There are ways to reduce the outward trust on a post that a tie beam is connected to, in order to reduce the tension to a level that a scarf joint will work.
Each frame design has to be looked at carefully for these reasons. And sometimes a different arrangement of timbers will be needed to accomplish the intended design.
I always like the story about a ladder leaning against a building, with the base of the ladder on a puddle which has frozen and is therefore ice and very slippery. At just about any angle, when you climb this ladder it will slide out and fail/fall down.
Now attach the top of ladder to the building. The ladder can no longer slide on the ice.....
Jim Rogers
