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Bearing and Friction Design Capacity for Helical Anchors and Piles - Reintroduction of a Time-Tested Paper Authored by Gary Seider

by Wayne Thompson

CTL / Thompson

October, 2014

Let’s look at a scenario.

Xavier Y. Zoolander is an engineer with 12 years of experience designing foundations on driven piles, footings, and drilled piers.  He is a P.E., a principal at XYZ Engineering, and a well respected engineer.  Abe’s Backhoe Company, a local contractor, just got into the helical pile installation business and is buying his piles from Midwest Pile Supply.  Abe walks into Xavier’s office and asks for 20 minutes to tell him about what his system can do.  So Old Honest Abe proceeds to tell Xavier about helical piles.  And what is the main thing Abe remembers from his franchise training?  “So Xavier, listen to Old Honest Abe here, the thing with these systems is that they are so easy to design, and you don’t even need a load test.  I just take my final installation torque on my torque motor, multiply by 8, and that’s the capacity of the pile.  What can be easier than that?”  If you were Xavier and knew nothing about helical piles, what’s your first impression?

I’ve never owned XYZ Engineering, but I have a similar story.  As I look at the commonly referenced books in my office, I see the ACI 318, IBC, IRC, Manual of Steel Construction, and many more.  For foundations, I have books by Das and by Bowles (both are falling apart at the bindings).  After nearly 20 years into my engineering career, some of the books that I got in college are still my primary reference materials, trusted and time tested.  That led me to ask a question at our Helical Piles and Tiebacks seminar in April – what is the “go to” reference for the helical pile industry?  Is it Dr. Perko’s book?  The answers varied, but I did not get what I wanted.

Months have gone by since the seminar, and I finally stumbled upon something close to what I wanted to see.  In my mind, I was hoping to have a 10-page (plus or minus) document that could be endorsed by DFI and sent out to university programs (as a PDF) so the foundation professors could distribute it to their students.  Picture something small enough to print double sided, fold, and slide into a text book.  Or inserted as extra pages in a PDF document.  What I stumbled across was a paper, written by Gary Seider of Hubbell-Chance, that described their proprietary helical pile and anchor design software.  If you scrape away the software references (which I have done), then you get a relatively concise document that can stand alone and act as a guide for design engineers.

So here is my request.  Take a look at this document and then think about its target audience.  Can we get this in front of Xavier before Old Honest Abe walks in the door with his sales pitch?”

Click here to read

Bearing and Friction Design Capacity for Helical Anchors and Piles


About Wayne Thompson and CTL|Thompson

Wayne is the manager of the Fort Collins, CO branch of CTL/Thompson - an engineering and materials testing firm with headquarters in Denver, CO.  The Fort Collins branch operates the only IAS certified laboratory in the world for the testing of helical piles and helical anchors per International Code Council’s Acceptance Criteria AC358.

Wayne can be reached via:

Phone: (970) 206-9455

Email: wthompson@ctlthompson.com

www.ctlt.com