what is the best connection for this? round timber pile to steel beam? 8

[delagina]

I can't figure out the best connection to do this.
if the timber pile was square, I could have used seat angle at the bottom of the beam.
but I prefer to use the more common round timber pile.
is there a round seat angle?

I could also install anchor bolts on top of the pile and bottom flange of the beam?

 

[mike20793]

If you're switching to steel beams instead of timber framing why not switch to H piles and save some headache?

How about making a pile cap with two plates in a T and knifing one into the pile with throughbolts. I've seen similar connections with round glulams.

 

[XR250]

KootK, also lags into the end grain of timber! And in a wet environment!

The angle detail doesn't look too bad, but use a deeper angle so you have some edge distance.

My thoughts exactly. Sorry KootK :>

 

[KootK]

No need to be sorry. It seems I've something to learn here.

1) Are lag bolts inappropriate in wet service?

2) Is end grain deficiency not simply addressed by applying the appropriate end grain capacity adjust meant factor?

Teach a KootK to fish damn it.





I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[jayrod12]

My issue with lags in wet service and in end grain is wood shrinkage and swelling. Depending on the conditions when installed it is possible to have the wood shrink entirely away from the lag. I have (only once) had a situation where you could shake the bolt in the hole, it must've only been grabbing the last 1/4" or 1/2" because I could wiggle it all around but couldn't quite get enough grip on it to pull it out.

 

[DaveAtkins]

My experience with this was the design of fixed docks on a river. I used 15" deep steel channels with multiple lag screws to create a moment connection--for lateral loads (I assumed it was pinned for gravity loads, as I recall, but then again the span was not large--10' or so). The lateral load was due to either a boat being moored to the dock (thus wind load) or an ice floe crashing into the timber pile.

Anyway, I kind of like KootK's sketch--you are not totally counting on the lag screws to support the load. There is a ledge below each channel, for redundancy.

And yes--you need to consider edge distance, spacing, wet service, etc. for the connection design.

DaveAtkins

 

[KootK]

Thanks for the anecdote Jayrod. Do end grain factors even apply to lags? I don't have time this morning to research it thoroughly but I'm starting to wonder now.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[jayrod12]

I can't answer that with any certainty. I avoid end-grain lagging like it's a Trump supporter.

 

[DaveAtkins]

With KootK's sketch (based on MY IDEA, I might add), there is no end grain issue--the lag screws go into the side grain of the pile. You do need to ensure the uppermost lag screw has adequate end distance to the top of the pile.

DaveAtkins

 

[KootK]

Hush. If he hears you he might make us build a wall. And there probably aren't enough of us to get it done. Granted, we've a few more available in AB now.

I generally avoid end grain dowel connections too. But, then it's usually somebody trying to stick a 1/2" lag in the end of a 2X. Here, I was imagining a long, large diameter galvanized lag in the clean cut end of a big old log. It doesn't generate the same negative visceral reaction in me for some reason. I'll try to imagine the piling 50 years in the future with checks and fungus growing from the top.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[jayrod12]

Canada-cy for U.S election

 

[Teguci]

 

[KootK]

Nice... Is it really that off putting though? I'd stand underneath it in the rain for 15 minutes if there were a case of beer on the line.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[KootK]

The last time that I pulled this stunt (same load) it was much more dire. Teguci's definitely got me with regard to artwork quality however.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[KootK]

11,000 lb test of an end grain connection at UBC: Link. And some related marketing material attached.

With KootK's sketch (based on MY IDEA, I might addglasses), there is no end grain issue--the lag screws go into the side grain of the pile. You do need to ensure the uppermost lag screw has adequate end distance to the top of the pile.

Yeah, I'm liking that scheme more and more too. I'd like to see it done with the framing in steel in one direction however (wood in the other). The main thing that was informing my earlier, flawed detail was the ability to accommodate tolerances in the location of the piles. With steel in both directions, and likely a desire to avoid field welding, a lot of the details that have both directions of the steel framing in the same plane would be problematic I wold think.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[EngineeringEric]

Kootk, sorry for the hiatus on your end grain question. The reduction in capacity factors are for perfectly fine wood, the end grain will be partially rotten in a few years. If you drill holes that allow water to penetrate it deeper, well then rot will occur even faster. I will say this, as you are rarely ever wrong on here, your design will have adequate and surplus load at first but the longevity will get you, the top of the pile will get weaker quicker and you will first loose your lateral capacity and will soon loose bearing capacity.

bolting through the sides with notched seats will allow the most compromised area to be lower in the wood and will allow more wood to protect the connection. The bolts will bend, they will slide but they will hold up.

I work with a few 'attraction' owners, we have completely disallowed lag screws from being used on any of our projects... I have seen the effects of the connection in 5,10,20,30 years of service each time i look at their older buildings... So i may be biased due to what i have seen in a short period working with them.

 

[KootK]

I will say this, as you are rarely ever wrong on here

That's gracious of you to say Eric. I've been tracking and I seem to be seriously wrong about something here about quarterly. You know: PT, obscure code provisions... statics. And I concede that I've been wrongheaded here. I'm just glad that I got my schooling via this venue rather than by way of a botched project.

Is it accurate to paraphrase your observations as follows:

1) no top side bearing solution should be employed because of the rot issues at the end of the pile and;

2) you don't advocate using lag bolts in any capacity in this context, even side grain?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[BUGGAR]

How can wood shrink away from a lag screw? If the wood shrinks, the hole shrinks.
When a concrete manhole riser ring shrinks, does the opening get bigger?

 

[IRstuff]

Shrinking is probably a imprecise word; certainly, it's most likely that the wood around an unprotected lag screw will probably deteriorate earlier than the rest of the wood, making it appear that the wood is "shrinking" away from the screw.

TTFN
I can do absolutely anything. I'm an expert!
faq731-376 forum1529

 

[Brad805]

I do not like lags in end grain for the simple fact it is very easy to strip out the threads during the install. One or two extra turns and you can have close to zero capacity. In engineered lumber this is less likely, but in a good ol log this is not that uncommon.

 

[EngineeringEric]

Kootk,

1) Top side is not horrible IMHO. I would prefer a seated edge connection as you nearly sketched for stability, but a top seated connection is not anything i shy away from... It is actually a common connection when using post caps, or other exterior light framed connections (only when they are not laterally loaded because we need additional connection capacity)

2) I would advocate the use of a through bolt over a lag screw in all applications. The way i look at it, a through bolt is just more effective and has more longevity, it is close in cost and takes as long to install.