Chris,

Bill,

I feel I must enter this thread one more time.

What about the vertical component of the tension in the beam FBD
on the left?


We can't include it as we know nothing about the kinds of joints
Steve intends to employ in the structure. I assumed that there are
pin joints at each end of the beam because this makes the structure
statically determinate. We know so little about the structure that
this is only assumption one can make. Granted, I did not draw a pin
joint. That was an honest mistake.


Amid your stream of criticism and confusion between horizontal and
vertical, I gave the answer to a different question: the question "Why
is there no vertical force shown on the left-hand FBD acting at the
junction of the horizontal and vertical members?" I stand by the answer
I gave to this question. The answer to your question is very simple. I
believe the free body diagram on the left to be complete and correct. No
horizontal force is shown acting on the top end of the beam because the
upper support provides a reaction against this (see the roller support
in my diagram). If you disagree with this, please elaborate.

I don't know how to be any more plain about it: you are wrong. The
horizontal reaction is one applicable force, but that does not change
the behavior of two-force members. Your FBD is incorrect. It's not
"less accurate" - it's wrong.

Bill