Second order theory with imperfections

Question

Need some help in understanding second order / P-Delta calculations in STAAD. 
 I've read this post by the way. 
 
 The calculation problem which I'm trying to calculate in Staad is described here. 
 
 My question is: 
 How do I make a second order theory calculation including imperfection on the Structure. 
 Probably someone could have a look at this calculation and point me to the correct definitions. 
 4.4 STAAD Steel column.std

Sye · Answer

The following changes were made to the file 
 Value of E changed from 2.05e+008 KN/m2 to 2.1e+008 to match with example 
 FIXED BUT supports were taken out as the model is defined as a PLANE frame anyway and so there cannot be any out of plane deformations 
 Imperfection is simulated through addition of notional load with PDELTA analysis as opposed to using DRIFT with imperfection analysis. 
 The results for load case 10 ( which includes the notional load) matches with those for the example. 
 A modified file is attached for your reference 4.4 STAAD Steel column_modified.std

Sye · Answer

Two staad files one for steel design and other for the buckling analysis are attached. For the steel design, you will need to add appropriate design parameters. Details of design parameters for the Euro code can be found in the online help as shown in the screenshot. 
 STAAD Steel column_Steel_Design.std 
 STAAD Steel column_BF.std

Modestas · Answer

You need to make some modifications in STAAD.Pro steel design so that the results would be close to FEM-Design results: 
 1) FEM-Design is using S355 steel. You need to use design parameter SGR 2 in STAAD.Pro in order to use S355 steel as well. By default STAAD is using S235 steel. 2) FEM-Design is using gammaM0 and gammaM1 as 1.05, while STAAD by default is using a value of 1.0 for these factors. So you need to use design parameters GM0 1.05 and GM1 1.05 in STAAD.Pro. 3) FEM-Design is using C1 factor for the calculation of Mcr as 1.4, while STAAD by default is using C1 as 1.132. So you need to use design parameter C1 1.4 in STAAD.Pro 4) STAAD by default uses a value of D/2 (D - depth of the section) for Zg - distance of the force application point from the shear center while calculating Mcr. I see that in FEM-Design C2 parameter is set to 0, meaning that C2xZg is 0. So in order to match with FEM-Design you need to use either the design parameter ZG 0 or C2 0. 
 With these modifications STAAD.Pro is reporting UR as 0.88 which is close to what FEM-Design is reporting. A modified STAAD.Pro file is attached. 
 STAAD Steel column_Steel_Design_MOD.std