Moment Capacity of Steel Column in Footing

[ridgeline]

Is there a code reference for determining the moment capacity of a steel column embedded in a concrete footing? AISC, ACI?

 

[msquared48]

Nothing specific that I know of. It depends on:

1. The capacity of the steel column on a P + M basis;
2. The soil capacity based on P + M for a spread footing condition;
3. The concrete and resteel capacity for a grade beam condition;
4. The capacity of the anchor bolts and/or bearing plate.

You have to look at your condition and find where the weak link is.

Mike McCann
MMC Engineering

 

[JLNJ]

I have not seen a design guide for an embedded column. If perfect rotational fixity is what you are shooting for I expect the embedment would be significant. You will get into some unusual concrete side bearing/splitting conditions. Maybe PCI has some design procedures for embedded steel shapes.

 

[ishvaaag]

I think to vaguely remember an AISC Journal paper dealing with this thing, I may be wrong, but will try to find.

 

[csd72]

I have seen one, look up the precast literature regarding fixed precast column bases.

 

[ChipB]

Hmm... Whether it's correct or not, attached is one I did a few years back. I didn't include the footing design portion.

Hopefully it will help.

 

[ishvaaag]

I didn't find the AISC Engineering Journal paper looking in my complete copy till 1994 CD ROM.

I found an article on prestressed columns embedments in footings that give at least the forces (if one is prepared to accept quite akin behaviour) in

ACI Structural Journal Vol. 3. Nº 3 May June 1996
Title 93-S24

Stress Transfer Mechanism of Socket Base Connections with Precast Concrete Columns.

Most should be fine for steel columns. For column load in shear transfer a bond stress will need be assumed and may use complementarily some studs to take shear friction. Have made some of these but with irrelevant loads.

Also, shear collars as in elevated slabs may be of use. These I also have practice with 30 cms thick slabs an maybe even over 9 meter span (the bigger of) two way floors with sound behaviour.

 

[InDepth]

Are you anchoring the column to a footing, and then casting grade beams to take out the moment and provide partial fixity. I usually model the gb in a model to capture the stiffness and partial fixity.