Greetings,

I'm running into some convergence issues. I had previously made 2D (deep)beam models using the SBeta material model, no issues there, however my professor suggested running the same model with the 3D non linear cementitious 2 material model. However, as soon as the model goes past the linear elastic load it seems to be unable to reach convergence. I've tried the various suggestions given in troubleshooting 2.1.19, severely reducing step size, changing to the modified Newton-Raphson method, none of which seem to help the model reach convergence. It feels like I'm missing something but I cannot seem to figure out what.

I know from experiments the failure loads for the normal beams(h=300), which isn't reached yet at the linear elastic loads, so I don't think this is structural collapse. For the deep beams(h=1200) the linear elastic load from Atena is higher than the failure load obtained in the experiments, so this might be structural collapse.

I would like to hear your suggestions on how to handle this.

Edit: seems like I misinterpreted the modified Newton-Raphson solution to convergence issues. I was using this for all load steps rather than just the problematic steps. I'll do some more testing with this.