von-Mises Stress vs. AISC allowables
von-Mises Stress vs. AISC allowables
(OP)
I've always considered von-Mises stress results as an "in-depth" analysis and not just a basic average stress across a section.
My question is this: Is it appropriate to compare a von-Mises stress against AISC allowables. Previously i've compared it to yield on the basis that it isn't an average stress result. I believe that the AISC allowables are used when average stresses are calculated/approximated.
Does this seem correct? More to it than this? Any help would be much appreciated.
My question is this: Is it appropriate to compare a von-Mises stress against AISC allowables. Previously i've compared it to yield on the basis that it isn't an average stress result. I believe that the AISC allowables are used when average stresses are calculated/approximated.
Does this seem correct? More to it than this? Any help would be much appreciated.





RE: von-Mises Stress vs. AISC allowables
RE: von-Mises Stress vs. AISC allowables
But von Mises represents a combined state of both shear and tensile stress.
One way to compare is to substitute the AISC limits into the von Mises equation to get:
((.6*Fy)^2+3*(.4*Fy)^2)^(1/2)=.9Fy
However, codes we work with, if they specify that von Mises stress can be used, only allow von Mises stress to go to 2/3 of yield.
RE: von-Mises Stress vs. AISC allowables
RE: von-Mises Stress vs. AISC allowables
Thanks pylandjw, i would have to agree on your assessment. Although i haven't seen much in AISC code covering von-Mises analysis. If you have, could you point me to the section it is covered?
RE: von-Mises Stress vs. AISC allowables
jt