Coupled shear wall with pt flat plate design
Coupled shear wall with pt flat plate design
(OP)
I am wondering what others thoughts are on 30+ story coupled shear wall building systems and their design. Typically, we design these in ETABS using shell elements for the flat plates and shear walls. We have found that due to the stiffness of the floor plates, they can greatly impact the building dynamic properties and force distribtuions. Typically, I have designed these types of buildings with two models, one for collecting lateral loads on the shear walls and one for gravity loads, and then post-processing this data for the shear wall design.
Typically, I find one of the most highly stressed elements are the coupling beams. As such, they are always one of the first items I look at, to make sure they are sufficiently sized for shear and moment, before the architect sticks us with an undersized link.
I have been reviewing a job that falls into this category, but there are no coupling beams. When you run the ETABS anaysis with the 8" slabs moedeled as shell elements building drifts and all seem to be fine, and the wall designs will be fine as well. But when I run the system ignoring the slab stiffness, the drifts shoot up. If I look at the stresses in the slab, they are well beyond allowable code limits.
How do others handle this in ETABS? Personally, for a building of this size, I am inclined to design the shear walls and coupling beams for the full lateral demand, and ignore whatever contribution the slab may have. Then once the lateral system is sized, design the for plate for gravity loads, and whatever lateral forces it may see due to compatability. Any thoughts?
Typically, I find one of the most highly stressed elements are the coupling beams. As such, they are always one of the first items I look at, to make sure they are sufficiently sized for shear and moment, before the architect sticks us with an undersized link.
I have been reviewing a job that falls into this category, but there are no coupling beams. When you run the ETABS anaysis with the 8" slabs moedeled as shell elements building drifts and all seem to be fine, and the wall designs will be fine as well. But when I run the system ignoring the slab stiffness, the drifts shoot up. If I look at the stresses in the slab, they are well beyond allowable code limits.
How do others handle this in ETABS? Personally, for a building of this size, I am inclined to design the shear walls and coupling beams for the full lateral demand, and ignore whatever contribution the slab may have. Then once the lateral system is sized, design the for plate for gravity loads, and whatever lateral forces it may see due to compatability. Any thoughts?






RE: Coupled shear wall with pt flat plate design
RE: Coupled shear wall with pt flat plate design
Perhaps if you reduced the height of the shear walls, say by six or eight stories and allow the lateral forces in that region to be carried by frame action, the stresses in the slab would be more acceptable.
Another possibility is to tie the shear walls to remote columns at roof level using very deep beams. This has the effect of reducing the rotation of the shear wall at the roof. The problem is, the architect may not like it.
RE: Coupled shear wall with pt flat plate design
However it seems to me difficult with such number of stories plates only 8 inches thick may meet their own demand in collaboration with to the lateral stiffness; hence some proper solution must be found, of which some have been named above.
RE: Coupled shear wall with pt flat plate design
RE: Coupled shear wall with pt flat plate design
i have then designed slabs by SAFE for gravity loading by exporting it from ETABS model.
RE: Coupled shear wall with pt flat plate design
It concludes that concrete shear wall/frame buildings are usually a lot stiffer than analysis predicts. Her research states that anywhere between 25-50% of slab is effective in trasmitting lateral forces.