strength limit states for local buckling

huangyhg

strength limit states for local buckling
i attended a seminar awhile back, and the most interesting thing was the subject of compact sections.  
  - most w-sections are always compact
  - only one w-section has a chance to be non-compact for fy=36ksi -- w6x15
  - only seven w-sections have a chance to be non-compact for fy=50ksi -- w6x15, w8x10, w10x12, w12x65, w14x90, w14x99, w40x174 --- so if you do not use these members you do not need to check for compact sections, and if you do they are 95%+ of the time will be compact.
  - all c-sections and mc-sections are compact for fy=36ksi and fy=50ksi
fyi
except if you are resisting seismic forces.  then the compactness limits are more stringent.
i personally have not calced every possible scenerio for the   
taro, are you referring here to the requirements for compactness limits in aisc seismic provisions (table i-8-1)versus lfrd design spec (table b5.1)?
yes, if you are using a response modification factor greater than 3, you need to use more compact sections to achieve the ductility.