How to model frictional resistance using FEM Software
How to model frictional resistance using FEM Software
(OP)
Can anyone please advice me on how to model sliding friction of a retaining wall. Currency I presume that It can be done by applying lateral springs. But is it correct? Any standard FEA approach on how I can check the sliding resistance of a retaining wall? Thank you.






RE: How to model frictional resistance using FEM Software
RE: How to model frictional resistance using FEM Software
Of course, I could manually calculate the soil load retained by the wall and subtract the friction force based on the vertical load. Then the the resultant load would be the unfactored shear force on the Shear key.
But how do I model this using a finite element approach. Is there a method in Finite element modelling tools?
Thanks.
RE: How to model frictional resistance using FEM Software
Like SteelPE has suggested, this problem wouldn't seem to warrant the heavy FEM. Few things involving soil do given the uncertainties involved. I'm an over-modeler myself though so I get the impulse. Sometimes an unnecessary FEM model that works just the way that you want it to is just good for the soul.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: How to model frictional resistance using FEM Software
The best way to model the friction depends on the FEA package you are using. The one I am familiar with (Strand7) has friction contact elements, but for a surface where the relative movement should be very small it should be adequate to model the soil with plane strain plate elements with Mohr-Coulomb properties.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: How to model frictional resistance using FEM Software
Sounds like a waste of time to me as you are trying to get too exact with this problem. I think I would stick with your original statement, " I could manually calculate the soil load retained by the wall and subtract the friction force based on the vertical load. Then the the resultant load would be the unfactored shear force on the Shear key. "
RE: How to model frictional resistance using FEM Software
Sounds like a waste of time to me as you are trying to get too exact with this problem. I think I would stick with your original statement, " I could manually calculate the soil load retained by the wall and subtract the friction force based on the vertical load. Then the the resultant load would be the unfactored shear force on the Shear key"
RE: How to model frictional resistance using FEM Software
RE: How to model frictional resistance using FEM Software
A straight retaining wall with uniform backfill may not warrant a FEA analysis but one with different restraints, corners, free ends, differing backfill conditions certainly.
RE: How to model frictional resistance using FEM Software
However since I am seeking for a friction modelling method using a FEM software approach, I found out this YouTube video ( https://www.youtube.com/watch?v=g-l2fuLNe_U&fe... ). The modeler is applying area springs using SAP2000 software. But is this method correct? How do a figure out the spring constants for lateral direction?
Thanks.
RE: How to model frictional resistance using FEM Software
I started modelling of pull out test technique in FEM Abaqus version 6.12-3.I use Connector damage evolution behavior for the rebar in the embedded region of concrete.I applied velocity at the top node of the rebar. I use (axial+Revolute) type of connection, however ,my problem is , Is the type of connection is Ok and in output I can see that there is damage (from the figure) but I do not know how to plot appropriate curve (Force vs Displacement).Could anybody help me regarding this issue.I am really faced with this problem.
Thank you in advance,
RE: How to model frictional resistance using FEM Software
Are you using Sap2000? If so, have a look at the link KootK posted, which seems to give good detailed advice.
If not, let us know what you are using, since how you go about it will depend on the facilities in your software.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: How to model frictional resistance using FEM Software
I use a trial and error approach. I choose a spring rate, solve the model and then calculate the coefficient of friction based on the displacement of my model . The last model I ran, I used a lateral spring of 5000#/in. When I solved the model I had a lateral displacement of 0.044in. Therefore a 220# lateral force exists per spring. The tributary wall section for that group of springs (there were 6 springs), weighed about 3000#. So six springs at 220# is 1320# of lateral force divided by the 3000# weight equals a coefficient of friction of about 0.44. I compare this value to a table and decide if it is acceptable based on the soil and concrete interface. Like I said earlier, I will also run my model with really stiff and really soft springs to see how sensitive the model is to the spring rate.
RE: How to model frictional resistance using FEM Software
RE: How to model frictional resistance using FEM Software
RE: How to model frictional resistance using FEM Software
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: How to model frictional resistance using FEM Software
@ IDS,
I am not sure RISA has the ability to due friction. Maybe with solids but not plates, that I am aware of.