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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·fa/FaSMY·Cmyfby/[(1 - fa/F'ey)Fby] +  SMZ·Cmzfbz/[(1 - fa/F'ez)Fbz] ≤ 1.0

    and Q1.6-1b

    SFC·fa/(0.6·Fy) + SMY·fby/Fby +  SMZ·fbz/Fbz ≤ 1.0

    when, fa/Fa > 0.15, as per section Q1.6.1 of the code.

  • Otherwise, equation Q1.6-2 must be satisfied:

    SFC·fa/FaSMY·fby/Fby + SMZ·fbz/Fbz ≤ 1.0

  • Members subjected to both axial tension and bending stress are proportioned to satisfy equation Q 1.6-1b:

    SFT·fa/(0.6·Fy) + SMY·fby/FbySMZ·fbz/Fbz ≤ 1.0

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