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Square Timber Pile Splice

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phamENG

phamENG

Structural
Feb 6, 2015
7,245
I know, I know...terrible idea.

8x8 timber piles will be embedded about 14' into the ground. The design called for them to be continuous up to a second level deck, but for valid-ish reasons they can't get piles that long installed. Splice would be located a few feet off the ground. Given the embedment, I'm thinking we it can be modeled as fixed pinned with a hinge in the middle and be made to work...but I don't love it. Maybe a pair of L7x7s on opposing corners and through bolted...

A few of these take lateral load, but given the height it's delivered through in plane braces and I can coordinate the reaction to get it directly into the embedded pile.

Anyone see a reason why this absolutely shouldn't be done? Kind of a touchy situation and not one that can be left to sit for more than about an hour...
 
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Gawd... why can't you ever ask a questions that's within my wheelhouse? I want a properly earned phamStar sooo bad. This won't be that.

I'm fine with this in general for axial and a little shear. If there's no tension, you could convince me to even use a dowel pin the center of the pile. With tension, I suppose you could use one of those dowels things with cross pins. It doesn't sound as though you've got time to procure something like that though. A pair of L7 works for me too. The setup feels a bit like how we splice multistory steel columns.

Are they wanting to toe nail it in place ASAP and tidy it up later?
 
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KootK said:
why can't you ever ask a questions that's within my wheelhouse?
Click to expand...

Because I'm stuck in the purgatory that is light frame residential construction. Someday I'll get to play with the big boys and girls again...maybe...

Thanks for the reassurance. I was thinking of a combined drift pin and angle solution, but the bolts aren't playing nice with the drift pin...may just have to forgo that. I've heard rumors of a similar solution published in an old Air Force construction manual, but haven't seen the source.
 
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Is L7x7 an actual size?

You may want to use galv. or SS material for the splice if corrosion is a concern. I'm assuming piles are pressure treated.
 
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Eng16080 said:
Is L7x7 an actual size?
Click to expand...

No, it isn't. I apparently don't know how to type. Thank you L7x4. L6x6 could also work.

Another option is to just set another pile next to it with a shallow embed and bolt them all together. That might be more palatable and executable, though continuing to stray further from 'clean' engineering solutions.

Eng16080 said:
You may want to use galv. or SS material for the splice if corrosion is a concern.
Click to expand...

Sans doubt. I wouldn't dream of doing otherwise.
 
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Would getting a 6ft ish long W8x31 be out of the question. cut a 1/4"+/- slot in the middle of the upper and lower pile slot the W8 and bolt up the flanges on either side to the timber piles.
 
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Indeed it would be out. Location is relatively remote, and the structure is in a perilous state. Sitting on cribbing on a beach. (Was in the surf,
being relocated out of the surf). Need to be smart and careful about the solution, but the risks of not selecting a solution that can be implemented in an expedient fashion are real.
 
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If the lateral loads are low enough at the splice, I would try to use steel plates at opposing sides and thru bolt. (I suppose you probably have a good reason not to do that though.)

Another idea is to clamp the piles between two 8" steel channels thru bolted with legs turned inward. This would require a small amount of trimming the edges of the piles for a snug fit.

Is there a reason you're using steel and not PT wood at the splice connection?
 
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The original idea was to restore the integrity of the continuous pile. Can't really do that with wood as the connections get really challenging. But as I'm backing off on that, I'm thinking the 'normal' fix that contractors use in the area of just bolting another pile to it may be sufficient. Need to vet it a little more to satisfy myself that it'll do and how it will or will not impact some of my bracing connections.

IceNine - I'm very selective in the contractors that I 'allow' to do that kind of work. Not saying these guys can't, but I haven't worked with them enough to know if they could execute properly. With my luck it would be the pile contractor trying to do it with a chainsaw...
 
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I would consider connection with sleeve (RHS) . The pile tips are inserted and
bolted ..

The following snap from TOMLINSON , Pile Design and Construction Practice..
Wooden_Pile_splicing_ohnyma.jpg







Use it up, wear it out;
Make it do, or do without.

NEW ENGLAND MAXIM
 
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Timber columns get set on helical piles quite commonly, which I think is a pretty similar base connection situation. I think I'd look at it more as a column base connection at the top of a free-head pile, rather than a splice. Don't think that changes the statics, but maybe just a frame of reference.
 
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Thanks, bones. That is helpful. Easy to corner myself with inaccurate nomenclature.
 
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Not sure if it helps the situation but could you add diagonals from the splice level up to the floor?

I envision some bracing beams near the slice with the diagonals/kicker running to the next pile over.
 
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HTURKAK - that's similar to what I was going to do with the angles. Drift pin with steel angles all around. Thanks for posting the picture.

structSU10 - Where lateral load transfer is required, that's already done (the piles were coming out of the ground a good 12 feet in some areas). This was more just to ensure I didn't end up with an unstable hinge. But given the rest of the construction and the embedment that will be reached, I've come around to what bones is describing. I don't need to SPLICE the pile, I just need to support a post on top of a free-head, cantilevered pile with sufficient lateral capacity to stabilize the joint.
 
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