I am using STAAD Pro for design a steel structre made with welded H section .
I am designing the structure according to EN1993-1-1:2005 with German NA .
While I'm assigning NA 10 with EN1933-1-1:2005 i'm getting a stress ratio lets say = 0.91
But when I'm designing the same structure without assigning the NA , i'm only modifying the GM1 as 1.1 instead of 1.0 & getting a stess ratio lets say =0.85 .
My question is why this is changing ? as we know only GM1 value in German NA is different than EN1993-1-1:2005 in general .
Please note MTH =1 with GM1 =1.1(without NA) & MTH =2 with NA 10 giving me same results.
But MTH =1 with NA 10 resulting a higher stress ratio.
I understand that MTH =1 with GM1 =1.1(without NA) or MTH =2 with NA 10(without modifying GM1) is the correct approach as all the members are welded H section .
Please check & suggest .