Special Concrete Shear Wall on Special Concrete Moment Frame

[jbjones2001]

Is there any code limitation (IBC 2003) that would prevent me from designing a 5 story building with the ground floor being special concrete moment frames, and the upper floors beaing special concrete shear walls. FYI, would be seismic design category D

I'm aware of all the overstrength requirements for elements supporting discontinues shear walls, etc.

Just want to make sure the code will let me use this system.

 

[shemp]

I do not believe that there is any code provision preventing you from doing this. You would have to use the R factor for the special shear walls when designing the special moment frames per IBC 2003 section 1617.2.3.1. Similarly you would you the greater overstrength factor of the two which is omega=3 for special moment frames.

Another code provision that would affect your design is ACI 318-02 Section 21.4.4.5. Where you have a shearwall being discontinued atop a column, this section requires you to add transverse reinforcement in the column below and to extend transverse reinforcement up into the wall for a distance at least equal to the development length of the column rebar.

 

[JAE]

This would probably throw you into a story irregularity such as a stiffness irregularity (soft story) condition.

Assuming you are not greater than 65 feet - you would have to include dynamic characteristics in your Equivalent lateral-force procedure.

 

[whyun]

I agree with JAE. Chances are, the moment frame below a shear wall may fall under "extreme soft story". For SDC-D, requirements are the same as a regular soft story; however, "extreme soft story" is not allowed for SDC-E and F.