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RE: Stucco or GWB as shear wall in seismic zone 4 (1997 UBC/2001 CBC)[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: RE: Stucco or GWB as shear wall in seismic zone 4 (1997 UBC/2001 CBC)
- From: "Truitt Vance" <Truitt(--nospam--at)adVanceEng.net>
- Date: Fri, 23 Jun 2006 10:03:57 -0700
LARUCP hasn’t “banned” it, just reduced the max capacity to 30plf for drywall and 90 for stucco, so why is it even considered? That combined w/ factoring up your forces by 20% per ST-12 or whatever if you are using a flexible diaphragm, there is no way any building will ever calc out at such low numbers, so they have in effect “banned such materials”….not even considering everything else everybody brought up.
I have a hard enough time getting regular
shear walls working in the land of la, really surprised to see even the most
penny pinching builder considering drywall, thought that argument was dead long
ago. Maybe he is from
From: Bill Allen
The client is not as interested in residual strength as I am. He is interested in meeting code. From that perspective, how do you think he would respond to the suggestion that the building be designed for a lower R value and lower SW capacity than the current building code prescribes as well as story and roofing system limitations not specified in the building code? Don’t get me wrong, I agree with all of your points that the structure you describe would perform much better. But if my customer is looking to meet building code minimums, I need more data that this (like LARUCP has banned such materials).
BTW, the project is in the city of
T. William (Bill) Allen, S.E.
I would try and convince him that plywood/OSB provides a lot more residual strength to resist seismic forces, especially racking action in a house..its just to brittle. Like Charley said, I am concerned about using GWB because of its lack of post peak strengthen beyond peak strength.
If I was to design with GWB it would have to be limited to a single story house (no tile roof), lots of walls so the seismic forces in the walls were less than 30 pounds/ft ..not the higher values shown in the UBC (also shear wall lengths no less than 8 feet long) and I would probably look at using an R value much less than 4.5 (97 UBC), probably closer to 2.0 (I believe R = 2.0 in the current IBC). At this point, I don't think GWB would work for the design loads unless you had a lot of long walls.
I think LA City limits GWB to 30 pounds a foot.
Mike Cochran S.E. SECB
In a message dated 6/22/2006 6:17:59 P.M. Pacific Standard Time, T.W.Allen(--nospam--at)cox.net writes:
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