How to calculate maximum load of the box

[hsji]

Hi I attached the file. there are 3 different types of forces applied.
and material's yield strength is 55.1 MPa or 8000 psi.
I want to find maximum load of box for each types.
I don't know which equation I can use. because the box is empty.
the dimension of box is
width: 70mm, length: 85mm, and height: 65mm.
and thickness of four sides 6mm and thickness of top and bottom is 10mm.
Which equation I can use for the three different types of forces applied

 

[Simon Bridge]

"Maximum load" before what happens?

That it deforms plastically? (hint: use defnition of "yield strength")
Or something else?

Note: Each pic appears to show two boxes.