Minimum Snow Load on Fabric Structures 2

[amecENG]

I am looking for some guidance on the minimum snow loads required on fabric structures. My question really relates to the Cs (roof slope factor) and I am more concerned about the National Building Code of Canada although I welcome any commentary from other code users.

I know both NBCC and ASCE have similar equations for Cs where it is a function of roof slope and slippery vs non-slippery surfaces. Essentially for a slippery surface with a roof slope of less than 60 degrees the Cs will be > 0 and therefore the structure must be designed for some value of snow load.

I am wondering if there is any reference or code commentary that suggest that a lower snow load value could be used for fabric roofs. I beleive ASCE has one but I can't find anything on NBCC. These companies have been building these structures for years in cold climates and I am wondering how they justify it to meet code?

Thanks in advance for your help.

 

[BAretired]

amecENG,
After reviewing your file on the structures built by Sprung Structures, I tend to believe that, for the type of structures illustrated, a lower snow load might be acceptable because all of the structures depicted in the photos had substantial slope and, apparently, a very low coefficient of friction. It would need the approval of the authority having jurisdiction, but if the structure can be shown to shed the snow completely, I think approval from the authorities could be obtained quite easily.

That does not mean to say that snow load may be reduced on all fabric covered structures. It would depend on the type of fabric and the configuration of the roof. Perhaps some guidelines could be prepared but, at the moment, approval would seem to be required on an individual basis, that is, for each fabric covered structure.

BA

 

[DavidKn]

It occurs to me that, depending on the exact nature of the fabric roof and its supporting framework, the fabric could sag, and collect more snow load, rather than shedding it, even if sloped. I have not designed many fabric and cable structures, but I recall that second order effects are very important.

 

[woodman88]

Per the 2009 IBC
"3105.3 Design and construction. Awnings and canopies shall
be designed and constructed to withstand wind or other lateral
loads and live loads as required by Chapter 16 with due allowance
for shape, open construction and similar features that relieve
the pressures or loads..."


Not sure if there is anything similar in the NBC.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.