Can I do a buckling analysis for cases where wind or seismic loads are combined with DL and LL ?

Buckling analysis can be only be carried out for static load cases. So if your seismic loading is defined using dynamic loading options like response spectrum or time history, then you cannot do a buckling analysis for these loads. Moreover buckling analysis is only carried out for primary load cases and not for load combinations. So if you have generated the wind load or a seismic load using one of the static load generation methods and would like to carry out a buckling analysis for situations where wind/seismic is combined with DL and LL, then you need to first generate REPEAT LOADs to combine these wind/seismic loads with the DL/LL and then carry out a buckling analysis for these cases.