Hey all,

I am trying to model a simply supported prestressed concrete  (I-shape) girder/beam using Drucker Prager model for simulating plasticity in concrete having tension softening property. I am not able to get convergence in my analysis. I have tried both initial stress and temperature loading criteria to apply prestress in the strands. Both General, Statics and General, Riks criteria have been used to analyze the model. But none of them converged. The analysis up to the step when it enters into plasticity mode and stops after few increments in the plastic mode.

With Static general, I get the following error:

***ERROR: TOO MANY ATTEMPTS MADE FOR THIS INCREMENT and the

Static, Riks gives the following error:

***ERROR: A ZERO DISPLACEMENT SOLUTION WAS FOUND IN THE FIRST ITERATION OF A RIKS STEP. THE ANALYSIS CANNOT PROCEED. THE MOST LIKELY CAUSE IS THAT ALL DISPLACEMENT DEGREES-OF-FREEDOM ARE CONSTRAINED TO BE ZERO.

In both the cases negative eigen value warnings are present. Can anyone please suggest a solution to the above problem. Any help will be greatly appreciated. Thank you..

Best regards,

Sud