Residual stresses 2D to 3D

Hello,

i have simulated welding in 2D model for beam attached with cover plates at both the flanges using Abaqus, now i want to use the same residual stress distribution for whole 3D cover plated beam with same cross-section,so that i can find load carring capacity of beam.

but i am not sure, is it possible to find stresses in 2D model then use the same residual stress in 3D model? i try using initial state and restart option but it is not reading the same stresses for whole lenght.so is there any other way of doing this??

and i want to know the approximation i am taking (finging residual stress in 2D insteade of 3D) is acceptable or not?

Thankyou