Steel Wheel Contact on Concrete

[AEng123]

Does anyone know how to design for the bearing stress of a steel wheel on concrete?

I found this article online:

http://www.burnsmcd.com/insightsnews/insights/tech-briefs/2011-issue-1/contact-mechanics

But according to this article, a 6" diameter x 3" wheel can only carry about 140 lb on 4000psi concrete. This seems too conservative. Any suggestions?

Thanks!

 

[IRstuff]

?? all I see mentioned is 12,000 lb load

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[BigH]

Might this help?? you would have to make an estimate of the contact area

http://www.buildingsguide.com/calculators/structural/FCSGSG/

 

[BigH]

Check out this thread:

http://www.eng-tips.com/viewthread.cfm?qid=356910

 

[LittleInch]

Did you only skim read the article???

The analysis is based on the load a 12000lb load applies via a 6" diam, 3" wide roller on 4000 psi concrete.

It concludes after adding various factors and loads multiplication for static and dynamic loads, that the bearing force for the 12,000lb load is approx. 9 times the capacity of the concrete to elastically support the load.

Therefore the maximum load for said roller (6" diam x 3") is approx 1,400 lb, just over half a tonne without cracking the concrete. Sounds reasonable to me.

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[AEng123]

Thanks for the replys!
IRstuff: I used the formulas they gave to calculate the maximum load on the wheel based on the 4420 psi allowable bearing stress of the concrete.
BigH: I have read through the thread but I did not see a solution, structSU10 had the same question I had about this formula being too conservative but then people were recommending reinforcing the concrete from that point as far as I can tell. It appears people agree it is too conservative but I was just hoping for another method for calculating the area with guessing the width.
LittleInch: For the 12000 lb load, the ultimate design bearing pressure 41408 psi is 9.3 times higher than the allowable bearing pressure of 4420 psi. Are you getting the 1400 lb from dividing the 12000 lb by 9.3 (12000lb/9.3 = 1290 lb)?
The equation is nonlinear so at 1400 lb, the bearing pressure would be 14144 psi which is still 3.2 times higher than the allowable 4420 psi.

Thanks

 

[LittleInch]

Yes, fair enough it's non linear, the load is still more than 140 lbs though? Like the report says, steel is very strong connotations to concrete so that's why you don't see this done much

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Also: If you get a response it's polite to respond to it.