Light gauge steel bracing spacing for an open structure? 1

[ProLuke]

Hello,

I am trying to figure out how much bottom-flange bracing to use on a LGS roof with no ceiling attached.

I am designing a car port that is open on all sides. I am in Houston, where I end up designing for 87 psf uplift.

I want to use light gauge steel roof joists, with a corrugated "R-Panel" roof over the joists.

I have a span of 20'.

I have found through tables that I can use 12 g. 10x3.25 joists @ 3' on center.

The tables say "This table assumes fully braced flanges."

Is there some spacing that I can specify strapping or even another flat Cee section on the bottom flange of the joists to brace them?

Is there tables, or some formulas? I am remembering "local flange buckling" from college... but not sure if the regular rolled steel shape formulas are valid for LGS sections.

Thank you!
--Luke



--Luke

 

[frv]

No, the rolled steel values are not valid. You need to get a hold of ANSI S100. That will have the information you need.

 

[JAE]

...or the AISI specification which has all the formulae for light gage bending and the buckling limits.

 

[abusementpark]

I agree with JAE and frv. You can download AISIWIN v8.0, which is a free light gauge metal framing design program. It should cover your scenario and properly implement the code provisions.