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RE: Wind load on sloped roof with parapet

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I guess I am missing something, but I do not see how B and D can be zero.  You could conservatively assume the parapet loading and apply it to the combined effects. 
 
I don't have a copy of the 2006 IBC Seismic Design Manual, but there are no zones any longer.  There are Seismic Design Categories to which I believe you are referencing.  Look at ASCE Section 11.1.2 for the scope for the exemptions. 

Regards, Harold Sprague






From: jeffsmith7(--nospam--at)comcast.net
To: seaint(--nospam--at)seaint.org
Subject: RE: Wind load on sloped roof with parapet
Date: Mon, 1 Dec 2008 14:14:56 -0800


Thanks, Harold and Conrad,
 
I am a bit embarrassed not to know this, I have not done an ASCE 7-05 wind analysis for a building yet.
 
For this building the B and D zones are zero. So do I take the pressure on the parapet from 6.5.12.4.1 and add that to zones A and C to get the force for the MWFRS in the transverse direction or would I take the A and C zones to the top of the parapet for the MWFRS and design the parapet separately per 6.5.12.4.1?
 
On another note, The 2006 IBC seismic design manual on page 202 only takes the minimum 10 psf check up to zones A & C, is that correct?
 
Jeff
 
 


From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com]
Sent: Monday, December 01, 2008 8:22 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Wind load on sloped roof with parapet

Jeff,
The conditions to design the MWFRS according to the simplified procedure are listed in ASCE 7-05, Section 6.4.1.1 OR 6.4.1.2.  I am not sure which of the 8 provisions of Section 6.4.1.1 are in question. 
 
You can not use the parapets to shield roofing elements.  You must assume the parapets are not there for the design of the roof.  You then design the parapet under 6.5.11.5.
 
Regards, Harold Sprague



> From: jeffsmith7(--nospam--at)comcast.net
> To: seaint(--nospam--at)seaint.org
> Subject: Wind load on sloped roof with parapet
> Date: Sun, 30 Nov 2008 13:21:22 -0800
>
> Say you have a small existing victorian wood building, 30' x 22', 12'
> ceiling with a 22.5 degree roof pitch, 5' ridge height, gable ends, but 2
> orthoganal walls have a 4' parapet (1 foot lower than the ridge.) The front
> gable end and one side have parapets. The front parapet perpendicular to the
> ridge is part of the victorian look and the side is essentially a dutch
> gutter against the property line.
>
> Can this be analyzed using the simplified procedure? For the MWFRS, how do
> you apply the B and D zones to a pitched roof that has a tall wall parapet?
> Seismic will probably govern in both directions for the MWFRS.
>
> Thanks
>
> Jeff
>
>
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