Concrete/wood building shear walls 2

[mytchell]

I'm working with a building design which has a large concrete room with 12 inch thick concrete walls connected to a wood frame building adjacent to it. My problem is that the seismic load is quite large for the whole building together with the weight of the concrete, resulting in a very high base shear. Can I deal with the seismic lateral forces separate for the concrete portion and the stick frame portion? Or do I have to deal with the combined seismic weight throughout the building resulting in some serious base shear?

EIT

 

[johnbridge231]

If the connection of the concrete part with the wood frame are rigid, I would choose to handle it as one combined structure.

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

 

[msquared48]

It depends if they are connected laterally or not.

Is this a bank vault that is separate from the structure?

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[mytchell]

It is for a secure data center, so in some ways similar to a bank vault. It will have a single doorway and shares two walls with the stick frame portion of the building. I would sure be nice to find separate base shears for each part of the building, but I'm not sure if I can justify that or not. As it is now including the whole structure's seismic weight, the base shear is quite large, which is okay for the concrete portion, but a pain to design the diaphragm/shear walls for on the wood portion.

EIT

 

[mytchell]

Can I separate the base shear like that? Or is there some type of ductile connection that would allow me to justify that?

EIT

 

[msquared48]

If it is a structure within a structure and separate laterally, sure you can separate them.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[Backcheckrage]

If you can justify that the concrete box is significantly stiffer laterally than the lateral systems around it, its mass will not want to be redistributed... so its supporting the rest of the building, not the other way round.

So you have to be comfortable with its relative stiffness if you don't want to redistribute its mass to timber walls....