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Re: Collector Design with 5% ECC & omega

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Will,
 
I had to read this a few times to be sure I understood what you were asking.  The typical answer is, no the force will not be less than the direct condition without applied eccentricity.  The applied eccentricity will typically increase the forces for some lines and decrease, or counteract, the forces for others as the torsion is resolved.  However, since the location of the center of mass is varied to either side, there should be an increased condition due to eccentricity on all lines within the load case envelope.  If eccentricity is ignored (and I assume you refer only to the accidental eccentricity), the forces are a direct result of applied force and could only be less if the applied force is less.
 
Typical analysis will frequently neglect any load reduction due to torsion.
 
----- Original Message -----
Sent: Thursday, March 24, 2005 5:49 PM
Subject: Re: Collector Design with 5% ECC & omega

Just wondering, if you have to derive the forces with the eccentricity on either side of the center of gravity, is it possible for the force in a collector to be less than when the eccentricity is ignored? I usually think about collectors being in flexible diaphragms anyway.

 

Will Haynes

 

>From: "Paul Feather" <pfeather(--nospam--at)SE-Solutions.net>

>Reply-To: <seaint(--nospam--at)seaint.org>
>To: <seaint(--nospam--at)seaint.org>
>Subject: Re: Collector Design with 5% ECC & omega
>Date: Thu, 24 Mar 2005 14:08:24 -0800
>
>MessageHow do you determine the collector force without accounting for the 5% eccentricity?  1612.4 requires Omega E.  E is calculated with and without the eccentricity.  Whichever is the governing force is the one you use.
>
>
>   ----- Original Message -----
>   From: Alex
>   To: seaint(--nospam--at)seaint.org
>   Sent: Thursday, March 24, 2005 12:10 PM
>   Subject: RE: Collector Design with 5% ECC & omega
>
>
>   David,
>
>   "Collector elements, splices, and their connections to resisting elements shall have the design strength to resist the combined loads resulting from the special seismic load of section 1612.4"(UBC1633.2.6)
>   Do you think for collector themselves we should also include both 5%ECC  and omega factor?
>
>
>
>   Alex,PE
>
>
>
>
>   -----Original Message-----
>   From: David Topete [mailto:davetopete(--nospam--at)yahoo.com]
>   Sent: Thursday, March 24, 2005 10:02 AM
>   To: seaint(--nospam--at)seaint.org
>   Subject: Re: Collector Design with 5% ECC & omega
>
>
>   Collectors themselves, include 5%eccen.  Connections
>   of collectors to LFR elements, include the 5% eccen
>   AND Omega factor.  The 5% accidental is only if you
>   have a rigid diaphragm.
>   I'm sure someone will correct me if I'm wrong....  :-P
>   David Topete, SE
>   SF, CA
>   --- Alex <seaosd(--nospam--at)hotmail.com> wrote:
>   > do we have to include 5% ecc with omega factor for
>   > collector
>   > design?(UBC1633.2.6)
>   >
>   >
>   >
>
>
>
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