[TowerTalk] Arizona Ice Loading

[kr7x at comcast.net]

Bud:

I sent you a *.pdf with ASCE 7-05 Chapter 10 Ice Loadings. It also includes an Ice Loading Map that shows for Arizona only the northern half of Coconino, Navajo and Apache counties have an Ice Loading requirement, the rest of Arizona do not. The ice loadings are from freezing rain and are for a 50-year mean recurrence interval. If you are above 5000 feet elevation then the likelyhood of freezing rain is unlikely. For your info the ice requirement in the above counties is 1/4" radial with 30 mph (3-sec) wind. 

As I said in my previous post when you consider ice loading and wind simultaneously the wind speed is the 30 mph and is reduced to 70% of its pressure at that speed and the ice dead load is reduced to 70% of its value. This is done to account for the very short term loading that this describes. 

The jist is you don't need to consider ice for your structure.

Regards
Lonberg Design Group, Ltd.

H.S. Lonberg, P.E.,S.E. / KR7X
President