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Re: LGSS - Light Gauge Steel Stud question

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Dennis,

The h/t ratio for both 20 gauge 8" and 12" sections exceed the AISI limit of
200 for unreinforced webs.  The allowable web crippling strength for a 20
gauge 8" section is about 300 lbs. and for 12" section is about 250 lbs.

For the 8" section, I would suggest removing the inside face of the header
and reinforce both members with vertical stiffeners (something like an 8"
piece of 3 5/8" track or stud material that would fit in between the flange
of the header and screw it to the header) at bearings and concentrated
loads.  With this kind of reinforcement, the load will transfer directly to
the stiffener and then to the web and prevent the web from buckling.  And
the member will meet the code h/t ratio limit of 260 for member with web
stiffener.

The h/t ratio of 12" section is still exceed the code h/t limit even with
the web stiffener and  it would be better of to remove them and replace with
heavier gauge material.

In theory for a CEE-Section,  the web most first likely buckle outward then
fail and not likely buckle inward.  I am not sure that the bolt method will
add any additional strength to web crippling strength.  The drywall will
somewhat help to brace the web but to what degree is uncertain.  When the
web starts to buckle, some of the load will transfer from the web to the
drywall.  And you might want to consider if the drywall is stiff enough to
prevent the screw from pulling through or cracking the drywall.  Personally,
I would not feel comfortable using drywall as a stiffener for web crippling.



Bao D. Pham
www.itecsteel.com