Pipe pile size for two story wood-framed structure

[skimboard20]

Hi all,

I am in communication with a geotechnical engineer regarding the foundation for a two-story, wood-framed residential structure in the pacific northwest. The stem wall foundation will sit on driven pipe piles. We are considering either 4" or 6" diameter steel pipe piles, and have determined that driving fewer 6" piles is more economical that driving more 4" piles. In general, the fewer piles they have to drive, the better (assuming the grade beams can span the additional distance). For 3" and 4" pipe piles, we typically specify Schedule 40 pipe, (0.216" wall). Is there any reason 6" piles would need a larger wall thickness? The only thing I can think of is that the wall might need to be thicker to withstand the larger impact of a larger driving hammer. Anyone think there is any truth to that?

Thanks for the insight!

 

[jayrod12]

What's the plan for transferring the lateral loads to the ground? In my experience the pipe piles have negligible lateral capacity.

 

[skimboard20]

Current plan is to batter some piles. I am more so curious what others think the pipe section needs to be in order to get driven.

 

[jayrod12]

You're likely better off to talk to the local pipe pile installers to get a feel for what sizes they generally see or carry. I know around here they have some stock sizing they'd prefer to use even if it means one more pile is required.

 

[skimboard20]

I think you're right. Time to start making some calls.