Snow Drift in 5psf GSL Region
Snow Drift in 5psf GSL Region
(OP)
How are Engineers in the southern US handling snow drift in a 5 psf ground snow load region?
The commentary states that a 3 or 4 foot drift could occur in regions of low ground snow load.
My roof length is causing a 6 foot snow drift. That seems completely reasonsable here in the Midwest. But I am getting some questioning looks from my Southern counterparts.
The commentary states that a 3 or 4 foot drift could occur in regions of low ground snow load.
My roof length is causing a 6 foot snow drift. That seems completely reasonsable here in the Midwest. But I am getting some questioning looks from my Southern counterparts.






RE: Snow Drift in 5psf GSL Region
RE: Snow Drift in 5psf GSL Region
RE: Snow Drift in 5psf GSL Region
Been awhile since I've done this calculation, given that I've lived/worked in an area with no snow for nearly the past decade. Anyway, if I remember correctly, aside from needing the geometry of the drift (to help get an equivalent psf) this involved (in part) calculating the density of the snow. I found the attached calculation online (see page four of the document; they ended up with a density of 17.25 pcf). Before even finding the document, 17 pcf was a number I had remembered running into on several occasions. Obviously you will need to specifically calculate it for your instance. If you're looking at ASCE 7-05 (for example; I didn't have a more recent version with me while typing this), you would need to look at section 7.7.1, equation 7-3. Additional detail/calculation can be found in the commentary, on page 331.
FWIW... this spreadsheet (http://www.steeltools.org/resources/viewdocument/?...) looked interesting, though you will obviously want to double-check the results.
RE: Snow Drift in 5psf GSL Region
I was just asking the OP what it weighed. I got better things to do on a Saturday than that calc :>
RE: Snow Drift in 5psf GSL Region
RE: Snow Drift in 5psf GSL Region
RE: Snow Drift in 5psf GSL Region
RE: Snow Drift in 5psf GSL Region
Large industrial and manufacturing complexes may have vast expanse of roof area and could cause a significant drift (I have 720 feet of upwind roof)
RE: Snow Drift in 5psf GSL Region
The leeward drift load provisions are based on
studies of snow drifts on roofs (Speck 1984, Taylor
1984, and O’Rourke et al. 1985 and 1986). Drift size
is related to the amount of driftable snow as quantifi
ed by the upwind roof length and the ground snow
load. Drift loads are considered for ground snow loads
as low as 5 lb/ft2 (0.24 kN/m2). Case studies show
that, in regions with low ground snow loads, drifts 3
to 4 ft (0.9 to 1.2 m) high can be caused by a single
storm accompanied by high winds.