Hi everytime i tries to mesh my model, i kept being prompt that there are bodies interfering but i couldnt figure out what exactly were interfering. What do i do?

And also after i briefly explained my model to my supervisor, he insist that i mesh my platform and the stiffeners using shell element. But it seems that solidworks dosent allow weldments to be meshed using shell? Please correct my if i am wrong. Thank you very much.