Concrete column with groove / slot / key for precast panel

[emilywalters]

I am attempting to design a concrete column which is an I section due to the fact that I wish to have two grooves running down either side of the column in order to slot a precast wall panel between columns. There is a horizontal pressure on each of the wall panels which transfers directly to the columns. I am looking for a heads-up on how to check that part of my column is not going to snap off. I have tried to design the grooves as though it is between two corbels but translating the problem this way is not particularly effective (or correct).

 

[emilywalters]

http://i.imgur.com/2WQAh.png

This is a sketch of the column and potential reinforcement layout

 

[JAE]

I'm not sure why the corbel approach wouldn't be the most applicable way to design them. Are you getting some weird results?

 

[emilywalters]

http://s9.postimage.org/47c1nvn25/corbel_oxd_bison.png

Here is my calculation so far - it seems that most of the time when I select trial dimensions for my corbels, there is no value of theta to satisfy the equation for total force in the steel tie.

 

[TXStructural]

Since the panel load is from one side, you probably need to make the beam-column asymmetrical. If the panels need to be captive, make the side taking the load deeper. But for constructibility, a T or plain rectangular shape might be preferable. If the axial load in the member is not significant, I would ignore the asymmetry in a T section for axial purposes. Also, unless there is a compelling reason to do otherwise, I might simply have the panels bear against the flat back of a rectangular beam-column.

 

[emilywalters]

Thanks for the replies...

Unfortunately the horizontal pressure is a nominal variable load which could potentially act on either side of the panels - so making the section asymmetrical isn't really an option.

 

[TXStructural]

Without getting into the numbers (you folks and your SI units - they have been trying here since I was in 6th grade), the practical consideration is that you cannot develop the rebar, and are left with only concrete shear as your resisting material. I suggest you design for Vc only. If this does not work, a welded bar arrangement could be fabricated, although this would be very expensive, compared to loose bar. Also, use of welded wire reinforcement might be useful in this case, since it could be bent quite a bit tighter. You may need to enlarge the flanges in any case. Cover depth could be reduced as long as the concrete mix design provides for proper consolidation and corrosion protection.

Concrete and construction quality will be primary in getting good performance out of this design, so performance spec the concrete, even specifying shear values if need be. Also, in your detailing, be sure you consider that there should be fillets on inside corners and chamfers on outside corners. These will affect the bearing area and clearances for the panels.

 

[concretemasonry]

Have you checked with the supplier of the precast walls (assuming they are not site-cast)? Often, they produce other products compatible with precast wall sections and have the availability of experience on many projects. - It also limits the liability problem from compatibility of components.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.