preventing shear walls from carring any shear force under seismic load case 1

[ayelamayem77]

I made a model for reinforced concrete structure using Etabs
consists of columns shear walls and flat slabs i want the columns to take all the shear force under seismic load case
(my specific question haw can i prevent the shear walls from carrying any amount of the shear forces?????

 

[slickdeals]

What???? Why do you have a shear wall and it not carry shear force? A flat slab with column, acting as a moment frame, in a seismic zone is catastrophe waiting to happen.

Size your shear wall to carry all the seismic loads, design the columns for deformation-compatibility moments so that it does not fail under punching shear when the building drifts under the design seismic event.

 

[Guest262653]

Excuse me?!?!? You want to do what?!?!?
The shear walls do what their name imply: carry shear forces (if properly designed, that is...). Why on earth would you try to send all the forces to the columns when you have flat slabs and shear walls? Force follows stiffness. Use it.

 

[ayelamayem77]

Dear all
my question seems to be silly !!!![highlight #FCE94F][/highlight] but please be patient and think with me about this rule in asce7-05 regarding dual frame system
(resistance to lateral forces is provided by moment-resisting frame capable of resist 25 present of the design base shear)
all i mean that i want to activate this rule in Etabs program so i made a separate model and i applied 25% of total base shear i need to design the columns under this seismic load case situation as you know the design in this particular case should be made under load combination consists of (seismic and gravity loads) as follows
(1.2d+1.0E+f1L+f2s 2006 ibc eq.16-5) & (0.9d+1.0E+1.6H 2006 ibc eq.16-7).
[highlight #FCE94F]I want to keep the shear walls in this model am taking about to support gravity loads with the columns according to their stiffness because if i remove the shear walls the columns will be subjected to high axial loads in accordance with the seismic forces which will lead to big columns sections when i start the design by Etabs
in other words in most design cases in dual frame system or shear wall-frame interactive system the resent rule in asce-7-05 will governs the design of columns.[/highlight]
thanks all for your support

 

[johnbridge231]

Dear ayelamayem77,

I got it. In such cases, I would release all bending degrees of freedom of the beams framing into walls. The shear force will then be taken (not entirely but vlose enough) by the frames.

Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis

http://www.engissol.com/cross-section-analysis-design.html

 

[johnbridge231]

Alternatively, you could create a second model with the walls modeled as frames (not shells) and apply releases to both their ends. So, these frames will only carry vertical loads.


Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis

http://www.engissol.com/cross-section-analysis-design.html