In SACS Fatigue, the Stress Concentration Factor (SCF) line allows users to define custom SCF values that will be applied in fatigue analysis. These user-defined factors override program defaults when the USR option is specified (column 26-30) on the FTOPT line.
The SCF input line provides a way to specify default SCF values for different section types when the user selects USR in columns 78–80 of the FTOPT line.
Each column range on the SCF line corresponds to a specific element type:
- Columns 6–10: Tubular SCF (overall)
- Columns 11–15: Wide Flange SCF
- Columns 16–20: Wide Flange Compact SCF
- Columns 21–25: Prismatic Section SCF
- Columns 26–30: Box Beam SCF
- Columns 31–35: Plate SCF
- (Further tubular-specific overrides may be provided on SCF/SCF2 lines if required)
If no SCF value is specified in a field, the program's default is applied automatically.
It is important to note that the SCF line is only effective when ‘USR’ is specified in columns 78–80 of the FTOPT line. Without this card, the program-calculated SCFs or other selected default methods are used.
Example:
For box beam elements, the SCF is defined in columns 26-30 of the SCF line. If no value is entered, the program's default = 5.0 is applied. If a user-specified value is entered in the SCF line, it will override the default and be used in the fatigue calculation.