Continuous Flight Auger pile design 1

[MIKE_311]

I need to design some CFAs. Basically a steel micropile tube pushed into grout. From what I gather they are designed either as micropiles or drilled shafts. These are small diameter CFA and will be seeing some moment. AASHTO doesn't really provide any guidance for design other than axial compression/tension.

Would they be designed similar to concrete filled steel tubes (CFST) for flexure or is there some other method I should use to evaluate the structural capacity?

 

[BridgeSmith]

Would they be designed similar to concrete filled steel tubes (CFST) for flexure or is there some other method I should use to evaluate the structural capacity?

I don't know of any easy way to quantify the effect of the auger flights on the flexural capacity. It could be worth doing an FEA, if 1) you need substantial flexural capacity, and 2) there's going to be a large number of them.

I don't think I understand using an auger for what you describe, rather than a just a pipe, or an HP or W section.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[HTURKAK]

Continuous flight auger (CFA) piles are a type of CIP bored pile which employ a continuous flight auger .(CFA) piles are drilled and concreted in one continuous operation then reinforcement cage is inserted into the wet concrete .

I will suggest you to look to the following doc and links to get answers to your questions ..

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https://www.keller.co.uk/expertise/techniques/cfa-piles

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https://www.fhwa.dot.gov/engineering/geotech/pubs/gec8/gec8.pdf

 

[EireChch]

The CFA is removed as the concrete is placed. Reinforcement is added as if it is a bored pile.