[TowerTalk] [Tower Talk] Was something else - Now Radian specs vs. Peoria specs ??

[Dick, W1KSZ]

I think they changed the windload from 75 mph to 90 mph.

73, Dick, W1KSZ

Jim Lux wrote:
> At 12:19 PM 6/26/2007, Clint Talmadge wrote:
>> Bob, AD5VJ asked a question about a concrete base for a Rohn tower.
>>
>> When Bob, NA6T posted this reply I thought the amount of concrete 
>> sounded a bit high. I checked the Radian site and sure enough that 
>> is what is listed.  So I drug out my old Peoria Rohn Catalog, circa 
>> 1983 and researched base dimensions. Peoria Rohn specs call for a 2' 
>> X 2' by 4' deep hole for the tower that Bob, AD5VJ is installing. It 
>> calls for guy anchors of 2' X 2' by 1' deep.
>>
>> Which raises the question: Did Radian re-engineer the base 
>> dimensions or did the fear of litigation cause Radian to up the numbers?
> 
> Purely speculation, but a lot has changed in the last 25 years, 
> including how windspeeds are specified (or, more properly, what load 
> corresponds to what rated speed), perhaps some assumptions about the 
> bearing capacity of soil, perhaps standard construction practices have changed?
> 
> One likes to hope that folks aren't motivated by "fear of litigation" 
> but, rather, a desire to "do the job right", and if a reanalysis 
> shows you need different dimensions, then so be it.  I sort of doubt 
> they just blindly increased the size in hopes that it would be "safer".
> 
> 
>> I've installed two towers for myself, both Rohn 25G, both in the 30' 
>> to 40' range ( I use a full section for the base) and both were 
>> planted in 2' X 2' X 4' holes. Neither came down (yet).
> 
> That's not surprising on a sample of 2. The footing design would 
> generally not be designed to fail at 1 mi/hr over the limit, but 
> would include some margin for things like variations in soil, 
> variations in material properties, etc.  Failure is a probability 
> thing, not a "exceed the limit and total destruction is certain" sort of thing.
> 
> Jim, W6RMK 
> 
> 
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-- 
73, Dick, W1KSZ