Hey Bruce,

Have you thought about housing the tie beam with a gain (reduction) on the bottom?









That is a 1" housing. 1.5 would probably be better.

How do you have your principal rafter meeting the tie? I agree with you about the thrust. From the critical bearing point of your rafter to tie there is significant tension in between, but outside of these points, I would think you only have a downward load. In essence the truss, which negates itself is just inside of the plate and posts.

What about two braces from post to tie?

One to stablilize the frame, and another with maybe a run equal to where the force from the principal rafter goes through the tie. One brace at a 3' run, and the other at a 1'? You might even be able to have the smaller brace join to the tie at the gain.?

Interested in others thoughts as well.