Auger Cast Piles

[jbjones2001]

I am working on the reinforcement design for axially, and laterally loaded auger cast piles, and am having difficulties understanding IBC section 1809.3.1. This section is entitled "allowable stress", does this mean that auger cast piles should be designed using ASD as opposed to LRFD? Does anyone have a good reference from ACI or other regarding the material design (not Geotechnical design) of auger cast piles?
Thanks in advance,
James B. Jones Jr., P.E.

 

[JAE]

ASD...that's the way it reads.

 

[jbjones2001]

So, it reads ASD, I agree. Next question...I have combined axial and flexural loads on the pile. Do I develop the interaction diagrams using ASD? Or do most of you check the axial compression using ASD, and then use LRFD for combined axial and flexural loading as indicated by ACI-543?

Anybody have any other good references for the design of auger cast piles?

 

[JAE]

OK, just a couple of thoughts on this. First, we usually try to avoid flexure on auger-cast piling as they are fairly small in diameter (we use between 12" and 16" dia.), and its difficult to push a rebar cage into the grout....usually just a single bar for the top 10 feet or so.

Even so, your question about ASD/LRFD - I would say that you would have to meet the stress guidelines in the code (its a minimum standard) and then go your next step further and check for the LRFD interaction. That way, you've satisfied the code AND you've satisfied yourself with the PM interaction check.

 

[haynewp]

My foundation test uses the stress limits of IBC 2000-1809.3.1 in regards to axial stress only, and then later combines moment in an ultimate strength check.

I have an ACP with axial and moment. The IBC doesn't say the stress limits of 1809.3.1 is for axial load only. I don't see how I will ever meet this requirement if it does mean axial load plus lateral moment. Does anyone know if this provision is supposed to be referring to AXIAL stress only check?