i am trying to model an FRP tendon in Pretensioned member.
I have entered following properties in property module (see attached image 1)
Also, i have defined the failure stress (attached image 2)
however, during prestress transfer( i am using thermal strain to transfer prestress) i am getting convergence error.
Can someone tell what is the problem?
Dear Prashant:
It is conveniently possible to model the reinforcement (non-prestressed as well as prestressed) in concrete by using one-dimensional (1-D), i.e. axial force transmission truss-type finite element. It could be modeled either through a discrete approach, or embedded approach; however, convenient approach appears to be the smeared reinforcement model in the concrete.
Because the reinforcing/ prestressing bars are relatively thinner, the 1-D elements can be embedded (smeared) within the concrete, such that only the mechanical properties of such embedded elements correspond to the re-bars'/ tendons' material properties; whereas, rest of the finite elements possess the mechanical properties of the concrete. Thus, the strain compatibility is ensured especially at the interface between the concrete and the rebar contained inside. Specifically, you may model perfect bond of the prestressing tendon with the surrounding concrete, and some calculated prestress may be applied as a predefined field, which will help you model the prestressing tendon in concrete.
Now, the prestressing tendons could be made of any material that has been chosen for a problem in hand, such as the fiber reinforced polymer (FRP) in your case. The material properties assigned to these embedded elements should pertain to the FRP in your case. I have also seen your definition of material property module (in the snapshot) and feel that it requires a re-look.
Please note that the approach I have explained above is one of the successfully applied approaches, and other approaches are also available and possible to adopt for such modeling of the prestressing FRP tendons in prestressed concrete member.
Hope this information is helpful in your research work.
Good luck,
Vasant Matsagar.
https://trid.trb.org/view.aspx?id=875179
Thank you for your detailed answer sir. I have identified the error and now I am able to run the simulation with tendons as 3D elements as my aim was to observe the bond stress slip relation between strands and concrete which cannot be seen in an embedment approach with 1D elements
thank you once again
Dear Prashant Motwani
You can be simulated the bond by 3D elements but that depends on the load-slip relationships between the prestress tendon and concrete.
Hope this information is helpful in your research and reducing the error.
Akram S. Mahmood
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