Hello, i modelled a Pretensioned beam with tendons as solid elements. the model ran fine.
Now i am planning to model the pretension beam with wire element instead of solid element, in place of prestressing tendons and then define a initial stress in the rebar.
Is it possible in abaqus?
For the question 'can prestress be defined in a truss element' - Yes it is possible.
You could apply a 'Predefined field' in the initial step. The field is of the type 'Mechanical', and 'Stress'- Choose S11 for axial stress in Truss element.
thank you for the answer. But I think defining stress as predefined field is not good. can you comment something on using temperature to define prestress in ABAQUS .
I tried defining both pre-stress and pre-strain.
Pre-strain is a much more stable approach for obvious reasons. I ended up implementing it using a predefined field (Initial condition) + UMAT for our specific application. Good luck!
Dear Andrew.
thank you for the answer. But i think predefined field (Initial) is not a good option to define prestress in ABAQUS. I am now using temperature to define the prestress.
What do you suggest on that?
I have done temperature field before for pointwise pre-strain, so that works fine as long as you understand how your results are reported. I usually stagger the solution to make sure everything works as expected: ramp up the prestrain, then apply the forcing
Good luck!
Hello Andrew, i have done the same mentioned by you and able to match the experimental load deflection curve quire well.
Now i want to update model with shrinkage of concrete.
For that i know shrinkage of concrete for pretensioning is 0.0002, this divided by coeff of expansion gives me the temperature.
Problem is when i apply this temp to the entire concrete part, it fails to converge after reaching 0.722 step.
Can you suggest the possible solutions?
this could be a number of things that are causing instability. Most of the times in my experience, it is due to inadvertently applying volumetric deformations that are incompatible with the prescribed displacement constraints
Hi
I should model pretension wire elements too, but since it would happen in the second step I can just use temperature predefined field. but I have problem with that, when I define it and apply it to my cables (I've defined thermal conductivity for cable material); nothing happen at the of the step! no stress or strain develop in cable by decreasing the temperature, is there anything that I missed?
Hi.
Temperature aproach is simple and fast. Nonetheless... you wont get the desired tension in your truss in the case the (concrete) piece being prestressed by the truss is not much stiffer.
¿How can you deal with that problem, and how do you get the correct presstress force if not by (manually) iterating?
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