how serious is the effect of a wall footing situated on top of a footing?

[keenkeem]

in situations where the wall footing is on top of the spread footing, is it recommended that I neglect the effects of the wall footing in designing a spread footing? what are thoughts anyone? for two stories is it recommended?

 

[keenkeem]

what are your thoughts anyone? is it wise enough to be neglected?

 

[jayrod12]

I'm not totally sure what you are asking.

You should include the self weight of the footing concrete when calculating your bearing pressure. Depending on the width of your footing you may want to design it for the bending it may see in the transverse direction.

 

[msquared48]

Anything that bears on the footing needs to be added to the total weight that the footing bears, if that is what you are asking....

Mike McCann
MMC Engineering

 

[cvengr]

If you are touching the design of others, then you are incurring the responsibility for that design. Depends upon the situation.

 

[Althalus]

If I understand correctly, you're talking about a continuous perimeter footing that is interrupted by a perimeter column. The column rests on a separate spread footing that is somewhat below the continuous footing.

Is this correct?

If the column's spread footing is not on the same level as AND interlocked via rebar to the continuous footing, then you should NOT include the continuous footing capacity into the support of your column. They act independently and therefore will have differential settlement when loaded.

Even if you footing above is locked in somehow to the column pedestal (or other mechanism) then you still have the issue of lower settlement nullifying upper settlement.

SHORT ANSWER: Do NOT combine their capacities.


Althalus

 

[Ron]

But you do have to combine their loads! If the wall footing bears on the individual spread footing, you need to include the effect of that wall footing on the spread footing by including its reactive load.

For two stories, the loads will be relatively small; however, you need to know and understand the influence so that you can answer questions in the event of an issue later on that might get blamed on you, rightly or wrongly.