AD.2007-07.2.13* Update to ANSI AISC N690 1984 & 1994 Codes

Four new Stress Limit Coefficients (SLC) parameters have been added for designs per ANSI/AISC N690 1984/1994 codes.

These parameters, SFC, SFT, SMZ, and SMY, all default to 1.0 and are used to control the interaction equations in Section Q1.6 of the ANSI/AISC N690 1984/1994 codes.

Equations Q1.6-1a, Q1.6-1b, Q1.6-2 and Q1.6-3 of code ANSI/AISC N690 1994 will be rewritten as follows:

Members subjected to both axial compression and bending stresses are proportioned to satisfy equation Q1.6-1a:

SFC·f_a/F_a + SMY·C_myf_by/[(1 - f_a/F'_ey)F_by] + SMZ·C_mzf_bz/[(1 - f_a/F'_ez)F_bz] ≤ 1.0

and Q1.6-1b

SFC·f_a/(0.6·F_y) + SMY·f_by/F_by + SMZ·f_bz/F_bz ≤ 1.0

when, f_a/F_a > 0.15, as per section Q1.6.1 of the code.
Otherwise, equation Q1.6-2 must be satisfied:

SFC·f_a/F_a + SMY·f_by/F_by + SMZ·f_bz/F_bz ≤ 1.0
Members subjected to both axial tension and bending stress are proportioned to satisfy equation Q 1.6-1b:

SFT·f_a/(0.6·F_y) + SMY·f_by/F_by + SMZ·f_bz/F_bz ≤ 1.0

Refer to D1.K.2.1 Design Process for additional information on using the ANSI N690 1984 and 1994 codes.