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Re: Eccentrically Braced Frame - Link Beam

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Oshin,

How did you determine that only 10% of the energy dissipation potential was
lost?  Are you indicating that the existing stiffeners have sustained
substantial deformation and need replacing or are you thinking of adding
additional stiffeners to restore the beams capacity?

Basically the intent of the eccentrically braced frame link is to limit the
load that can be delivered to the brace.  I would be careful about modifying
the basic properties of the link assembly without due consideration for the
balance of limit states in the system.  If you over strengthen the link, the
desired yield / post-yield behavior may not develop leading to brace failure
prior to plastic hinge formation in the link assembly.

If the experienced deformation is minor, as you seem to indicate, the best
solution may be not to interfere with the existing construction at all.  The
link may develop full post-yield behavior earlier, and the drift will
increase, but these may still be acceptable from an overall system
performance perspective.


Paul Feather PE, SE
pfeather(--nospam--at)SE-Solutions.net
www.SE-Solutions.net
----- Original Message -----
From: "Oshin Tosounian" <oshin(--nospam--at)kcematrix.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Tuesday, September 10, 2002 11:04 AM
Subject: Eccentrically Braced Frame - Link Beam


>
> I have a situation where some link beams in an eccentrically braced frame
> show signs of yielding after being subjected to an earthquake. There are
no
> significant distortions in the link beams, but the paint has crack lines
> consistent with cyclic loading. Assuming the link beams have yielded to a
> certain degree and only 10% of the energy dissipation potential was lost,
> would it be sufficient to add new stiffeners to the link beams to restore
> their original capacity or would it be necessary to replace the beams?
>
> Your input is appreciated.
>
> Thanks.
>
> Oshin Tosounian, S.E.
> Los Angeles
>
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