thermal gradient and stress in concrete

[beyfadn]

Hi
I'm a future civil engineer and i'm working on a marine concrete structure (solide).
I'm looking for a good finite elements software that can give me stress du to the variation of température (gradient).
I found a good one but it gives me only température and i'm interested in stress.
If you have any idea, please saaaaaave me

 

[Ron]

If you know the thermal variation, you can compute the thermal strain from published data. From there, you can determine the stress based on the elastic properties of the concrete. Be careful though...elastic properties of concrete are much more variable than in homogeneous materials like steel.

You can do this in a spreadsheet.

 

[chicopee]

Ron, Elastic properties of concrete???

 

[Ron]

chicopee...Yup. Concrete is an elastic material in the same context as steel or other elastic materials...it just has different properties. As an example, concrete doesn't exhibit a yield point as with steel...it's yield is essentially its ultimate strength (with some exception, but for generalities, that's true), but up to that point, there is a clear stress-strain relationship that is reversible below fracture or crack development.

 

[beyfadn]

Thanks Ron,
I have to do with a solid of concrete, so i supposed that the gradient acts only on a depth of 80 centimetres and the concrete dilatation coefficient is about 10e-5.
But if it's possible i'm looking for a program that gives me the stress in every point (x,y,z)
this is the solid section and the variation of temperature :

 

[Ron]

I doubt that you'll find anything as clear-cut as your are looking for, outside of academia. In most concrete applications, thermal stresses are of little concern and are handled by generalized assumptions. In some applications, thermal strains are important and must be considered (long buildings, bridges, roadways, airfields, etc.).

I would suggest that you consider either writing your own program or using a spreadsheet to predict stresses at a point. You are combining two or three premises into one, so expect some difficulty.

 

[dik]

Mass concrete thermal gradients can be measured using thermocouples and the object is to minimise the differential.

Dik