Problem calculating structure strengh

[Username107]

Hello, I don’t know much about physics and I am building a rack for my pickup truck. For my own safety, I need to know in how much load I can put on this rack. I drew up a diagram to clear up miscommunication for whoever wants to solve that problem. It would be highly appreciated.


Distance CD is 6 feet
Distance AC and BD is 3 feet
Distance CJ and JD is 3 feet
Distance AE is 14 feet
Black diamonds are points where I would attach weight
All material Is A500 steel rectangle tube 4 inches by 2 inches with the 4 inch side drawn on the diagram. All contact points would be professionally welded.

I would like to know how much weight can I safely put on individual pressure points F, G and E and on the whole structure with the thickness of rectangular steel pipe being either 3/16 or 1/4 inch thick (I don't know yet which thickness to choose) I would be able to multiply the answer by 2 and get the total weight I can apply to both sides because the other side is the exact copy of first one.
Thanks in advance for whoever decides to take on this problem.

 

[Mech_Engineer]

Generally speaking, you will need to perform a static truss analysis of the structure. This Wikipedia page will give you a good overview starting point: http://en.wikipedia.org/wiki/Truss#Statics_of_trusses