Torsion in I beams 1

[bangerjoe]

hello
I have a lug on a beam loaded at a fleet angle.
this may be a very elementary question but am i ok to check for biaxial bending.

can't find any standards/examples that use torsion and biaxial bending.

Thanks for any help

 

[JoshPlumSE]

Good point KootK. The simplified method is supposed to always be conservative. That's why you can get away with moving the load out a bit further towards the center of the flange or the extreme fiber. I tend to forget about that because I'm not doing my own calcs very often.

Instead, I'm usually trying to teach the concept to engineers who are unfamiliar with the whole concept of warping in wide flanges. Just trying to get folks to understand in a physical sense where these stresses are coming from and approximately what the magnitudes are. Sometimes this is for our younger support engineers, other times for users who don't quite understand what the torsion results in RISA are telling them, or who are concerned about a warning message that RISA throws up when their loading doesn't match our case2 assumptions.

If I were doing my own calcs, I would probably dig in a little deeper and see how far apart I could stretch that force couple.

 

[JoshPlumSE]

Also, (for what it's worth), I think those equations (from DG-9) are too conservative. To me, they're more like ASD 9th equations that haven't yet been adjusted for an LRFD / Strength level world.