Snow Drifting
Snow Drifting
(OP)
In ASCE7-05 the drift height is calculated by a graph or equation involving the ground snow load and the length of roof upwind of the drift. My question is "Is there a reasonable maximum length of roof upwind to consider in the drift?" This is a result of a maufacturing facility that is adding a addition on the side of their exsitng building. The change if roof height is around 10'. The problem though is the length of the existing factory building 1000'. I have calculated the drift using lu=1000 but I am wondering if I can reduce this value.






RE: Snow Drifting
RE: Snow Drifting
They do allow you to use 3/4 of the calculated drift height for windward drifting. (See 7.7.1)
RE: Snow Drifting
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Snow Drifting
RE: Snow Drifting
RE: Snow Drifting
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Snow Drifting
A lawyer would eat you up if you were ever involved in a lawsuit due to a roof collapse were you used a lesser snow load than the graph shows.
I once investigated a low roof collapse similar to the building you described but only about 300 feet long. There was only about 8" of snow on the ground but the lower roof had about 8' of snow on it when it collapsed.
The snow density could not be determined but it was probably less than the max assumed by the graph but the snow height was also considerably higher than the graphs indicated.
When dealing with snow drifts Murphy's Law should always be used.