builder] Tower Foundations I did some courses about this decades ago and remember very little but by adding some side excursion I remember something about a quadripling effect .. don't quote me of course as your consulting engineer can better answer this but certainly well worth it . -- To: Repeater-Builder@yahoogroups.com From: mafl...@att.net Date: Sun, 13 Sep 2009 15:42:46 + Subject: [Repeater-Builder] Tower Foundations One of my family members is putting up a tower to support his business radio (farm) , the family GMRS repeater, and a fairly large microwave dish to obtain internet. The choice so far is a Rohn SSV compromised of the following sections: 10NH, 9NH, 8N, 7N, and 6N. Here the question: The local PE who approved the prints suggested using drilled belled foundations. This nearly doubles the cost of each foundation in terms of drilling and concrete. Typically how much additional resistance to overturning motion do they add above straight sided holes? -- Find out how here Use Messenger in your Hotmail inbox
