Scaffold Buckling

One initial observation:

If the inner diameter is 45.05 and the outer 48.3: then the thickness is 1.625mm. Half of what you worked out.

Appologies, you are correct Di = 41.8mm

The best method would be to carry out practical testing in a laboratory.

After all, the age of the <...pipe...>, its corrosion condition, its materials-of-construction and the number of holes in it are among the things not known (otherwise these things would be stated among the <...following information...> in the original post).

Are you actually a consultant for a portable amusement ride manufacturer?

Apparently, a support beam was rusted out from the inside. I wonder how many more are out there...

https://twitter.com/Aly10TV/status/894258324354605057/photo/1

I've always considered it a joke when people say that if it weren't for the paint holding "it" together there would be nothing there at all..

Structural paint job indeed.

The dim bulbs who have given theses rides a clean bill of health over and over need to learn how to do their job. .. lesson learned for the casual observer. A few new cotter pins do not a safe ride make.

I can't believe these safety officers were not trained to look for catastrophic rust. Truckers are held liable if a rusted chunk flies off.

Seriously wrong.

Absolutely true, a cursory inspection of incidental hardware is useless when structural integrity fails.

There is one ironic aspect this memo and report does bring to light. This ride and the fatality were both the same age. It may become necessary for amusement rides older than some mark (10 years?) to get a periodic (2 year?) structural x-ray to determine how much corrosion exists.

You left out the most important information, the distance between supports. Also, a drawing would convey a lot more than words...

Here is a rough idea of what I have. Please forgive the drawing ability

With the forces applied, there is a bending moment that is maximum at the force points. The tube will fail when it buckles under compression. Try it with a soda straw.

Here are the formulas for calculating stress and deflection from bending a pipe:

http://www.atcpublications.com/Sample_pages_from_FDG.pdf

Here is an online calculator that might help in calculating strength:

https://www.roguefab.com/tube-calculator/

Be safe, leave a good safety factor.

That's great I will start there, thanks for the help.

That's like saying I have a car, how fast will it go with the gas pedal depressed halfway....There are so many underlying factors and variables it's impossible to say...for all we know it may collapse under it's own weight...

Why don't you just tell us what you're trying to do? Build a support structure for a solar array? It won't pass code without certification of some sort...

Any <...equation...> is only ever a mathematical abstract of observed reality.

I still love George Box's quote:

All models are wrong; some models are useful.

an off topic comment, be it deals with scaffolding.

China uses Bamboo Scaffolding quite effectively.

The reflection of the cone threw me off for a second.. And I'm still trying to decide what they might be working on?

..I can't say it doesn't look like a rigging I wouldn't come up with myself. I do love me some bamboo

That's one way of being high on grass!

First, to what specific purpose is the structure to be put ?...

Second, is it to be an exterior, or an interior, structure ?...

Third, is this to be for a permanent, or a temporary, structure ?...

Fourth, where is this project to be geographically located, and subject to what loading, weather, geotechnical, seismic, etc. conditions, extremes, etc., year-round ?...

Do you have a Strength-of-Materials (or similar) textbook handy ?...

There's more to it than just bending stress. Buckling is a stability issue. Check code requirements for lateral bracing and spacing as even tho' you may satisfy allowable stress, the deflections (i.e. sidesway) can induce instability.

The simple beam equations don't directly expose this potential effect. Look for key phrases like Euler buckling and P-Delta effects in your research.

AISC have a steel design code book that covers most of this.

Manufacturing imperfections and variability in material properties are covered by the code stress utilization factors however "used" material needs be inspected and integrity verified when making these assumptions.

Add "lateral torsional buckling" to that list of search topics...