Bill Schwab wrote:

snip

My first model may have been fairly inaccurate,


tactOff
Chris, it was nonsense.
/tactOff

Bill, you have yet to propose a model of your own. You could have
proposed a model in the time you spent criticising mine.

but that's the way it goes: you build one model, think about it and
discuss it, then build a better one.


Not in this case. You clearly lack understanding of the basics that
go into such a model.

An easy insult to offer, but as I asked, where is your model?

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.


Again, nonsense. You called it a tension member, hence you were assuming
frictionless pins and negligable weight. Otherwise known as a two force
member, and it's item one in any engineering statics course.

Consider my above answer retracted. Your question does not make it clear
which member you're talking about, and now you've changed the force
you're talking about from vertical to horizontal.

And no one here has yet claimed to be a professional structural
engineer...


Wisely so. A pro won't touch something like this - responsibility w/o
compensation. Some time ago, a poster suggested that the OP needs to
find a structural engineer, which was very good advice.

So here we have three guys who know a little about structural
engineering having an argument. If we'd worked together we could
possibly have been helpful, but I do not believe we are helping Steve
now, so I will not continue this discussion.

I do, however, stand by my recommendation that Steve should try to avoid
subjecting his 2" x 2" x 0.25" vertical column to a bending moment. I
think he should either place one stand-off at the very top (15' level)
and one at the level of the horizontal member (14' level), or change the
design to something stronger like the "stiff leg" style of crane. People
are welcome to agree or disagree with this opinion.

Chris