New Column with Moment on Existing Footing

[Nameless_One]

Looking for suggestions on installing a new column that is fixed as part of a moment frame (induces a moment on the footing) onto an existing footing (with an existing column). The new column will be placed on the footing ~2' off the center of the column. Was wondering if anyone has dealt with anything similar to this in the past. Any info is appreciated.

 

[JoshPlumSE]

As long as you know the loading from the other column, then it should be pretty straight forward. Just a regular old "combined footing" with two column.

Granted, the column anchorage is a little trickier, but it shouldn't be too bad. If it's a lightly reinforce footing as most are you can usually just use post-installed anchors to attach the column base plate.

 

[KootK]

Two common difficulties:

1) Most footings without moment transfer will not have top reinforcing. And many footing with moment transfer require it.

2) As JP mentioned, and especially without top reinforcing in the footing, it can be difficult to detail the column to footing connection properly for moment transfer. I agree with JP that, if you can transfer the moments using anchorage principles that rely on concrete in tension rather than rebar, that is a valid, if not particularly desirable, strategy.

 

[Nameless_One]

Thank you for your response KooT & JP. Since the existing footing was not designed for moment (therefore has only bottom reinforcement), I foresee this being an issue since a part of this foundation will have a negative moment component. Is there anything that is typically done for a situation like this?

 

[BAretired]

Make sure the existing footing has adequate size to accommodate the additional load and moment. If not, remedial measures will be required. I can't be more specific without knowing the precise situation.

BA

 

[Nameless_One]

I will upsize the column sizes (to control drift) and pin the bases to avoid the foundations from seeing moments. Thanks for all the replies.