[TheForge] Re: (no subject) Timber Straps

[Joe Chadwick]

Ray-

If there are engineer's design drawings, this could be a cinch. Cut, punch, 
weld, finish.

If the builder just gave you a couple of his own sketches beware.
Contemporary timber frames are frequently constructed with members having 
higher-than optimum moisture content. As the wood shrinks, extra stress is 
put on the bolt patterns in the wood, simple bearing sometimes goes away, 
and lots of unintended force vectors convene at joints never designed for 
the load. So the thickness of the gusset, the diameter of the bolt and the 
pattern of the bolt need to be figured together. Most of the time, the 
number of bolts needed to transmit a load to the wood will  remove so much 
of the wood that there is no capacity left in the member. There are 
however, a few styles of  "shear" connectors that can be bought or made 
depending on the  look of the joint.

When I worked on coal-breakers (collieries) in my lost youth, gussets and 
straps usually started at 1/2". Granted, corrosion was a consideration, but 
later in school, the math proved out. Gravity load is only part of the 
picture, and a small part too. Wind loads, and the resulting stress 
reversals are spooky, especially since there is little in the way of 
redundancy in timber frames. I also don't know if your codes require 
seismic design for houses.
I'm not trying to sound whiny. Like your contractor, everybody wants to 
shed job-costs and liability. Even if you (or whomever eventually does make 
these) hired an engineer to design the joints, that team holds more 
liability than if one were simply fabricating.

Jeeze. Now that I took all the fun out of that job, I better get back to 
feeding the fire in the boiler of the bureaucracy.