D1.A.6 Design Parameters
Design per AISC 36005, 36010, and 360016 (Unified) specifications is requested by using the CODE parameter. Other applicable parameters are summarized in the following Table. These parameters communicate design decisions from the engineer to the program and thus allow you to control the design process.
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.
Parameter Name  Default Value  Description 

CODE  AISC UNIFIED 
Used to designate this code (default is the 2016 edition). CODE AISC UNIFIED (2016) CODE AISC UNIFIED 2010 CODE AISC UNIFIED 2005 
ALH
(AISC 36016 only) 
0.5  Distance of applied point torsion
from start of member as a fraction of member length. Represented by
"
α
" in the torsional case options in Appendix B of AISC Design
Guide 9.
To be used with TND values of 3, 6, or 9. (0<ALH<1). Set TORSION 1 to enable Torsion check as per DG9. 
BEAM  1.0 
See Note 9 below.

BRC
(AISC 36005 and 36010 only) 
1 
Specifies the bracing type for the member used for seismic provision checks:

CAN  0 
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 D1.B.1.2 Design Parameters) 
CB ^{2}  1.0  Coefficient C_{b} per Chapter F. If C_{b} is set to 0.0, it will be calculated by the program. Any other value will be directly used in the design. See Note 2 below. 
CSPACING  12 in  Spacing between connectors in current length units. Refer to Section E6.1 and E6.2 of AISC 360. 
DFF  none (mandatory for deflection check) 
"Deflection Length" / Maximum allowable local
deflection. See TR.40 Load Envelope for deflection checks using serviceability load envelopes. 
DJ1  Start Joint of member  Joint No. denoting starting point for calculation of "Deflection Length" (see D1.B.1.2 Design Parameters) 
DJ2  End Joint of member  Joint No. denoting end point for calculation of "Deflection Length" (see D1.B.1.2 Design Parameters) 
DMAX  1000.0 mm  Maximum allowable depth for member selection. 
DMIN  0.0 mm  Minimum allowable depth for member selection. 
DUCT
(AISC 36016 only) 
0  The ductile category of the
member as per AISC 34116:

FLX  1 
Parameter for specifying the lateraltorsional restraint condition for a single angle. Refer to Section F10 of AISC 36005, 36010, and 360116.

FRM
(AISC 36005 and 36010 only) 
0 
Specifies the seismic forceresisting system used in seismic provision checks:

FU  400 MPa  Ultimate strength of steel. 
FYLD  250 MPa  Yield strength of steel. The program considers a valid range of input values between 10 ksi  100 ksi (69 MPa  689 MPa). 
KX  1.0  K value for flexuraltorsional buckling. 
INTERACTION  0 
Directs the program which interaction equations to check per section H1:

KY  1.0  Effective length factor to calculate slenderness ratio for compression buckling about local yaxis. Usually this is the minor axis. 
KZ  1.0  Effective length factor to calculate slenderness ratio for compression buckling about local zaxis. Usually this is the major axis. 
LBRC
(AISC 36016 only) 
1 
Type of flange lateral bracing:
Used to calculate bracing requirements as per seismic provisions in AISC 34116. 
LEG  0 
This parameter is meant for plain angles (Section E5).

LX  Member Length  Length for flexuraltorsional buckling. See Note 8 below. 
LY  Member Length  Length to calculate slenderness ratio for buckling about local yaxis. 
LZ  Member Length  Length to calculate slenderness ratio for buckling about local zaxis. 
MAIN  200  Allowable slenderness limit for compression members. A value of 1 suppresses this check. Any value greater than 1 is used as the compression slenderness check value. 
METHOD  LRFD  Used to specify LRFD or ASD design methods. 
MTYP  1 
Specifies whether the member is a beam or column. Used for seismic provisions checks.
For AISC 36016 only:

NBRC
(AISC 36016 only) 
1  Number of braced points within the span. Represented by "n" in Appendix 6.3.2(a) of AISC 36016. Required for Seismic Provisions. 
NSF  1.0  Net Section Factor for tension members, equal to A_{n}/A_{g} ,used to account for reduction in section used for tension checks (clause B 4.3b.) combined with the SLF parameter to determine the rupture strength. (see also SLF parameter) 
PROFILE  Used in member selection. Refer to TR.48.1 Parameter Specifications for details.  
RATIO  1.0  Permissible ratio of actual load to allowable strength. 
SEISMIC  0  Used to instruct the program to add additional checks per the
AISC 341, Seismic Provisions for Structural Steel
Buildings.
AISC 360 – 05, check according to AISC 341 – 05 AISC 360 – 10, check according to AISC 341 – 10 AISC 360 – 16, check according to AISC 341 – 16 See section D1.A. American Codes  Steel Design per AISC 360 Unified Specification for more detials.
See D1.A.9 Seismic Provision Checking per AISC 341 for details. 
SGR
(AISC 36016 only) 
Select ASTM steel grades:
The yield stress and ultimate stress will be
autocalculated based on the grade selected. Note that any
SGR value greater than 0 will take priority
when calculating the yield stress and ultimate stress over any
supplied FYLD and FU value.


SLF  1.0  Shear Lag Factor, value " U " normally taken from table D3.1, combined with the NSF parameter to determine the net effective area used to calculate the section rupture strength. (see also NSF parameter) 
SNUG  1 
Type of connection for the builtup members:

SOE
(AISC 36016 only) 
0  Second Order Effects have been
considered in analysis forces or not:
By default, Second Order Effects are not considered in the analysis forces. This is related to Torsion checks as per DG9. Set TORSION 1 to enable Torsion check as per DG9. 
STFB
(AISC 36016 only) 
0.0  Stiffener width for onesided web stiffeners, twice the individual stiffener width for pairs of stiffeners. Represented by "bs" in Appendix 6.3.2(a) of AISC 36016. Required for Seismic Provisions. 
STFT
(AISC 36016 only) 
0.0  Thickness of web stiffeners. Represented by "tst" in Appendix 6.3.2(a) of AISC 36016. Required for Seismic Provisions. 
STIFF  Member Length or depth of beam, whichever is greater  Spacing of stiffeners for plate girder design. 
STP  1.0  Section Type used for
design

TBRC
(AISC 36016 only) 
Type of torsional bracing:
Used to calculate bracing requirements as per seismic provisions in AISC 34116. 

TFA
(AISC 36016 only) 
0  Tension field action to be
considered in shear design:

TMAIN  300  Allowable slenderness limit for tension members. A value of 1 suppresses this check. Any value greater than 1 is used as the tension slenderness check value. 
TND
(AISC 36016 only) 
1 
Torsion loading and end condition as in Table in Appendix C.4 of AISC Design Guide 9:
The number corresponds to the case number of the case chart in Appendix B of DG9. Set TORSION 1 to enable Torsion check as per DG9. 
TORSION
(AISC 36010 and 36016 only) 
0 
Specifies design for torsion per AISC Design Guide 9. See D1.A.5.6 Design for Torsion

TRACK  0 
Specifies the amount of detail included in design output

UNB  Member Length  Unsupported length of the bottom flange for calculating flexural strength. Will be used only if compression is in the bottom flange. See Note 3 below. 
UNL  Member Length  Unsupported length of left extreme flange for LTB that will be used as lateraltorsional buckling length for the section with the vertical axis as major principal axis and where the left extreme fiber is in compression. If member is assigned with any value of UNL and FLX=2 concurrently, LTB length of the member will be treated as zero. 
UNR  Member Length  Unsupported length of right extreme flange for LTB that will be used as Lateraltorsional buckling length for the section with the vertical axis as major principal axis and where the right extreme fiber is in compression. If member is assigned with any value of UNR and FLX=2 concurrently, LTB length of the member will be treated as zero. 
UNT  Member Length  Unsupported length of the top flange for calculating flexural strength. Will be used only if compression is in the top flange. See Note 3 below. 
WTYPE
(AISC 36005 and 36010 only) 
0 
Weld type for HSS per Sect. B3.12 (AISC 36005) or Sect. B4.12 (AISC 36010):
For HSS Rectangle and Round profiles from AISC databases, the weld type will always be determined based on profile table (grade A1085 or not). WTYP will have no effect on these. For any other hollow profiles (pipe, tube, box, etc.) from AISC databases, all hollow profiles from any other country databases, and User Provided tables, the weld type must be specified using the WTYP parameter. 
Notes

For the AISC 360 unified code, an angle is automatically checked for geometric axis bending (in addition to principal axis bending) provided one of the following conditions is met:
The AXIS parameter is only used by the deprecated AISC 36005 code checking method (CODE AISC UNIFIED OLD). If this code is used, then AXIS 1 specifies design based on principle axes, where AXIS 2 specifies design based on geometric axes.
 Nondefault values of CB must be reentered before every subsequent CHECK CODE or SELECT command.
 Top and Bottom represent the positive and negative side of the local Y axis (local Z axis if SET Z UP is used).
 For a description of the deflection check parameters DFF, DJ1, DJ2 see the Notes section of D1.B.1.2 Design Parameters of this manual.
 NSF is the Net Section Factor as used in most of the steel design codes in STAAD.Pro. It is defined as the Ratio of "Net cross section area" / "Gross section area" for tension member design. The default value is 1.0. For the AISC 360 code, it is described in section D.3.2.
 SLF is the Shear Lag Factor, as used in Section D.3.3 of the AISC 36005 code. This factor is used to determine the effective net area by multiplying this factor with net area of the cross section. Please refer to Table D3.1 of the 360 code for a list of acceptable SLF values. In STAAD.Pro, the default value for SLF is 1.0. The effective net area is used to determine the tensile strength for tensile rupture in the net section, as per equation D.2.2.
 To summarize, the Gross Area (Ag) is multiplied by NSF to get the Net Area (An) of the section. The Net Area (An) is again multiplied by SLF to get the Effective Net Area (Ae) of the section.
 For the design of a single angle for flexure, the parameter LX should be used to specify the value of the term "L" in equations F104a, F104b, F105 and F106 of AISC 36005 and the term "Lb" in equations F104, F105, F106a, and F106b of AISC 36010.

When BEAM is 1.0 (default), the design is performed at 13 evenly spaced points along the length of the beam, including start and end points (i.e., 1/12th points or at ends of 12 equal length segments).
When BEAM is 0.0, the start and ends along with up to three locations specified in TR.41 Section Specification are designed.
 For AISC 36016, the material strength values are first taken from the SGR parameter if specified (and not zero). If SGR has not been specified, then the values of the FYLD and FU parameters will be used if specified. If no design parameters have been specified for material strengths, then the values in the material definition are used. If no material definition has been assigned, then the STAAD.Pro default values of Fy = 36 ksi and Fu = 58 ksi are assumed.