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type 3 semi-rigid moment connections

type 3 semi-rigid moment connections

type 3 semi-rigid moment connections

regarding type 3 semi rigid moment connections
(aisc asd pg 4-100)--
designed to rotate under gravity loads but resist wind
moments--as a practical matter, (3 story bldg: 475 ft long
by 175 ft wide) how critical is the unwelded length
of 1.5x flange width
for the top flange plate for the successful performance
of this type of connection?

RE: type 3 semi-rigid moment connections

The size/dimensions of the structure are imaterial.  What is important is the ability of the plates to elongate, thus permitting rotation of the joint (the amount of rotation of course is a function of the length of the beam).  That said, how critical is the unwelded length of the plate?  Probably not critical to the fraction of an inch, but it would be better to be longer (more unwelded length)than shorter.  The closer the weld is to the column, the more rigid the joint will be.

HTH, Scott

RE: type 3 semi-rigid moment connections

I gave the bldg size to point out the structure is inherently stable-not a leaning tower of pisa.
My problem is a bldg which is essentially finished and not enough length was provided for the semi rigid mom conn
flange plates to elongate,properly --4" instead of 8".
We are talking about a couple of w16x26 roof beams
spanning 30ft with 30k-ft wind moments. If the semi rigid
mom conn worked perfectly the wind drift would be 1.5". If
the structure was analized assuming pinned conn where the semi rigid joints currently are the wind drift would be 1.75".
Does it make sense to go back into a finished bldg ( mech
ducts,elect conduit,wall board etc)and correct these welds?
What is going to happen if left as is?

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