If I understood your question, Contraction joint may be provided depending upon temperature condition in the site. If the site is at hot zone, it is suggested to provide contraction of expansion joint within 25m of the buildig length.
Prachan Man Pradhan
Structural engineer
It would be better to do 3-D analysis for such case. Yet if you decide for 2-D analysis, then still it is not a problem, you can just take this particular model as it is and start analysing, it does not really matter to much.
Prachand Man Pradhan
Structural Engineer