Erik Kostson
Ansys Employee

I do not have much to add/discuss. Except that the nonlinear controls in mechanical (as shown in the image above) I never change so in that demo it is all program controlled, as shown below (not recommended to change those, at least those related to the convergence criteria, e.g., force convergence).

As I said before, from my little experience modelling concrete the most critical parameter that can make the biggest difference improving convergence is the msol material solution option in ansys, as seen in that demo, and for much larger and complex structures. With the msol we can look at failure and even go way post failure of the structure (see image below), so I would recommend to use that. That is all I can say, and again there might of course still be some challenges with convergence with nonlinear analysis (even with msol), especially for concrete, and unfortunately there is no special setting that will make it always solve/converge, if there was a fea software would be using this settings of course as default :).

That is all I can add,
all the best