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D1.D.1.3 AASHTO (ASD) Design Parameters

The following table outlines the parameters that can be used with the AASHTO (ASD) code along with the default values used if not explicitly specified.

Table 1. AASHTO (ASD) Design Parameters
Parameter Name Default Value Description
BEAM 1.0

0.0 = Design at ends and those locations specified by the SECTION command.

1.0 = Design at ends and every 1/12th point along the member length.

CB 1.0

Cb value as used in the calculation of Fb

0.0 = Cb value to be calculated

Any other value will be used in the calculations.



0.85 for sideswayand calculatedfor no sidesway Cm value in local y & z axes
DFF None.(Mandatory for a deflection check) “Deflection length” / Maximum allowable local axis deflection.
DJ1 Start joint of member Joint No. denoting starting point for calculating “Deflection Length”.
DJ2 End joint of member Joint No. denoting ending point for calculating “Deflection Length”.
DMAX 1000.0 Maximum allowed section depth (in current length units) for a section to be selected with the SELECT command.
DMIN 0.0 Minimum allowed section depth (in current length units) for a section to be selected with the SELECT command.
FYLD 36 KSI Yield strength of steel in current units.
KY 1.0


KZ 1.0


LY Member Length Length to calculate slenderness ratio for buckling about local Y axis.
LZ Member Length Same as above except in local z-axis.
MAIN 0.0

0.0 =check for slenderness

1.0 =suppress slenderness check

NSF 1.0 Ratio of "Net cross section area" / ‘Gross section area’ for tension member design.
PROFILE None Used in member selection. Refer to TR.48.1 パラメータの設定 for details.

1.0 = K-Overlap

2.0 = K-Gap

3.0 = T and Y

4.0 = Cross with diaphragms

5.0 = Cross without diaphragms

RATIO 1.0 Permissible ratio of the actual to allowable stresses.
SSY 0.0

0.0 =Sidesway in local y-axis.

1.0 =No sidesway in local y-axis

SSZ 0.0

0.0 =Sidesway in local z-axis.

1.0 =No sidesway in local z-axis.

STIFF Greater of member length or depth of beam. Spacing of stiffeners for plate girder design in current length units.

Level of detail in Output File:

  • 0 = Print the design output at the minimum detail level.
  • 1 = Print the design output at the intermediate detail level.
  • 2 = Print the design output at maximum detail level.
UNF 1.0 Unsupported length factor of the compression flange for calculating the allowable bending compressive strength.
UNL Member Length Unsupported length of compression flange for calculating allowable bending compressive stress.
WSTR 0.4 x FYLD Allowable welding stress