FEA of steel tubes filled with concrete

[dieguito]

Hi guys, I’m a student of civil engineering who is doing his thesis, that’s why I started to learn Abaqus. In particular, I should do an elasto plastic buckling analysis of columns made with steel tubes filled with concrete (In other worlds, I should check the results of some experimental tests of columns loaded axially). I checked the load carrying capacity of the single steel tube with a Riks analysis, and now I’m trying to introduce the concrete in the model. For this cause I introduced a surface to surface interaction property (Tangential behavior-penalty.. I should use the coulomb model..) but unfortunately the Riks analysis doesn’t work (Too many attempts made for this increment). I read on the manual that the Riks analysis doesn’t work in problems where there is loss of contact, so maybe that’s why abaqus aborted the analysis (or maybe it aborted the analysis because I made mistakes introducing the contact behavior, I don’t know). So can you give me some suggestions? Which is the best kind of Analysis for this problem? Do you have any suggestion about how to model the contact behavior between the steel tube and the concrete core?

I’m sorry if my questions seems stupid but nobody knows how to use Abaqus in my faculty, so I have to learn it by myself.
Thank you in advance for the answers.

Diego

 

[Mustaine3]

With only these informations it is impossible to say what the problem is. Upload some images or the model.