The force necessary to bend a scaffold pole

[Kevin Gutridge]

Hi, I have a question on the force necessary to bend a scaffold pole.

I have a barn made of curved scaffold poles approximately 20 ft high at the apex and 30 ft wide at the base, having a hemispherical cross section. These ribs are spaced approximately 7ft apart.

Along the sides of the structure are horizontal poles running the length of the structure, spaced approximately at 5ft intervals vertically. The structure is covered with corrugated iron sheets.

I have removed a section of pole from one rib between the ground and the first horizontal pole. The pole bent downwards approximately 1.5 mm.

I would like to calculate the force that is acting on the central pole causing the bending, this would give me an idea as to the weight acting on it.

I realize there are two main forces resisting the bending. The torsional strength of the pole and the shear résistance to the creation of the rhomboids from the previous squares. I have the torsional strength which is approximately 5 kN.

This would make a brilliant exam question in the UK for a physics exam, but I did mine in 1974.

Can someone help me as I can''t find my old school books...

Thanks in advance

Kevin (London, UK).

 

[CWatters]

I have removed a section of pole from one rib between the ground and the first horizontal pole

I'd try bending the pole you removed to see how much force is required.

 

[Kevin Gutridge]

I'd try bending the pole you removed to see how much force is required.

It is not the same length and doesn't have the support of the structure above, very good simple solution though, may do it anyway. Thanks Mate.

Kevin