What is best notch for king Truss Tie beam at intersection outside walls?

[Neil Stasilli]

 

[PEG688]

What ever the engineer called out  in the truss engineering package. 

Except no substituted ( unless the engineer approves them) , Use no hooks, No Not remove the label. 

[Neil Stasilli]

There is no notch specified.  Thinking of full scribe square notch and pinning with rebar thru into second log below tie beam.  Only removing about 3 inches from bottom of full round tie beam mean dia of 12 inches.  No saddles on intersecting wall logs.  I do not want to compermise tie beam at notch.  I will square notch wall log to allow for cap log to support roof rafters.  Is there a better notch?      Thanks for your interest.

[Don_P]

It depends... have you got a drawing(s)?

If you can bury the toe of the top chord into the tie with enough relish beyond the notch to take the shear then that is a good way. That's usually only possible if large purlins sit over the trusses.

I've ended up with this method several times, use the  heel of the top chord to resist the horizontal thrust. The rod there is a threaded rod to keep the birdsmouth down in pocket in an uplift.





again check the shear against the available area and allowable shear stresses.
You can lay a steel strap along the top of the bottom chord, lag it down sufficient to the load, set the top chord and wrap the strap over the top of the top chord, again lag down sufficient for the thrust.
There is a 6' piece of 3x3 angle iron embedded and lagged into the top of the bottom chord, there is a piece of 8" wide x 1/8" plate folded around the toe of the top chord, welded to the angle. In the background is the truss from the drawing above.

Generally speaking if you can resolve the heeljoint forces you can make the truss work, it is the place to start. I agree with PEG, I'd be happy to offer my opinion which might help speed you along and give a better understanding when you talk to an engineer, but this is ultimately a job for an engineer

The TF Guild has a publication for free download (or did) Historic American Timber Joinery.
althought to be honest I don't think it's in there. There is also a series on Historic Trusses in conjunction with the Nat'l Park Service, these are free downloads as well. I think you'll find one of the 5 is on kingpost trusses although several get into various tie configurations.

If there is much load a rebar pin isn't going to be enough.

[Don_P]

This is kind of timely, I've been emailing back and forth with some of the volunteers planning for some buildings we'll be doing and I had planned on digging up some reference material;

Scott,
I was thinking of starting a webpage under the about page on the market website that links to the drawings and animations of raising order, publications for reference, etc.
One good publication, I've used a couple of the tie joints out of it in the drawings as they've evolved.
http://www.tfguild.org/downloads/publications/Historic-American-Timber-Joinery.pdf

A Glossary of timberframing terms
http://tfguild.businesscatalyst.com/downloads/publications/Glossary-of-Timber-Framing-Terms.pdf

Historic American Roof Trusses;

http://www.tfguild.org/downloads/publications/Trusses-I-Scissor-Trusses.pdf

http://www.tfguild.org/downloads/publications/Trusses-II-Queenpost-Trusses.pdf

http://www.tfguild.org/downloads/publications/Trusses-III-Kingpost-Trusses.pdf

http://www.tfguild.org/downloads/publications/Trusses-IV-Composite-and-Raised-Bottom-Chord-Trusses.pdf

http://www.tfguild.org/downloads/publications/Trusses-V-Evolution-of-Roof-Trusses.pdf

Resources for anyone that really gets the bug, an engineer in the making? A job for the right person, there are about 25 really qualified timberframe engineers... in the world.
http://www.timberframeengineeringcouncil.org/library.html

Don

Just as an aside Neil, take a look at Palladio's "Four Books on Architecture"
http://books.google.com/books/about/The_Four_Books_on_Architecture.html?id=BNBva2kKm0wC
Go to his drawing of the bridge at Cismone, I think it was pg 176 there, look closely at the heeljoints, they are basically what I pictured above. In the kingpost article, fig 15, the buried toe, but notice the amount of tie beyond that notch, if it gets too short for the shear it pops off and the top chord slides out (another reason for that threaded rod, warning)

[Neil Stasilli]

I will wade through the info. you suggested and come up with a plan.  I will keep you up to date with my project as I reach log row 9 and setting the tie beem.  Good luck with your web sight, and if I can be any help, contact me through this site.  This project of putting logs on the wall is 14 months long to date, and going great.  My first log home, Full scribe saddle and notch corners and Swedish cope latterials.  32 X 32, 1 1/2 stories.  Dream comming true.  No problems with building inspector and still under permitt.