Lateral Torsional Buckling of cantilevered flat bar (plate) subject to transverse load

[dreber]

I have a 12x1/4" plate beam cantilevered a short distance from a support beam and subjected to a point load which causes bending about it's strong axis.

So I go to AISC 360-10 Section F11 and notice that all of the equations use Lb where Lb is the "length between points that are either braced against lateral displacement of the compression region or between points braced to prevent twist of the cross section"

However, I don't have two points which either brace against lateral displacement or prevent twist. I only have one fixed point.

So if I'm cantilevered out 12 inches, is Lb 12 inches?

Note that Section F1(3) says Cb = 1 for cantilevers and overhangs, so perhaps that is the only concern.

 

[KootK]

Depends on the nature of your support restraint and the position of your load. See this doc for which case matches yours best:Link. If your span is less than twice your depth, consider modelling it as a fictitious truss. At short spans, the equations lose meaning and you can get more capacity with a truss model

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[dreber]

Thanks, KootK!

 

[KootK]

Glad to help Dreber.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.