Importance Factor for Signs

[southard2]

What importance Factor would you recommend for a 16ft tall school sign that would be located in an area away from the ordinary walk paths. Sign to be located in Florida so hurricane winds control the design.

ASCE and the Florida Building Code don't really help much and this seems to be a grey area. Because of its size I might lean towards I = 1.0. But their are arguments for I=0.77 and I=1.15 as well. To me the risk to human life in a hurricane would be very low. Worst case is this thing overturns. The only reason someone would be their at that time would be if they were taking temporary cover. But at the loads necessary to push it over you would be nuts at that point to be out in the open.

John Southard, M.S., P.E.

http://www.pdhlibrary.com

 

[oldrunner]

If this sign breaks, will it fly?

 

[southard2]

Nope. The uprights are 16x16 masonry pilasters on concrete footings. Some of the wood signage I suppose could break off and fly but that is it. The brick, pilasters, and footing would definatly be too heavy.

John Southard, M.S., P.E.

http://www.pdhlibrary.com

 

[MiketheEngineer]

Usually not much difference in design for 1 or 1.15. So, if there is not - use the 1.15
.77 Seems low.

 

[Lutfi]

I debated this question with several building officials. My judgment would be as follows:

1. If it poses no risk to humans, (located in the middle of a field or nowhere close that it could endanger humans), use 0.77
2. If located on a school property but poses no danger for human life, use 1.0
3. If located in school property on a roof of a classroom or right next to a class room, use 1.15

I hope this helps.

Regards,
Lutfi

 

[rscassar]

I think the correct c&c loading would be critical to ensure that windbourne debris is generated during the hurricane. For the pilister design I would use an I of 0.77. No-one will be outside when the hurricane crosses and the masonry won't become windbourne.

 

[csd72]

I am sure we used to use 1.0.

 

[a2mfk]

I like Lutfi's logic. For what you describe I don't see a big difference either way (little more or little less), its just a sign structure.

 

[rb1957]

i know it's "only" a school sign, but it seems to me that it'd be a good idea to minimise the amount of stuff flying around in a hurricane. maybe you could design the sign to "fail safely" ... maybe have the sign facing spilt into two pieces but remain attached to the pilings ?