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. 

D2.B.8.1 Notes

1. DFF, DJ1, and DJ2 – Deflection calculations

   Compute  Delta = SQRT((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.

   Note: Deflection calculations are not applicable to PMEMBERs.

   1. 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.

      PARAMETERS
      DFF 300. ALL
      DJ1 1 ALL
      DJ2 4 ALL

   2. 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.

   3. It is important to note that unless a DFF value is specified, STAAD.Pro will not perform a deflection check.  This is in accordance with the fact that there is no default value for DFF.

2. LHT Parameter

   If the shear force is constant within the segment, longitudinal position of the load is assumed to be at the segment end.

   If there is any variation of the shear force and the load is acting downward determined from shear force variation and load height parameter indicates the load is acting on top flange (flange at the positive local y axis) and restraints at the end of the segment is not FU (FRU) or PU (PRU) Kl is assumed to be 1.4.

   If there is any variation of the shear force and the load is acting upward determined from shear force variation and load height parameter indicates the load is acting on top flange (flange at the positive local y axis) and restraints at the end of the segment is not FU (FRU) or PU (PRU) Kl is assumed to be 1.0 as the load acting at the top flange is contributing to stabilize against local torsional buckling.

3. SGR Parameter

   Rolled profiles typically use an AS/NZS 3679.1 grade (i.e., SGR 2 or SGR 3), hollow profiles typically use an AS/NZS 1163 grade (i.e., SGR 4 to SGR 6), welded profiles typically use an AS/NZS 3678 grade (i.e., SGR 7 to SGR 11), and pressure vessels typically use an AS/NZS 3597 grade (i.e., SGR 12 to SGR 14).

   When an explicit grade has not been specified or the option SGR 0 has been specified, the program determines the steel grade as follows:

   Table 2. Default steel grades used for the SGR parameter

   Section Type	Steel Grade Used
   WB, WC, Tee section cut from WB and WC, other welded and UPT sections	AS 3678 300
   UB, UC, Tee section cut from UB and UC, EA, UA and all UPT sections UB, UC, Tee section cut from UB and UC, EA, UA and all other rolled sections	AS 3679.1 300
   Pipe, Tube, CHS, RHS, SHS Pipe, Tube, CHS, RHS, SHS	AS 1163 C250

   Note: If a value for the FYLD parameter has been specified, then that value will be used. Otherwise, the SGR value will be used to determine the yield strength and tensile strength values for the steel. based on maximum thickness of the individual elements of the section. Only for shear capacity calculation web thickness is used. Similarly, Tensile Strength is determined either from FU parameter or from SGR parameter.
   CAUTION: A check is introduced to see if yield stress is more than 450 MPa or not. If it is, a warning is issued and the yield stress is set to 450 MPa.