Concrete Shear Walls with Irregular Geometries

[abusementpark]

Hi guys,

I am looking for some information on concrete shear walls with irregular geometries and how they behave. Does anyone here have direct experience with this or can point me in the direction of some literature on the topic?

I have attached a file with a sketch of the basic type of irregularity I am referring to. I understand some interesting things can happen with the foundation when this occurs. Thanks.

 

[Vinny7]

Looking at your sketch I would design the top section as normal and then design the lower section as a cantilever with the hoiizontal reaction at the top of this section from the wall over. I think the vertical tension and compression could forces for foundation design could be checked assuming the longer wall was full height but reducing the dead load as I would assume the load would transfer/spread through the longer wall.

 

[slickdeals]

You will have to do some careful detailing to transfer the tension from the top wall to the bottom wall. I would suggest extending the top wall core reinforcement down to the foundation unless this happens at a much higher elevation.

 

[csd72]

It should be designed as a deep beam.

 

[abusementpark]

I am not particularly interested in the design of the concrete, but more or less how to properly model the reaction at the foundation. I am curious if anyone knows if this has been investigated before.

 

[csd72]

This is simple statics. The reaction would be the same as a square shear wall except for the missing weight of concrete on one side.

 

[Vinny7]

Your foundation will have the vertical loading and a horizonal loat at its top. This can then be designed like a moment resisting pad foundation but you woll have to watch the uplift force on foundation at the tension side of the wall

 

[abusementpark]

Seems to me like it would not be that simple. I would think since the shorter wall is the much stiffer element, then more load would be attracted to that portion of the foundation.

 

[slickdeals]

When you say Load will be attracted to that portion, what load are you talking about?

 

[abusementpark]

The lateral load.

 

[slickdeals]

When you say lateral load do you mean shear or moment?

 

[abusementpark]

Both.

 

[Lion06]

is there a diaphragm at both "levels" or just one? If it is just one, which one is it?

 

[drile007]

Why don't you model the wall with simple FEM program?

 

[slickdeals]

For shear I dont think there will be any difference. However, for moment the centre of mass of the wall group is not the same as the centre of mass of the individual walls. Hence you will have a non-symmetrical moment distribution about the centre of mass of the lower wall. Any FEM program will give you this behavior.

 

[abusementpark]

StructuralEIT, there would be a diaphragm at both levels.

drile007 and slickdeals, I know that running a FEM would answer all the questions for a specific loading. I just thought that this situation would have been a common enough occurrence for someone to at least have put something on paper discussing this issue, especially the general foundation requirements.

 

[abusementpark]

One more thing,

Thanks a lot for the responses!!