in a question i have been asked to assess a steel structure made of two IPE beams given the attached schematic my question is regarding the buckling of the IPE400, to find the coefficient "K" i have used the julian-lawrence nomogram. as far as buckling about the Z axis goes, the picture is very clear to me, i need to use the sums of the inertia/length of the beams and collumns (using their weak inertia in this case), and need to divide the IPE400 into 2 seperate components my problem comes when i am asked to address the buckling about the "X" axis, ie perpendicular tho the pages plane. initially i thought i could do the same as in the previous case, using the other inertia (about the cross sections strong axis). then after some thought i realised that the case os not that simple since it is not their bending that resists buckling here but rather their torsion. i then thought that since the torsion has a minimum resitance (I beams) i can not take their effect into account and consider the column a cantilever with a length of 10m. BUT i now think that since the IPE500 is lying with their STRONG direction resists their bending about the y axis, which resists movement of the IPE400, this must have some effect on the IPE400's buckling,. af far as i can see the IPE500 acts as a support preventing movement of the IPE400 in the y direction since they resist their own bending. so i think i need to somehow consider this and like before divide the IPE400 into 2 sections and calculate for each seperately. how do i take this effect into consideration when calculating the coefficient of buckling "K", do i need to take this effect into consideration is this really a 10m cantilever?