Structural design computation

[EDMA]

Hi guys,

I hope all is well on your end.

I encountered a problem with the design attached here, and I really need your help, please.

How do the braces between the longest channel and the front channel affect the reactional force when calculating the bending stress of each channel?

Is there any condition to determine the safe working load of the platform?

Note: There should be gratings at the top of the structure.