Abaqus problems with transverse stiffeners

Hello my name is Raghid and I am currently doing my MSc in structural engineering on

transverse stiffeners in steel plate girders. I modelled the plate girder using shell elements

and I fear I might be doing something wrong since the stresses throughout the entire

span of 35m and I am not sure if the end panel which is successfully buckling in shear

is developing its post-buckling strength.

Any tips or suggestions as to why this is happening?