Adjacent Buildings, Drift Snow 1

[ToadJones]

What approach do you think is best for determining drift snow loads between two adjacent parallel gable roof buildings?

Should the drift surcharge height be taken run flat between the two roofs ?

 

[RHTPE]

ToadJones,

I've attached my interpretation of ASCE 7-10, Ch 7, for your case. Note that I had to make some assumptions for Ce & Ct. Page 1 is my summary, Page 2 is my loading diagram. I'd be interested in hearing from others as well.

I'll post the errata next. It was really buried in ASCE's web site.


Ralph
Structures Consulting
Northeast USA

 

[RHTPE]

Errata dated 11 Jan 2011 for ASCE 7-10.


Ralph
Structures Consulting
Northeast USA

 

[ToadJones]

Ralph, I basically came up with the same thing.
I had 7.7 psf at ridge and 30 psf at valley.
I like this approach. Very reasonable.

Did you mean for the valley load to be 29.6psf rather than 26.9 psf?



Thanks for taking time out your day Ralph.

 

[RHTPE]

TJ, The valley load is 2x pf, then DIVIDE by Ce. If Ce >1 then the valley load is less than twice pf, or in this case 26.9 PSF.

ASCE 7-10 is not too clear about applying the drift surcharge just downwind of the ridge. I feel it belongs there as everything I see after a windy snowstorm seems to confirm.

The snow accumulation in the valley also makes sense. For your case (with my assumptions) I came up with a snow density of 16.6 PCF, so the valley snow depth is about 20" and the depth at the ridge about 5". I finished looking at a project here in CT and the snow density calc'd at 18.6 PCF. Seems a bit high from what I observed last winter.


Ralph
Structures Consulting
Northeast USA

 

[ToadJones]

yea, I'm looking at your calcs now....my factors vary a little form yours ....making the difference.

 

[RHTPE]

ASCE 7-10 Chapter 7 seems pretty straightforward once you've run through a few.

Now Chapters 26 thru 30 on the other hand ...


Ralph
Structures Consulting
Northeast USA

 

[ToadJones]

I agree...snow loads have always been very practical (although they can really make for numerous load combos).
I have just never had to check this exact situation.

Thanks again for the input.