How to perform non-linear geometric buckling analysis of a hollow concrete column with varying cross section according to BS EN 1992-2 ?  

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Answer:

Buckling analysis present in MIDAS civil is linear in its nature. Therefore Nonlinear geometric buckling analysis can not be performed directly in the current version. But nonlinear (geometric/material) static analysis can be performed with a loading sequence on the new structure (with initial imperfections) to find the critical buckling load manually (by checking the structure at each step). In this way, the program will consider all the non-linear effects during analysis. 

Step1:- Perform linear buckling analysis to get imperfection as per various modes. Now update the model with these imperfections by using the following option:- 

Step2:- Now update the load as per the result we get from linear analysis and define the Nonlinear static load case with load increments. 

Step3:- Now check the results at each step to get the critical load.