# Thermodynamic coupling analysis

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• Last Post 10 December 2018
qianduoduo posted this 06 December 2018

In the Assembly building node, between the beam and column, or on the beam node of the sleeve grouting and slurry anchor bonding, how to use ANSYS modeling analysis, including the consideration of thermal resistance, friction coefficient

peteroznewman posted this 06 December 2018

Please add images that show geometry and labels that point from the term to the geometry so we can understand what you are describing. What is the objective of building a simulation model? What are the outputs you want from the model?

qianduoduo posted this 06 December 2018

I want to simulate the thermal coupling of an assembled building node, which is the node of the sleeve grouting, and then how to build the model between the sleeve, the grouting material and the steel bar and the concrete.

qianduoduo posted this 06 December 2018

like this

peteroznewman posted this 06 December 2018

Please add images that show geometry and labels that point from the term to the geometry so we can understand what you are describing.

You can't use the Paste function to insert an image. You have to have the image file saved on your computer first, then you click the Image button on the post toolbar and select that image file.

qianduoduo posted this 06 December 2018

peteroznewman posted this 06 December 2018

Thanks for the photographs.

How about some definitions and more images?

• beam: the horizontal member
• column: the vertical member
• assembly building node?
• beam node?
• sleeve grouting?
• slurry anchor bonding?
• thermal resistance:  what is the source of the heat?  where is the heat going?
• friction coefficient: at what interface?

You have to put in a lot more work to get enough detail to formulate a problem to model in ANSYS.

qianduoduo posted this 10 December 2018

like that ,how do I simulate the thermal coupling of it

peteroznewman posted this 10 December 2018

Okay, this is a good start.

5. Is the sleeve steel?  It threads onto the rebar on the left, the connected rebar is inserted into the sleeve and the grout fills the gap. Is that right?  Does this grout get cured before the Cast-in-situ concrete is poured?

4. How is the stirrup connected to the rebar?  Is it welded?  Is it a hook shape that just hangs on the rebar?

You say you want to do a thermal analysis. Here is some of the data you are going to need. This is not a comprehensive list. I suggest you do some research and read some academic papers from researchers studying concrete thermal modeling.

For each material: Steel, Concrete, Grout and Slurry you need the material properties of

• Density
• Conductivity
• Specific Heat (Cp)

In addition, you must define the Heat Generation in W/m^3  vs. Time for the Slurry.

You will need to generate the geometry for all these components. Do you have solid model geometry for them?  If not, you can create that yourself in SpaceClaim, but you still need a drawing of the cross section to reference.  Do you have those drawings? You create a a solid in the Geometry editor to represent the slurry, which is the finished shape minus all the precast parts, rebar, sleeve and grout.

You use a Transient Thermal system. You set the initial temperature for all the parts, say 22 C. You assign the Heat Generation vs. Time to the slurry. You assign boundary conditions to all the surfaces. I assume there is a mold (mould) or form that encloses the precast concrete to make the sides to hold the slurry. If that form is made of wood, it is a good insulator and those surfaces could be assumed to be insulated. If the form is made of steel, that is a good thermal conductor and the heat will be conducted to the other side of the steel where the air as some temperature, say 22 C, will convect the heat away. You will need to know the convective film heat transfer coefficient. The top of the slurry will be exposed to air directly and will convect heat into the air.

Then you start the simulation and let the heat conduct through the precast concrete, through the rebar, and through the walls of the form and into the air.

Don't they run water on concrete to help it cure?  That complicates things a bit as the water will convect some heat away.

This is a large project that will take a lot of work to accomplish.

If you are new to ANSYS and simulation, I suggest you first build a very simple Steady State Thermal model. After that, build a very simple Transient Thermal model, then begin on this large model.

Regards,
Peter

jj77 posted this 10 December 2018

This is a large task (if you need to look at heat of hydration - if not then it is not that complex). This type of analysis is called heat of hydration, and is not trivial so one needs to be careful what to recommend. One main thing that is difficult to know is the amount of heat generated during the curing of the concrete (it is a exo-thermal reactions depending on many things). Further more, all of the material properties depend om how mature the concrete has become thus one needs to have a measure of that (maturity) and then assign it/make properties dependent on that.

Finally all this is coupled, so not trivial at all (I have done some of this in a simplified way though).

On top of that you have cracking of concrete, shrinkage and creep, as well .

For more information and to see how complex this is, see this paper from LUSAS.

Lusas paper

Diana also and other civil structural packages have specific capabilities to analyse this (not sure how accurate it is). Of course it could be perhaps done in ansys as well but it will take really some effort and expertise mostly within civil (not product development or mechanical  engineering).