Cold form Cee Section Stiffening for very high moments

[FLR84]

Hi everyone,

I am designing a building where I need a cold form section to resist 280 kNm, 125 kN shear, and 185 kN compression axial force. I am intending to use back to back C40030 sections with stiffeners of some sort to cover the length of the member where the extremely high moment is. The high moment is created by a knee brace connection.

Usually I would bolt C35030 sections to either sides of the web of the back to back C40030 but in this case I don't think I will achieve the capacity in bending. Another solution I sometimes use is to bolt a C30030 section to the top and bottom flanges of the back to back C40030 (lying them flat). This roughly doubles the flange area of the back to back C40030 and so roughly doubles its capacity in bending.

However in this case, I think that will still fall a little short.

Does anyone have any ideas for how I can stiffen a back to back C40030 section to achieve 280 kNm capacity? I cannot reduce the bayside of the building.

Thank you.

 

[bones206]

Maybe weld a round bar at the web-flange junction. One bar on each side of the web.

 

[GC_Hopi]

Swap out the member for a hot rolled member. Add more cold form members to build out a stud pack then use a horizontal member to distribute the brace load across the stud pack. A sketch might help...