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D1.J.3 Design Parameters

The program contains a large number of parameter names which are required to perform design and code checks.  These parameter names, with their default values, are listed in Table 22A.1. These parameters communicate design decisions from the engineer to the program.

The default parameter values have been selected such that they are frequently used numbers for conventional design. Depending on the particular design requirements for an analysis, some or all of these parameter values may have to be changed to exactly model the physical structure. For example, by default the KZ value (k value in local z-axis) of a member is set to 1.0, wile in the real structure it may be 1.5. In that case, the KZ value in the program can be changed to 1.5, as shown in the input instruction (Section 5). Similarly, the TRACK value of a member is set to 0.0, which means no allowable stresses of the member will be printed.

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. American (API) Steel Design Parameters
Parameter Name Default Value Description

Must be specified as API

Design code to follow. See TR.48.1 Parameter Specifications.

BEAM 1.0

Beam parameter:

  • 0.0 = design only for end moments or those at locations specified by the SECTION command.
  • 1.0 = calculate moments at twelfth points along the beam, and use the maximum Mz location for design.
  • 2.0 = Same for BEAM 1.0, but additional check is made at each end.
CB 1.0

Cb value as used in Section 1.5 of AISC

0.0 = Cb value to be calculated

Any other value will mean the value to be used in design



0.85 for sidesway and calculated for no sidesway Cm value in local y & z axes
DMAX 100.0 in Maximum allowable depth
DMIN 0.0 Minimum allowable depth
FSJ 1.6 Factor of safety used for joint checks.
FYLD 36 ksi Yield strength of steel.
KY 1.0 K value in local y-axis. Typically the minor axis.
KZ 1.0 K value in local z-axis. Typically the major axis.
LY Member Length Length in local Y-axis to calculate slenderness ratio.
LZ Member Length Length in local Z-axis to calculate slenderness ratio.
MAIN 0.0

Design for slenderness.

  • 1.0 = Main member
  • 2.0 = Secondary member
NSF 1.0 Net section factor for tension members.
RATIO 1.0 Permissible ratio of the actual to allowable stresses
SSY 0.0

Design for sidesway.

  • 0.0 = Sidesway in local y-axis
  • 1.0 = No sidesway
SSZ 0.0 Design for sidesway in local z-axis

Controls the level of detail in the output:

  • 0.0 = Print design output at the minimum level of detail.
  • 1.0 = Print design output at an intermediate level of detail.
  • 2.0 = Print design output at the maximum level of detail.
UNF 1.0 Same as above provided as a fraction of actual member length
UNL Member Length Unsupported length for calculating allowable bending stress

Weld type, as explained in section 3.1.1 of the API code.

  • 1.0 = Welding is one side only except for wide flange or tee sections, where the web is always assumed to be welded on both sides.
  • 2. 0 = Welding is both sides. For closed sections like pipe or tube, the welding will be only on one side.
WMIN 1.16 in. Minimum thickness
WSTR 0.4 X FLYD Allowable welding stress
Note: The parameters DMAX and DMIN are only used for member selection.