Concrete Shear strength ?? 1

[kreecki]

Hi All
I don't know how to calculate the shear strength of circular column of concrete. Base of the column is supported on one half and other half is unsupported. On the top end of collumn axial load is applied but only on the half which is unsupported on the bottom.
Is it possible to quantiffy a shear strength of Portland Cement mixed with water (assume that 38% of water was added)if we do not have any metal reinforcement inside the concrete column?
Another questions relates to the shear strength of bond created by the concrete and the metal surface. How to calculate such a strength?

 

[swearingen]

Can you give some dimensional details? What is the diameter of the column? What is the height of the column? How is the load applied to the top and bottom? Is it flat, steel plates?


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[msquared48]

I'd be more worried about the column eccentricity than I would about the shear strength from what you describe.

Which direction are you concerned about for shear - across the column, or longitudinally?

Mike McCann
MMC Engineering

 

[HamishMcTavish]

what about rebar, need detail for that or is the column unreinforced?

why would someone use a column in that site/situation anyway? You're wasting a huge amount of material...what's the application?

regards, HM

No more things should be presumed to exist than are absolutely necessary - William of Occam

 

[kreecki]

Hi Guys

The dimensions of hollow column:
OD 200; ID 100; height 200.
Base of the column i supported on the ring with dim.: OD 200; ID 150.
Axial load applied from top on the OD 150; ID 100.
The column is inside the steel housing, and the iside diameter ID is supported by steel shaft.
This problem can exists in downhole tool after cementation process when space between mechanical parts is filled with liquid concrete.
I tried to find the data for shear strength of concrete but i can find only the compresion and tension strengths.

The next question is about the strength of the bond created by the concrete with steel shaft. Is there any formula describing this strength including the metal surface roughness?

 

[swearingen]

I didn't think this was a standard structural column problem. By the way you describe it, I'm picturing an annular space between two steel pipes filled with concrete with the two steel pipes trying to move relative to each other axially.

You don't give any units, but assuming that your numbers refer to millimeters, and assuming that you're downhole with adequate confinement, I think your issue is steel on concrete friction. With the aspect ratios you're talking about, I'll bet the concrete plug will slide before it breaks. I don't have any friction numbers at hand right now, but when I do I'll repost (unless somebody beats me to it...)


If you "heard" it on the internet, it's guilty until proven innocent. - DCS

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[civilperson]

Concrete bonding to steel ranges from 40 psi to 200 psi. Use 2x(F'c<0.5) for shear strength per square inch of sectional area.

 

[LittleWheels]

From vague memory, Mohr's Circle relates tensile, compressive and shear strength. You have two of them and should be able to derive the third.

 

[CalculatorDave]

DaveMinter,

There is a formula that relates shear modulus to elastic modulus, i.e. the elastic behavior of a material.

HOWEVER, there is NO general formula relating the ULTIMATE (fracture) strengths in tension, compresion, and shear. To find the shear strength of concrete, one must carefully research empirical data for that particular concrete.

 

[LittleWheels]

Thanks for the correction SolarDave

 

[IFRs]

Will the shrinkage of the concrete donut as it cures prevent it from sticking to the inside and outside pipes for at least some of the length?