adina - eigenvalue problem

huangyhg

adina - eigenvalue problem
i am doing an linearized buckling analysis using adina for a column-type structure. for the same model of the structure, with the same load, i am do two analysis. in the first analysis i ask two modes and 15 modes in the second. the results are different.
my question is what is the resason of this difference?
you need to explain some more.  were modes 1 and 2 not the same in both?  they should be.  beyond mode 2 you've got nothing to compare to.
does your software allow a shift? this could be different between your two models.  it's really hard to say without seeing the model.
please post some more info and i'll try and help some more. (if i remember, my forgetter is working pretty good.)