Static Riks method..how to give imperfection???

hi,i have been doing non-linear buckling analysis using STATIC RIKs method

my model specification:   length:65 metre, dia=2.85metre,thickness=0.38meter 

 and i am having the following doubts:

 1.i have done Eigen value buckling analysis first and got the mode values..but for getting the mode shapes which load value i have to apply????(whether calculated euler buckling load value)

2.i have given imperfection as 0.0038  i.e..,10% of thickness value is it correct????

hi,i have been doing non-linear buckling analysis using STATIC RIKs method

my model specification:   length:65 metre, dia=2.85metre,thickness=0.38meter 

 and i am having the following doubts:

 1.i have done Eigen value buckling analysis first and got the mode values..but for getting the mode shapes which load value i have to apply????(whether calculated euler buckling load value)

2.i have given imperfection as 0.0038  i.e..,10% of thickness value is it correct????