] [Thread] [Date] [Author]

["David Maynard" <d_maynard(--nospam--at)wester-wetstein.com>]

John Pack, PE, of IMR, Inc. out of Denver, CO, has done extensive studies
with AB Chance Helical Piers.  If you do an installation torque of 10,000
ft. lbs, you could get an Ultimate Capacity of the pier to be 100 kips.
With a factor of safety of 2.0, that's a 50 kips design capacity.  If they
have the materials to build a 50 kip (design capacity, 100 kip ultimate
capacity) helical pier (heavier shaft, several helix flights, etc., then you
can use a local helical pier for this particular load and isolate it from
the rest of the foundation.

Otherwise, with the spread that you have, you would have to design the
foundation as a concrete beam between these two piers.  I might not have a
clear understanding of your problem.  If you had a diagram to share, I might
have more information.

Dave Maynard
Gillette, WY


-----Original Message-----
From: Jordan Truesdell, PE [mailto:seaint2(--nospam--at)truesdellengineering.com] 
Sent: Wednesday, June 11, 2008 9:28 AM
To: seaint(--nospam--at)seaint.org
Subject: 1 or 2 piles under a cap

Does anyone have a rule of thumb for using less than 3 piles (helicals, 
in my case) under a pile cap?  I've got a condition where I have some 
lightly loaded pile caps - about 45k - but their supporting pyramidal 
piers which have a 40" square base.  The tops of the piers will support 
a beam line and concrete plank, so there's no lateral loads.  The piers 
are 16-20' apart and are in a (roughly) straight line, so I can't 
efficiently combine multiple piers under a single footing.

-- 
Jordan


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