D1.K.1.1 General Comments
For steel design, STAAD compares the actual stresses with the allowable stresses as defined by ANSI/AISC N690-1994 and as amended by ANSI/AISC N690 1994(R2004)s2.
All the design steps are done as described in D1.B.1.1 Allowables per AISC Code
except for allowable stress in compression for AUSTENITIC STAINLESS STEEL
.
Section Q1.5.9 is used to calculate allowable compressive stress for Austenitic Stainless
Steel. Correction made in Supplementary s1 published in April 15, 2002 has been applied.
STYPE
โ to change material type to either Stainless Steel (STYPE=1) or Carbon Steel (STYPE=0). D1.K.1.1.1 Design Process
Members subjected to both axial compression and bending stresses are proportioned to satisfy equation Q1.6-1a:
and Q1.6-1b:
when, fa/Fa > 0.15, as per section Q1.6.1 of the code.
Otherwise, equation Q1.6-2 must be satisfied:
It should be noted that during code checking or member selection, if fa/Fa exceeds unity, the program does not compute the second and third part of the formula, because this would result in a misleadingly liberal ratio. The value of the coefficient Cm is taken as 0.85 for side-sway and [0.6 - 0.4ยท(M1/M2)], but not less than 0.4 for no side-sway.
Members subjected to both axial tension and bending stress are proportioned to satisfy equation Q1.6-3:
Where:
-
SFC
,SFT
,SMZ
, andSMY
are stress limit coefficient parameters used to control the components of the interaction equations. Refer to D1.K.1.2 Design Parameters for details.