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Re: more on gusset plate design

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The Uniform Force Method is not the only method, there are other approaches.  To use the UFM you have to size the plate first for offsets, weld length of brace, etc required for the SCBF, and then design the gusset plate as if its an existing diagonal brace connection (you have moments to deal with)
 
I personally favor welding a large gusset plate to the column and frame the beam web into the end of the gusset plate.  I will provide horizontal slotted lap plates on the gusset plate to lap over the beam flanges to stiffen the gusset plate and provide more continuity to the beam.  Using one single large gusset plate provides for a uniform plate thickness as oppose to when you weld a thick gusset plate to the flange of the beam web, where typically the beam web is thinner than the gusset plate.  By using a single gusset plate at the column connection, the design becomes similar to the brace frame beam midspan connection, your just rotating the connection 90 degrees.
 
Mike Cochran
 
In a message dated 10/15/2004 6:47:49 PM Pacific Standard Time, elig(--nospam--at)psm-engineers.com writes:

List –

 

Do any of you have some helpful comments on methods that you use for designing concentric brace – gusset plate connections.  Is the Uniform Force Method the preferred solution procedure these days (and all of its 15 (!!!) glorious pages of calcs in the AISC manual).  The UFM looks pretty straight forward, but I’m wondering how practical it is.  Without explicitly designing and specifying the precise dimensions of each and every gusset plate on a project, how can the UFM equations be applied?  The alpha and beta dimensions (weld group centroid) require you to know the exact gusset dimensions. 

 

I have typically just designed the gusset plate welds to take the brace component forces – and also considering the Work Point eccentricities using table 8-38 for eccentric welds.  I specify minimum weld size/length and let the steel fabricator work out all of the gusset dimensions for all of the various brace connections, because they are never standard. 

 

Murphy’s Law for structural engineers:  “Anything that you attempt to specify as typical will always end up different.”

 

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Eli S. Grassley

PETERSON, STREHLE, MARTINSON, INC.

SEATTLE, WA