I was working backwards to determine the maximum elastic drift under strength level design seismic loads.
1/(0.02/4) = 200
Although, even that is not an apples-to-apples comparison as that value would need to be divided by 0.7 for service level.
200/0.7 = 286
The commentary in ASCE 7-02 gives a range of H/400 to H/600, which is for serviceability, but then goes on to say that this is excessively conservative. It recommends using 0.7*W to determine service load deflection for frames, which would be:
400*0.7 = 280
That might be the source of the 0.7 factor for wind deflection limits in IBC/CBC Table 1604.3, footnote f. Anyway, these wind and seismic drift limitations seem comparable. Thanks for all the help.
Doug Mayer, SE
From: Gerard Madden, SE [mailto:gmse4603@gmail.com]
Sent: Wednesday, November 04, 2009 12:42 PM
To: seaint@seaint.org
Subject: Re: Deflection
Those are inelastic limits.
On Wed, Nov 4, 2009 at 12:30 PM, Doug Mayer <doug.mayer@taylorteter.com> wrote:
Seismic drift limitations are often in the realm of H/200 (using 0.020*hx and a Cd=4)…why so much more stringent for wind?
Doug Mayer, SE
From: Stuart, Matthew [mailto:mStuart@cmxengineering.com]
Sent: Wednesday, November 04, 2009 12:18 PM
To: seaint@seaint.org
Subject: RE: Deflection
H/400
D. Matthew Stuart, P.E., S.E., F.ASCE, SECB
Senior Project Manager
Structural Department
Associate
Engineers and Consultants - CMX
200 Route 9
Manalapan, NJ 07726
732-577-9000 (Ext. 308)
908-309-8657 (Cell)
732-298-9441 (Fax)
mstuart@CMXEngineering.com
From: Doug Mayer [mailto:doug.mayer@taylorteter.com]
Sent: Wednesday, November 04, 2009 3:15 PM
To: seaint@seaint.org
Subject: Deflection
When wind governs in your lateral system design, what is the building drift limitation? There doesn’t seem to be any specified building drift limitation for wind loads (that I can find) in the code. What do you wind country folks do?
Thanks,
Doug Mayer, SE