closed C-Purlings box attaching to another

[sedonas]

For a C-purlin of thickness 1.8mm.. is it advisable to connect a closed box (where two C-purlins are welded into one box or tube) and framing one on the body of another (such as secondary beam on another beam)? Is it stable with only 1.8mm thickness? What is the consensus in other area. Worry is that if welding is not full welding since it's very thin at 1.8 and if it got brittle at the point. The point may fail in future like from small rust, etc. Usually what is the rule for the minimum thickness when you can frame one closed C-purlins over another one. Thanks in advanced.

 

[hokie66]

If you need two purlins together, it is best to place them back to back. And connect them by bolting, not welding. If you need a tube, use a tube rather than making one.

 

[sedonas]

I was asking about connecting already bolted or welded back to back c-purlins (turning into a tube cheaper) and connecting two such perpendicularly as in secondary beam framing into a primary beam at its thirdpsan. Or this illustration may help:

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My concern is the thickness is only 1.8mm.. would it be stable when the two tubes were connected?

 

[ajh1]

There is an entire welding code, AWS D1.3, dedicated to proper welding of thin sheet steel. This can be a very effective way to make compression struts for bracing for conditions where you don't need the capacity levels of a regular HSS tube.

 

[BUGGAR]

Not clear what your details are. AISI and the Light Gage Framers documents should cover this. Did you check these?