I am doing a problem of I bean subjected to uniform transverse load actiong downward on beams. Since the load is acting same (downward) through out the beam, I understand that the nature of stress should be same through out the beam i.ie. compressive at top fibers and tensile at bottom fibers. The contour plots I get from NX 11.0, shows that the stress is negative near the centre of beam length and positive near the two corners. Also when I see the beam cross section view, at element near beam centre it shows, top fibers in compression and bottom fibers in tension while when I choose an element near beam ends, it shows top fibers in tension and bottom fibers in compression.
Can anyone explain why am I getting theses kind of results or is my understanding wrong and I am supposed to get theses kind of results only.
I cross checked using few other problems also and getting the same type of results. .