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D9.C.7 Design Parameters

You are allowed complete control over the design process through the use of parameters in the following table. 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 of the situation, some or all of these parameter values may have to 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. 2002 Japanese Steel Design Parameters
Parameter Name Default Value Description

Must be specified as JAPANESE 2002 to invoke the AIJ 2002.

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

BEAM 1.0

Locations of design:

  • 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.

Specifies the method used for deflection checks

  • 0) deflection check based on the principle that maximum deflection occurs within the span between DJ1 and DJ2.
  • 1) deflection check based on the principle that maximum deflection is of the cantilever type (see note a)
CB 0

C value from the AIJ code. Refer to D9.C.5 Member Capacities Bending Stress for how C is calculated and applied.

Use 0.0 to direct the program to calculated Cb.

Any other value be used in lieu of the program calculated value.

DFF None(Mandatory for deflection check) "Deflection Length" / Maximum allowable local deflection
DJ1 Start Joint of member Joint No. denoting starting point for calculation of "Deflection Length" (See note b)
DJ2 End Joint of member Joint No. denoting end point for calculation of "Deflection Length" (See note b)
DMAX 100 cm Maximum allowable depth for member.
DMIN 0.0 cm Minimum allowable depth for member.
KY 1.0 K value in local y-axis. Usually, this is the minor axis.
KZ 1.0 K value in local z-axis. Usually, this is the major axis.
LY Member Length Length in local y-axis to calculate slenderness ratio.
LZ Member Length Same as above except in z-axis
FYLD 235 MPA Yield strength of steel in Megapascal.
MAIN 200 Allowable Slenderness Limit for Compression Member
  • 0.0) check for slenderness using default value
  • 1.0) suppress compression slenderness check

Any value greater than 1 = Allowable KL/r in compression (up to 250)

MBG 0 Specifies how to calculate the section modulus about the Z-Z axis for H-shape, I-shape, and channel sections when performing major axis bending checks:
  • 0) Consider the flanges and the web
  • 1) Consider only the flanges; the web is ignored for the calculation of the section modulus.
Von Mises check options:
  • 0) Do not perform von Mises check.
  • 1) Standard AIJ calculation. The direct stress σx is determined by calculating the stress at each of the corners of the section using signed forces and the appropriate elastic modulus. The magnitude of the maximum stress is used.
  • 2) τy excludes torsion stresses. The same as option 1, but in the calculation of the shear stress, the torsional moment is excluded.
  • 3) σx based on absolute forces, The direct stress σx is calculated using the absolute value of the force at the section divided by the minimum of the elastic section moduli for each axis.
  • 4) σx based on absolute forces and τy excludes torsion stress. Same as option 3, but excluding the torsional moment when calculating the shear stress.

For more details, refer to D9.C.10 Von Mises Stresses Check.

NSF 1.0 Net section factor for tension members.
RATIO 1.0 Permissible ratio of the actual to allowable stresses.
SLF 1 Slender section design option:
  • 0) Slender sections are not designed - an error message will be presented that design of these sections is not supported
  • 1) Slender sections designed with unreduced profile (i.e., full profile) - an error message will be presented that this may be an unconservative design

Allowable Slenderness Limit for Tension Member

  • 0.0) check for slenderness using default value
  • 1.0) suppress slenderness check

Any value greater than 1 = Allowable KL/r in tension.

Level of output detail:
  • 0) Produce design summary only
  • 1) Produce intermediate detailed output
  • 2) Produce maximum detailed output
UNF 1.0 Unsupported length for calculating allowable bending stress provided as a fraction of actual member length.
UNL Member Length Unsupported length for calculating allowable bending stress.

Method for evaluating Young's modulus, E, for equation 5.8:

  • 0) Use equation 5.8 from Design Standard for Steel Structures
  • 1) Use equation SSB-1.10 of JSME

D9.C.7.1 Notes

  1. When performing the deflection check, you can choose between two methods. The first method, defined by a value 0 for the CAN parameter, is based on the local displacement. Refer to TR.44 Printing Section Displacements for Members for details on local displacement..

    If the CAN parameter is set to 1, the check will be based on cantilever style deflection. Let (DX1, DY1,DZ1) represent the nodal displacements (in global axes) at the node defined by DJ1 (or in the absence of DJ1, the start node of the member). Similarly, (DX2, DY2, DZ2) represent the deflection values at DJ2 or the end node of the member.

    Compute Delta = ( DX2 DX1 ) 2 + ( DY2 DY1 ) 2 + ( DZ2 DZ1 ) 2

    Compute Length = distance between DJ1 and DJ2 or, between start node and end node, as the case may be.

    Then, if CAN is specified a value 1, dff = L/Delta

    Ratio due to deflection = DFF/dff

  2. If CAN = 0, the "Deflection Length" is defined as the length that is used for calculation of local deflections within a member.  It may be noted that for most cases the "Deflection Length" will be equal to the length of the member. However, in some situations, the "Deflection Length" may be different. A straight line joining DJ1 and DJ2 is used as the reference line from which local deflections are measured.

    For example, refer to the figure below where a beam has been modeled using four joints and three members. The "Deflection Length" for all three members will be equal to the total length of the beam in this case. The parameters DJ1 and DJ2 should be used to model this situation. Thus, for all three members here, DJ1 should be 1 and DJ2 should be 4.
    D = Maximum local deflection for members 1, 2, and 3.
    DFF 300. ALL
    DJ1 1 ALL
    DJ2 4 ALL
  3. If DJ1 and DJ2 are not used, "Deflection Length" will default to the member length and local deflections will be measured from original member line.
  4. The above parameters may be used in conjunction with other available parameters for steel design.