Lateral deflection calcs for Auger Cast Piles
Lateral deflection calcs for Auger Cast Piles
(OP)
I am tasked with the structural portion of an auger cast secant wall retaining structure. I have received all of the design moments, anchor forces, shears, etc. from the geotech. The controlling criteria, however, seems to be the deflection. Because of buried utilities in the vicinity, the Owner has specified a rather stringent maximum deflection for the wall.
At present, the pile design is expected to be 18" diameter ACP (at the client's request). For moment capacity, it appears as though an HP12 will be adequate in lieu of a reinforcing cage, but the I for this section alone is inadequate for the deflection calcs.
Are there any published analysis methods for determining the moment of inertia of a round ACP with an embedded H-pile? I "know" the composite section will be sufficient, but I need to be able to prove it on paper. A Google search has thus far been fruitless.
TIA
At present, the pile design is expected to be 18" diameter ACP (at the client's request). For moment capacity, it appears as though an HP12 will be adequate in lieu of a reinforcing cage, but the I for this section alone is inadequate for the deflection calcs.
Are there any published analysis methods for determining the moment of inertia of a round ACP with an embedded H-pile? I "know" the composite section will be sufficient, but I need to be able to prove it on paper. A Google search has thus far been fruitless.
TIA





RE: Lateral deflection calcs for Auger Cast Piles
In my experience the contractor always prefers a larger shaft with a larger steel beam to a smaller shaft and a smaller steel beam with studs is cost is the only factor.
RE: Lateral deflection calcs for Auger Cast Piles
RE: Lateral deflection calcs for Auger Cast Piles
RE: Lateral deflection calcs for Auger Cast Piles
Increasing pier diameter
Use HP beam with largest Sx that can still fit in the shaft
Increase f'c of the mix
Remove and replace upper 5B soils with slurry (this increases lateral subgrade reaction value).
If you increase the pier diameter and discount the I of the HP beam you should be o.k. with deflection. Ultimately your design is based on Mu and not induced Moment in the pier. Alternatively, you can get the equations form Foundation Design by Cernica and set up a spreadsheet so that each row has the composite E and I values.
RE: Lateral deflection calcs for Auger Cast Piles
Aside from the specific project requirements, however, I was mostly wondering if there is a generic, non-software analysis method for determining the properties of a circular cracked section with either rebar or encased steel section. I mean, they wrote the software based on an existing algorithm, right?
RE: Lateral deflection calcs for Auger Cast Piles
Look around in this Florida DOT site for a free program.
www.PeirceEngineering.com