steel member design in staad pro

Question

Hi, 
 I have attached a simple 2D design of a steel structure.In one design i have broken the beam into some segments and the member is passed.Then i wanted to check the entire beam as one member with the same section and same loading.This time the beam is not passed.how to solve the problem? thanks in advance. 
 
 01-design with member breaking.std 
 
 02-design without member breaking.std

Modestas · Answer

In one model you use the LY 0 parameter, while in the other model this is not used. Also, you need to use the design parameter UNL so that it would have the same values in both models. Once you set up that these parameters and both models, the design results should be the same.

Modestas · Answer

You have applied LY as 0, so this means that the beam is restrained along its length and is prevented from buckling about local Y axis. You have also used UNT and UNB as 0. The parameters UNT and UNB are for specifying the unsupported length of the compression flange for the purpose of computing allowable stresses in bending compression. So if UNT and UNB is 0, it means that compression flange is fully supported along its length. If this is what you wanted to model, then the design parameters are assigned correctly. 
 The LX is the effective length used in calculating the axial compression capacity for flexural torsional buckling.