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RE: 125' long steel truss, connection question

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You would be being conservative if you assumed all connections were pinned.  Using a K factor of 0.9 is reasonable for each panel of the top chords. 
Similarly, you could use a K factor of 0.75 for the web pieces instead of 1.0 to take advantage of the end fixity.
 
The REALLY important thing is to ensure that the detailing results in the centres of all of the pipes intersecting properly to avoid induced moments in the chords. 
 
I highly recommend a text to you.  "Hollow Structural Section Connections and Trusses" 2nd ed.. by Jeff Packer and J.E. Henderson, published 1997 by the Canadian Institute of Steel Construction. ISBN 0-88811-086-3   http://www.cisc-icca.ca.  There is information on calculating the fixity of all members, even for cases with different top and bottom chord sizes, etc.  References are made to Canadian, USA and international codes.
-----Original Message-----
From: Simon Solorio [mailto:simon(--nospam--at)solorio.com]
Sent: Wednesday, June 23, 1999 17:02
To: seaint(--nospam--at)seaint.org
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.
Questions;
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.