Rack welded structure - peak stress

Hello,

I'm involved in a steel static storage calculation. Every cell 150x150 mm is being loaded at least with 300 kg. To simplify the system (just to see what happens) I have modeled an elementary unit 7 cells witdh and 5 height.

My question concern with the peak of stress near clamped section.. which is not compatible with the history of the system. Teoretically it should be broken (carbon steel with working stess 160 Mpa) but it is still there from at least 30 years.

Refining mesh the stress raise... I know about the singolarity but what is the correct way, the right mesh, to demonstrate that model is really representing the racks behaviour?

I will attach the 3d part.

Thank you for any appreciated suggestion.

Gianni

SolidworksSimulation