Reinforced Concrete Shearwall 1

[otto_eng]

Hi folks,

I have a rather seemingly complex but relatively easy question for the experienced structural engineers. I am designing 6 box shaped 6 storey buildings. The buldings are fully connected in between floors and also at the foundation level(raft /pile foundation). The buildings have timber floor framing (glulam beams / CLT floor diaphragm) and concrete walls along the sides of each building and concrete cores.
In this case because the reinforced concrete walls along the sides of each building are long enough , I am not even bothering to transfer the shear to these corewalls. because also some of these core walls are sitting on concrete beams.. Just wanted to give a bit of information before my question..
As I mentioned , I am using these walls at the sides of each building as shear walls, some portion of these walls are sitting on rectangular concrete beams at the ground level, and the other portion goes all the way down. Because there is a big trapezoidal compression force occurs on these rectangular concrete beams as a result of wind pressure, I am only considering the partial length of these concrete walls as a shearwall and the rest I do not consider as part of my shear wall even though it will be poured together in practice..I was thinking of using the reinforcement calculation based on this partial length calculation and not consider the other length so also no compression applied on the concrete beams at the ground level as well.
Do you think that this apporach is alid in practice ? In my opinion, and in theory it seems to me valid enough.
Looking forward to hear your feedbacks and maybe suggestions ..
Cheers!

 

[BAretired]

You have an excess of shear walls to resist lateral forces; seems a nice problem to have. For convenience in calculation, you are going to ignore some walls which you recognize will have stiffness, hence will carry some of the wind shear. Just be careful that the shear they do carry will not result in excessive cracking or other service conditions in unexpected places. If the lateral forces are seismic, you should probably reinforce the assumed non-participating walls as if they are participating.

 

[KootK]

I don't necessarily disagree with the strategy but it is always worth remembering that structures don't have ears. They're shitty listeners and telling them how to respond is often a fool's errand. Places that might get you into trouble:

1) The end walls won't fully engage until your diaphragm moves through the core walls or over turns them.

2) Parts of shear walls designated to not participate will participate until something yields, breaks, or softens via cracking. You want to control that hierarchy of damage.

3) For a high ductility seismic design, ignoring available capacity means underestimating seismic load, perhaps massively.

 

[otto_eng]

@KootK
I also do not necessarily disagree with your comment however as I mentioned in my post it is an assumption, and maybe giving additional information about the way I am trying to solve this problem would give more insight to you.
First of all the building is not in a seismic zone so the only active lateral force is wind and for that reason I am assuming to resolve all this lateral at the end of the floor diaphragm which are starting right at the beginning of the facade where the wind is introduced. If the building was in a seismic zone I would not even consider this apporach at all.
I would be curious to hear your opinion to see if you still think in the same way..