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RE: welded truss design assumptions

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>I am reviewing someone elses truss design and question one
>of his assumptions.  When we do trusses, we typically assume
>that the web members are pinned and that these members only
>carry axial load - even if the connections are welded.  The truss
>that I am reviewing was designed with all of the members assumed
>to be fixed ends.  It is a typical WT top and bottom chord truss with
>angle webs.  No special connections - just gussets in line with the
>WT webs and welds on one leg of the angles.  Just curious what
>the general concensus is out there.
 
Perhaps the designer has read the paper by Nair in the AISC Engineering Journal (4th Qtr. 1988) regarding secondary stresses in trusses and is trying to account for flexural effects. However, I'm not sure from what you've indicated if the designer used this to reduce K. The connections will have some rigidity in plane, but what about out-of-plane buckling? I'd be hesitant to use the secondary stress analogy to economize the truss if that is what they did.

Charlie