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RE: steel brace

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Greg,

Since I don't have the 1997 UBC (I am in BOCA/IBC country), I will take
your word as far as section 2213.8.4.3.

One thing to keep in mind is that the type of brace would not necessarily
fit the typical definition of an eccentric brace mainly because typically
in such systems the "link" beam would normally be shorter than half a bay.
It may still "fit" under the eccentric brace category though.

Charlie Carter might be able to offer some words of wisdom.  Also, take a
look at AISC's 1997 Seismic Provisions for some addition information on
eccentric brace systems.

HTH,

Scott
Ypsilanti, MI


On Tue, 23 Jul 2002, Greg Meyer wrote:

> Scott, Thanks for your input.  It would just be a single brace member.
> Essentially what I have is 1/2 of a inverted "V" chevron brace.
> I guess that it would fit the criteria of  UBC 2213.8.4.3 Nonconcentric
> bracing.
> 
> Greg
> 
> -----Original Message-----
> From: Scott Maxwell [mailto:smaxwell(--nospam--at)engin.umich.edu]
> Sent: Tuesday, July 23, 2002 2:17 PM
> To: 'seaint'
> Subject: Re: steel brace
> 
> 
> Greg,
> 
> Based upon your limited description, I would say yes you can use this type
> of brace, but a little more information would be helpful.
> 
> Is there another brace that meets this one at the middle of the beam
> coming from the beam to column connection at the other side of the beam?
> 
> If so, does the working point of the braces (essentially the centerlines)
> meet roughly at the centerline of the beam?
> 
> If the answer to the first question is "no", then it sound like an
> eccentric brace system.
> 
> If the answer to the first and second question is "yes", then is sounds
> like a concentric brace system.
> 
> If the answer to the first question is "yes" and the second is "no", then
> it sounds like another configuration for an eccentric brace system.
> 
> FYI, an eccentric brace system relies on getting its brace force into a
> beam or column by both bending and resolution of the axial loads into
> component forces (like a truss member), in general terms.  An eccentric
> brace system will have a "link" beam segment that is designed to create
> the ductility in the system (note an eccentric brace system is typically
> more ductile than a concentric brace system).  A concentric brace system,
> OTOH, will not rely on any bending to transfer force from the brace to
> beam or column.
> 
> HTH,
> 
> Scott
> Ypsilanti, MI
> 
> On Tue, 23 Jul 2002, Greg Meyer wrote:
> 
> > 	I would like to use a brace that goes from a beam to column connection at
> > one level to the middle of a beam at the next level.
> > The brace would be part of the lateral resisting system for a building
> > located in a seismic zone 3  (1997 UBC).
> > It doesn't seem to meet any of the definitions for braces in the UBC.
> >
> > Can I use this type of brace?
> >
> > If I can, how would this brace be classified? (Eccentric, Concentric, etc)
> >
> >
> > Thanks in advance,
> >
> > Greg Meyer
> >
> >
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