solution procedure

[partla]

Hi dear all,
I have a question about solution procedure in OpenSees. I’ll be happy hearing from you.
I’m working on a geotechnical model for my theses. It’s a concrete frame box (using elastic beam column element) buried in dry sand (using PDMY material). I’m going to have time history analyses. I’ve seen in the almost similar examples that use one transient analysis with a very large time-step, and very large gamma (parameter of the Newmark integrator). Then use the same analyses changing the material stage to plastic. After finishing that two step (as static analyses), they use time history analyses. The problem is that when I use this method, it doesn’t converge.
I’m really confused, Please help me.