Combining shaft & grade beam resistance

[theonlynamenottaken]

We've got a situation where a possible foundation solution consists of running a large grade beam across the top of two drilled shafts, something like an upside down "U". My question is whether or not we could consider the end bearing of the drilled shafts to be combined with the shallow bearing under the grade beam? We are trying to find a way to resist ridiculously large fixed base column moments combined with very high shear and downforce. Thoughts?

 

[Lomarandil]

Not very likely -- the stiffness of your strata probably changes enough that one will take up before the other.

Any chance you can batter piles instead?

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The name is a long story -- just call me Lo.

 

[Okiryu]

I thought that grade beamas are designed assuming not soil is beneath them. But, perhaps you can treat it as a wall footing?