On 9/8/97 8:24 AM, Fred Hopengarten at k1vr@juno.com wrote:
>
>For example, Rohn uses a safety
>factor of 3, while Cushcraft uses a safety factor of 1.25. My friends
>who are mechanical engineers tell me that 1.25 is closer to
>"appropriate," and comment that the real reason for Rohn to use 3 is to
>sell Rohn 55 when Rohn 45 would do. No serious mechanical engineer has
>ever told me to use more than 1.5. Ever.
>
About two years ago I looked into safety factor for a broadcast tower.
The structural consultant was kind enough to send me copies of the
specifications/rules. The required safety factors are not constant.
For example, guy wires require a 2:1 safety factor but the reserve in
the steel depends on several factors including use (leg or brace),
overall height, and length to diameter ratio. In general, my
recollection was that tower steel called for a safety factors between
1.3 and 1.8 to 1.
I will see if I can find the equitions/reference in the file at the
office ...
73,
... Joe Subich, W8IK ex-AD8I
<w8ik@ibm.net>
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