Allowable Load/Moment of Structural Steel Tubing?

[DerekYY]

Are there any standard tables or literature listing the allowable load and/or moment of structural steel tubing used as a beam. Specifically, I'm looking for a 6"x2"x1/4" used as a joist over a 7.75ft span. The AISC ASD Manual doesn't list this info for structural tubing. Just wondering if it is published or do I have to calculate differently?

 

[dougantholz]

For ASD design you would just compare the load with the allowable: Section F3-1 (pg 5-48 in the green book) the allowable stress for a tube is either 0.66 Fy or 0.6 Fy.
No lateral torsional buckling so just a straight stress is all that is needed.

 

[dooron]

I suggest
that when loading structural tubing in bending as well as calculating stress=My/I ,you consider buckling stress on the compression side ( allowable compressive stress is given in Chimney codes etc), my experience shows this to be the more critical stress especially on thin tubes. Also local crippling of the tube due to point load.

 

[MMOT]

For future reference the Steel Tube Institute does publish beam and column capacity tables for HSS sections.

(

http://www.steeltubeinstitute.org)

AISC has also published a specification geared specifically to tube shapes (It is available in the Hollow Structural Sections Connections Manual) but it is in LRFD

Appendix B5 of the AISC ASD manual (the green book) addresses the buckling of tubes with thin walls mentioned by dooron (determined in accordance with Chapter B5)

 

[RG88]

One other source worthy of mention is Troitsky's Tubular Steel Structures. It is only $15.00 and available from Lincoln Arc Welding Company (James F. Lincoln Foundation). It is an excellent reference for designing with Steel Tubing.