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RE: 125' long steel truss, connection question

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I might have missed something but....
When designing a truss, you MUST assume all joints are pinned.  If you assume all the joints are fixed, I believe you would have to design it almost like a braced frame.
   Todd Blake, E.I.T.
-----Original Message-----
From: Simon Solorio [mailto:simon(--nospam--at)]
Sent: Wednesday, June 23, 1999 8:02 PM
To: seaint(--nospam--at)
Subject: 125' long steel truss, connection question

I'm designing a 125' long steel truss, a section view of the truss is a triangle. The top chords (2 top chords) are pipes and the bottom chord (1 bottom chord) is also a pipe. The web members are pipes.
1. the top and bottom chords are going to be a continuous pipe, so when I analyse the truss should I assume the connection at the node intersections (at the chords only) fixed or should I analyse it assuming the the chords are pinned between each node of the truss?
2. the pipe web members are going to welded to the pipe chord members with fillet welds, where can i find information on how much fixity i should design this connection.
The architect does not want to see any plates, so I think if the connection of the web to chord is all welded then the connection has some fixity.
I've check the truss with all the members fixed and the truss with all the members pinned but i think, with the fillet weld connections, the percent of fixity is in-between a fixed and hinged connection. The reference books I have show a welded connection like the one I need to design and seem to assume the connections are pinned.
Thank you in advance
Simon Solorio, P.E.