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Re: Moment Connections

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Refugio:

There has been testing on this type of connection done.  In general, the
testing has resulted in three basic mechanisms that I am aware of...

1) Face plates and "butt" plate (or two sets of face plates if the
connection is two sided) are added to the steel beam.  The "face plates"
basically look like full height stiffners and are used on the face of the
column where the beam comes into the column and generally are the same
width as the flange of the beam.  A "butt" plate (my term) is bascially
like a cap plate that is welded to the end of the beam and coinsides with
the back face of the column (this assumes a one sided beam connection).
These sets of plates on either face of the column plus the flanges of hte
beam create a nice confined space within the width of the steel beam.
Within that width, compression struts will form in the concrete when the
connection is loaded with a moment.

2) Stirrups in a close spacing are used above and below the connection to
create a compression strut system (with the stirrups being the tension
ties) that works within the concrete that is outside of the width of the
steel beam.

3) Shear in the beam web helps as the last mechanism to resist the moment
(kind of sharing load with mechanism #1).

I will note that this type of system generally has a steel erection column
embedded within the concrete column (i.e. a steel column that is strong
enough to resist maybe a couple floors of construction dead load, but not
all the final load of a high rise).

And I will note that this research was for situations where the concrete
column was wider than the steel beam (generally close to twice as wide),
which appears to NOT be the case for your situation.

If you want to look up paper, then authors have been Jim Wight & Gustavo
Parra-Montesinos of U of Michigan (Gustavo took over the research that I
was doing as a PhD student with Jim Wight when I decided a PhD was not for
me).  I don't recall the other researchers at the moment, but I know that
some was done at Texas A&M, I believe.  If you want, then I can find out
the other sources.

Regards,

Scott
Adrian, MI


On Thu, 29 Jun 2006, refugio rochin wrote:

> Anyone have experience with Steel Beam to Concrete Moment Connections ?
> I have a W21x166 coming into a Concrete Column 12x32".  The Beam enters the
> 12" side.
> So the beam sticks out past the sides of the column a bit.
>
> So I am trying to come up with a best way to detail this connection.
>
> 1)  I bring the beam into the column, embedded inside the column, and
> provide long dowels through both beam flanges vertically, then restrain the
> whole system with lots of ties.  Also to contain the temperature and
> Shrinkage stresses.
>
> 2) the argument against the #1 connection, is that the difference in
> concrete and steel materials will cause alot of cracking in the concrete.
> So the second idea is to use a huge plate, at the face of the column, weld
> the column to the plate, and then use anchors into the column to restrain
> the moments, spreading the load a bit farther apart.
>
> I see advantages to both systems.  The first system takes into it, the
> compression from the wall continuing above, and removes any possible shear
> at an exterior face, bringing it vertically into the column.  Whereas the
> second system is able to spread the load.
>
> Personally I feel more comfortable with the first system, but I would like
> some suggestions or comments from experience.
>
> Best Regards,
> Refugio Rochin
>

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