I need to do eqn. 9.3-3 in ASD. My LRFD version of it has a phi of 0.75. Is the eqn. the same for ASD and what is omega so I can replace phi with 1/omega?
You need to be careful. I don't know what exactly you are looking to design, but method of analysis and method of design are not always independent. It may be fine, but it seems like you may need to consult with someone familiar with steel design.
That equation is no longer used. It has been replaced with equation K1-10 in the 2005 AISC specification, which is available for free from AISC's web site. It includes provisions for both ASD and LRFD.
Considering flexure on rectangular or square Hollow Structural Steels, the section must be checked on its yielding, flange local buckling and web local buckling to determine its normal moment capacity. The lowest nominal capacity to be considered shall be the lowest of the three conditions. To get the design flexural strength of a section whether HSS or not, the nominal capacity would be multiplied by 0.90 when considering LRFD. On the other hand, a divisor of 1.67 shall be used when considering ASD. The 0.90 and 1.67 are the omega values for LRFD and ASD respectively.
