Do we consider SNOW loading for the soil bearing capacity ?

[gasma1975]

Hi,

My geotechnical gave me a soil capacity (considering a 1 inch settlement). I was wondering when evaluate the reaction force on that footing. Do I have to add snow loading ? All my books are only mentioning the DEAD LOAD and the SERVICE LOAD (LIVE) but nothing about the SNOW load. My Geotechnical told me that SNOW is a transitory loading and should not be considered for long term settlement. Is it TRUE ?

That I should consider the SNOW load only for the ULTIMATE SOIL CAPACITY, Is it TRUE ?

 

[SteelPE]

I consider snow loads when designing my footing in accordance with the building codes loading combinations.

 

[msquared48]

Not considering drifting, the uniformity of the snow load at the roof gets concentrated at the foundation by the effects of walls, beams and columns. So, yes, you have to add in snow load when designing footings.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[connect2]

Yes snow load is considered. Depending upon the soil type we'll either use the full snow load, cohesionless soils (sands) or we'll use 50% of the snow load in cohesive soils (clays). Settlement being instantaneous in sandy soils and taking several months to occur in clayey soils. Some what aproximate but that's about it.

 

[steellion]

Yes, snow load is considered in foundation design.

 

[frv]

You consider snow when designing for Total load, but you neglect it when designing for dead-load only condition. Usually (but not always) you will be given two allowable soil bearing capacities: a capacity considering permanent loads (i.e. dead and long-term live) and a capacity considering total loads (all loading combinations). The former, obviously, will be lower than the latter. You can neglect snow load in the first case because it is sufficiently short lived so as not to contribute to long-term settlement, but you definitely need to consider it in the second, as the snow can contribute quite a bit to the total load.

 

[gasma1975]

Thank you frv, this is exactly what my Geotech told me.

Thanks all for helping,

gasma1975,