cant verify cnt buckling force

thank you steve for your reply.
Actualy there is an article that has modeled the same work ( which i wanna verify my code with) and the results are as i explained in my previous mail. so im kind of sure that there is a trick in the coding that i am missing.
i would really be appreciated if anyone here who has already done the same work help me out.
thank you for you attention.
Hamed Badjian