Response Spectrum Analysis as per SP14.13330

Dear All,

I am doing response spectrum analysis in STAAD Pro as per russian standard SP14.13330.

While defining spectrum I am creating load case in X, Y & Z direction separately.

Eventhough in output file for Load case - Spectrum in X direction, I am getting base shear value in X, Y & Z all direction.

If I analyse the same structure with different code (Like IS, UBC/IBC, ASCE) I am getting the expected result as Seismic load spectrum if it is in X direction then base shear also in same X direction.

Can anyone please throw some light on this and share the things need to take care while analysing strcutre for response spectrum through SP14.13330.

Thanks in advance !