Custom Steel Truss Connection
Custom Steel Truss Connection
(OP)
I am working on connection detailing of very long custom steel trusses. They are about 168 ft long, 28 ft deep, 8 bays. I use W14-shapes as top and bottom chords, and steel tubes as vertical and diagonal webs. What is the best way to connect them? I am thinking use gussets to connect them, weld gussets to chords, notch ends of steel tubes, use long bolts to fasten them together. The sizes of square tubes about 12". However, I don't think it is good anyway. Anyone has better suggestion on the connection or even selection of truss members?
Thanks a lot fo any suggestion or idea.
Thanks a lot fo any suggestion or idea.






RE: Custom Steel Truss Connection
RE: Custom Steel Truss Connection
Most of the long span steel trusses I have experience with use bolted splice plates to the flanges and webs for chord connections.
RE: Custom Steel Truss Connection
Chord members should be made continuous by cover plates, it could be made away from pannel point to avoid congestion, especially true for 3D truss.
RE: Custom Steel Truss Connection
RE: Custom Steel Truss Connection
The gusset to W14 flanges could be shop welded and the W12's could be field attached prior to erection.
RE: Custom Steel Truss Connection
You will also be able to lower your web sizes if you reduce their lengths. A pratt configuration is your best alternative if you don't have uplift to deal with.
RE: Custom Steel Truss Connection
Actually the whole length of my trusses is 336 ft long but there are supports at the mid-span of the whole length of 336 ft, either by columns or by other deep trusses. Yes, 28 ft deep is for mechanical facilities and duct placements.
I don't like to weld gussets to the flanges of chords. I just feel it is not good especially considering seismic loading.
By the way, the W-shapes of top and bottom chords are placed vertically, not horizontally. If they are set horizontally, then a huge heavy W-shape will be required. This is a not option in my mind anyway.
Thanks for your inputs.
RE: Custom Steel Truss Connection
In addition, you might use intermediate bracing in your web members to reduce their sizes based on a large unbraced length.
RE: Custom Steel Truss Connection
RE: Custom Steel Truss Connection
RE: Custom Steel Truss Connection
Wide flange can be used successfully for your case, just watch out its orientation to avoid difficulty in making good simple connections. You are correct in using all bolt connections, except for minnor areas, weld should not be used.
RE: Custom Steel Truss Connection
I just checked my STAAD analysis. It looks like I am not luck enough. The largest channle MC18x58 is just a little bit short for strength, about 5-8% less to meet the required design strength. Does anyone know there are some manufacturers make larger non-standard steel channels than MC15x58 in US?
Thanks,
RE: Custom Steel Truss Connection
RE: Custom Steel Truss Connection
RE: Custom Steel Truss Connection
It seems like you cannot get any additional bracing for the weak axis. If you could, I would brace the weak axis at midpoint and design it that way. I am sure the mechanical ducts don't need 20' openings.
RE: Custom Steel Truss Connection
Is this a double trusses with duct running in between accross the 336' length? Without adequate bracing, you might need to stiffen your joints to assist in lateral stability (not a easy task).
Anyway, one more suggestion is to avoid mixing different shapes in main members (chord, column, diagonal), which would complicate the design
RE: Custom Steel Truss Connection
Thanks,
RE: Custom Steel Truss Connection
How about using a gusset connection shop welded to the WF and into a split tube stub. The remainder of the diagonal or vertical tube member may be continued from the stub using a sleeve splice and connected on both sides of the splice with holobolt fasteners. See ht
RE: Custom Steel Truss Connection
RE: Custom Steel Truss Connection
RE: Custom Steel Truss Connection
RE: Custom Steel Truss Connection