D3.E.4 Design Parameters

The design parameters outlined in Table 2E.1 are used to control the design procedure. These parameters communicate design decisions from the engineer to the program and thus allow the engineer to control the design process to suit an application's specific needs.

The default parameter values have been selected such that they are frequently used numbers for conventional design. Depending on the particular design requirements, some or all of these parameter values may be changed to exactly model the physical structure.

Note: Once a parameter is specified, its value stays at that specified number until it is specified again. This is the way STAAD.Pro works for all codes.

Table 1. British Cold Formed Steel Design Parameters
Parameter Name	Default Value	Description
CODE	BS5950 COLD	Design code to follow. See TR.48.1 Parameter Specifications.
BEAM	1.0	When this parameter is set to 1.0 (default), the adequacy of the member is determined by checking a total of 13 equally spaced locations along the length of the member. If the BEAM value is 0.0, the 13 location check is not conducted, and instead, checking is done only at the locations specified by the SECTION command (See STAAD manual for details. For TRUSS members only start and end locations are designed.
CMZ	1.0	Coefficient of equivalent uniform bending C_b. See BS:5950-5:1998,5.6. Used for Combined axial load and bending design.
CMY	1.0	Coefficient of equivalent uniform bending C_b. See BS:5950-5:1998,5.6. Used for Combined axial load and bending design.
CWY	1.0	Specifies whether the cold work of forming strengthening effect should be included in resistance computation. See BS:5950-5:1998,3.4 0 – effect should not be included 1 – effect should be included
FLX	1	Specifies whether torsional-flexural buckling restraint is provided or is not necessary for the member. See BS:5950-5:1998, 5.6 Values: 0 – Section subject to torsional flexural buckling 1 – Section not subject to torsional flexural buckling
FU	430 MPa	Ultimate tensile strength of steel in current units.
FYLD	250 MPa	Yield strength of steel in current units.
KX	1.0	Effective length factor for torsional buckling. It is a fraction and is unit-less. Values can range from 0.01 (for a column completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for twisting for determining the capacity in axial compression.
KY	1.0	Effective length factor for overall buckling about the local Y-axis. It is a fraction and is unit-less. Values can range from 0.01 (for a column completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for determining the capacity in axial compression.
KZ	1.0	Effective length factor for overall buckling in the local Z-axis. It is a fraction and is unit-less. Values can range from 0.01 (for a member completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for determining the capacity in axial compression.
LX	Member length	Unbraced length for twisting. It is input in the current units of length. Values can range from 0.01 (for a member completely prevented from torsional buckling) to any user specified large value. It is used to compute the KL/R ratio for twisting for determining the capacity in axial compression.
LY	Member length	Effective length for overall buckling in the local Y-axis. It is input in the current units of length. Values can range from 0.01 (for a member completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for determining the capacity in axial compression.
LZ	Member length	Effective length for overall buckling in the local Z-axis. It is input in the current units of length. Values can range from 0.01 (for a member completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for determining the capacity in axial compression.
MAIN	0	Specify the design for slenderness against the maximum slenderness as per Clause 6.2.2: 0 – Do not check slenderness ratio 1 – Check members resisting normal loads (180) 2 - Check members resisting self-weight and wind loads (250) 3 - Check members resisting reversal of stress (350)
NSF	1.0	Net section factor for tension members
DMAX	2540.0 cm.	Maximum allowable depth. It is input in the current units of length.
RATIO	1.0	Permissible ratio of actual to allowable stresses
TRACK	0	This parameter is used to control the level of detail in which the design output is reported in the output file. The allowable values are: 0 - Prints only the member number, section name, ratio, and PASS/FAIL status. 1 - Prints the design summary in addition to that printed by TRACK 1 2 - Prints member and material properties in addition to that printed by TRACK 2.