shear wall system etabs model

[KaremHajj]

hello,

i have many questions concerning the shear wall system modeling in etabs:

1)i have assigned for slabs 0.01 modifiers for M11,M22, and M12 in order to transfer the earthquake load to shear walls only . is this correct?.in this case i have problem in mode shape the fundamental modes are not translations generally it is in vertical direction deformation.

2)what is the best way to transfer the earthquake forces to shear walls only and prevent columns to take horizontal loads .

3)can i use membrane to transfer the horizontal load to shear walls only, in this case what is the type of diaphragm that should i use rigid or semi rigid?

 

[Ahmad Alhamad]

the modifiers for slab according to ACI equal 0.25 less than this value as you made 0.01 that mean the slab almost work as membrane just translate the load vertically (no horizontal load carry). However; in this case the slab doesn't work as a diaphragm.
the best way to transfer all seismic load to shear wall (building frame system) is releasing the shear on the top of columns ,so the walls carry all lateral load.

 

[KaremHajj]

thank you Ahmad .i have assigned the slab as 0.01 modifier only for moments not for in plane forces (F11,F22,F12) in this case the slab can transfer in plane forces resulting from lateral load.