Learning Forum

[Amin]

Hi

I am using ANSYS Workbench to perform a cyclic loading test of a reinforced concrete column.

As showing in figure 1, there are two loads: vertical and lateral, according to the experimental, the vertical load is a force controlled considered to be constant during the test, and the lateral is applied as a displacement controlled represent the cyclic loading.

I would like to know how can I applied a constant value for the vertical load, with using a multiple number of steps (in order to define the cycles of the second load).

Figure 2 shows the cycles used in the experimental.

How can I applied this load?. Is the method showed in figure 1 correct?, or should I input zero between the positive and negative values.

Finally, to validate the model I need to compare the experimental force-displacement curve of the experimental test (figure 3) to that of numerical. 

How can I obtained the force-displacement curve from ANSYS Workbench?

 

 

[jj77]

Just define the curve in excel (as function of time, thus two columns), then define your load in ansys and copy + paste it in the spreadsheet table for the load (called Tabular data).

See the chapter for more info

Graph and Tabular Data Windows, In ansys help.

Also this post from Peteroznewman is very good:

/forum/forums/topic/importing-acceleration-time-history-data/

 

 

You can create this using charts.

See how  this is done here and in the video below: http://www.padtinc.com/blog/the-focus/making-charts-and-tables-in-ansys-mechanical

https://www.youtube.com/watch?v=CQF2WVVV_A8

 

[Amin]

@jj77 thank you for your replying, it is very clear how to obtained force-displacement curve from ANSYS.

 

[jj77]

This one is related on how to copy paste loads/disp. into ansys workbench:

 

/forum/forums/topic/how-do-we-input-displacement-in-ansys-transient-dynamic-analysis/

[Amin]

Hi jj, thank you again for you reply. and sorry for delay

I did a nonlinear analysis under monotonic cyclic loading, the force displacement curve is obtained. As you can see the negative part is not similar to the positive one. I would like to know how can I fix this problem?

 

 

 

 

 

[peteroznewman]

Is the result you output Displacement?  That is always positive.

You need to output Directional Displacement which can go negative, but it is only tracking one axis. You might need two Directional Displacements if the point you are tracking does not travel along a straight line.  If the straight line is tracked, but just not one of the Global directions, you can make a rotated coordinate system and request Directional Displacement along one of the axes of that rotated coordinate system.

[Amin]

Hi peter, thank you for you reply, and sorry for delay.
I will try it and make you updated.

[Amin]

@Peter Hi again, I create another coordinate system and rotate it (the attached file contains the model) but the obtained results are not correct. I hope you can check the file for any errors 

[Amin]

Hi Peter, I have succeeded to obtain the cyclic load. But I see from the curve obtained that the positive part is similar to the negative part (figure below). Is there a way to include the stiffness degradation in the curve (I mean when the cracks start a degradation in the stiffness will appear). How can I include this degradation in concrete.

[peteroznewman]

Hi Amin, I'm not the expert in concrete, so I will let other members comment on your question, like jj77, who has more experience with concrete models.

[Amin]

Ok. Thank you Peter for your help. 

Regrads, 

Amin.

[jj77]

Not much in ansys unfortunately it is what ever I see  and learn from here .

[Amin]

Thank you jj77 for your reply, until now I didn't find anythings about stiffness degradation of concrete. Hope that any one can help

[Filtz]

Hello Amin, please can you share the ANSYS file without error? Thank you!

[vaibhavtaranekar]

Hi Peter, I have succeeded to obtain the cyclic load. But I see from the curve obtained that the positive part is similar to the negative part (figure below). Is there a way to include the stiffness degradation in the curve (I mean when the cracks start a degradation in the stiffness will appear). How can I include this degradation in concrete.

 

Hi amin, can you tell us how did you perform cyclic loading analysis on reinforced concrete? i am trying it using apdl commands with SOLID65 and LINK180 element, however i am not getting the desired graphs as the plot are linear.

[Islam]

Hi Amin Did you fond any way to modify the unloading branch in you hysteresis? I am modeling the seismic response of shear walls in APDL and I am facing the same problem

[abdalla]

Dear AllnI think to consider concrete stiffness degradation during cyclic loading, it must be use Mender concrete model as APDL commands and also define the bond slip interaction between steel bars & concrete (NOT full tied )n

[Dr. / Abdalla Mohamed]

To account cyclic degradtion , you need to adjust shear reduction coef. in Solid 65 model command