UBC Snow Loading

[JAE]

Does anyone have a 1985 UBC (or one not later than 1986) that indicates how they determined snow loading? I'm looking for a particular area of the country (central Nebraska). Just wondering if this was still in the era where engineers used 30 psf on the roof vs. calculating an actual snow load less than that.

 

[jdgengineer]

Just read through the 85 UBC. From my quick review, (although I haven't even designed using 85 UBC), there isn't a whole lot of guidance in it. It states that where Snow Loads occur the loading shall be determined by the building official. It does give a reduction equation for roof slope. Rs = S/40 - 1/2. Rs is the snow load reduction in psf per degree of pitch over 20 degrees.

 

[woodman88]

Back than I always used the Appendix Chapter 23 Snow Load Design. It was rarely required by the building officials I designed under. But the main sections of the UBC (see section 2305 (d)) only stated the "Pontential accumalation of snow at valleys, parapets, roof structures and offsets in roofs of uneven configuration shall be considered." plus what jdgengineer states.

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.

 

[MiketheEngineer]

Plain old 30 psf sounds about right for back then!!

 

[msquared48]

You mean they have snow in Nebraska?

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[JAE]

Thanks for the replies.

jdgengineer - can you look in your 1985 UBC appendix to see if there is an appendix 23?

 

[jdgengineer]

There is an Appendix Chapter 23. I could post the pages online, but I'm guessing that would not be allowed per Forum Rules.

 

[jdgengineer]

Although looks like you can buy it from ICC if you need it...

http://www.iccsafe.org/Store/Pages/Product.aspx?id=8855P85B_PD-X-UC-P-1985-000001

 

[JAE]

Don't post it online as I'm sure it is still copywrited.

I would just ask that if they have a map back there - can you see what the ground snow load was for central Nebraska? I think it was 30 psf but just wanted to check.

 

[woodman88]

JAE maybe the attached hand drawn map will help.

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.

 

[jdgengineer]

I just read through Appendix Chapter 23. It states the same thing "The basic roof, as well as the ground, snow loads Pg to be used in the design of buildings or other structures shall be established by the building official"