Piles: To batter or not to batter?

[cessna98j]

Recent studies suggest that battered piles do not perform well in liquefiable soils during a seismic event, and that piers and wharves supported by battered piles have historically not done so well in past earthquakes because they attract significant loads and typically fail the deck, pile or both.

Thus the modern practice in moderate to high seismic zones is to design piers and wharves supported on plumb piles as the lateral SFRS.

What happens if you have a large piece of material handling equipment (over water) that requires a fairly rigid in-water foundation? You still have to design the foundation for seismic, and maybe even take a lower R-factor, but it seems like an all battered pile configuration is most efficient for these structures. It would sure reduce the total number of piles and minimize lateral deflections of the equipment under operating loads.

But this goes against the trend that seems to be "no battered piles".

What do you all think?

 

[SlideRuleEra]

I would use battered piles... BUT, use the modern design guidelines that overcome previous shortcomings in most soils. For an overview, see this article in a 2006 issue of "Pile Driver Magazine":

http://www.piledrivers.org/files/uploads/45463155-400B-45AB-9D09-19237ADD497F.pdf

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[BUGGAR]

Without going into all the reasons, we use only vertical piles on all the wharves and piers we do for the Navy. There are usually crane rails with at least one rail on the outboard edge, and we reduce the spacing of the piles at the crane beams. The whole thing has to be designed to function with the loss of any one adjacent pile or any two piles in the worst locations. We design for failure and a series of vertical piles in bending fail more better than a fewer number of "hard" batter piles.