Crush Strength Of Donut Shaped 1.5 x 1.5 Square Tubing

[pedalquickly]

Hi All, I am working on a project where I am using a donut shaped 1.5 x 1.5 square tubing. It is mild steel and I am assuming it has a 16 gauge wall thickness. I bought this already fabricated and don't know for sure (its possible its 14 gauge). The outside dimension of the donut is 89.5". I am using this as a base for a rotating small gazebo. This donut will sit on top of twenty 3" casters, The casters are inverted with the wheels up. I will have a central pivot to keep the donut on track.

My question is at what point weightwise will the tubing begin to flatten or distort?
Thanks!

 

[jrmichler]

There are two ways that I can interpret your question:

1) The ring will flatten so as to conform to the base under the weight of you standing on it. If you set it on a concrete base, and that concrete is well placed, the ring will be straight.
or
2) Will the weight of the gazebo crush the 1.5 X 1.5 tubing into 0.12 X 3 flattened tubing? Without running a detailed calculation, you would need several thousand pounds force on one caster to flatten the tubing. Any normal caster would be crushed before flattening the tubing.

This steel ring needs a flat concrete base to be properly supported. Concentrate your efforts on making sure that the concrete base is as flat as possible. Setting it on the ground, on gravel, or on posts would be a serious mistake.

 

[pedalquickly]

Hi jrmichler. Thanks for the response. Your # 2 response is what I'm looking for I think. I'll explain further: I will make a circular concrete footing. I will mount the casters inverted with wheels facing upward. The tops of the wheels will be level and on a flat plane. The donut will sit on top of those wheels. The donut will be kept aligned by a central pivot point and alowed to rotate. Approximately how much weight can the circular shaped square tubing withstand before it starts to deform into a .12 x 3 tubing as you described.
Thanks Again!

 

[Lnewqban]

Approximately how much weight can the circular shaped square tubing withstand before it starts to deform?

Will the wheels be rolling on both vertical walls of the tubing?
If their width is much less than the 1.5-inch width of the horizontal surface of the tube, that surface could bend transversely.

 

[pedalquickly]

Will the wheels be rolling on both vertical walls of the tubing?
If their width is much less than the 1.5-inch width of the horizontal surface of the tube, that surface could bend transversely.View attachment 324942

Hi and thanks for responding. I will be using casters where the wheel is about 3/4" wide. So no , they will not be rolling and supporting the vertical walls.