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RE: Structural steel end-plate moment connection question

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End-plate connections are used frequently here in Denmark and not only for moment connections. I have used them for tension bracing, simple shear connections, torsional connections, column splices and ordinary moment connections, both flush and extended, stiffened and unstiffened, and for milled and welded sections varying in depth between 6 in. and 7 feet and widths between 6 and 16 in.
Flush end-plate connections are preferred, since that leaves a plane top flange for cladding, access platforms, etc. The end-plates are often made a bit shorter than the beams, leaving room for double-sided fillet welds at the flanges. The plates are usually designed using yield-line theory, although I, personally, prefer the T-stub analogy method.

Steel detailers preferences, with respect to fit-up, varies from using theoretical dimensions to "shortening" the beams up to half an inch and applying shims.

I recall one project, a boiler structure, where all connections were end-plate connections. All the braces, delivered to the site, were from 1 in. and up to 1 ft. too long, and the end-plate splices in the main boiler columns had an 1/2 in. gap at the flanges, due to surface milling prior to weldment to the columns. Needless to say, the owner removed that steel manufacturer from his list of clients.

Gunnar H. Isleifsson
Denmark



-----Original Message-----
From: Clifford Schwinger [mailto:clifford234(--nospam--at)yahoo.com]
Sent: Thursday, February 13, 2003 23:29
To: seaint(--nospam--at)seaint.org
Subject: Re: Structural steel end-plate moment connection question


Thank you to everyone for the answers you've been
posting so far regarding my question about end-plate
moment connections - keep them coming!

My take on some of the "disadvantages" are as follows:

I spoke to a fabricator about end-plate connections
and he said that they overcome the "beam too long"
problem by detailing and fabbing the beams 1/8" short.
It's easier to install a beam that is 1/8" too short
than one that is 1/8" too long.

I would think that the "problem" of the out-of-square
column flange causing fit-up problems might not be too
much of a problem if you have four bolts in the top of
the end-plate connection, that when tightened will
crank the column flange and end-plates in contact with
one another. (Four 1" dia A325 bolts x 51k pretension
force = 204k of clamping force squeezing the column
flange to the end-plate.)

I'm told that the equipment in most modern fabrication
shops is capable of accurately fabbing steel to the
tolerances required for accurate fit-up.

Our office indicates the design moments on the
contract documents and we allow fabricators the option
of designing their own moment connections if they
don't like what we designed.

Are there any fabricators, detailers, or connection
experts out there reading this? Is what I am saying
correct? If you have a moment, I'd shear like to hear
your thoughts!

Cliff Schwinger







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