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RE: eccentric braced frames

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A link to column connection is essentially a moment connection, which in this case, a prequalified connection per AISC 358 can be used for. However, this is not the best type of EBF in terms of performance. A link in the middle of a beam between to braces is the best method for designing an EBF, since you avoid any potential problems with connection at the end of the link.

 

Ben Yousefi, SE

Santa Monica, CA

 


From: Bruce Holcomb [mailto:bholcomb(--nospam--at)brpae.com]
Sent: Friday, January 05, 2007 1:44 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: eccentric braced frames

 

I must be confused… I’m looking at the 2002 AISC Seismic Provisions, section 15.4:  “Link-to-column connections shall be demonstrated to satisfy the above requirements by one of the following:

            (a) Use a connection Prequalified for EBF…

            (b) Provide qualifying cyclic test results…”

 

This is specifically discussing “link-to-column” connections and I am planning a link in the middle of the beam.  I was at an AISC seismic seminar where I made the note “It is best to put the link in the middle of the beam… there are no prequalifed connections for link / column.”  I was under the impression that there are prequalifed connections for the link in the middle part of the beam.  Did I misunderstand?  Is a prequalified connection or qualification testing not required UNLESS the link is at the column?

 

 

 

Bruce D. Holcomb, PE, SE

Butler, Rosenbury & Partners

Springfield, Missouri

Phoenix, Arizona


From: Gerard Madden, SE [mailto:gmse4603(--nospam--at)gmail.com]
Sent: Friday, January 05, 2007 3:12 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: eccentric braced frames

 

There is a Steel Tips on EBF's you can download from AISC or http://www.steeltips.org/

I have seen the link done with WF braces and Tube Steel Braces.

Not sure about pre-qualification, but I don't think you need to have full scale testing of this done, that's only for SMRF's. If you are using Moment Connections @ the end of the beams (which I think is required), those should follow the FEMA guidelines.

I'm sure someone who does these all the time could help better.
-g

On 1/5/07, Bruce Holcomb <bholcomb(--nospam--at)brpae.com > wrote:

Are there any references with prequalified connections for eccentric braced frames?  I'm looking designing an eccentric braced frame (inverted V) with a link for the brace to beam connection.  I definitely don't want to do qualification testing… are there prequalifed connections for this condition?

 

 

 

Bruce D. Holcomb, PE, SE

Butler, Rosenbury & Partners

Springfield, Missouri

Phoenix, Arizona

www.brpae.com




--
-gm