1. The problem statement, all variables and given/known data In this question, we are interested inthe buckling of column, so we should calculate the moment of inertia (Ixx) or (Iyy) at the column,right? 2. Relevant equations 3. The attempt at a solution Why the author calculate (Ixx) and (Iyy) using the cross sectional area of beam? is it wrong? And for critical load applied at y-axis (Pcr_y) , why the Le used is 3000 , why not 250mm?