Torsional stiffness of a square section

[izax1]

This should be simple enough, but I am struggling with finding the torsional stiffness (polar moment of Inertia)for a closed square channel with different thicknesses on top and bottom. A little background: We have a beam with square closed section, but need too design for higher loads (bending and twisting of beam) and to accomplish the higher stiffness required, we plan to weld on a flat beam on top of the beam section. (thus different thickness on top and bottom of the section) I am concerned about the stresses in the welding. Thankful for any hints in the right direction?

 

[dhengr]

rb1957:
Would you please send me some of whatever you are smokin. My typin is just too good.

 

[rb1957]

well other than not reading (carefully) what i've typed (yes, i don't touch type ... something i meant to learn) i think the problem (it's not just me !?) is the wireless keyboard drops characters every so often ... i reckon it's saving them and selling them on "wheel of fortune"