Gravity members participating in mode shapes

[UcfSE]

I'm rather new to ETABS. I have a shear wall structure with steel gravity framing. I'm getting the steel gravity columns participating in the mode shapes of the building. How can I keep the gravity members out of this, any advice? The steel columns are creating mode shapes in bending, obviously not what I'm going for. I'm also getting some walls that participate in the mode shapes with out of plane bending. I'm sure I can add more details, but without writing a short story I'll see what details you need and try to keep my posts reasonably short.

T-shaped building, 1-2 stories, concrete shear walls, steel roof beams, steel composite beams at second floor, steel roof deck diaphragm modeled as flat for horizontal semi-rigid diaphragm, concrete filled steel deck for second floor rigid diaphragm. gravity framing is pinned

 

[ATOOMUS]

Hi,

all steel columns can release to ignored lateral moment resistance effects. So, all wall becomes the main lateral moment resistance system. (shear wall system)

Try it then send me your results and conclusions if you can do.

Best Regards,
Atoomus

 

[alexbzeta]

To get rid of vertical modes, make sure you define mass source to include lateral mass only. Go to define/mass source, and select the check box.