Snow load on lattice/mesh roof

[bouk715]

I'm working on a project where the architect would like to have a canopy with a lattice-style roof. The "lattice" would consist of 1"x1" steel bars welded in a 1-foot x 1-foot square pattern. So basically there will be a series of 11"x11" openings throughout the roof.

My question is, should the snow load taken on the canopy just be the amount on top of the bars (i.e. a 1" strip)? Or could the snow somewhat "bridge" that distance and I would design for full snow load with some sort of reduction taken.

Just wondering what other people have done if they've ever encountered this situation. ASCE 7 seems to be silent on this, at least from what I could find - they address wind on lattice but not snow.

My initial thoughts are to take either the full snow load acting on the 1" strip (drift + balance snow since the canopy is against a building) or ice loading (~1" nominal thickness in my area), whichever is greater. Any help is greatly appreciated, thanks.

 

[msquared48]

1/4" to 2" diameter radial Ice load applied just to the bars, depending on your location, would be more substantial than snow. I would investigate that.

Mike McCann
MMC Engineering

 

[TDIengineer]

I can't see the snow filling in the 11"x 11" gap and forming a solid canopy. I think M^2 has it right and consider some ice loads.

 

[bouk715]

Thanks to both of you. I agree...I have a tough time seeing snow filling an entire 11" gap. Design thickness for ice in my project is about 2.5". This weight of ice on the 1"x1" bar is slightly greater than the flat snow + drift on a 1" surface(ground snow load = 55 psf), so I'll go with that.

Thanks again and have a great holiday.