Hello everyone

I am having a problem here and looking for some insights; and allow me to layout the scenario for discussion:
I have a model, when I ran it with Z662 code (F1=0.9, F2=0.87)
the sustain case result is 45.8 MPa, but when I ran with B31.3 (Liberal stress allowed, F1 and F2 blank but with all the SH and Sy not altered) the result is 55.4 MPa.
With all the other conditions are the same, what would cause CAESAR II to have this difference?

I thank you and appreciate your knowledge and insights.

I heard SIF value is different for defferent codes

Z662 is closer to B31.8 than it is to B31.3. The stress equations and the allowable equations are completely different. You will not see the same results between these two codes.