manstrom
Structural
- Jan 15, 2013
- 409
I haven't spent much time with ASCE 7-22 yet. I was just made aware that the snow loads provisions are changing from a allowable measurement to an ultimate measurement. Similar to wind load revisions in previous ASCE-7 editions.
Load combination factors are changing:
However, for the mid atlantic region, snow loads are increasing significantly from 25-30 psf to 60-70 psf.
For example, Washington DC is moving from pg=25 psf to pg=62 psf (43 psf ASD). When considering the ASD load factor, that is a 74% increase in snow load.
For LRFD that's 62/1.6/25 = 65% increase.
I wouldn't be surprised at 10-15% bump, but this is rather significant. Is there some other reduction factor that I am missing? I find it hard to believe that any houses or apartment designed before this code won't work with the new code by a significant amount. This has a big impact for wood framed structures and renovations.
new map website
Load combination factors are changing:
The ASD factor is now 0.7S (down from 1.0S). LRFD is now 1.0S (down from 1.6S)However, for the mid atlantic region, snow loads are increasing significantly from 25-30 psf to 60-70 psf.
For example, Washington DC is moving from pg=25 psf to pg=62 psf (43 psf ASD). When considering the ASD load factor, that is a 74% increase in snow load.
For LRFD that's 62/1.6/25 = 65% increase.
I wouldn't be surprised at 10-15% bump, but this is rather significant. Is there some other reduction factor that I am missing? I find it hard to believe that any houses or apartment designed before this code won't work with the new code by a significant amount. This has a big impact for wood framed structures and renovations.
new map website
