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Moment Connections - Steel to Concrete

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Some discussion off the board for this topic...
Randy -

i think you are saying, that instead of the ties that i have in the
core, you will embed a long plate strap (or a series thereof) into the
concrete column, and to the exterior face of the beam, you will put a
plate flange to flange, and then bolt this strap to this flange to
flange plate one per side. ?  would you still choose to bring the beam
into the column?  or prefer to use an exterior embedded plate (my no.
2 discussed)?


thanks again all for your input !
Refugio Rochin
www.systemscaribbean.com

On 6/29/06, Collier, Randy <rhcollier(--nospam--at)winkinc.com> wrote:

Refugio,

What I have done in the past is design an external three-sided strap, in which I also have bolts (either embedded or through-bolts) on the two sides that are parallel to the web of the steel beam. This avoids the discontinuity that Michelle is talking about and if you embed the bolts prior to pouring the column, you will avoid interfering with the column reinforcing (as Chris is addressing).


I hope this helps,

Randall H. Collier, P.E.

Chris wrote:


We do  this kind of stuff all the time on Integral bridge abutments.  The girders  are cast into the abutment stem without any problem.  The difference is on  integral abutments, we try NOT to transfer moment.

Michelle wrote


I personally have not used them but I think they are  specifically marketed for steel to steel.  I was just thinking that  you could try to design something similar using top and bottom flange plates  connected to side plates to get around the concrete column.  I guess  one concern would be plate bucking in the side plates since your column is so  deep in the direction of the plate unless you tried to stabilize it against the  column or used channels in lieu of the side plate. The side  plate could also interfere in the connection of any members which frame in  at 90deg to the W21 unless you made the side plate do "double-duty" as an embed  with studs.

Just in a brain storming mood today, normally not much good  comes out of it... :)
Good luck

Michelle


refugio wrote:


here are two of my options with the first method.
 thanks, anymore comments?
 michelle, does sideplate do a steel do concrete connection?  i thought they just do steel to steel?

 Michelle replied:
 I have not come across this in the middle of a column but what about something similar to the "Sideplate" moment connection (http://www.sideplate.com/) with a seat for erection and shear transfer.  This would allow continuity in the column.

Michelle Motchos, PE
 Stevens & Wilkinson of South Carolina, Inc.
Columbia, Sc


Chris replied:


A problem with the first option could be getting the rebar placed within the required tolerances to thread them through the flanges when setting the beam.  We have a hard enough time getting contractors to get anchor bolts put in correctly even with oversized holes in the base plates.
Have you thought about using shear studs?  If you can cope the flanges inside the column, weld the bottom flange to your bearing plate with shear studs and have shear studs welded to the top flange.  I'm not sure if you could get enough studs to transfer your load, but that could be something you could look into.

Chris Towne


- Hide quoted text -
Refugio 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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