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RE: Timber Bulkhead Design References

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Pat,

Thanks for getting back to me.  I emailed AWC and they set me scanned copies of those publications, which is great, but they are a little difficult to read.

The wall we are currently working on has a 13'-6" exposed height, so a cantilever wall won't work.  From what I can make out, none of these 3 publications really addresses in depth the design of an anchored timber bulkhead. 

We are using 3" thick sheets, four levels of walers, and 12" dia. face piles at 4-ft o.c.  The anchor is at the second waler from the top (around 3-4 feet from top).  We've sized the sheets using the SPW911 program from Pile Buck, using the free-earth method.  In doing this, we modeled the wall as being braced by the four walers.  This gave us the sheet size and the forces on the walers.  With the forces on the walers and the face pile spacing, we were able to size the walers.  That much wasn't too difficult. 

Our main problem has been in trying to design the face pile and anchor.  Nothing we can find seems to address the design of these elements.  Our thoughts have been to design the face pile similar to the way you design a regular sheet pile wall with one anchor using the free-earth method. 

Instead of active soil pressures acting on the back face of the wall, we used the waler loads we got from the SPW911 analysis.  We then calculated the passive pressures in front of the wall as you would normally do, except to reduce them by a "form factor" of 0.8 to account for the roundness of the pile (as per an old article I have on pole foundations).  We then sum moments about the anchor to find the required embedment and increased that by 40% for a factor of safety.  Given the required embedment (without 40% increase), we then sum forces horizontally to find the anchor load. Then we found the point of zero shear and calculated the max moment in the pile.

Sorry, I know that was long-winded, but what do you think about the methodology?  See anything I've missed?  Any comments?

All input is welcome.

Thanks for your help.

Tripp Howard

 Pat Symons <psymons(--nospam--at)tlowell.com> wrote:

Tripp
 
Contact the American Forest & Paper Association @ http://www.awc.org
 
Ask for:
    Designing retaining walls, bulkheads and seawalls of treated timber
    Improved standard designs, pressure treated timber crib walls 
    Notes on, Earth retaining structures
 
If they aren't readily available, let me know and I'll fax a copy to you (they are short)
 
hth
Pat Symons 
-----Original Message-----
From: Tripp Howard [mailto:tripphoward(--nospam--at)yahoo.com]
Sent: Thursday, March 06, 2003 7:07 AM
To: seaint(--nospam--at)seaint.org
Subject: Timber Bulkhead Design References

Does anyone know where I can get a good design guide for designing timber bulkheads?

Tripp Howard



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Tripp Howard



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