Snow Load on Moment Frames

[BikeDrD]

I am in SDC D designing a steel moment frame for a two-story 20-foot tall moment frame. My roof snow load is on the order of 150 psf. Can I use an ordinary moment frame? the code says I can if my dead load is less than 35 psf. It doesn't say seismic mass, which would include the snow load. I appreciate your feed back and comments!

 

[civilperson]

The snow is not connected to your building in a rigid manner. What load combination with snow are you using with seismic loads?

 

[BikeDrD]

I'm not combining with snow. The only load on my frame is seismic.

I should elaborate: It seems to me that the ASCE 7-05 is not allowing ordinary moment frames in SDC D when the frame is bracing heavy structures (12.2.5.7). Wood framed buildings are not heavy. However given the amount of snow here we design with 20% of snow load as part of the seismic weight (12.7.2).

In response to your first comment: I'd agree with the code regarding the percentage of snow that is added to the seismic weight. Last winter I had three feet of incredibly dense and hard packed snow over (and completely bonded to) about a foot of ice which was completely interlocked with my asphalt shingles, all locked into a maze of valleys and prevented from sliding by an ice dam at the eave.