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RE: DL weight vs Ordinary/Special Moment Frames[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: RE: DL weight vs Ordinary/Special Moment Frames
- From: "Joseph R. Grill" <jrgrill(--nospam--at)cableone.net>
- Date: Wed, 24 Sep 2008 19:31:51 -0700
Thank you very much for the reply. Much appreciated.
You are correct on all your assessments. Reducing the roof dead load will resolve the issue.
Yousefi, SE, CBO
From: Joseph R. Grill
I am looking at a project located in a SDC D. It is a custom home, with (at this point) exposed steel frames so appearance is critical to the client. At this point the roofing is a tile roof which is running the dead load up to about 27 psf. The architect also has some very heavy rock veneered walls with a DL >20 psf (closer to 100psf with veneer on two sides). The structure is less than 35 ft in height and only one story.
ASCE 7-05 Section 184.108.40.206 would suggest (in my understanding) that an Ordinary Moment Frame would not be acceptable due to the weight of the roof DL. The weight of the roof tributary to the frames is greater than 20 psf. It appears that even though the veneered walls are greater than 20 psf it is not a problem since the heavy walls are less than 35’ in height (or at least the heavy walls are not over 35 ft above the base).
ASCE 7-05 Section 220.127.116.11 seems to push the frame design into the Intermediate or Special Frames. Although it allows the heavier roof for the Ordinary Frame, it seems to limit the weight of the walls to 20 psf not matter the height.
My first question is, is my understanding of these two sections correct?
My second question is, if the architect changes the roofing to a lighter shingle which will reduce the roof DL to something below 20 psf can I design the frames for an Ordinary Moment Frame even with the heavy veneered walls?
Thank you all for the help.
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