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Re: "Cantilevered Column" Structures

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It is not a cantilevered column system. But it is a moot point because
wind will govern.

Stan Scholl, P.E.
Laguna Beach, CA

On Thu, 19 Jul 2001 15:44:09 -0700 Chris Roper <croper(--nospam--at)bjginc.com>
writes:
> For what it's worth, I would say you do not have to consider this a
> cantilevered column system.  The lateral force resisting system 
> you're
> concerned with is the building above grade.  The mat and piles are 
> the
> foundation at and below grade.  The structure above grade generates 
> seismic
> load and transfers it to the foundation.  If it's a metal building, 
> wind
> probably controls anyway.  Perhaps someone else will chime in and 
> give us
> some other schooling.
> 
> -----Original Message-----
> From: Kevin Harris [mailto:Kevinh(--nospam--at)jhiengineering.com]
> Sent: Thursday, July 19, 2001 1:24 PM
> To: Seaint(--nospam--at)seaint.org
> Subject: "Cantilevered Column" Structures
> 
> 
> Greetings
> 
> I have a question that has been bugging me for awhile that I hope 
> someone
> can give me some guidance on.
> 
> Here are the facts:
> 
> 1) A lightweight pre-engineered building (say 20 psf) bearing on a 
> pile
> supported mat that supports tanks and equipment (say 500 psf+).
> 
> 2) UBC seismic zone 3.
> 
> 3) Point of fixity of piles is 20 ft below grade, per geotech.
> 
> Would this structure have to be considered a "cantilevered column 
> building
> system" (R=2.2)?  I was wondering if I would be released from this 
> low R
> value because the structure is essentially just an equipment 
> foundation.
> 
> Also, if I have to use R=2.2 for the foundation, would the light 
> metal
> building shell have to be designed with R=2.2 as well (unless it can 
> be
> shown to have 10 times the metal building stiffness)?
> 
> Thank you for your thoughts.
> 
> Kevin Harris, P.E.
> 
> 
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