CHS section, one inside another 1

[Ussuri]

I have an arrangement where I have a 219mm external diameter CHS slotted into a 230mm internal diameter CHS. The 230mm section acts as a 'shoe' to hold the 219mm section as a cantilever.

I need to make sure that the two sections have sufficient engagement to take the applied moment. My gut feeling is that if I make the shoe depth equal to twice the diameter, then the bearing and tear out should be OK. But I would like some way to back it up.

Any suggestions?

 

[csd72]

The cantilever will act as a push and a pull reaction on the side of the outer tube. take the reaction point at say 10mm below the top of the outer tube and at 10mm above the bottom.

calculate the reactions at each of these 2 points using equilibrium of load and reaction moments.

check the buckling of the internal tube due to the bearing reactions calculated above in accordance with the appropriate code. Use an effective width of say 100mm top (50mm above and below the point of reaction) and 60mm bottom.

If this works, ensure the outer tube is the same thickness. This is conservative as the outer tube will be in local tension rather than compression.

I would also double check with the manufacturer that these 2 sections can be 'telescoped' in to each other since fabrication tolerances need to be allowed for. If you are in Australia check the AISC blue hollow section design charts for telescoping information.