3D MR frame mass definition

[xxlsunshine]

Dear Opensees Expertise,
I have 3D MR frame, needed to be modeled in opensees, and its floor plan is like follows, and "0" means the column position.

frame5: 0-----0-----0-----0-----0
I I I I I
I I I I I
frame4: 0-----I-----I------I-----0
I I I I I
I I I I I
frame3: 0-----0-----0-----0-----0
I I I I I
I I I I I
frame2: 0-----I-----I------I-----0
I I I I I
I I I I I
frame1: 0-----0-----0-----0-----0 ------->X direction

due to the architectural needs, there are fewer columns along the 2nd and 4th frame (frame means X direction frame).
so my question is that, should set mass on these nodes, which there is no column on, like 2nd frame cross 2nd pier or 4nd frame cross 3nd pier? Why?

[fmk]

you don't need to .. it is your model .. BUT your results would be garbage as you want the total mass acting to be that equal to that of the building.

[xxlsunshine]

Thank you so much, and I changed my model