Ice loads on wind covered structures
Ice loads on wind covered structures
(OP)
Hope somebody can help me with another issue the code fails to clarify. At least it isn't clear to me.
In section 10.7 of ASCE 7-05 (wind on ice-covered structures) 1. states Vc shall be determined from figures 10-2 - 10-6 which are wind maps. These wind loads avg 30, 40, 50 mph.
7. states qz shall be determined using Vc according to 6.5.10 (basic qz formula)
My question is this:
Does the 10 psf minimum apply here. Using a Vc from the wind maps in 10-2 gives qz loads lower than 10 psf.
Thanks for your help
In section 10.7 of ASCE 7-05 (wind on ice-covered structures) 1. states Vc shall be determined from figures 10-2 - 10-6 which are wind maps. These wind loads avg 30, 40, 50 mph.
7. states qz shall be determined using Vc according to 6.5.10 (basic qz formula)
My question is this:
Does the 10 psf minimum apply here. Using a Vc from the wind maps in 10-2 gives qz loads lower than 10 psf.
Thanks for your help






RE: Ice loads on wind covered structures
That would be wind loads on ice covered structures
RE: Ice loads on wind covered structures
RE: Ice loads on wind covered structures
Out of interest, what "ice-sensitive structure" are you designing.
Timing has a lot to do with the outcome of a rain dance.
RE: Ice loads on wind covered structures
Paddington, you are saying to use the Vc given in fig 10-2 (which gives you lower than a 10psf load) and the min does not apply?
Mike, you think the 10 psf min applies?
IMO, I think you may use less than a 10 psf load. My thinking is this:
The code tells you to use the Vc from the map in 10-2, it states that explicitly in 10.7 #1
The reason I don't think the min applies is because all these values give numbers below 10 psf
Thanks for the input
RE: Ice loads on wind covered structures
akastud
RE: Ice loads on wind covered structures
RE: Ice loads on wind covered structures
Yes, you do your regular design using all of the regular loads including wind, then, as a special case, use the lower wind load on the larger width, heavier, ice coated structural members.
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akastud, we once used 4psf wind per NESF on transmission lines. I think you use more ice than we did too. Climate change?
Timing has a lot to do with the outcome of a rain dance.
RE: Ice loads on wind covered structures
That's one of the other reasons I would be ok with dropping the load less than 10 psf. Life safety is usually not an issue (when ice on wind applies), the owner does not want to pay to design these things for 70% solid, and usually the net fails at the connections and falls due to the additional weight of the ice.
RE: Ice loads on wind covered structures
What it finally comes down to;
1. Can you live with the risk? will your insurance cover you in the event of failure? the owner may turn around and sue you for doing a lousy job if something happens. It has happened before, an owner pushes, verbally, for a cheap and nasty job, and then sues when one of the chickens comes home to roost.
2. If you go along, can you get it past the Building Official for permits?
Timing has a lot to do with the outcome of a rain dance.
RE: Ice loads on wind covered structures