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Re: Truss Diagonals in Compression (AASHTO)

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>>> "Polhemus, Bill" <wlpolhemus(--nospam--at)sbinfra.com> 04/24 1:59 PM >>>
I

Problem is, I typically calculate the "effective length" of truss members
from panel point to panel point. The peer review guys claim that "the code"
allows you to go from actual end of member to actual end of member. I
disagree strenuously with this, since I happen to know that gusset plates
aren't infinitely rigid.

So, what do you think? Who's right?

Thanks.

AASHTO 10.7.4 states:

Actual unbraced length, L, shall be assumed as follows:

For the top chords of half-through trusses, the length between panels points laterally supported as indicated in article 10.16.12; for other main members, the length between panel point intersections or centers of braced points or centers of end connections; for secondary mfembers, the length between the centers of the end connections of such members or centers of braced points.


So it would depend on whether you have a main or a secondary members.

I'm guessing that the top and bottom chords are larger than the diagonals, so I would probably say the diagonals are secondary members, hence center to center of the connections would seem to apply.