Laterally unsupported spec STAAD

[GerhardSA]

Hi guys,

What is the easiest way of extending a members effective length for a laterally unsupported situation? Like two members in the bottomcord of a truss. I don't get that comand in steel designer, maybe I'm just doing it wrong. Any help?

Cheers

 

[n8engr]

Use the Ly or Lz command for the member in question. Depending on which direction the member is braced in apply an Ly (weak axis) or Lz (Strong Axis) parameter and use the value for the effective length of the member that you want it to be.
Example: If member 100 is unbraced for 20 ft. along the strong axis and you want to make the effective length 22 ft. use "Lz 22 Member 100" in the input file.

 

[structuresguy]

What n8engr said is true, but only for axial KL/r check. If you need to define the unbraced length for bending, use the Ub and Ut variables, for unbraced bottom and top chords, or UL for overall unbraced length. The way you input them is the same as the Lz variable above.