Design of the members subject to compression is performed per chapter E of AISC 360-16.
All the cross-section profiles described in section 1A.10 are considered for compression.
The design compressive strength is calculated based on the applicable limit states of flexural buckling, torsional buckling, and flexural-torsional buckling modes as per Cl.E.1.
The nominal compressive strength, Pn , shall be the lowest value obtained based on the applicable limit states of flexural buckling, torsional buckling, and flexural-torsional buckling. In general, Table.E1.1 is followed for the choice of applicable sections/clauses for the various cross section shapes.
The gross area is used for members with non-slender elements whereas the effective area, Ae, is used for slender elements. The effective width of a slender element of any section other than round HSS is calculated for each limit state of compression as per eq. E7-2 or eq. E7-3 depending on the condition mentioned in the specification. The effective area (Ae ) for a slender HSS round section is calculated as per cl. E7.2.
The code does not mandate the maximum slenderness limit for members in compression. However, the program will check against a maximum slenderness ratio (L/r) which is specified using MAIN parameter whose default value is 180. The length considered to calculate the compression slenderness will be the full member length.