Restraining Concrete Pier Breakout with Compression Struts

[CN-EIT]

I am currently designing PEMB foundations and am getting shear failures in the concrete pier due to the lateral load. Outward thrust is being restrained by headed rebars (i.e. with terminators) in tension with a tie-beam spanning between the rigid frame columns. However I have a load case wherein the lateral load will not be restrained by the tension rods. My thought in this case, instead of providing a massive concrete pier, is to consider the "tie-beam" as a "compressive strut". The thought being that the concrete pier wont shear since the lateral load will transfer to the strut through bearing. Does anyone have any thoughts on this or know of design codes/provisions/studies that would help guide my thinking?

 

[KootK]

Sure, if you have a load case that actually puts the tension tie into compression than I expect that you can use that to help with shear transfer. In a sense, you're just adding an infinite amount of edge distance in the direction parallel to the shear load. This classic document might be of help to you: Link. If not, come back and ask some more questions.

For what it's worth, my expectation on this is that we'll eventually need a somewhat accurate plan view sketch of your situation in order to get you to the finish line.

 

[CN-EIT]

We do indeed have have a load case where that tension tie is in compression. To your point, while the pier and tie-beam/compression strut are not monolithic, for a shear failure in the pier to occur it would have to crush the strut. Also, that link was pretty helpful, so thank you!