Problems during modelling process of composite steel-concrete structures

Greetings to all,

I would like to ask you, if you have been engaged in the design of composite steel-concrete structures, to briefly list the problems you encountered during the process of modelling them...

Thus, various disturbances, errors, perhaps a bad choice of elements when using the software, any problem that forced you to do a certain part of the calculation, analysis, or taking into account some effect (such as creep, shrinkage, cracking of concrete) manually on paper...

So, any obstacles related to the modelling process of the mentioned constructions that slowed you down during work, you can mention the specific software you used...

Of course, any of your general comments or opinions on the previously highlighted issue are welcome...

Thank you all in advance...

I wish you quality and safe construction...