huangyhg

metal stud to track connection - out of plane wind loads
can anyone give me some information on how to calculate the capacity of a metal stud to track connection for out of plane windloads.
i would like to eliminate the use of angles or clips if possible.
thanks in advance
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i'm pretty sure the metal stud guys have a slicker way of doing it, but what i've done is check one flange in bending. i assume some trib length of flange, maybe 3" or so. if that becomes a problem, i may use both flanges of the track in bending since the stud will bear on one and the screw will pull on the other. if that doesn't work, then you'll probably need to use clips or a heavier gauge track. from a pure strength standpoint, you may be able to use the stud spacing as the trib width in checking the track flange bending. that would be a yield line analysis and isn't worth the trouble, because other yield lines will form and it's not extremely easy. another reason not to do this is because you will get so much track flange movement at service loads that it could be a serviceability problem.
tha latest paper on the subject is the following:
'lateral strength of wind load bearing wall stud-to-track connections', year 2000 proceedings of international specialty conference on cold-flormed steel structures.
you may be able to get a copy of this from a manufacturer's engineering dept. another good source may be the cold-formed steel engineer's institute.
assuming you are talking about a sill track, and not a deflection track:
the tributary width for the track leg is 3.5 times the height of the track leg (which is usually 1.25"), plus the width of the stud. as noted above, if this doesn't work, use a heavier gauge track or assume the screw at the leeward track leg helps.
the other thing you can do is not assume the load is applied at 1/2 or 1/3 of the track leg height, but rather is applied at the centroid of the required bearing length based on web crippling in the stud.
daveatkins
thanks for the input everyone.
i orginally used the proceedure that structural eit mentioned with one flange of the track in bending and an effective flange width 3x the flange of the stud. i then calculated the stress by using the formula m/s. i compared the actual stress to the allowable stress = 0.70 x fy.
my result was a 12 gauge track (600t125-97 50ksi). can anyone tell me if this seems excessive for a wind velocity of 150, exposure c, 12.8 ft tall wall?
if you check the aisi specification for metal stud framed walls, all you need to check is web crippling for the stud. they have a method in the spec that gives more capacity because of the stud being screwed to the track.
but if you use the standard web crippling equations that will work too.
nfexp,
there are too many variables for us to check your work. is this stud near a corner? what is the internal pressure? mean roof height? i could go on and on.
daveatkins
dave,
i understand. at the corners i am using angles. my interior zone component and cladding pressure is 64psf.
stud 600s250-54-50ksi @ 16" on-center
curtain wall hieght - 12'-10"
lateral bracing @ 4' on-center
at the stud head i'm using a light gauge track and deflection angles
the bottom track is what i need to design. i have calculated that i need a (600t125-97 50ksi).

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