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RE: Wind drift requirement

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Terence,

Greg pointed you in the right direction with the AISC Design Guide #3 -
Serviceability Design Considerations for Low-Rise Buildings.  But please
note that the wind for lateral drift is based on a 10 year wind as opposed
to a 50 year wind.  The h/400 is a rather stiff requirement for the
pre-engineered metal building world, but I have run out cost figures before,
and was surprised how little an impact it was on the overall project.  It is
a big deal on the bare frame, but generally not on the overall project.  It
is worth running the costs.

I have frequently had to specify h/400 due to interior masonry area
separation walls.  

Regards,
Harold O. Sprague


> -----Original Message-----
> From:	Effland, Greg [SMTP:geeffland(--nospam--at)butlermfg.com]
> Sent:	Thursday, March 15, 2001 9:45 AM
> To:	seaint(--nospam--at)seaint.org
> Subject:	RE: Wind drift requirement
> 
> Terence,
> 
> The maximum allowed drift for your building should also take into account
> the siding/wall panels, connection details, supporting members, etc...
> 
> h/400 sounds pretty stiff unless you have some wall covering that is
> susceptible to undesirable cracking.  However, L/400 might well be
> resonable
> for the supporting members (girt, spandrel, channel, etc.).
> 
> More flexible wall panels can withstand more drift without detrimental
> effects.  Pinned base details (at cmu/masonry/tilt-up wall bottoms) also
> allow more drift.  Tilt-up wall panels will typically have a pin base
> detail, whereas a cast in place wall extending from a retaining wall will
> have a more rigid/fixed base detail.
> 
> As Mark had stated, the drift is primarily a serviceability criteria and
> as
> such most building codes to date have not set specific limits (for most
> codes... not all).  A good reference for acceptable drift is AISC Design
> Guide #3 - Serviceability Design Considerations for Low-Rise Buildings.
> Another reprint of this is in Appendix A15 of the 1996 Low-Rise Building
> Systems Manual (MBMA )
> 
> As far as building codes, the City of Chicago has their own code.
> Outlying
> areas around Chicago would most likely be BOCA or UBC (not sure which).
> 
> From looking at BuildingTeam.Com it looks as though Cook County has their
> own building code also.  Not familiar enough with that code, if you don't
> know the required code or have the specific code then you probably should
> get a reply from an Illinois PE/SE (or building official) regarding the
> building code from the area.
> 
> Hope this helps,
> Greg Effland, P.E.
> KC, MO
> 
> -----Original Message-----
> From: Jones, Mark A (Battle Creek) [mailto:Mark.A.Jones(--nospam--at)jacobs.com]
> Sent: Wednesday, March 14, 2001 9:35 PM
> To: 'seaint(--nospam--at)seaint.org'
> Subject: RE: Wind drift requirement
> 
> 
> Normally, I would direct you to the building codes, specifically the
> general
> ones, where you would look in section 16 (usually) and the applicable
> material code (e.g. ACI318 for concrete) .  Your school should have a copy
> of the applicable ones for the Chicago area.  However, in this case, you
> won't find it there.  I know because I've looked MANY times.  The long
> standing rule of thumb is h/400.  This is primarily based on
> serviceability
> requirements, such as not popping off siding and keeping windows plumb.
> 
> Mark Jones
> Jacobs Engineering
> 
> -----Original Message-----
> From: tlee4 [mailto:tlee4(--nospam--at)uic.edu]
> 
> Hi, I was wondering if anyone could help a my group out by providing some 
> answers.  We our designing and analyzing a 1-story frame arch building.
> It 
> would be built in the Chicago land area.  We are having trouble determine
> the 
> maximum drift and deflection for our building.  So if anyone could help us
> our 
> with the criteria for it we would appreciate it.  Thank you,
> 
> Terence Lee
>