Partially embedded post in caisson fotting

[ruready]

Anyone done this before? We don't want to extend the column to the bottom of the footing but need a way to calculate how the moment in the column dissipates in the footing relative to the embedment and how to reinforce the remaining concrete if needed. Thought of subtracting the resulant from the passive pressure below the bottom of the column from the moment and doing it that way. Anyone know of any books, etc. Thanks

ACI 318-05 specifically states in 1.1.5 that it does not govern the design of caissons (unless high seismic zone). Tried finding anything on the literatue that they refence with no luck and couldn't find anything in any books we have or on the internet.

 

[civilperson]

Design for the full moment for the full length of the caisson. There is a theoretical pivot point below the grade, with the soil pushing on opposite sides of the caisson with respect to the pivot point. A horizontal subgrade modulus will give the respective push along the length of the caisson. ( A restrained vs. unrestrained condition at the surface due to surrounding pavement will modify the deflection and the flexure.)

 

[ruready]

That would be contrary to the constrained caisson eq in the IBC 1805.2.2, the assumption is, when you disect the equation, that the pivot point is at the top of the footing... Its just summing the forces about the top, the resisting passive has to be equal to the moment. Took all morning looking at it